Study On The Interaction Mechanism Between Anti-slide Pile And Soil Microscopic

The slope problem is one of the most common problems in human engineering activities,and the anti-slide pile is a main form of retaining structure for controlling the slope problem.Therefore,the interaction between anti-slide pile and soil is getting more and more concerns from people in the field of geotechnical engineering.Predecessors have done many experiments on the interaction of piles and soil to explore the mechanism of action.However,due to the invisibility of the soil and the discontinuity of the embedded stress strain gauge test,the interaction between the pile and the soil cannot intuitive display at the fine micro level.With the development of science and technology,artificially produced transparent soil and PIV technology make it possible to study the micro-interaction between the anti-slide pile and the soil.At the same time,the development of numerical simulation software can also model the engineering examples.In addition,most of the current research on pile-soil interaction are based on rectangular piles.This paper will use round piles to study the mechanism of pile-soil interaction at the fine-microscopic level.The main research contents are as follows:(1)Preparation of transparent soil instead of sand as test materialDue to the invisibility of the slope soil itself,the internal displacement evolution characteristics of the soil itself cannot be obtained,which makes people have different views on the pile-soil interaction.In this paper,the physico-mechanical properties of transparent soil are tested experimentally.The results show that transparent soil can replace natural sand as a visual model test for pile-soil interaction.The transparent soil can directly observe the displacement strain inside the soil,and solves the shortcomings of collecting data by inserting strain gauges and stress boxes in the past,and creates conditions for studying the mechanism of the fine microscopic level of the pile soil.(2)Analysis of the evolution process of pile soil interactionFirstly,using the single working condition of the model test,the displacement vector in the process of pile-soil interaction,the displacement in the direction perpendicular to the moving direction of the model box,the displacement along the moving direction of the model box,the total displacement and the strain are analyzed and summarized,The displacement and strain laws of pile-soil interaction in space are obtained.,and the regional division,arch axis and arch height equation of pile-soil interaction behind the round pile are given.Secondly,using PFC3 D numerical simulation software to numerically simulate the test model,the general characteristics of the force chain inside the soil,the force on the pile,the displacement of the granular body in the space and the crack of the soil particles are obtained.(3)Comparison of the influence of different pile diameters,pile spacing and depth on pile-soil interactionBy analyzing the results of model tests and PFC3 D numerical simulations,it can be obtained that the greater the interaction force after increasing the pile diameter,the greater the influence range on the soil particles,The slower the formation of the soil arch,the slower the development of the crack,Therefore,it can be concluded that the larger the pile diameter,the better the anti-sliding effect of the pile.The effect of pile spacing on pile-soil interaction is the smaller the pile spacing under the constant displacement within a certain range,the faster the arched area is formed and the faster the damage is.The faster the crack develops,the smaller the width of the arched formed region and the lower the height;It can be concluded that the pile spacing is not as small as possible in the anti-sliding effect.The small spacing will cause the soil arching effect at the rear of the anti-slide pile to fail after sliding a small amount of displacement on the slope.and reasonable pile spacing can allow for greater displacement and reduction cost.Comparing the total displacements at different depths,it is concluded that the bottom arching effect of the single-row circular anti-slide pile is the most developed in the actual project,and the arch height is the highest;The closer to the top of the pile,the more the soil arching effect lags and the smaller the arch height.This paper starts from the two aspects of visual model test and discrete element numerical analysis,and studies the formation,development and failure mechanism of the interaction between pile and soil at the micro level.The effects of different pile diameters,pile spacings and depths on pile-soil interaction are compared,which provides useful reference for the desi-gn and longterm maintenance of anti-slide piles for sand landslides.