| Accumulation landslide is one of the basic types of landslides, its slope component is gravel soil (coarse grained soil), and anti-slide pile has been widely used in the type of landslide; one of the main anti-slide the arrangement of anti-slide pile design is the pile spacing, reasonable spacing arrangement can form a soil arch, to maximize self-carrying capacity of the soil between the anti-slide pile. The formation mechanism of the anti-slide pile of soil arching remains to be further researched. Therefore, this thesis carried out theoretical and numerical study of the formation mechanism of the anti-slide pile of soil arching, to analyze the pile-soil interaction mechanism and the load transfer law of the anti-slide pile, and to provide technical support for the anti-slide pile design and to determine the pitch.This thesis starts from the analysis of the basic characteristics of Accumulation landslide, selecting the Three Gorges Reservoir Accumulation landslide-Majiagou landslide. Basic physical and mechanical parameters and stress-strain relationship for the study are obtained by laboratory test, and utilized in the correction of the PFC3D numerical triaxial test, then the sliding mass of coarse grained soil micromechanics parameters are gained and applied to the generalization Majiagou Landslide in three dimensional pile-soil interaction numerical model, and combined with the mechanical derivation. This research process serves to study the comprehensive system of typical Accumulation landslide formation mechanism and the process of anti-slide pile of soil arching.The main research contents are as follows:(1) Summarized the Three Gorges Reservoir Area of the basic characteristics of the Accumulation landslide and studied the engineering geological characteristics of one typical Accumulation landslide in this area-Majiagou landslide.(2) Elaborated the soil arching effect theory, and studied the anti-slide pile of soil arching effect of the substance and the soil arching pass the landslide thrust; according to the mechanical characteristics of the anti-slide pile, plane mechanical model is built by using the mechanical theory of anti-slide pile is exposed rectangle and triangle landslide thrust under the action of the pile soil behind the arch, derived the stress field distribution of the soil body behind the piles. the stress contour of the soil arching effect is analyzed.(3) Majiagou landslide body coarse-grained soil physical and mechanical properties is studied, PFC3D software is used to carry out the coarse-grained soils numerical triaxial shear test for coarse grained soil micro-mechanics parameters and analysis of shear displacement field formation and development of the law.(4) The particle flow model of three-dimensional pile-soil interaction process is built, the analysis of soil arching formation and development of the process of change from the perspective of micromechanics is carried out to study the soil arching mechanical transmission mechanism, based on the modeling result, the internal stress variation of soil arching formation is summarized, and the formation of soil arching mechanism is discussed.The thesis work contains the following innovations:(1) Improved anti-slide pile rectangular and triangular landslide thrust of the plane of the soil mass stress field distribution function, comparative analysis of the soil arching stress contours formation is studied.(2) The micromechanical nature of the coarse grained soil of the landslide in the accumulation layer in the reservoir area is studied; the coarse-grained soil triaxial shear test shear displacement field variation is analyzed and summarized.(3) The micromechanical process of the three-dimensional pile-soil interaction is studied, and the internal stress variation caused by soil arching between piles is analyzed, the variation patterns of the soil arching distribution according to the change of the loading process and the buried depth are summarized... |
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