Numerical Analysis Of Composite Foundation Settlement With Inclined Hard Layer In Soft Soil Area

Along with the rapid development of our country’s infrastructure construction inaspects of highway and high-speed, crossing soft soil areas such as rivers, lakes,swamps, valleys and depressions in the engineering construction is unavoidable,which leads to the encounter with soft soil foundations with inclined hard layer. Theengineering is facing many problems like uneven settlements and poor stabilitybecause of the poor uniformity and large difference in engineering properties of softsoil itself and the influence of inclined hard layer. However, the related research ofsoft soil foundations with inclined hard layer is very lack in the aspect of theoreticalanalysis, experimental research, as well as fast and efficient treatment technology andthe corresponding design and calculation method.Firstly, as for the natural soft soil foundation with inclined hard layer underflexible load, related research is carried on to investigate the influence of inclinedbedrock on foundation settlements under non-uniformly distributed load in terms oftwo key variables: the depth of the compressible soil to the bedrock/the width of thefoundation (the depth–width ratio) and the bedrock inclination (assuming the dipperpendicular to the direction of the strip foundation), which is based on the elastictheory of settlement analysis and the finite element numerical analysis method.According to the numerical results, design charts of settlement influence factors anddifferential settlement influence factors under different load conditions are given tohelp practice application. Besides, parameter analysis of influence of calculatingparameters on settlements and position variation of the largest settlement with thechange of the depth–width ratio and the bedrock inclination are given. At the end ofthis paper, a design example is presented to illustrate the use of the design charts.Secondly, as for the research of composite foundation with inclined hard layer,which is reinforced by gravel pile, simplifying simulation test plan according to theprinciple of the orthogonal experiment and carrying on numerical simulation work ofgravel pile composite foundation with inclined hard layer by combining the powerfulmodeling function of ANSYS and constitutive model of FALC3D. Based on theresults of numerical calculation, study on the research of the influence of inclinedhard layer on gravel pile composite foundation and position variation of the largestsettlement in terms of four key variables: thickness of soft soil layer, slope Angle of hard layer, rate of replacement of gravel pile and compression modulus of soft soillayer. Based on the elastic theory of settlement analysis, regression analysis ofnumerical test results is performed and achieved settlement calculation method ofgravel pile composite foundation under the influence of the four key parameters.