Experimental Study On The Performance Of The Arch Anti-slide Pile-wall Supporting Structure System

According to the problems that the stress state in the traditional anti-sliding treatment structure is unreasonable and the deformation is bigger, the anti-slide piles are arranged into arch and the top-beam with certain stiffness is set on the top of the pile in this paper. Under the action of the sliding mass thrust on the anti-slide pile cantilever segments, the pile head and the embedded pile are restrained respectively by top-beam and slide bed. The pile, top-beam and slide bed together form a semi-rigid space anti-sliding structure, which is called arch anti-slide pile-wall supporting structure system. In the process of the residual down-slide thrust increasing, the internal stress change and adjustment of arch anti-slide pile-wall supporting structure system, as well as the deformation and the destruction caused by that are all influenced by the slide body, slide bed and anti-sliding structure itself.The study takes the loess landslide as the prototype. The loess landslide is governed with arch anti-slide pile-wall structure whose rise-span ratio is for1:10. By the large physical model test whose geometric similar ratio is for1:20and numerical experiments, the performance of the arch anti-slide pile-wall supporting structure system, such as the mechanical character, load transfer mode and deformation and damage rule, are studied. The research results will provide basic data for subsequent landslide treatment research and engineering practice. The main research results are as follows:1.The basic idea of the arch anti-slide pile-wall supporting structure system is systematically described according to the deficiency of traditional anti-sliding structural stress and control deformation, combining successful practices of the arch supporting structure in the excavation engineering and research results of the space anti-sliding structure.2.Taking the loess landslide in ShanBei as a prototype, based on the basic requirement of the coordinate stress between pile and soil, the similarity relation of the model test is deduced whose geometric similar ratio is for1:20, and the reinforcement coefficient is defined, and the equivalent reinforcement problem between prototype structure and model structure is solved.3.The concrete and steel in the model are developed meeting similar relations. The performance of the model material is studied by the bending test of the model single pile. The experimental results show that model single pile and prototype pile have roughly the same bending deformation and destruction features. The strain of tensile steel in any section and its corresponding bending moment has certain mapping relation, which provides the basis for reversing section bending moment through the steel strain.4.The large physical model test is designed and implemented whose geometric similar ratio is for1:20and the soil pressure of pile body, the strain of tensile steel and the displacement of pile head are measured and analyzed. The results show obviously a spatial signature that the landslide thrust in the middle is much bigger than the both wings. Arch anti-slide pile-wall supporting structure system can transfer the central larger landslide thrust effectively to the two wings of the pile body with smaller thrust, and make them working together to reduce the possibility that the central piles destroy first then the adjacent piles damage gradually. But this kind of structure failed to change the traditional anti-sliding structural damage mode. The each pile is still bending failure when the limit load is acted on the arch anti-slide pile-wall structure system.5.The numerical experiments are implemented on the arch anti-slide pile-wall supporting structure system, the traditional anti-sliding structure, the arch anti-slide pile-wall supporting structure system with anchorage and the arch anti-slide pile wall supporting structure system with tensile bar. Compared with the traditional anti-sliding structure, the imbalanced force and deformation on each pile of the arch anti-sliding pile-wall supporting structure system are improved obviously. The displacements of pile head reduced about60%but the total control bending moment of the system did not change. When the piles Z1and Z11are expanded to anchorage, the bending moment of the piles Z2and Z10decreased obviously, the bending moment of the pile Z6with a little change. So the gap of bending moment and deformation between Z10, Z2and Z6are enlarged. After adding bars between Z1and Z11, the displacement of the top-beam is limited in x direction, the constraint ability to incongruous stress and deformation of each pile are enhanced, and more slide bed soil participate into the anti-sliding system. The controlling moment distribution of each pile in the system is more reasonable. Total controlling bending moment of anti-sliding system are reduced by about7%to8%compared to traditional sliding structure and the displacements of pile head are reduced by about70%. 6.Defining the adaption to parameters randomness and the adjustment ability of the structure as the s robustness of tructure and use the structural robust degrees-Ds as its numerical measure. The arch anti-slide structure and the arch anti-slide structure with tensile bar can better adapt to and adjust the unbalanced thrust of the landslide between each pile. Thus it has higher structural robust degrees compared with the traditional anti-slide structure with lower structural robust degrees. When achieved the management target with a5%structure failure probability of the same landslide, the safety factors of the arch anti-slide structure, the arch anti-slide structure with tensile bar and the traditional anti-slide structure are respectively1.72,1.32and1.23.Due to the positive correlation between the project cost and the structural safety factor, the project cost of the arch anti-slide structure with tensile bar and the arch anti-slide structure are reduced by29%and24%respectively compared with the traditional anti-slide structure.