| The micro-pile has the advantages of non-excavation mechanical hole,strong applicability to the stratum,flexible arrangement of pile location,small disturbance to the sliding body,safe and fast,It has been applied more and more in the rapid treatment of slope and emergency rescue.However,the small cross section area of the pile and the large length diameter ratio lead to the limited bearing capacity of the pile,under the action of landslide thrust,it is easy to produce large deflection and lateral tilt.Therefore,in the actual project,the micro-pile is prone to bending shear failure.Anchor-micro pile composite anti sliding structure using a plurality of vertical or inclined micro pile,pile cap beam,oblique anchor and surrounding rock and soil constitute a composite pile anchor structure compared with the ordinary micro pile structure,the passive force is changed to the active force,and the sliding bearing capacity of the composite structure is improved to some extent.This paper uses theoretical analysis,numerical simulation and field monitoring method of Anchor-micro pile composite structure anti slide mechanism,internal force calculation,bearing performance and practical application effect to carry out the related research work and achievements are as follows:(1)From the aspects of plane,section and space combination,this paper introduces the configuration of the anchor pile composite structure in three aspects.In this paper,the reinforcement mechanism of the anchor pile composite structure is analyzed,and the interaction mode and deformation failure characteristics of the anchor pile rock soil interaction are put forward.(2)This paper summarizes the design and calculation method of the existing anchor-micro pile composite structure,analyzes the shortcomings existed in design,put forward to reflect the anchor-micro pile deformation coordination design method,establishing the structure calculation model,deduces the deformation coordination model based on the research at home and abroad on the design steps are given,for the application of composite structures in engineering play a role in promoting.(3)Micro pile group belongs to the interaction of pile and soil,pile-soil load share ratio of 8:2,micro pile group pile,pile spacing,row spacing reasonable should be 3～7 times of the pile diameter,the reasonable anchorage length for pile length of 1/3～1/2.The share ratio of soil pressure between 1 and 3 rows of piles is 1:0.8:0.5.(4)The top constraint micro pile of prestressed anchor cable not only can effectively limit the displacement of pile top,and can share part of the landslide thrust;anchor pile setting can improve the stress state of the micro pile can be calculated;the optimal anchoring angle and anchoring force according to slope engineering,pile anchor load sharing ratio is 0.5-1,the optimal anchor angle values of 15°～30 °.(5)Numerical analysis of K16 landslide in Guizhou control measures,the design scheme of micro pile diameter 150mm,length 7.5～12M,according to 1*1m rectangular arrangement of prestressed 800kN is reasonable,but tend to be conservative,set aside a larger safety factor.The landslide deep displacement,pile bending stress,pile lateral soil pressure,prestress loss on-site long-term monitoring,analysis of motion state of different stages of landslide and retaining force characteristics of structure,monitoring data show that the combination structure of landslide treatment engineering effect is good. |
