Research And Risk Assessment Of Slope Stability Under Rainfall Infiltration Conditions

For a long time,the stability of the western slope of the Changpo open-pit mine has always affected the safety of the mine.To this end,this article takes the western slope of the Changpo open-pit mine as the research object,analyzes the chemical elements and mineral components of the rock mass of the slope,and develops the slope-related rock and soil mass to resist disintegration in water,uniaxial compression,indoor Based on a series of laboratory tests such as direct shear,a three-dimensional physical model of the slope is established,and the stability of the slope is analyzed using the finite difference method.At the same time,a fuzzy analytic hierarchy process is used to construct a slope instability risk evaluation system.The important index weights that cause slope instability are calculated and analyzed,and a slope instability risk assessment is made.The main content and conclusions of the paper are as follows:(1)Qualitative and quantitative analysis of the chemical composition of rock samples by X-ray diffraction.The test results found that the rock samples contained a large amount of oxides.The cations such as Ca²⁺and Mg²⁺provided by the oxides had high activity and hydrophilicity.Therefore,the rock mass is easy to soften when it encounters water,and the rock mass is rich in chlorite,illite,montmorillonite and other clay minerals that are easily disintegrated and swelled.It is found that the water medium has a great influence on the mechanical properties of the rock mass through the immersion resistance test.Large,the rock disintegrates completely after 6 hours of immersion in water,and the rock has poor resistance to disintegration.(2)Through uniaxial compression tests of slope rock samples under different immersion times,it was found that with the increase of immersion time,the peak value of compressive strength decreased,and the stress-strain curve compaction phase of the slope rock samples increased significantly,the elastic phase and yield The stage is significantly shortened,and the compressive strength should have fallen rapidly after reaching the peak;as the immersion time increases,the stress-strain curve declines slowly after the peak and a multi-level falling platform appears;the rock sample loading and morphology vary with different immersion times."And single-slope shear failure.(3)The indoor direct shear tests on slope rock samples show that the rock samples fall rapidly after reaching the peak stress under different water immersion times,and the rock samples show obvious brittleness characteristics.With the increase of water immersion time,the elastic modulus E,Both the friction angle?and the cohesive force c have a non-linear exponential function decreasing law.Therefore,the continuous soaking of the water medium will gradually reduce the bearing capacity of the slope mud.(4)Using FLAC 3D software to perform numerical simulation calculations to analyze the seepage field,stress field and velocity field of different rainfall durations under the condition of heavy rainfall on the west slope of Changpo open-pit mine.With the increase of rainfall time,the pore water pressure of the slope gradually increased,and the pore water pressure of the slope lasted for 16 hours tended to be stable;the amount of displacement of the slope displacement field increased continuously,and the vertical displacement gradually expanded from the trailing edge of the slope and was in the pit.A bottom drum is generated at the bottom,and the horizontal displacement expands from the middle position of the slope to the bottom of the slope.The deformation speeds in the horizontal and vertical directions show strong fluctuations in the first 16 hours.At this stage,the slope rock and soil are extremely prone to deformation loss.With the increase of rainfall time,the slope safety factor gradually decreases.After 16 hours of rainfall,the slope safety factor is stable at about 1.03.After that,the slope is in an unstable state,and the slope has a higher risk of instability.(5)Evaluate the slope instability risk by fuzzy analytic hierarchy process,establish a slope instability risk evaluation system,obtain the index weights that cause the slope instability risk,and know the duration of rainfall among the factors affecting the slope instability The weighting is the largest,and the other weighting factors that affect slope instability are ranked as follows:rainfall duration>daily rainfall>cohesion>permeability coefficient>internal friction angle>slope shape>slope angle>degree of rock and soil weathering>rock and soil Type>Slope height;the weights of the indicators determined in the analytic hierarchy process are introduced into the fuzzy comprehensive evaluation to obtain the fuzzy grade vector of the risk of slope instability.According to the principle of maximum degree of membership,the comprehensive risk of the slope of the Changpo surface mine It is 0.408,which is a high-risk slope,that is,the possibility of danger is extremely great.