Study On The Force Calculation Of Pile And Wall Composite Structure Considering Horizontal Soil Arching Effect

The existence of soil arching effect between anti-slide piles has been widely recognized and applied to the determination of pile spacing.However,because the stress influence of soil arch structure and soil arching effect on the anti-slide pile combination measures(retaining wall between piles,sheet pile wall,soil nailing wall between piles,etc.)is not fully clear,the soil arching effect is rarely considered in the design practice of anti-slide pile combination measures at this stage,which limit the application of soil arching theory in engineering.Adopting the widely distributed granite and the red bed sand-mudstone residual soil,this paper tries to explore the structure,height and influencing factors of horizontal soil arching between piles comprehensively through experimental study of horizontal soil arching traits of slope anti-slide piles,and then put forward the arch axis equation and arch high calculation method of soil arching which takes soil properties into account and is applicable for engineering;carry out the theoretical analysis and numerical simulation study of stress mechanism of pilling wall combination measures considering horizontal soil arching effect,and then put forward stress calculation method and optimization design idea of anti-slide pile and inter-pile structure in combination measures;through numerical simulation and mechanical analysis,the paper studies the soil arching structure including type and height between piles,changing rule along the direction of pile length and its influencing factors,and then achieve the soil arch type and soil arch height at different positions of pile length,and the influence of pile section size.The main research results are as follows:(1)Based on the theory of Prandtl-Vesic Passive Zone,it is proposed that the arch axis of the soil arch behind the anti-slide pile can be simplified to isosceles triangle.The arch axis equation is mainly controlled by the internal friction angle of soil,the height of soil arch is controlled by the internal friction angle of soil and the distance between piles,and the cohesion of soil and the size of pile section have obvious influence on the soil arch effect,such as the arch springing and failure condition of soil arch.(2)The horizontal soil arch traits between slope anti-slide piles changes obviously along the direction of pile length,and it is related to the magnitude of post-pile load(residual sliding force or soil pressure).The horizontal soil arch effect only exists in the range that is below the pile top and above the sliding surface.As the distance from the pile top increases,the height of the soil arch gradually decreases.As the load behind the pile increases gradually,the soil stress first concentrates on the back of the pile,forming end bearing arch.After the end bearing arch is destroyed,the soil stress will concentrate on the side of the pile,forming friction arch.(3)The size of anti-slide pile section has a significant influence on the horizontal soil arch effect of anti-slide pile,because different sizes of anti-slide pile section will lead to different stresses acting on pile back and pile side.When the width of pile is larger,the height of end bearing arch between piles is larger.When pile height is larger,friction arch height between piles is larger.With the increase of pile length and depth,the horizontal soil arch between piles is easier to change from end bearing arch to friction arch.(4)The horizontal soil arch effect has a significant effect on the stress of anti-slide pile combination measures.The stress calculation method of retaining wall between piles considering horizontal soil arch effect is put forward.In the pile-wall combination measures,the pile bears the residual sliding force generated by the soil after arch,and the retaining wall bears the soil pressure and residual sliding force generated by the soil before soil arch.In the combination measures of soil nailing wall between piles,the stress of pile is the sum of the residual sliding force generated by soil after arch and that of soil nailing wall,the soil nailing wall bears the greatest of the soil pressure generated by soil before arch and the residual sliding force,and the dividing line between the free section of soil nailing and the anchorage section is the horizontal soil arch trace.