Experimental Study And Numerical Analysis On Spatial Soil Arching Evolution Of Pile-Sheet Retaining Wall

Because of anti-slide pile with a small use of material,anti-skid ability,good retaining effect,etc.,it has been widely used in the field of geotechnical engineering.However,the soil between the piles is in the emptying state,for the cantilever anti-slide pile.Although the design of the anti-slide pile can meet the correspondi?g design requirements at this time.Due to factors such as excavation or continuous rainfall of the front slope of the pile,Soil collapse,local instability and other signs of failure will happen.So the pile-sheet retaining wall supporting system came into being.However,due to the complexity of geotechnical engineering,the diversity of pile layout and the lack of research on pile-plate-soil interaction,the current arching mechanism and influence factors of arch effect,there is still a lack of in-depth and systematic research.First of all,this paper focuses on two types of typical soil of sandy soil and granite residual soil,taking into account the laying position of the plate between the piles(three kinds of conventional forms of pile front plate,pile post plate and no plate).Laboratory physical model of evolution of soil arching between piles was tested.By this physical model test,the deformation of pile board under different pile spacing(4 times of pile width,5 times of pile width and 6 times of pile width)was obtained,and the stress along the depth direction between piles and along the load direction of the middle soil was obtained.The results show that:(1)The earth pressure on the middle of the pile and the back of the plate is larger,and the top and bottom are smaller.The stress in the Y direction across the mid-position soil mass changes along the loading direction.(2)Compared with the pile post plate,the arching effect of the soil between the piles is more significant;(3)With the increase of pile spacing,the arching effect of the pile-sheet retaining wall gradually increased.(4)The reasonable piles spacing corresponding to the maximum soil arching effect of the piles supporting system with granite residual soil is greater than the supporting system of pile wall supported by piles with sandy soil.Secondly,based on the model test,the three-dimensional numerical model of pile-wall-soil interaction is established by ABAQUS numerical analysis software.The rationality of the three-dimensional numerical model is verified by the indoor physical model test.Based on the numerical model,the effect of internal friction angle and cohesion and plate stiffness on the spatial arch effect of pile-sheet retaining wall is discussed.The results show that:(1)the increase of internal friction angle and cohesion,the arching effect of soil behind the wall is strengthened,and the change of cohesion has more influence on the effect of arch effect.(2)In a certain range the reduction of stiffeners of plate,the effect of arching effect of soil behind the wall is also gradually improved.At the same time,the conventional two-dimensional plane strain numerical analysis model and three-dimensional numerical analysis model of the evolvement of arch wall effect of pile wall are comparatively analyzed.The results show that the traditional two-dimensional numerical model results are conservative and difficult to reflect the soil between piles spatial evolution of arching effect.At last.Based on multiple numerical analysis,it is proposed that the ratio of soil pressure at the back of piles and earth pressure at middle section of piles should be taken as a quantifiable parameter to quantify the extent of arching effect in order to guide engineering practice.