Calculation Of Anti-slide Piles With Protection-wall Based On Strain Wedge Theory And Study On Passive Soil-arching Effect In The Front Of Piles

The anti-slide piles are one of the most important supporting structure in the project of landslide control.When to design and calculation a anti-slide pile,the key question is how to consider the interaction between pile and soil.On the one hand,for the calculation of anti-slide pile with protection-wall,almost all existing methods don't consider the contribution of protection-wall to piles,instead regarding the protection-wall as a kind of temporary supporting structure.What's more,pile always be taken as a one-dimensional beam on elastic foundation while it is three-dimensional impact with soil actually.On the other hand,because of the influence of adjacent piles,when the piles work in rows,the additional stress in passive zone soil before piles will generate a phenomenon of mutual effect,thus a passive soil-arching effect may appear in the front of piles.However,the current research about the above two aspects is still very rare.The theoretical analysis and numerical simulation experiment were used in this text to conduct a research on calculation method of anti-slide pile based on the strain wedge theory and the passive soil-arching effect in the front of piles,the main work and conclusions in this paper are as follows:1.Three kind of equivalent cross section was proposed to consider the contribution of protection-wall to the stiffness of pile body,and using the idea of cantilever pile method,the deformation of loading segment of pile is calculated as a cantilever beam,and the deformation of embedded segment is calculated based on the method of modified strain wedge,an example shows that it is feasible when apply the strain wedge theory to calculate the anti-slide pile;and by comparing the deformation characteristics between pile with protection-wall and pile without protection-wall under the same load,it turns out that the protection-wall has a positive effect to pile for bearing horizontal loads,and it reduces about 23.6% of the horizontal displacement of pile top.2.The method for calculating horizontal bearing capacity of anti-slide pile based on the control of displacement of pile top was proposed,and the formula for calculating the flexural capacity and the shear capacity of pile with protection-wall based on the control of material strength of pile body was proposed.On this basis,the method to compute contribution of protection-wall to the horizontal bearing capacity of pile based on the above two factors was also proposed.3.Based on the Mindlin stress solution under the action of horizontal concentrated force,and a pile-soil interaction analysis model was set up under plane problem,the expression for calculating additional stress at a depth plane of soil before anti-slide piles was deduced,then the stress contours were obtained through an example,and combined with the results of numerical simulation experiment,it shows that the passive soil-arching effect appears in the passive zone of soil in the front of piles under a certain conditions.4.The analysis of 3-D numerical model was constructed to study influence factors of passive soil-arching effect in the front of anti-slide piles by using ANSYS.The results indicate that the passive soil-arching effect weakens with the increase of pile-space,the shape of soil-arching becomes steep firstly and then becomes smooth gradually.And with the increase of horizontal displacement of pile,the passive soil-arching effect plays more fully,the range of soil-arching grows larger.On the depth direction of pile,the passive soil-arching effect weakens with the increase of depth,and the range of soil-arching is smaller.The soil cohesion plays a positive role in passive soil-arching effect,but the internal friction angle has little influence on passive soil-arching effect.