Deformation And Earth Pressure Research On The Supporting Structure Of Dual-purpose Diaphragm Wall

At present,routine supporting methods adopted in deep foundation pit engineering are widely used,but lots of building materials have been wasted because of those methods can not be reused.What "dual-purpose diaphragm wall”means is underground diaphragm wall.It not only used as basement outer wall which palys a role in vertical load-bearing,but also as impervious supporting structure of retaining wall.Therefore,dual-purpose diaphragm wall has already been widely adopted in many projects.It is charactered with primary temporary supporting structure and loading and deformation as eternal structure.What.s more,the soil pressure is the main load,so it makes a very significant effect on the loading and deformation of supporting structure.So it is important to study the influence of deformation and earth pressure of the supporting structure of dual-purpose daphragm wall on the designing and construction of engineering.Based on foundation pit of Tongde square in Kunming,this paper makes a simulation analysis on its construction process by the finite element software to establish a three-dimensional finite element model of interaction among soil,construction and surroundings.Its calculation results are basically the same as the actual monitoring data,which demostrates its reliability.What's more,the author analyzes the results of numerical simulation.Their conclusions are as follows:(1)On the basis of the seniors' research,tha article set up dispalcement—soil pressure formula.In term of hard soil layer without roundstone,the calculation results of this formula is close to those of numerical simulation,which can provide similar foundation pit designs with some references.(2)The lateral displacement curve of continuous wall is shifted into convex shape from cantilever,with the ratio between maximum lateral value and excavation depths of corresponding operation condition ranging from 0.09%?0.32%and its shift removing from wall crown to excavation face.In the process of foundation pit excavation,the distribution models of soil pressure can be divided onto two patterns:the undulatingly progressive increase pattern and the sloping echelonment pattern with flute.The changes in soil pressure can be distributed into two parts:the increased tendency between wall crown and the one third height of wall and the decreased one for the left wall.Relationships between soil pressure and displacement can be viewed as hyperbolic curve,quadratic function and skew lines.(3)On the basis of above-entioned engineering instance,the article analyzes change rules of deformation of underground continuous wall and soil pressure caused by some factors including soil mechanical parameter(cohesion and internal friction angle),the thickness of the underground continuous wall,the depth of cantilever excavation,the support structure insertion ratio,the distance from nearby buildings to foundation pit,the ground overload(the size and length of overlaod,the distance from overload to foundation pit),nearby basement(the distance from nearby basement to underground continuous wall,the height and length of nearby basement).