Study On Stability Of Soil Slope Of Subgrade Along River Under Rainfall And Water Level Fluctuation

Due to the complex situation of the topography of mountainous terrain in Yunnan Province of China,many roads responsible for connecting mountainous towns and villages must not face mountains on one side and rivers on the other.At the same time,in the face of the mountainous climate characteristics of rain,along the river highway often suffer from heavy rainfall,and the river level will also change rapidly after the rainstorm.Faced with the double test of rainfall and rapid fluctuation of river level,how to ensure the safety and stability of the soil slope along the river Subgrade has become a major problem.In view of this,this paper takes the Gudong-Zizhi highway in Yunnan Province as the engineering background,and analyzes the seepage field and stability of the slope under the action of rainfall,river water level and the combination of the two in stages by means of theoretical analysis,numerical simulation and physical test,in order to reveal the mechanism of each influencing factor on the stability of the slope and help to develop more scientific and effective slope control measures:(1)Based on the finite element analysis method,32 sets of orthogonal experiments were designed,and the sensitivity ranking of each stability influencing factor was obtained through orthogonal analysis as follows: friction angle > slope ratio > cohesion >water table drop rate > capacitance > rainfall intensity > infiltration coefficient.(2)The seepage field and stability of the slope under the action of multi-factor composite conditions are studied by using Midas GTS NX finite element software in conjunction with the engineering situation.Firstly,a rainfall slope model with different rainfall intensity,different rainfall duration,different initial water level height in the slope and the same total amount of rainfall was established;secondly,a slope model with different river water level rise and fall rates was established;finally,based on the previous study,a slope model with a combination of rainfall-water level rise and water level fall in stages was established,and the slope model with a waterproof layer on the slope was The simulation was validated.It is found that extreme rainfall and rapid fall of river water level have the greatest influence on slope seepage field and stability,and are very likely to cause slope instability damage.(3)With reference to the actual project,the size of the slope model and the soil used were determined based on the similar principle,and the geotechnical test was carried out on the soil to obtain the basic parameters of the soil.The main test is divided into two parts.Firstly,the experimental study of the slope under different rainfall holding time and rainfall intensity is carried out;secondly,the dynamic process of water level rise-fall in front of the slope is articulated on the basis of the rainfall test,and a three-dimensional finite element model is established to restore the test in order to verify the reliability of the test.The research shows that the seepage and scouring effect of rainfall will produce damage to the slope from inside to outside,and the damage is mainly concentrated in the slope corner.The process of water level rise and fall in front of the articulated slope after rainfall will intensify the original damage phenomenon and increase the probability of slope instability.