2 slide.Sel- a rapid, stormy mud or mud-stone flow, consisting of a mixture of water, sand, clay and rock fragments, suddenly appearing in the basins of small mountain rivers. The reason for its occurrence is intense and prolonged downpours, rapid melting of snow or glaciers, breakthrough of reservoirs, less often - earthquakes, volcanic eruptions.
3 slide. Having a large mass and high speed of movement (up to 40 km/h), mudflows destroy buildings, roads, power lines, and lead to the death of people and animals. The steep leading front of a mudflow wave with a height of 5 to 15 m forms the “head” of a mudflow (the maximum height of the water-mud flow shaft can reach 25 m), the length of mudflow channels ranges from several tens of meters to several tens of kilometers.
Mudflows are especially active in the North Caucasus. Due to the negative role of the anthropogenic factor (destruction of vegetation, quarrying, etc.), mudflows began to develop on the Black Sea coast of the North Caucasus (Novorossiysk region, Dzhubga - Tuapse - Sochi section).
4 slide. Protective measures:
Strengthening mountain slopes (planting forests);
Anti-mudflow dams, dikes, ditches;
Periodic release of water from mountain reservoirs;
Construction of protective walls along river beds;
Reducing the rate of snow melting in the mountains by creating smoke screens.
Catching mudflows in special pits located in river beds.
Effective warning and warning system.
5 slide.Collapse- this is a rapid separation (separation) and fall of a mass of rocks (earth, sand, clay stones) on a steep slope due to loss of slope stability, weakening of cohesion, and integrity of rocks.
A collapse occurs under the influence of weathering processes, movement of ground and surface water, erosion or dissolution of rock, and soil vibrations. Most often, collapses occur during rainy periods, snow melting, and during blasting and construction work.
6 slide. The damaging factors of a collapse are the fall of heavy masses of rocks that can damage or crush even strong structures or cover them with soil, blocking access to them. Another danger of landslides is the possible damming of rivers and collapse of the banks of lakes, the waters of which, in the event of a breakthrough, can cause floods or mudflows.
Signs of a possible collapse are numerous cracks in steep rocks, overhanging blocks, the appearance of individual rock fragments, blocks separating from the main rock.
Slide 7Landslide- sliding displacement of rock masses down the slope under the influence of gravity; occurs, as a rule, as a result of erosion of the slope, waterlogging, seismic tremors and other factors.
8 slide. The following factors can be the causes of landslides.
1. Natural:
Earthquakes;
Overmoistening of slopes with precipitation;
Increase in slope steepness as a result of erosion by water;
Weakening of the strength of hard rocks due to weathering, washing out or leaching
The presence of softened clays, quicksand, and fossil ice in the soil:
Slide 9. Anthropogenic:
Deforestation and bushes on slopes. Moreover, deforestation can occur much higher than the site of a future landslide, but water will not be retained by the plants above, as a result of which the soils become waterlogged far below;
Blasting, which is essentially a local earthquake and contributes to the development of cracks in rocks;
Plowing slopes, excessive watering of gardens and vegetable gardens on slopes;
Destruction of slopes by pits, trenches, road cuts,
Clogging, clogging, blocking of groundwater outlets;
Construction of housing and industrial facilities on slopes, which leads to destruction of the slopes and an increase in the force of gravity directed down the slope.
10 slide. The damaging factor of landslides is heavy masses of soil that fall asleep or destroy everything in its path. Therefore, the main indicator of a landslide is its volume, measured in cubic meters.
Unlike landslides, landslides develop much more slowly, and there are many signs that allow timely detection of an incipient landslide.
11 slide. Signs of an incipient landslide:
· gaps and cracks in the ground, on roads;
· disruption and destruction of underground and surface communications;
· displacement, deviation from the vertical of trees, poles, supports, uneven tension or breakage of wires;
· curvature of the walls of buildings and structures, the appearance of cracks on them;
· change in water level in wells, boreholes, and any reservoirs.
Landslide prevention measures include: monitoring the condition of slopes; analysis and forecasting of the possibility of landslides; carrying out complex engineering protective works; training of persons living, working and resting in a hazardous area on life safety rules.
12 slide.Snow avalanchesarise as a result of the accumulation of snow on mountain peaks during heavy snowfalls, strong snowstorms and a sharp drop in air temperature. Avalanches can also occur when deep frost forms, when a loose layer (quicksand snow) appears in the thickness of the snow.
Slide 13 Most avalanches descend along certain chutes - narrow hollows on steep mountain slopes. 200–300, and sometimes up to 500 thousand tons of snow can fall down these hollows at the same time.
Avalanches often occur suddenly and begin their initial movement silently. When avalanches move in narrow mountain gorges, an air wave of increasing strength moves ahead of them, causing even greater destruction in comparison with the falling mass of snow. Repeated avalanches leave deep traces in the mountain landscape. Avalanches often fall into river beds and block them, forming dams for a long time.
14 slide. Avalanche danger is caused by sudden changes in weather, heavy snowfalls, heavy snowstorms, and rain. To prevent avalanche danger, there is a special mountain avalanche service.
Catastrophic avalanches in the world occur on average at least once every two years, and in some mountainous areas - at least once every 10–12 years.
The general condition for the occurrence of these dangerous natural phenomena is: The beginning of the displacement of soil, rock or snow down the slope. The beginning of the movement of soil, rock or snow down a slope. Territories of our country where landslides, mudflows, avalanches, and avalanches often occur: the North Caucasus, the Urals, the Sayan Mountains, Primorye, Kamchatka, Sakhalin. Northern Caucasus, Urals, Sayan Mountains, Primorye, Kamchatka, Sakhalin.
Causes of landslides. Natural factors. Anthropogenic factors. (related to human activities). Earthquakes. Laying roads. Waterlogging of the soil (rains, floods). Water is the “lubricant” between rock layers. Deforestation and bushes. Blasting near landslide areas. Uncontrolled plowing and watering of land on a slope.
Mudflows form in the mountains. Causes of mudflows. Natural factors. Anthropogenic factors. (related to human activities). Earthquakes. Laying roads. (incorrect) Volcanic eruption. (water and ash) Deforestation and bushes. Natural destruction of mountains. Blasting near landslide areas.
An avalanche is a rapid, sudden movement of snow and (or) ice down steep mountain slopes, posing a threat to human life and activity. They appear in the mountains. An avalanche is accompanied by the formation of an air pre-shock wave, which produces the greatest destruction.
Factors influencing the occurrence of avalanches: A lot of snow A lot of snow A slope whose slope angle exceeds 14 degrees (if the slope angle is 30 - 40 degrees, then an avalanche is inevitable). A slope whose inclination angle exceeds 14 degrees (if the slope angle is 30 - 40 degrees, then an avalanche is inevitable). The presence of an open slope 100 - 500 meters long. The presence of an open slope 100 - 500 meters long.
“Even in the last century, in the Alps, people covered in snow were helped to find large, strong St. Bernard dogs, named after the high-mountain monastery of St. Bernard, where they were bred. Near Paris, in a special dog cemetery, there is a monument to St. Bernard Barry, who saved 40 people. These good-natured large dogs found more than 2,000 people in the mountains. Now the St. Bernards have been replaced by East European Shepherds.”
Characteristics, causes, countermeasures, security measures"
Introduction1. Landslides
2. Sat down
3. Landfalls
5. Rules of behavior for people in the event of mudflows, landslides and collapses
Introduction
Natural disasters have threatened the inhabitants of our planet since the beginning of civilization. Somewhere more, somewhere less. One hundred percent security does not exist anywhere. Natural disasters can cause colossal damage, the amount of which depends not only on the intensity of the disasters themselves, but also on the level of development of society and its political structure.
Natural disasters typically include earthquakes, floods, mudslides, landslides, snow drifts, volcanic eruptions, landslides, droughts, hurricanes and storms. In some cases, such disasters can also include fires, especially massive forest and peat fires.
Are we really so defenseless against earthquakes, tropical cyclones, and volcanic eruptions? Why can’t advanced technology prevent these disasters, or if not prevent them, then at least predict and warn about them? After all, this would significantly limit the number of victims and the extent of damage! We are not nearly so helpless. We can predict some disasters, and we can successfully resist some. However, any actions against natural processes require good knowledge of them. It is necessary to know how they arise, the mechanism, conditions of propagation and all other phenomena associated with these disasters. It is necessary to know how displacements of the earth's surface occur, why rapid rotational movement of air occurs in a cyclone, how quickly masses of rocks can collapse down a slope. Many phenomena still remain a mystery, but, it seems, only over the next few years or decades.
In the broadest sense of the word, an emergency situation (ES) is understood as a situation in a certain territory that has arisen as a result of an accident, a dangerous natural phenomenon, a catastrophe, a natural or other disaster that may result or has resulted in human casualties, caused damage to human health or the surrounding natural environment. environment, significant material losses and disruption of people's living conditions. Each emergency situation has its own physical essence, causes of occurrence and nature of development, as well as its own characteristics of impact on humans and their environment.
1. Landslides
Mudflow, flow, collapse, landslide
Landslides- This is the displacement of rock masses down a slope under the influence of gravity. They are formed in various rocks as a result of disruption of their balance and weakening of their strength and are caused by both natural and artificial causes. Natural causes include an increase in the steepness of slopes, erosion of their bases by sea and river waters, seismic tremors, etc. Artificial, or anthropogenic, i.e. caused by human activity, the causes of landslides are the destruction of slopes by road excavations, excessive removal of soil, deforestation, etc.
Landslides can be classified according to the type and condition of the material. Some are composed entirely of rock material, others are composed only of soil layer material, and others are a mixture of ice, rock and clay. Snow landslides are called avalanches. For example, a landslide mass consists of rock material; stone material is granite, sandstone; it can be strong or fractured, fresh or weathered, etc. On the other hand, if the landslide mass is formed by fragments of rocks and minerals, that is, as they say, the material of the soil layer, then we can call it a landslide of the soil layer. It may consist of a very fine granular mass, that is, clay, or a coarser material: sand, gravel, etc.; this entire mass can be dry or water-saturated, homogeneous or layered. Landslides can be classified according to other criteria: the speed of movement of the landslide mass, the scale of the phenomenon, activity, power of the landslide process, place of formation, etc.
From the point of view of the impact on people and on construction work, the speed of development and movement of a landslide is its only important feature. It is difficult to find ways to protect against the rapid and usually unexpected movement of large masses of rock, and this often causes harm to people and their property. If a landslide moves very slowly over months or years, it rarely causes accidents and preventive measures can be taken. In addition, the speed of development of a phenomenon usually determines the ability to predict this development; for example, it is possible to detect harbingers of a future landslide in the form of cracks that appear and expand over time. But on particularly unstable slopes, these first cracks can form so quickly or in such inaccessible places that they are not noticed, and a sharp displacement of a large mass of rock occurs suddenly. In the case of slowly developing movements of the earth's surface, it is possible to notice a change in the features of the relief and the distortion of buildings and engineering structures even before a major movement. In this case, it is possible to evacuate the population without waiting for destruction. However, even when the speed of the landslide does not increase, this phenomenon on a large scale can create a difficult and sometimes insoluble problem
Another process that sometimes causes rapid movement of surface rocks is the erosion of the base of the slope by sea waves or a river. It is convenient to classify landslides according to the speed of movement. In its most general form, rapid landslides or collapses occur within seconds or minutes; landslides develop at an average rate over a period of time measured in minutes or hours; Slow landslides form and move over a period of days to years.
By scale Landslides are divided into large, medium and small scale. Large landslides are usually caused by natural causes. Large landslides are usually caused by natural causes and occur along slopes for hundreds of meters. Their thickness reaches 10-20 m or more. The landslide body often retains its solidity. Medium and small-scale landslides are characteristic of anthropogenic processes.
Landslides may occur active and inactive, which is determined by the degree of capture of bedrock slopes and the speed of movement.
The activity of landslides is influenced by the rocks of the slopes, as well as the presence of moisture in them. Depending on the quantitative indicators of the presence of water, landslides are divided into dry, slightly wet, wet and very wet.
By place of education landslides are divided into mountain, underwater, snow and landslides that occur in connection with the construction of artificial earthen structures (pits, canals, rock dumps, etc.).
By power landslides can be small, medium, large and very large and are characterized by the volume of displaced rocks, which can range from several hundred cubic meters to 1 million m3 or more.
Landslides can destroy populated areas, destroy agricultural land, create danger during the operation of quarries and mining, damage communications, tunnels, pipelines, telephone and electrical networks, and water management structures, mainly dams. In addition, they can block the valley, form a dam lake and contribute to flooding. Thus, the economic damage they cause can be significant.
2. Sat down
In hydrology, a mudflow is understood as a flood with a very high concentration of mineral particles, stones and rock fragments, occurring in the basins of small mountain rivers and dry ravines and usually caused by rainfall or rapid snow melting. Sel is something between a liquid and a solid mass. This phenomenon is short-term (usually it lasts 1-3 hours), characteristic of small watercourses up to 25-30 km long and with a catchment area of up to 50-100 km2.
The mudflow is a formidable force. The stream, consisting of a mixture of water, mud and stones, rapidly rushes down the river, uprooting trees, tearing down bridges, destroying dams, stripping the slopes of the valley, and destroying crops. Being close to a mudflow, you can feel the shaking of the earth under the impact of stones and blocks, the smell of sulfur dioxide from the friction of stones against each other, and hear a strong noise similar to the roar of a rock crusher.
The danger of mudflows lies not only in their destructive power, but also in the suddenness of their appearance. After all, rainfall in the mountains often does not cover the foothills, and mudflows appear unexpectedly in inhabited areas. Due to the high speed of the current, the time from the moment a mudflow occurs in the mountains to the moment it reaches the foothills is sometimes calculated in 20-30 minutes.
The main reason for the destruction of rocks is sharp intraday fluctuations in air temperature. This leads to the formation of numerous cracks in the rock and its fragmentation. The described process is facilitated by periodic freezing and thawing of water filling the cracks. Frozen water, expanding in volume, presses on the walls of the crack with enormous force. In addition, rocks are destroyed due to chemical weathering (dissolution and oxidation of mineral particles by subsoil and groundwater), as well as due to organic weathering under the influence of micro- and macroorganisms. In most cases, the cause of mudflows is rainfall, less often intensive snow melting, as well as outbursts of moraine and dam lakes, landslides, landslides, and earthquakes.
In general terms, the process of formation of a mudflow of storm origin proceeds as follows. Initially, water fills the pores and cracks, simultaneously rushing down the slope. In this case, the adhesion forces between particles sharply weaken, and the loose rock comes into a state of unstable equilibrium. Then the water begins to flow over the surface. Small particles of soil are the first to move, then pebbles and crushed stone, and finally stones and boulders. The process is growing like an avalanche. All this mass enters the ravine or channel and draws new masses of loose rock into movement. If the water flow is insufficient, then the mudflow seems to fizzle out. Small particles and small stones are carried down by the water, while large stones create a blind area in the riverbed. The stopping of a mudflow can also occur as a result of attenuation of the flow velocity as the river slope decreases. There is no specific recurrence of mudflows observed. It has been noted that the formation of mud and mud-stone flows is facilitated by the previous long-dry weather. At the same time, masses of fine clay and sand particles accumulate on mountain slopes. They are washed away by the rain. On the contrary, the formation of water-stone flows is favored by previous rainy weather. After all, the solid material for these flows is mainly found at the base of steep slopes and in the beds of rivers and streams. In the case of good previous moisture, the bond of stones with each other and with the bedrock weakens.
Shower mudflows are sporadic. Over the course of a number of years, dozens of significant floods can occur, and only then in a very rainy year a mudflow occurs. It happens that mudflows are observed quite often on the river. After all, in any relatively large mudflow basin there are many mudflow centers, and downpours cover first one or another center.
Many mountainous regions are characterized by the predominance of one or another type of mudflow in terms of the composition of the transported solid mass. Thus, in the Carpathians, water-rock mudflows of relatively small thickness are most often encountered. In the North Caucasus there are mainly mud-stone streams. Mud streams, as a rule, descend from the mountain ranges surrounding the Fergana Valley in Central Asia.
It is significant that the mudflow, unlike a water flow, does not move continuously, but in separate shafts, sometimes almost stopping, then again accelerating its movement. This occurs due to the delay of the mudflow mass in the narrowing of the channel, at sharp turns, and in places where the slope sharply decreases. The tendency of a mudflow to move in successive shafts is associated not only with congestion, but also with the non-simultaneous supply of water and loose material from various sources, with the collapse of rock from slopes and, finally, with the jamming of large boulders and rock fragments in constrictions. It is when jams break through that the most significant deformations of the riverbed occur. Sometimes the main channel becomes unrecognizable or is completely submerged, and a new channel is developed.
3. Landfalls
Collapse- rapid movement of masses of rocks, forming predominantly steep slopes of valleys. When falling, the mass of rocks detached from the slope is broken into separate blocks, which, in turn, breaking up into smaller parts, cover the bottom of the valley. If a river flowed through the valley, then the collapsed masses, forming a dam, give rise to a valley lake. Collapses of the slopes of river valleys are caused by river erosion, especially during floods. In high-mountain areas, the cause of landslides is usually the appearance of cracks, which, saturated with water (and especially when water freezes), increase in width and depth until the mass separated by the crack from some shock (earthquake) or after heavy rain or some other - for any other reason, sometimes artificial (for example, a railway excavation or a quarry at the foot of a slope), will not overcome the resistance of the rocks holding it and will not collapse into the valley. The magnitude of the collapse varies widely, ranging from the collapse of small rock fragments from the slopes, which, accumulating on flatter sections of the slopes, form the so-called. scree, and until the collapse of huge masses, measured in millions of m3, representing enormous disasters in cultural countries. At the foot of all the steep slopes of the mountains you can always see stones that have fallen from above, and in areas that are especially favorable for their accumulation, these stones sometimes completely cover significant areas.
When designing a railway route in the mountains, it is necessary to especially carefully identify areas that are vulnerable to landslides, and, if possible, bypass them. When laying quarries in the slopes and carrying out excavations, you should always inspect the entire slope, studying the nature and bedding of rocks, the direction of cracks, and sections, so that quarry development does not violate the stability of the overlying rocks. When constructing roads, especially steep slopes are laid with pieced stones dry or on cement.
In high mountain areas, above the snow line, snow avalanches often have to be reckoned with. They occur on steep slopes, from where accumulated and often compacted snow periodically rolls down. In areas of snow landslides, settlements should not be built, roads should be protected with covered galleries, and forest plantations should be planted on the slopes, which best keep the snow from sliding. Landslides are characterized by the power of the landslide and the scale of manifestation. According to the power of the landslide process, landslides are divided into large and small. According to the scale of manifestation, landslides are divided into huge, medium, small and small.
A completely different type of collapse occurs in areas of rocks that are easily leached by water (limestones, dolomites, gypsum, rock salt). Water seeping from the surface very often leaches large voids (caves) in these rocks, and if such a cave is formed near the earth's surface, then upon reaching a large volume, the ceiling of the cave collapses, and a depression (funnel, failure) is formed on the surface of the earth; sometimes these depressions are filled with water, and the so-called. "failed lakes" Similar phenomena are typical for many areas where the corresponding breeds are common. In these areas, when constructing permanent structures (buildings and railways), it is necessary to conduct a soil study at the site of each building in order to avoid destruction of the constructed buildings. Ignoring such phenomena subsequently causes the need for constant repair of the track, which entails high costs. In these areas, it is more difficult to resolve issues of water supply, search and calculation of water reserves, as well as the production of hydraulic structures. The direction of underground water flows is extremely whimsical; the construction of dams and the excavation of ditches in such places can cause the occurrence of leaching processes in rocks previously protected by artificially removed rocks. Sinkholes are also observed within quarries and mines, due to the collapse of the roof of rocks above mined-out spaces. To prevent the destruction of buildings, it is necessary to fill the mined-out space under them, or leave the pillars of the mined rocks untouched.
4. Ways to combat landslides, mudflows and landslides
Active measures to prevent landslides, mudflows, and landslides include the construction of engineering and hydraulic structures. To prevent landslide processes, retaining walls, counter-banquets, pile rows and other structures are constructed. The most effective anti-landslide structures are counter-banquets. They are located at the base of a potential landslide and, by creating a stop, prevent the soil from moving.
Active measures also include fairly simple ones that do not require significant resources or consumption of building materials for their implementation, namely:
- to reduce the stressed state of slopes, land masses are often cut off in the upper part and laid at the foot;
-groundwater above a possible landslide is drained by installing a drainage system;
-protection of river and sea banks is achieved by importing sand and pebbles, and slopes by sowing grass, planting trees and shrubs.
Hydraulic structures are also used to protect against mudflows. Based on the nature of their impact on mudflows, these structures are divided into mudflow control, mudflow dividing, mudflow retention and mudflow transforming structures. The mudflow control hydraulic structures include mudflow passages (chutes, mudflow diversions, mudflow diversions), mudflow control devices (dams, retaining walls, rims), mudflow release devices (dams, thresholds, drops) and mudflow control devices (half-dams, spurs, booms) constructed in front of dams, rims and retaining structures. walls.
Cable mudflow cutters, mudflow barriers and mudflow dams are used as mudflow dividers. They are installed to retain large fragments of material and allow small parts of the debris flow to pass through. Mudflow-retaining hydraulic structures include dams and pits. Dams can be blind or with holes. Blind-type structures are used to retain all types of mountain runoff, and with holes - to retain the solid mass of mudflows and allow water to pass through. Mudflow-transforming hydraulic structures (reservoirs) are used to transform a mudflow into a flood by replenishing it with water from reservoirs. It is more effective not to delay mudflows, but to direct them past populated areas and structures using mudflow diversion channels, mudflow diversion bridges and mudflow drains. In landslide-prone areas, measures can be taken to move individual sections of roads, power lines and objects to a safe place, as well as active measures to install engineering structures - guide walls designed to change the direction of movement of collapsed rocks. Along with preventive and protective measures, an important role in preventing the occurrence of these natural disasters and in reducing damage from them is played by monitoring landslide, mudflow and landslide-prone areas, harbingers of these phenomena and predicting the occurrence of landslides, mudflows and landslides. Observation and forecasting systems are organized on the basis of hydrometeorological service institutions and are based on thorough engineering-geological and engineering-hydrological studies. Observations are carried out by specialized landslide and mudflow stations, mudflow batches and posts. The objects of observation are soil movements and landslide movements, changes in water levels in wells, drainage structures, boreholes, rivers and reservoirs, groundwater regimes. The obtained data characterizing the preconditions for landslide movements, mudflows and landslide phenomena are processed and presented in the form of long-term (years), short-term (months, weeks) and emergency (hours, minutes) forecasts.
5. Rules of behavior for people in the event of mudflows, landslides and collapses
The population living in hazardous areas must know the sources, possible directions and characteristics of these dangerous phenomena. Based on forecasts, residents are informed in advance about the danger of landslides, mudflows, landslides and possible zones of their action, as well as the procedure for submitting danger signals. This reduces the stress and panic that can arise when communicating emergency information about an immediate threat.
The population of dangerous mountainous areas is obliged to take care of strengthening houses and the territory on which they are built, and to participate in the construction of protective hydraulic and other engineering structures.
Primary information about the threat of landslides, mudflows and avalanches comes from landslide and mudflow stations, parties and hydrometeorological service posts. It is important that this information is communicated to its destination in a timely manner. Warning of the population about natural disasters is carried out in the established order by means of sirens, radio, television, as well as local warning systems that directly connect the units of the hydrometeorological service, the Ministry of Emergency Situations with settlements located in dangerous zones. If there is a threat of a landslide, mudflow or landslide, early evacuation of the population, farm animals and property to safe places is organized. Houses or apartments abandoned by residents are brought into a state that helps reduce the consequences of a natural disaster "and the possible impact of secondary factors, facilitating their subsequent excavation and restoration. Therefore, the transferred property from the yard or balcony must be removed into the house; the most valuable things that cannot be taken with you must be covered from exposure to moisture and dirt. Close doors, windows, ventilation and other openings tightly. Turn off electricity, gas, water supply. Remove flammable and toxic substances from the house and place them in remote pits or separate cellars. Otherwise, proceed in accordance with the procedure , established for organized evacuation.
If there was no advance warning of the danger and residents were warned about the threat immediately before the onset of a natural disaster or noticed its approach themselves, everyone, without worrying about property, makes an emergency exit to a safe place on their own. At the same time, relatives, neighbors, and all people encountered along the way should be warned about the danger.
For an emergency exit, you need to know the routes to the nearest safe places. These paths are determined and communicated to the population based on the forecast of the most likely directions of arrival of a landslide (mudflow) to a given settlement (object). Natural safe routes for emergency exit from the danger zone are the slopes of mountains and hills, which are not prone to landslides.
When climbing to safe slopes, valleys, gorges and recesses should not be used, as side channels of the main mudflow may form in them. On the way, assistance should be provided to the sick, elderly, disabled, children and the weak. For transportation, whenever possible, personal transport, mobile agricultural machinery, riding and pack animals are used.
In the event that people and structures find themselves on the surface of a moving landslide area, they should move upward if possible and beware of rolling blocks, stones, debris, structures, earthen ramparts, and screes. When the speed of a landslide is high, a strong shock is possible when it stops, and this poses a great danger to people in the landslide. After the end of a landslide, mudflow or collapse, people who had previously hastily left the disaster zone and waited out the danger in the nearest safe place, making sure that there is no repeated threat, should return to this area to search for and provide assistance to the victims.
NATURE OF APPEARANCE AND CLASSIFICATION
Landslides, landslides, mudflows, snow avalanches
The most typical natural disasters for some geographical regions of the Russian Federation include landslides, landslides, mudflows and avalanches. They can destroy buildings and structures, cause death, destroy material assets, and disrupt production processes.
COLLAPSE.
A landslide is the rapid separation of a mass of rock on a steep slope with an angle greater than the angle of repose, which occurs as a result of loss of stability of the slope surface under the influence of various factors (weathering, erosion and abrasion at the base of the slope, etc.).
Landslides refer to the gravitational movement of rocks without the participation of water, although water contributes to their occurrence, since landslides more often appear during periods of rain, melting snow, and spring thaws. Landslides can be caused by blasting operations, filling mountain river valleys with water during the creation of reservoirs and other human activities.
Landslides often occur on slopes disturbed by tectonic processes and weathering. As a rule, landslides occur when layers on the slope of a massif with a layered structure fall in the same direction as the surface of the slope, or when the high slopes of mountain gorges and canyons are broken into separate blocks by vertical and horizontal cracks.
One of the types of landslides is avalanches - the collapse of individual blocks and stones from rocky soils that make up steep slopes and slopes of excavations.
Tectonic fragmentation of rocks contributes to the formation of separate blocks, which are separated from the root mass under the influence of weathering and roll down the slope, breaking into smaller blocks. The size of the detached blocks is related to the strength of the rocks. The largest blocks (up to 15 m in diameter) are formed in basalts. In granites, gneisses, and strong sandstones, smaller blocks are formed, up to a maximum of 3-5 m, in siltstones - up to 1-1.5 m. In shale rocks, collapses are observed much less frequently and the size of the blocks does not exceed 0.5-1 m .
The main characteristic of a landslide is the volume of collapsed rocks; Based on volume, landslides are conventionally divided into very small (volume less than 5 m3), small (5-50 m3), medium (50-1000 m3) and large (more than 1000 m3).
In the whole country, very small collapses account for 65-70%, small - 15-20%, medium - 10-15%, large - less than 5% of the total number of collapses. In natural conditions, gigantic catastrophic collapses are also observed, as a result of which millions and billions of cubic meters of rock collapse; the probability of such collapses occurring is approximately 0.05%.
LANDSLADES.
A landslide is a sliding movement of rock masses down a slope under the influence of gravity.
Natural factors that directly influence the formation of landslides are earthquakes, waterlogging of mountain slopes due to intense precipitation or groundwater, river erosion, abrasion, etc.
Anthropogenic factors (associated with human activity) are cutting of slopes when laying roads, cutting down forests and shrubs on slopes, blasting and mining operations near landslide areas, uncontrolled plowing and watering of land on slopes, etc.
According to the power of the landslide process, i.e. the involvement of rock masses in the movement, landslides are divided into small - up to 10 thousand m3, medium - 10-100 thousand m3, large - 100-1000 thousand m3, very large - over 1000 thousand m3.
Landslides can occur on all slopes, starting from a steepness of 19°, and on cracked clay soils - at a slope steepness of 5-7°.
SAT down.
A mudflow (mudflow) is a temporary mud-stone flow, saturated with solid material ranging in size from clay particles to large stones (bulk mass, usually from 1.2 to 1.8 t/m3), which pours from the mountains onto the plains.
Mudflows occur in dry valleys, ravines, ravines or along mountain river valleys that have significant slopes in the upper reaches; they are characterized by a sharp rise in level, wave movement of the flow, short duration of action (on average from one to three hours) and, accordingly, a significant destructive effect.
The immediate causes of mudflows are heavy rains, intensive melting of snow and ice, breakthrough of reservoirs, moraine and dam lakes; less often - earthquakes and volcanic eruptions.
The mechanisms of debris flow generation can be reduced to three main types: erosion, breakthrough, landslide.
With the erosion mechanism, the water flow is first saturated with debris due to the washout and erosion of the surface of the mudflow basin, and then the formation of a mudflow wave in the channel; The saturation of the mudflow here is closer to the minimum, and the movement of the flow is controlled by the channel.
With the breakthrough mechanism of mudflow generation, the water wave turns into a mudflow due to intense erosion and the involvement of debris masses in the movement; the saturation of such a flow is high, but variable, turbulence is maximum, and, as a consequence, the processing of the channel is the most significant.
During the landslide initiation of a mudflow, when a massif of water-saturated rocks (including snow and ice) is torn off, the flow saturation and the mudflow wave are formed simultaneously; The flow saturation in this case is close to maximum.
The formation and development of mudflows, as a rule, go through three stages of formation:
1 - gradual accumulation on the slopes and in the beds of mountain basins of material that serves as a source of mudflows;
2 - rapid movement of washed away or disequilibrium material from elevated areas of mountain catchment areas to lower areas along mountain beds;
3 - collection (accumulation) of mudflows in low areas of mountain valleys in the form of channel cones or other forms of sediments.
Each mudflow catchment consists of a mudflow formation zone, where water and solid materials are fed, a transit (movement) zone, and a mudflow deposit zone.
Mudflows occur when three natural conditions (phenomena) occur simultaneously: the presence of a sufficient (critical) amount of rock destruction products on the slopes of the basin; accumulation of a significant volume of water for flushing (carrying down) loose solid material from the slopes and its subsequent movement along the riverbed; steep slope slopes and watercourse.
The main reason for the destruction of rocks is sharp daily fluctuations in air temperature, which leads to the appearance of numerous cracks in the rock and its fragmentation. The process of rock crushing is also facilitated by the periodic freezing and thawing of water filling the cracks. In addition, rocks are destroyed due to chemical weathering (dissolution and oxidation of mineral particles by subsoil and groundwater), as well as due to organic weathering under the influence of microorganisms. In areas of glaciation, the main source of formation of solid material is the terminal moraine - a product of the activity of the glacier during its repeated advance and retreat. Earthquakes, volcanic eruptions, mountain falls and landslides also often serve as sources of accumulation of mudflow material.
Often the cause of the formation of mudflows is rainfall, which results in the formation of an amount of water sufficient to set in motion the products of rock destruction located on the slopes and in the channels. The main condition for the occurrence of such mudflows is the rate of precipitation, which can cause the washout of rock destruction products and their involvement in movement. The norms of such precipitation for the most typical (for mudflows) regions of Russia are given in Table. 1.
Table 1
Conditions for the formation of mudflows of rain origin
There are known cases of the formation of mudflows due to a sharp increase in the influx of groundwater (for example, a mudflow in the North Caucasus in the Bezengi River basin in 1936).
Each mountain region is characterized by certain statistics of the causes of mudflows. For example, for the Caucasus as a whole
The causes of mudflows are distributed as follows: rains and downpours - 85%, melting of eternal snow - 6%, discharge of melt water from moraine lakes - 5%, outbursts of dammed lakes - 4%. In the Trans-Ili Alatau, all observed large mudflows were caused by the outburst of moraine and dam lakes.
When mudflows occur, the steepness of the slopes (relief energy) is of great importance; The minimum slope of the mudflow is 10-15°, the maximum is up to 800-1000°.
In recent years, anthropogenic factors have been added to the natural causes of the formation of mudflows, i.e. those types of human activity in the mountains that cause (provoke) the formation of mudflows or their intensification; such factors, in particular, include unsystematic deforestation on mountain slopes, degradation of ground and soil cover by unregulated livestock grazing, improper placement of waste rock dumps by mining enterprises, rock explosions during the laying of railways and roads and the construction of various structures, neglect of land reclamation rules after stripping operations in quarries, overflow of reservoirs and unregulated discharge of water from irrigation structures on mountain slopes, changes in soil and vegetation cover due to increased air pollution from waste from industrial enterprises.
Based on the volume of one-time removals, mudflows are divided into 6 groups; their classification is given in table. 2.
table 2
Classification of mudflows by volume of one-time emissions
Based on the available data on the intensity of development of mudflow processes and the frequency of mudflows, 3 groups of mudflow basins are distinguished: high mudflow activity (recurrence
Mudflows once every 3-5 years and more often); average mudflow activity (once every 6-15 years and more often); low mudflow activity (once every 16 years or less).
Based on mudflow activity, the basins are characterized as follows: with frequent mudflows, when mudflows occur once every 10 years; with averages - once every 10-50 years; with rare ones - less than once every 50 years.
A special classification of mudflow basins is used according to the height of the sources of mudflows, which is given in Table. 3.
Table 3
Classification of mudflow basins according to the height of the sources of mudflows
According to the composition of the transported solid material mudflows are distinguished:
Mud flows are a mixture of water and fine earth with a small concentration of stones (volumetric weight of the flow is 1.5-2.0 t/m3);
- mud-stone flows- a mixture of water, fine earth, gravel pebbles, small stones; there are large stones, but there are not many of them, they either fall out of the flow, then move again with it (volumetric weight of the flow is 2.1-2.5 t/m3);
- water-stone streams- water with predominantly large stones, including boulders and rock fragments (volumetric flow weight 1.1-1.5 t/m3).
The territory of Russia is distinguished by a variety of conditions and forms of manifestation of mudflow activity. All mudflow-prone mountainous areas are divided into two zones - warm and cold; Within the zones, regions are identified, which are divided into regions.
The warm zone is formed by temperate and subtropical climatic zones, within which mudflows occur in the form of water-stone and mud-stone flows. The main reason for the formation of mudflows is rainfall. Regions of the warm zone: Caucasus, Ural, South Siberian, Amur-Sakhalin, Kuril-Kamchatka; regions of the warm zone of the North Caucasus, Northern Urals,
Middle and Southern Urals, Altai-Sayan, Yenisei, Baikal, Aldan, Amur, Sikhote-Alin, Sakhalin, Kamchatka, Kuril.
The cold zone covers mudflow-prone areas of the Subarctic and Arctic. Here, under conditions of heat deficiency and permafrost, snow-water mudflows are predominantly common. Cold zone regions: Western, Verkhoyansk-Chersky, Kolyma-Chukotka, Arctic; cold zone regions - Kola, Polar and Subpolar Urals, Putorana, Verkhoyansk-Chersk, Priokhotsk, Kolyma-Chukotka, Koryak, Taimyr, Arctic islands.
In the North Caucasus, mudflows are especially active in Kabardino-Balkaria, North Ossetia and Dagestan. This is, first of all, the river basin. Terek (rivers Baksan, Chegem, Cherek, Urukh, Ardon, Tsey, Sadon, Malka), river basin. Sulak (Avar Koisu, Andean Koisu rivers) and the Caspian Sea basin (Kurakh, Samur, Shinazchay, Akhtychay rivers).
Due to the negative role of the anthropogenic factor (destruction of vegetation, quarrying, etc.), mudflows began to develop on the Black Sea coast of the Caucasus (region of Novorossiysk, Dzhubga-Tuapse-Sochi section).
The most mudslide-prone areas of Siberia and the Far East are the areas of the Sayano-Baikal mountain region, in particular, the Southern Baikal region near the northern slopes of the Khamar-Daban ridge, the southern slopes of the Tunkinsky loaches (the Irkut river basin), the Irkut river basin. Selenga, as well as certain sections of the Severo-Muysky, Kodarsky and other ridges in the area of the Baikal-Amur Mainline (north of the Chita region and Buryatia).
High mudflow activity is observed in certain areas of Kamchatka (for example, the Klyuchevskaya group of volcanoes), as well as in some mountain basins of the Verkhoyansk Range. Mudflow phenomena are typical for the mountainous regions of Primorye, Sakhalin Island and the Kuril Islands, the Urals (especially the Northern and Subpolar), the Kola Peninsula, as well as the Far North and northeast of Russia.
In the Caucasus, mudflows form mainly in June-August. In the area of the Baikal-Amur Mainline in the lowlands they form in early spring, in the middle mountains - at the beginning of summer, and in the highlands - at the end of summer.
SNOW AVALANCHES.
A snow avalanche or a snowfall is a mass of snow set in motion under the influence of gravity and falling down a mountain slope (sometimes crossing the bottom of a valley and emerging onto the opposite slope).
Snow accumulating on mountain slopes tends to move down the slope under the influence of gravity, but this is opposed by resistance forces at the base of the snow layer and at its boundaries. Due to overloading of slopes with snow, weakening of structural connections within the snow mass, or the combined action of these factors, the snow mass slides or crumbles from the slope. Having begun its movement from a random and insignificant push, it quickly picks up speed, capturing snow, stones, trees and other objects along the way, and falls to flatter areas or the bottom of the valley, where it slows down and stops.
The occurrence of an avalanche depends on a complex set of avalanche-forming factors: climatic, hydrometeorological, geomorphological, geobotanical, physical-mechanical and others.
Avalanches can occur anywhere there is snow cover and sufficiently steep mountain slopes. They reach enormous destructive power in high mountain areas, where climatic conditions favor their occurrence.
The climate of a given area determines its avalanche regime: depending on climatic conditions, dry winter avalanches during snowfalls and snowstorms may predominate in some mountain areas, and spring wet avalanches during thaws and rains may predominate in others.
Meteorological factors most actively influence the process of avalanche formation, and avalanche danger is determined by weather conditions not only at the moment, but also over the entire period since the beginning of winter.
The main factors of avalanche formation are:
- amount, type and intensity of precipitation;
- depth of snow cover;
- temperature, air humidity and the nature of their changes;
- temperature distribution inside the snow layer;
- wind speed, direction, nature of their changes and blizzard snow transfer;
- solar radiation and cloudiness.
Hydrological factors influencing avalanche danger are snow melting and infiltration (seepage) of melt water, the nature of the influx and runoff of melt and rain water under the snow, the presence of water basins above the snow collection area and spring swamping on the slopes. Water creates a dangerous lubrication horizon, causing wet avalanches.
High-altitude glacial lakes pose a particular danger, since the sudden displacement of a large amount of water from such a lake when ice, snow or soil masses collapse into it or a dam breaks causes the formation of snow-ice mudflows, similar in nature to wet avalanches.
Of the geomorphological factors, slope steepness is of decisive importance. Most avalanches occur on slopes with a steepness of 25-55°. Flatter slopes can be avalanche-prone under particularly unfavorable conditions; There are known cases of avalanches falling from slopes with an inclination angle of only 7-8°. Slopes steeper than 60° are practically not dangerous for avalanches, since snow does not accumulate on them in large quantities.
The orientation of the slopes relative to the cardinal points and the directions of snow and wind flows also affects the degree of avalanche danger. As a rule, on the southern slopes within the same valley, other things being equal, snow falls later and melts earlier, its height is much less. But if the southern slopes of the mountain range face moisture-carrying air currents, then the greatest amount of precipitation will fall on these slopes. The structure of slopes affects the size of avalanches and the frequency of their occurrence. Avalanches that originate in small steep erosion grooves are insignificant in volume, but fall most often. Erosion furrows with numerous branches contribute to the formation of larger avalanches.
Avalanches of very large sizes occur in glacial circuses or pits transformed by water erosion: if the crossbar (rocky threshold) of such a pit is completely destroyed, then a large snow funnel is formed with slopes turning into a drainage channel. When a blizzard transports snow, a large amount of precipitation accumulates in the clearings and is periodically discharged in the form of avalanches.
The nature of watersheds influences the distribution of snow across landforms: flat plateau-like watersheds facilitate the transfer of snow into snow collection basins, watersheds with sharp ridges are an area for the formation of dangerous snow blows and cornices. Convex areas and upper bends of slopes are usually places where snow masses are released, forming avalanches.
The mechanical stability of snow on slopes depends on the microrelief associated with the geological structure of the area and the petrographic composition of the rocks. If the surface of the slope is smooth and even, then avalanches occur easily. On rocky, uneven surfaces, a thicker snow cover is required so that the gaps between the ledges are filled and a sliding surface can be formed. Large blocks help retain snow on the slope. Fine-clastic screes, on the contrary, facilitate the formation of avalanches, as they contribute to the appearance of mechanically fragile deep frost in the lower layer of snow.
Avalanches form within the avalanche source. Avalanche source- this is the section of the slope and its foot within which the avalanche moves. Each avalanche source consists of zones of origin (avalanche collection), transit (trough), and stopping zone (alluvial cone) of the avalanche. The main parameters of the avalanche source are the elevation (the difference between the maximum and minimum heights of the slope), the length, width and area of the avalanche catchment, the average angles of the avalanche catchment and transit zones.
The occurrence of avalanches depends on a combination of the following avalanche-forming factors: the height of old snow, the state of the underlying surface, the amount of increase in freshly fallen snow, snow density, the intensity of snowfall and subsidence of snow cover, snowstorm redistribution of snow cover, temperature conditions of air and snow cover. The most important of them include the increase in freshly fallen snow, snowfall intensity and snowstorm redistribution.
During the period of absence of precipitation, an avalanche can occur as a result of processes of recrystallization of the snow layer (loosening and weakening of the strength of individual layers) and intensive melting under the influence of heat and solar radiation.
Optimal conditions for the occurrence of avalanches occur on slopes with a steepness of 30-40°. On such slopes, avalanches occur when the layer of freshly fallen snow reaches 30 cm. Avalanches form from old (stale) snow when the snow cover is 70 cm thick.
It is believed that a flat grassy slope with a steepness of more than 20° is dangerous for avalanches if the snow height on it exceeds 30 cm. Shrub vegetation is not an obstacle to avalanches. As slope steepness increases, the likelihood of avalanches increases. When the underlying surface is rough, the minimum snow depth at which avalanches can form increases. A necessary condition for the avalanche to start moving and gain speed is the presence of an open slope 100-500 m long.
Snowfall intensity is the rate of snow deposition expressed in cm/hour. A thickness of 0.5 m of snow deposited in 2-3 days may not cause concern, but if the same amount of snow falls in 10-12 hours, widespread avalanches are possible. In most cases, the snowfall intensity of 2-3 cm/h is close to the critical value.
If, in calm conditions, avalanches cause a 30-centimeter increase in freshly fallen snow, then in strong winds, an increase of 10-15 cm can already be the cause of their descent.
The influence of temperature on avalanche danger is more multifaceted than the influence of any other factor. In winter, when the weather is relatively warm, when the temperature is close to zero, the instability of the snow cover increases greatly - either avalanches occur or the snow settles.
As temperatures drop, periods of avalanche danger become longer; at very low temperatures (below -18 °C) they can last up to several days or even weeks. In spring, an increase in temperature inside the snow layer is an important factor contributing to the formation of wet avalanches.
The average annual density of freshly fallen snow, calculated from data over several years, usually ranges from 0.07-0.10 g/cm3, depending on climatic conditions. The greater the deviation from these values, the greater the likelihood of avalanches. High densities (0.25-0.30 g/cm3) lead to the formation of dense snow avalanches (snow boards), and unusually low snow densities (about 0.01 g/cm3) lead to the formation of avalanches of loose snow.
Based on the nature of the movement, depending on the structure of the underlying surface, avalanches are distinguished between wasps, flume and jumping avalanches.
Osov - separation and sliding of snow masses over the entire surface of the slope; it is a snow landslide, has no defined drainage channel and slides across the entire width of the area it covers. Clastic material displaced by wasps down to the foot of the slopes forms ridges.
Trough avalanche- this is the flow and rolling of snow masses along a strictly fixed drainage channel, which expands funnel-shaped towards the upper reaches, turning into a snow collection basin or snow collection (avalanche collection). Adjacent to the avalanche chute below is an alluvial cone - a zone of deposition of debris thrown out by the avalanche.
Bouncing Avalanche- This is the free fall of snow masses. Jumping avalanches arise from flume avalanches in cases where the drainage channel has steep walls or areas of sharply increasing steepness. Having encountered a steep ledge, the avalanche lifts off the ground and continues falling at a high jet speed; this often generates an air shock wave.
Depending on the properties of the snow that forms them, avalanches can be dry, wet or wet; they move through snow (ice crust), air, soil, or have a mixed nature.
Dry avalanches from freshly fallen snow or dry firn during their movement are accompanied by a cloud of snow dust and rapidly roll down the slope; Almost all avalanche snow can move this way. These avalanches start moving from one point, and the area covered by them during the fall has a characteristic pear-shaped shape.
Avalanches of dry compacted snow (snow boards) usually slide across the snow in the form of a monolithic slab, which then breaks into sharp-angled fragments. Often, a snow board that is in a stressed state cracks immediately due to subsidence. When such avalanches move, their frontal part becomes very dusty, as fragments of snow boards are crushed into dust. The separation line of the snow layer in the avalanche initiation zone has a characteristic zigzag shape, and the resulting ledge is perpendicular to the surface of the slope.
Wet avalanches from firnized snow (soil avalanches) slide along the ground, moistened by seeped melt or rainwater; when they descend, various debris materials are carried away, and avalanche snow has a high density and freezes together after the avalanche stops. With an intensive flow of water into the snow, catastrophic avalanches sometimes form from the snow-water and mud mass.
Avalanches also differ in the time of fall relative to the cause that caused the avalanche. There are avalanches that occur immediately (or within the first days) from intense snowfall, blizzards, rain, thaw or other sudden weather changes, and avalanches that arise as a result of the hidden evolution of the snow layer.
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Slide captions:
Landslides, mudflows, landslides, avalanches.
The general condition for the occurrence of these dangerous natural phenomena is: The beginning of the displacement of soil, rock or snow down the slope. Territories of our country where landslides, mudflows, avalanches, and avalanches often occur: the North Caucasus, the Urals, the Sayan Mountains, Primorye, Kamchatka, Sakhalin.
Landslide is the displacement of rock masses along a slope under the influence of its own body and additional load due to erosion of the slope, waterlogging, seismic tremors and other processes.
Causes of landslides. Natural factors. Anthropogenic factors. (related to human activities). Earthquakes. Laying roads. Waterlogging of the soil (rains, floods). Water is the “lubricant” between rock layers. Deforestation and bushes. Blasting near landslide areas. Uncontrolled plowing and watering of land on a slope.
Mudflow (sayl - “stormy stream”) is a mountain stream consisting of a mixture of water, mud, stones (there are mud, stone, mud-stone).
Mudflows form in the mountains. Causes of mudflows. Natural factors. Anthropogenic factors. (related to human activities). Earthquakes. Laying roads. (incorrect) Volcanic eruption. (water and ash) Deforestation and bushes. Natural destruction of mountains. Blasting near landslide areas.
A landslide is the separation and catastrophic fall of large masses of rocks, their crushing and rolling down steep mountain slopes. Types of landslides: Rockfalls. Landfalls. Glacier collapse.
Causes of collapses Mainly anthropogenic (up to 80%) and improper work during construction and mining. Natural causes of heavy rain.
An avalanche is a rapid, sudden movement of snow and (or) ice down steep mountain slopes, posing a threat to human life and activity. They appear in the mountains. An avalanche is accompanied by the formation of an air pre-shock wave, which produces the greatest destruction.
Factors influencing the occurrence of avalanches: A lot of snow A slope whose inclination angle exceeds 14 degrees (if the slope angle is 30 - 40 degrees, then an avalanche is inevitable). The presence of an open slope 100 - 500 meters long.
“Even in the last century, in the Alps, people covered in snow were helped to find large, strong St. Bernard dogs, named after the high-mountain monastery of St. Bernard, where they were bred. Near Paris, in a special dog cemetery, there is a monument to St. Bernard Barry, who saved 40 people. These good-natured large dogs found more than 2,000 people in the mountains. Now the St. Bernards have been replaced by East European Shepherds.”
Landslide is a mass of rocks that has slipped or slid down a slope or slope under the influence of gravity, hydrodynamic pressure, seismic and some other factors. By destroying slopes and slopes, landslides create a specific landslide relief.
Distribution As a rule, landslides are most widely developed in areas of rugged and sharply rugged terrain, in mountainous areas, on the banks of rivers, seas and reservoirs. As a rule, landslides are most widespread in areas of rugged and sharply rugged terrain, in mountainous areas, on the banks of rivers, seas and reservoirs.
Causes of landslides Increasing the steepness of a slope or slope. Weakening of the strength of rocks due to changes in their physical state during wetting, swelling, decompaction, weathering, disruption of their natural composition, etc. The action of hydrostatic and hydrodynamic forces on rocks, causing the development of filtration deformations. Changes in the stress state of rocks in the zone of slope formation and slope construction. External influences - loading of a slope or slope, as well as areas adjacent to their edges, microseismic and seismic vibrations.
The mechanism of the landslide process. 1. Sliding (shifting) of a block or blocks of rocks occurs - structural landslides (sliding landslides). 2. The movement of rock masses occurs in the form of a flow, like a viscous liquid - plastic landslides (flow landslides).
Dynamics of the landslide process Stages of development of the landslide process Preparation of the landslide Actual formation of the landslide Existence - stabilization of the landslide Gradual decrease in the stability of rocks Relatively fast or sharp loss of stability of the GP Restoration of the stability of the GP masses gradually or spasmodically Duration of the stages Months, years, can be reduced to zero, bypassing the preparatory phase stage Develops quickly or slowly, repeats many times with stops, periodically or continuously The process is completed, but with a new position of the relief
Classification of landslides 1. According to A.P. Pavlov: Delapsive Detrusive P P P P ooooo i i i xxxx s s s tttt rrrrr ooooo eee nnnn iiiiii juyuyuyu ((((FFFF.... PPPP.... SSSS aaaa vvvv aaaa rrrr eee nnnn ssss kkkk iiii yyyy ))))3. By age (I.V. Popov): Modern - moving - suspended - stopped - finished Ancient - open - buried
Consequences of landslides of 1903 1903 1903 1903 October 1963 October 9, 1963 October 9, 1963 October 9, 1963
Italy. River valley Piave Near the Vayont dam (height 265.5 m) a landslide occurred with a volume of more than 240 m 3, the reservoir bowl within a second. was filled, the landslide speed was m/sec. A water shaft was formed 260 m above the water level in the reservoir. 5 cities were demolished. About 3 thousand people died.
Consequences of landslides In 1903 in Canada, in the town of Frang, the top of Mount Turtle collapsed, throwing more than 30 million m 3 of rock onto the mining village. 70 people died and the Trans-Canada Railway was buried. in 1903, in Canada, in the town of Frang, the top of Mount Turtle collapsed, throwing more than 30 million m 3 of rock onto the mining settlement. 70 people died and the Trans-Canada Railway was buried. In 1959, a landslide caused by an earthquake in Montana led to the formation of the new Lake Efquake. 28 people died. In 1959, a landslide caused by an earthquake in Montana led to the formation of the new Lake Efquake. 28 people died
Consequences of landslides At least 30 people are missing after a landslide hit a village in Peru. At least 30 people are missing after a landslide hit a village in Peru. 26 people died in a landslide in southwest China. The landslide occurred on Friday, June 5, in Wulong County, Sichuan Province. Among the dead were 19 employees of a mining company caught in the disaster-stricken area. Another 27 miners were in the mine at the time of the landslide; they are listed as missing. The fate of 25 local residents also remains unknown. 26 people died in a landslide in southwest China. The landslide occurred on Friday, June 5, in Wulong County, Sichuan Province. Among the dead were 19 employees of a mining company caught in the disaster-stricken area. Another 27 miners were in the mine at the time of the landslide; they are listed as missing. The fate of 25 local residents also remains unknown.
Consequences of landslides The number of victims of the mud landslide that hit the third largest Sicilian city of Messina on October 2 reached 20 people. At the same time, according to the local press, 18 people are considered victims of the landslide. 80 were injured, and 35 residents of Messina are considered missing. The reasons for the landslide are said to be heavy rains that occurred in Sicily last Thursday, as well as illegal buildings that disrupted drainage systems. The death toll from the mudslide that struck the third largest Sicilian city of Messina on October 2 has reached 20 people. At the same time, according to the local press, 18 people are considered victims of the landslide. 80 were injured, and 35 residents of Messina are considered missing. The reasons for the landslide are said to be heavy rains that occurred in Sicily last Thursday, as well as illegal buildings that disrupted drainage systems.
Consequences of landslides In Indonesia, as a result of a landslide that covered an area equal to two football fields, several dozen people were buried under a layer of mud. According to various sources, from 40 to 72 people are listed as missing. At the time of writing, five deaths were reported. About 50 houses were caught under a landslide, triggered by heavy rain the day before. According to eyewitnesses, the height of the collapsed layer of mud exceeds the height of the buildings underneath. In Indonesia, a landslide that covered an area the size of two football fields left dozens of people buried under a layer of mud. According to various sources, from 40 to 72 people are listed as missing. At the time of writing, five deaths were reported. About 50 houses were caught under a landslide, triggered by heavy rain the day before. According to eyewitnesses, the height of the collapsed layer of mud exceeds the height of the buildings underneath.
Anti-landslide measures Consolidation of rock masses with retaining and anchoring structures Consolidation of rock masses with retaining and anchoring structures Consolidation of rock masses with retaining and anchoring structures Consolidation of rock masses with retaining and anchoring structures Regulation of surface flow Regulation of surface drainage Drainage of watered rocks Drainage of watered rocks Protection from undermining and erosion Protection against undermining and erosion Redistribution of rock masses Redistribution of rock masses Artificial improvement of rock properties Artificial improvement of rock properties Forest reclamation work Forest reclamation work Preventive measures Preventive measures
Anchors and retaining walls Scheme of anchor tightening: Scheme of anchor tightening: 1 - lower anchor; 2 – bedrock; 3 – landslide soils; 4 - anchor rod; 5- well; 6 - anchor plate; 7 - upper anchor 1 - lower anchor; 2 – bedrock; 3 – landslide soils; 4 - anchor rod; 5- well; 6 - anchor plate; 7 - upper anchor Retaining wall
