Research On The Design Technology Of The Micropile Reinforcing Landslide In Shallow Accumulation Layer

As a new type of micro pile reinforcement retaining structure, is generally between 100-300mm small diameter anti sliding pile. This kind of small diameter pile branch with the traditional retaining structure compared with non excavation construction, the advantages of smaller, flexible layout location, fast construction speed and economic good perturbation of soil around the pile, the shallow layer accumulation landslide is applied more and more widely. But the micro pile landslide reinforcement of theoretical research lags far behind in its application in practical engineering is still not formed a than systematic micro pile calculation theory and design method, to a large extent restricts the application and popularization of micro pile. In view of this, in order to draw the reinforcement mechanism and design technology of micro pile, this paper is based on the similar model tests in the laboratory, for shallow landslide, mainly for the following research work and conclusions:1) According to the elastic plastic theory, the study of the soil pile row transmission mechanism, by the pile-soil deformation compatibility principle, the analysis of micro pile reinforcement mechanism, comprehensive comparison, recommended the use of the transfer coefficient method to determine the landslide thrust, combined with common anti slide pile calculation method, cantilever pile method and follow the example of micro pile internal force calculation, bearing capacity and flexural bearing capacity and shear capacity determined by the level.2) through the model test and comparison of different test conditions, micro pile ultimate failure forms of consistency, near the surface, above the sliding surface by load pile to slide on the front of the body bending deformation, below the surface anchoring section to slide bed trailing edge bending deformation, smooth curved point between pile occurred inclination deformation, distortion in the remaining part of the pile body no, keep into the vertical state. The three failure modes of micro pile group, respectively. The overall damage, single pile failure and local failure.3) With the elastic plasticity theory and model test result analysis, summarizes the design principle of micro pile, namely reasonable pile spacing should be 8-12d, row spacing should be 10d, this range can not only effectively exert their anti slide force can best play between piles soil arching effect; the pile anchor depth to 1/3-2/5 pile length best; Pile soil around Dense real-time, pile group should adopt the arrangement of the layout of soil is loose, pile group should adopt the plum shaped arrangement; group pile top shall be provided with coupling beams, both limiting pile top displacement and the force of pile more uniform and plump; on the basis of the actual rainfall, set the corresponding drainage system.This paper uses elastic-plastic theory and method of model test is discussed. The micro pile reinforcement design problems of shallow accumulation landslide, the research results can provide theoretical guidance and reference for practical engineering applications.