The PIV Model Test Research On Earth Pressure Of Retaining Wall With Finite Fill

The engineering construction such as urban underground space and highway construction often meet with limited width of retaining structure before and after filling,the width of the soil is limited,which is the so-called "finite fill".In recent years,the earth pressure of the retaining wall with finite fill has become one of the hot research topics in soil mechanics.At present,a lot of model test research focused on the semi-infinite filling or considering the wall displacement model of earth pressure,but the stress distribution and deformation of finite fill lack systematic research.Particle image velocimetry(PIV),is an instantaneous speed measurement technology,dynamic,non-contact and full field,has been widely used in rock and soil deformation measurement study.In view of the current research situation of finite fill,model test device is designed to measure the pressure of the finite fill in this paper.Using PIV measurement technique,in combination with numerical simulation,the law of deformation and distribution of soil pressure in the process of the failure of soil mass are studied.The main conclusions are as follows:(1)Using PIV measurement system to obtain the images that after the retaining wall the whole process of failure,the displacement field indicates that the typical finite fill along the bed rock excavation surface integral sliding,with the width of lower soil increases or bedrock excavation surface angle decreases,to fill the Limited will be a first integral sliding after partial slip phenomenon;the loose sand failure surface is always located on the Coulomb failure surface lateral,densely sand failure surface always located in the Coulomb failure surface inside.(2)When the rock excavation surface inclination angle as 60 degree,change the width of lower fill D,on the whole,the nonlinear distribution of horizontal earth pressure is gradually increasing with the increase of depth,and the observed maximum appears in the lower part of the retaining wall.At first,with the increase of the width of lower fill,the earth pressure gradually increased,when the width of lower fill is greater than 2.5 cm,the soil pressure distribution law is closer to the classical Coulomb earth pressure into the situation of finite fill.(3)Through the numerical simulation analysis,the soil displacement is mainly affected by the vertical settlement of the Y direction,the overall displacement of the cloud is funnel shape distribution.The distribution of the main stress is in accordance with the actual law,and the value is within a reasonable range.Through the analysis of the influencing factors of soil pressure,found that a limited range of earth pressure distribution is not affected by the rock excavation surface inclination angle or the width of lower fill.The overlying load not only affects the size of earth pressure,but also influences the distribution of stress.The appearance of the load,resulting in the joint action point obviously moved up,the maximum value appears in the upper part of the soil,which is about the height of the wall top 1/5 wall.