Study On Bearing Capacity Of Subsoil Of Red Clay In Consideration Of Stress State

Red clay is a special kind of soil mainly distributed in the southwest of Sichuan,Guangxi,Yunnan and Guizhou.With the rapid development of China’s economy and the implementation of the western strategy,red clay engineering has become an important part of China’s modernization construction.As one of the important topics in geotechnical engineering,the bearing capacity of foundation has some problems,such as large calculation results and dangerous engineering design without considering the real initial stress state.Based on this,through data investigation,laboratory test,numerical simulation,fitting analysis and other research means,this paper studies in detail the bearing capacity and bearing capacity determination method of red clay foundation considering stress state,which has a certain reference for practical engineering.Specific research contents include the following four aspects:(1)the achievements and shortcomings in determining the bearing capacity of red clay foundation are studied.At present,the method of determining the bearing capacity of foundation ignores the influence of initial stress state of soil.After considering this condition,domestic scholars put forward a new approximate formula,but did not make pertinent analysis for the characteristics of red clay.(2)the basic mechanical properties and engineering properties of red clay are analyzed.The common engineering problems in red clay area are summarized,and combined with these problems,the shortcomings of existing methods for determining bearing capacity of red clay foundation are analyzed.The soil parameters of the samples were determined by laboratory tests.(3)the bearing capacity of red clay considering stress state is studied.The model is established by ABAQUS,a large-scale general finite element analysis software,and the physical and mechanical parameters of red clay in Guizhou are investigated and the data based on indoor geotechnical tests are supported.The load-settlement curves,stress distribution of soil and failure modes of red clay foundation under K0=1 are compared with those under real initial stress state.On this basis,eight methods for calculating the static earth pressure coefficient K0 are collected,and the influence of different methods for calculating the static earth pressure coefficient K0 on the bearing capacity of the red clay foundation is analyzed when the internal friction angle,cohesion,foundation size and foundation width of the red clay are changed by comparing the real initial stress state of the red clay.Furthermore,the influence of internal friction angle,cohesion,foundation size and foundation width on the bearing capacity of foundation is analyzed,which has a good reference value for similar red clay projects.(4)the method of determining bearing capacity of red clay foundation is studied.Based on the previous research on bearing capacity of red clay foundation considering stress state,the load-settlement curves of red clay considering real initial stress state are fitted and analyzed by using hyperbolic model and exponential model which are widely used at present.Compared with the exponential model,the exponential model is more suitable for predicting the ultimate bearing capacity of red clay foundation,and the internal friction angle,cohesion and foundation are analyzed.The influence of size and foundation width on settlement attenuation factor in exponential model.By comparing the numerical simulation results,the index model is modified to predict the bearing capacity.Based on the consideration of the allowable value of settlement and deformation of foundation,a method for determining the bearing capacity of red clay foundation is proposed,which provides a reference for practical engineering.