Study On The Horizontal Displacement And Internal Force Distribution Of Pile Anchor Retaining Structure

The foundation pit engineering combines the characteristics of geotechnical engineering,structural engineering and geological engineering.Due to its complexity,the theoretical system of the foundation pit engineering is not perfect,and the foundation pit failure occurs frequently.At the same time,the foundation pit engineering has distinct regional characteristics,and the supporting structure of foundation pit is complex and diverse,this article mainly aims at the pile anchor supporting structure which is widely used in the northwest region,combined with the actual project,the factors which affecting the horizontal displacement of foundation pit was comprehensively analyzes,then the research methods and ideas of load transfer law and failure form of anchor system was expounded,then the numerical simulation method is used mainly to study the influence of the weak interlayer on the horizontal displacement of pile anchor supporting structure in foundation pit.Then,considering to the anchor rod in actual engineering body surface is not smooth,the load transfer model was established and analytic solution of the distribution of axial force on anchor was calculated.The main results and conclusions of this paper are as follows:(1)Taking the pile anchor supporting system with two rows of prestressed anchor as an example,considering the influence of prestressing of adjacent anchor bolts,the calculation method of bolt axial force under different excavation conditions is given.The solution provides a theoretical basis for further analysis of the axial force distribution along the length of the bolt.(2)Based on the background of one deep foundation pit engineering,the influence of soft interlayer on the horizontal displacement of foundation pit is studied.The finite element analysis software Plaxis2 D was used for the numerical simulation of pile with pre-stressed anchor support section in the engineering,and Mohr-Coulomb constitutive model was used in the simulation.Then the influence of the changes about cohesion,internal friction angle,different thickness and different embedment depth on the horizontal displacement in deep foundation pit was compared and analyzed and then got the impact curve of horizontal displacement by these factors.The results show that: the existence of soft interlayer do have larger effects on the horizontal displacement of deep foundation pit,and as can be seen from the curve,the two basic mechanical parameters of soil: cohesion and internal friction angle,internal friction angle has more important impact on the displacement of horizontal displacement of deep foundation pit.(3)In order to consider the effect of surface roughness on the mechanical characteristics of anchor,the load transfer model considering the surface roughness was selected,and with the load transfer method,the mechanical characteristics of anchor solid under three states: elastic,elastic-plastic and fully plastic respectively was studied,the analytical solutions of axial force distribution in anchor solid in different states are obtained.As can be seen from the results,the size of the rolling angle has a great influence on the mechanical properties of anchor bolt.At the same time,combined with practical engineering,it was found that the calculation result has good agreement with experimental data,and it shows that the computing model is conforms to the actual situation,the results are reasonable and reliable.