Discrete Element Analysis Of Anti-slide Piles And Reasonable Pile Space Calculation

In engineering practice, pile driving is one of the commonly methods to reinforce landslide. The principle is that landslide thrust will be transferred to anti-slide piles by soil arching effect, then soil and piles can burden the load together. So occurrence and development of soil arching effect have a great influence on result of reinforced slope by anti-slide piles. The current studies of soil arching effect in numerical field are most of using finite element or two-dimensional discrete element. However, soil is one of heterogeneous granular materials and soil arching effect occurs in three-dimensional space. In the calculation of reasonable pile space, soil arch in the piles side and behind the piles are considered separately, but under some certain condition, both of them can bare the landslide thrust together. Based on the predecessors’ research results, in this paper, the main contents are as follows:(1)By YADE, a three-dimensional discrete element simulation is set up to analyze soil arching effect between anti-slide piles in different soil layers. Effect of variation of space between piles and soil inhomogeneity are taken into account. As results, in horizontal direction, with depth increasing, rise of soil arching is decreasing and shape of soil arching changes from’rear vault’ to ’flat’, while strength of soil arching is increasing. Influence of soil arching effect will decrease when space between piles increasing, result in the ratio of load bearing by anti-slide piles decreasing, but trend of decrease gradually slow down. Soil arching effect will take shape in advance when non-uniform degree of soil particles increasing, however, the ultimate bearing capacity of soil arching basically remains unchanged.(2)Under the condition of taking soil arch in the piles side and behind the piles into account together. In two-dimensional plane, a calculation method is proposed to work out the reasonable pile space with assumption of reasonable arch axis. Then through an example, different distributions of landslide thrust along piles are analyzed, the calculation method is also validated. Some parameters in the method are analyzed at the same time.(3)Based on the simulation of single rank of piles, discrete element simulation of double-row piles is set up. Soil arching effect and variation of landslide thrust acting on piles in this system is analyzed. Changing piles row space and arrangement styles of piles to study the influence on soil arching effect. The results show that soil arching effect and landslide thrust acting on back rows of piles will remain unchanged when piles row space and arrangement styles of piles changed. But soil arching effect of front rows of piles will enhance when piles row space increasing. More load displacement is required to achieve ultimate bearing capacity of front rows of piles when arrangement styles of piles changing from parallel arrangement to quadrilateral arrangement.