Research On The Mechanism Of Bank Slope Stability Under The Condition Of Reservoir's Water Level Fluctuation

The instability of reservoir bank slope is often seen in the world.Its condition of stability has a great relationship with the variety of reservoir's water level.At present,the existing research results are mostly aimed at the natural slope.However,the research results of the stability mechanism of artificial slopes are relatively few.When using the engineering waste soil to control the landslide of reservoir or lake,the mechanism of the stability of the waste soil artificial slope caused by the fluctuation of reservoir water level is also the topic that engineers pay close attention to.In this paper,the whole process of the water level's variety and the change of the phreatic line after that is called the whole process of water level's rise or fall.Based on the analysis of the results of previous studies,this paper takes plain filled clay soil artificial slope as an example.By means of theoretical analysis,laboratory test and numerical simulation,this paper tries to find out the influence factors of slope stability,and this paper educes the mechanism of the effect on the shear strength of the soil because of water.Then this paper simulates the condition of the slope during the whole process of water level's rise or fall.Through the numerical simulation,this paper has analysed the general situation of seepage,the change of shear stress,pore water pressure and stability safety factor of the slope during the whole process of water level's rise or fall.Finally,the mechanism of plain filled clay soil artificial slope stability under the condition of water level fluctuation is summarized.The main achievements are as follows:(1)The cohesive force of soil shows the trend of decreasing with the increase of soil moisture content,and the rate of decrease is stable.When the water content increases to a certain value,the value of cohesive force tends to be stable and no longer varies with the change of water content.Generally,the internal friction angle of soil decreases with the increase of water content,but in some intervals of the increase of water content,the angle of internal friction increases with the increase of water content.(2)Through the numerical simulation,this paper analyzed the seepage situation of the bank slope in the whole process of the water level's rise and fall,and sum up the fundamental factors that cause the seepage of bank slope in two aspects.On one hand,it is the position potential energy of the difference between the reservoir's water level and the phreatic line of the bank's underground water.On the other hand,because the reservoir's water level fluctuation will lead to the change of the stress of the soil,so that the volume of soil will change or tends to change,then the excess pore water pressure can be generated,which can be regarded as the potential energy of pressure.The seepage situation of bank slope is the reflection of the interaction of these two aspects.(3)When the water level rise,the maximum shear stress value of bank soil is generally decreased first and then tended to be stable.When the water level fall,the maximum shear stress value of bank soil decreases first and then increases,and finally tends to be stable.(4)No matter in the reservoir's water level rising or falling period,the pore water pressure of bank soil in the saturated area generally increased.In the following period of the change of phreatic line,the pore water pressure of bank soil in the saturated area showed the spatial distribution trend of homogenization.