| China is a country with frequent geological disasters.And landslide disasters occupied a large part of geological disasters.Landslide disasters have caused great damage to human production and life.The traditional retaining structure is difficult to fully meet landslide hazards.As a new type of combined retaining structure that mainly uses grouting technology and steel pipe pile forming technology,micro pile has features of small disturbance to the soil around the pile,fast construction speed,and flexible location of the piles and flexible.In recent years,it has been widely used in the treatment of small and medium accumulative landslides,especially in the case of complex geological conditions.However,the micro pile reinforcement technology theory is still not perfect,especially the research on the effect of coupling beam on the stress state of micro piles is still immature,which restricts the application and promotion of micro piles to some extent.Therefore,this thesis based on the existing theory of micro piles reinforcement,a three-dimensional numerical model was established based on known experiments.By comparing the bending moment and displacement of the micro pile,the deformation characteristics of the micro piles under different coupling beam types were analyzed.And the influence of the coupling beam on the stress state of the micro piles was discussed.In this thesis,the author controls parameters such as pile spacing,row spacing and anchorage depth.In the micro-pile plum-shaped arrangement,the working conditions of six different connection beam types are designed.In the rectangular arrangement,two groups of different connection beam forms are designed for comparison.The simulation results show that the integrity of the pile group system is strengthened after the micro-piles are installed on the top of the pile.The bending moment and displacement distribution pattern of the micro-piles is similar,but the numerical values are greatly reduced;Coupling beams have different effects on the stress state 'of micro piles.Under the miniature pile plum arrangement,the maximum value of the bending moment can be seen that the horizontal and vertical cross-linked beams are slightly smaller than the vertical cross-linked beams,and the two are relative to the maximum bending moment value of the independent micro-piles.Three rows of piles(front,middle,and back)decreased by 30.7%,23.2%,22.2%and 28.8%,21.6%and 20.6%,respectively.Compared with the displacement at the top of the pile,it can be known that the horizontal and vertical cross-linked beams are slightly smaller than the vertical cross-linked beams,and the three-row piles are reduced by 40.7%with respect to the maximum bending moment of the independent micro-piles by 35.1%,24.8%and 39.4%,34.8%,24.6%;The moment value and displacement value of the pile body from small to large are horizontal and vertical cross-linked beam forms,longitudinal cross-linked beam forms,transverse cross-linked beam forms,cross-linked beam forms.Cross-linked beam form,independent micro pile form.The extreme values of the bending moment of the piles in the form of longitudinal cross-linked beams and transverse-longitudinal cross-connected beams are very small,which indicates that the reinforcement effects of the two are similar.When the micro-piles are rectangularly arranged,the maximum value of the bending moment of the pile and the displacement value of the pile top are far less than the working conditions of the horizontal connecting beam.It can be inferred that the lateral connection plays a limited role in resisting bending moment and displacement of the pile body.Taking into account the economy and ease of construction,it is most appropriate to choose the type of transverse cross-linkage beam in the project.In this thesis,through the study of micro piles to control the accumulation of landslides,a more reasonable layout of connecting beams is obtained,which provides theoretical guidance and reference for engineering practice. |
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