Study On The Structural Behavior Of Reinforced Soil Retaining Wall Under Rainfall Infiltration Conditions

In order to explore the structural behavior of reinforced soil retaining wall under rainfall infiltration conditions,based on the reinforced soil retaining wall project of Yichang North Station of Shanghai-Yurong High-speed Railway,based on the results of indoor tests and actual engineering,a numerical simulation calculation model of reinforced soil retaining wall was established based on PLAXIS software,the influence of rainfall infiltration on the reinforced soil retaining wall was studied,and the specific influence of rainfall infiltration on the deformation of the retaining wall was explored by changing the properties and parameters of filler and reinforcement.The main research contents and conclusions are as follows:(1)The interfacial pulling test of reinforced soil was carried out for fillers with different moisture content and geogrids of different strengths: the interfacial shear stress of reinforced soil was the largest at 1.7% moisture content of the original soil,slightly smaller than that of the original soil at the optimal moisture content of 3.3%,and rapidly decreased when the moisture content was 6.3% and 9.3%;The moisture content of the packing increases,and the rigid body translation occurs earlier in the drawing process of the geogrid.The similar cohesion and friction angle of the reinforce-soil interface decreased with the increase of moisture content,and the change of the moisture content of the filler had a greater impact on the cohesion of the reinforce-soil interface.After reinforcement,the interfacial cohesion increased compared with the original soil,and the internal friction angle decreased.After the increase of moisture content,the maximum increase of the interface coefficient of geogrid reinforcement is about 50.0%,and under the same moisture content,the interface coefficient of high-strength grid is slightly greater than that of low-strength grid.(2)According to the actual working conditions,PLAXIS software is used to establish the numerical model of the reinforced soil retaining wall,and according to the precipitation intensity division standard and the maximum single-day rainfall in Yichang City,different rainfall conditions are set to simulate and analyze the reinforced soil retaining wall.The conclusions are as follows: compared with 400 mm/d(t=1 d)rainfall,50 mm/d(t=8 d)rainfall significantly increases the pore water pressure range inside the retaining wall.Compared with no rainfall,the deformation of 400 mm/d(t=1d)rainfall increased by 1.5%,0.8% and 3.5%,respectively,while the 50 mm/d(t=8 d)rainfall increased by 9.3%,3.4% and 25.4%,respectively,indicating that when the total amount of rainfall was the same,long-term low-intensity rainfall had a greater impact on the deformation of the retaining wall.Compared with the conditions without rainfall,the maximum horizontal earth pressure and vertical stress of the reinforced soil retaining wall panel increased by about 13.5% and 10.6% under rainfall conditions.The tensile force of reinforcement increases with the increase of rainfall intensity and time,but the value added is small.The potential fracture surface of the retaining wall gradually develops to the rear of the retaining wall with the increase of rainfall,and the sliding surface range becomes larger.(3)By changing the properties and parameters of the reinforced soil retaining wall filler and reinforcement,the deformation influencing factors of the retaining wall under the same rainfall conditions were studied.The conclusions are as follows: with the increase of packing cohesion and internal friction angle,the deformation of the retaining wall gradually decreases under the two working conditions of rainfall and no rainfall,and the change of friction angle in the packing has a greater deformation of the retaining wall under rainfall than the change of cohesion.Changing the elastic modulus of the filler has little effect on the deformation gap of the retaining wall under the above two working conditions.Increasing the strength and length of the geogrid and reducing the laying spacing of the grid can reduce the deformation of the retaining wall under two working conditions: the strength of the geogrid is from small to large,the deformation difference of the horizontal displacement of the wall in the two conditions of rainfall and no rainfall is reduced from 10.6% to 3.3%,the laying spacing of the reinforcement is from large to small,the deformation difference of the horizontal displacement of the wall under the two working conditions is reduced from 11.4% to7.8%,the length of the grid is from small to large,and the deformation difference of the horizontal displacement of the wall under the two working conditions is reduced from 11.7% to 6.3%.(4)The anti-drainage measures used in the general stepped reinforced soil retaining wall are briefly introduced,and the waterproof measures mainly include the installation of composite geomembrane and concrete sealing,and the drainage measures include the installation of drainage holes and reverse filtration layers;A new type of drainage geogrid is introduced to achieve rapid drainage by setting drainage channels on ribs.