The Pile-anchor Supporting Numerical Simulated And Supporting Parameters Design Research

In the past 40 years since the reform and opening up,China's economic construction has been developing rapidly,and the national comprehensive strength has been improved.At the same time,the material living standards of the people have been greatly improved,therefore higher requirements have been put forward for the living environment.This makes the gradually increasing scale of urbanization,high-rise buildings springing up,emerged a large number of deep foundation pit engineering.Meanwhile,for the support of deep foundation pit,it has been a research subject for many scholars in China and abroad.The soil nail wall support is not good at control that lateral deformation of the foundation pit and the subsidence of the surrounding ground surface because its rigidity is relatively small.Although the internal support structure is relatively rigid compared to the soil nailing wall,it has the capability of resisting deformation,but it will occupy more construction space after the internal support support,which will hinder the normal operation of construction machinery and delay the construction period.There are many kinds of supporting forms of the deep foundation,and the pile-anchor structure is formed by a series of piles and prestressed anchor,which is very safe,small construction,convenient,so it's widely used.In the process of designing the supporting structure,the engineer is inclined to the conservative design in order to guarantee the absolute safety of the structure in the working life,so that the structure has too much safety reserve,which can lead to waste of materials,increase the project cost,and don't achieve the goal of saving cost.On the contrary,the wrong design rule can void the structure,causing engineering safety accidents,causing significant loss of life and property.Therefore,a scientific and reasonable method should be used to design and calculate the pile anchor support structure.This paper applies the large-scale finite element software ABAQUS to conduct numerical simulation study on the foundation pit of Beijing world garden hotel.The main tasks are as follows:1.Firstly,this paper introduces the foundation pit engineering basic situation of the park hotel in Beijing,using the equivalent beam method and combining the Rankine's earth pressure theory to design the pile-anchor supporting structure.Through the simplified calculation method,the calculation parameters of the support structure are obtained,and the calculated results are compared with the original design scheme to discuss whether the original design scheme is reasonable.2.The foundation pit engineering covers an area of large,support type is more,including The pile-anchor support,retaining wall support,combined support of soil nailing wall and retaining piles.In this paper,we select a more sophisticated pile-anchor support structure made up of two-layer prestressed anchor and supporting pile as a research object,using the large finite element software ABAQUS to analyze pile-anchor support structure located in the 1-1 section of foundation pit.In combination with the geotechnical investigation report and field measured data of the project,the elastic modulus E of the rock soil body in the excavated area of the foundation pit will be back-analyzed and obtain the equivalent elastic modulus.3.We use ABAQUS software to simulate that excavation and support process of foundation pit,to investigate the stress and deformation rule of foundation pit and pile anchor support structure.And the problem of cracks in the brick wall of the retaining wall is to be discussed,and some suggest of solution summarized based on the numerical simulation,which is a reference for similar projects.4.Quality of foundation pit supporting is not a single index,but many comprehensive effects.Based on this consideration,this paper,based on the numerical model,takes the safety factor of the pile anchor supporting structure,the horizontal displacement of the supporting pile and the maximum tensile stress of the pile as the evaluation criterion and takes built-in depth of the pile anchor supporting structure,diameter of support pile,the vertical spacing of prestressed anchor as the evaluation factors.Firstly,we discuss that influence of four factors to judge criteria in the case of different levels,based on the result obtained,the reasonable value range of each factor is determined.According to this range,the orthogonal test model of multiple indexes was established,and the numerical simulation calculation of orthogonal test was carried out.The index score and comprehensive score of each orthogonal test were obtained,and the comprehensive score was analyzed by the method of variance analysis,and the key factors influencing the effect of anchor support were found,and the optimal supporting combination was obtained.The resultsprovide a reference to the design of similar projects,reducing the cost of engineering,improving the safety of the structure.