Research motivation
In recent years, major mudslides, landslides and other natural disasters have occurred frequently. For example, on September 10, 2008, a mudslide occurred in Shanxi Linfen Thaksin Mining Co., Ltd., causing 128 people to die. 2008 165438+200810.5, the landslide and debris flow disaster in Yunnan has caused 40 deaths and 43 missing, and the infrastructure such as power, transportation, water conservancy and communication has been damaged to varying degrees, resulting in a direct economic loss of 592 million yuan.
Second, the purpose of the study
Let people know the seriousness of natural disasters, learn to avoid such disasters, know how to protect themselves even if they happen, and learn to minimize losses.
Third, research methods.
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Four research contents
Cause of formation of 1: earthquakes are caused by plate movements, and earthquakes can cause landslides and mudslides. The reduction of vegetation on the mountain will also increase the risk of landslides and mudslides.
The difference between the two types of disasters: I think we should first understand the scale of the accumulation body, then understand its composition, understand the composition of the surrounding rock and soil, and then determine it according to the nature of these accumulation bodies. Generally speaking, the rock and mineral composition of landslide is generally consistent with the soil and rocks nearby, while the material composition of debris flow accumulation body is more complex and its source is wider and farther, so most of this accumulation body can be investigated. If the local rocks are sandstone and there are granite fragments in the deposits, it can be preliminarily inferred that they are debris flow deposits and glacier deposits. The formation of debris flow requires that the upper reaches of the valley are relatively open and the slope is relatively slow, so that the runoff confluence area is large, which is conducive to the accumulation of loose deposits. Landslide mainly depends on slope, trailing edge and vegetation.
Distribution area: mountainous area
Treatment method: Debris flow prevention is a systematic project, which consists of various measures. It mainly includes four measures: ① prevention and weakening of the prevention and control system of debris flow activities-protecting and controlling the basin environment through biological and engineering measures to eliminate or weaken the conditions for debris flow; (2) Prevention and control system for controlling debris flow movement-engineering measures such as retaining dam, valley workshop, drainage ditch and silt yard are adopted. Adjust and dredge debris flow circulation channels and silting places to reduce disaster damage losses; (3) Protection engineering system for preventing and controlling debris flow disasters ~ (1) Construction of aqueducts, culverts, tunnels, open-cut tunnels, slope protection, retaining walls, dikes and other projects to protect against important disasters; ④ Forecasting, forecasting and disaster relief system: timely transfer and evacuate residents, enterprises and important engineering facilities seriously threatened by mudslides, and carry out effective emergency rescue and disaster relief when disasters occur to reduce losses caused by disasters. Landslide can be treated in the following two aspects: (1) Eliminate and reduce the harm of surface water and groundwater. Landslides are often closely related to the action of water, and water is often the main factor that causes landslides. Therefore, it is particularly important to eliminate and reduce the harm of water to slope. Its purpose is to reduce pore water pressure and hydrodynamic pressure, prevent the softening and dissolution of rock and soil, and eliminate or reduce water scouring and wave impact. The specific measures are as follows: to prevent peripheral surface water from entering the landslide area, intercepting ditches can be built at the landslide boundary; In landslide areas, drainage ditches can be built on slopes. Mortar sheet or artificial vegetation can be used to cover the covering layer to prevent surface water from infiltrating. For rock slopes, shotcrete can also be used to protect the surface or hang steel wire mesh on shotcrete. There are many measures to remove groundwater, which should be selected according to the geological structure characteristics and hydrogeological conditions of the slope. The commonly used methods are: ① horizontal drilling and drainage; ② Vertical drilling and drainage; ③ Shaft pumping; ④ Tunnel drainage; ⑤ Support the blind ditch. (II) Improving the mechanical strength of the slope rock and soil mass Through certain engineering and technical measures, the mechanical strength of the slope rock and soil mass is improved, its sliding resistance is improved, and the sliding force is reduced. The commonly used measures are: ① slope cutting and load reduction; Slope stability can be improved by reducing slope height or slowing slope angle. In the design of cutting slope, the height of unstable rock and soil should be reduced as much as possible, and the rock and soil that prevents sliding should not be reduced. This method is not always the most economical and effective measure, so economic and technical comparison should be made before construction. (2) artificial reinforcement of slope; The commonly used methods are: ① building retaining walls and retaining walls to support unstable rock mass; (2) Using reinforced concrete anti-slide piles or reinforced piles as anti-slide supporting works; (3) Prestressed anchor rods or cables are suitable for reinforcing rock slopes with cracks or weak structural planes; ④ Consolidation grouting or electrochemical reinforcement method to enhance the strength of slope rock mass or soil.
The precursors of collapse are: falling blocks, falling, small collapses and small collapses occur continuously at the front of collapse; There are new fracture marks on the collapsed feet; Occasionally, I hear the tearing and rubbing sound of rocks from time to time; Abnormal heat, gas and groundwater; This animal is abnormal. The precursors of landslide are: transverse and longitudinal cracks appear at the front of landslide, and the soil at the front rises; The cracks at the trailing edge of the landslide widen and lengthen sharply, and new cracks are constantly produced. The rear part of the landslide sinks rapidly, and the surrounding rock and soil become loose and collapse and slip on a small scale. The rock and soil in the slip zone make noise due to friction dislocation, and gas or water gushes out from the cracks; At the slope angle of the front edge of the landslide, there are springs whose revival is blocked or springs and wells suddenly dry up; Animals have abnormal panic phenomenon; The observation point on the landslide body is obviously displaced; The front edge of the landslide appears uplift; The house is tilted and cracked, and there are drunkards, saber trees and so on.
6. Emergency avoidance: avoiding the victims and the disaster-causing effect. It can be divided into active and passive situations, namely active avoidance and passive evacuation. For projects and personnel in dangerous areas, the methods adopted are: prevention, avoidance, evacuation and treatment. Each of these four links contains great opportunities for disaster prevention and mitigation. The emergency preventive measures of collapse and landslide disaster are: evacuating people and materials from dangerous areas in time according to dangerous situations; The dynamic role of stopping disasters in time; Those who have early warning should make an evacuation plan as soon as possible. Avoid debris flow, don't run downstream along the ditch, run to both sides of the ditch bank, but don't stay at the concave slope.
The research conclusion of verb (abbreviation of verb)
Eliminate and reduce the harm of surface water and groundwater. Landslides are often closely related to the action of water, and water is often the main factor that causes landslides. Therefore, it is particularly important to eliminate and reduce the harm of water to slope. Its purpose is to reduce pore water pressure and hydrodynamic pressure, prevent the softening and dissolution of rock and soil, and eliminate or reduce water scouring and wave impact. The specific measures are as follows: to prevent peripheral surface water from entering the landslide area, intercepting ditches can be built at the landslide boundary; In landslide areas, drainage ditches can be built on slopes. Mortar sheet or artificial vegetation can be used to cover the covering layer to prevent surface water from infiltrating. For rock slopes, shotcrete can also be used to protect the surface or hang steel wire mesh on shotcrete. There are many measures to remove groundwater, which should be selected according to the geological structure characteristics and hydrogeological conditions of the slope. Commonly used methods are: 1, horizontal drilling drainage; 2, vertical hole drainage; 3. Shaft pumping; 4. Drainage of the tunnel; 5. Support the blind ditch. Through certain engineering and technical measures to improve the mechanical strength of slope rock and soil, improve the mechanical strength of slope rock and soil, improve its sliding resistance and reduce sliding force.
Six research experiences ....