Numerical Calculation Of Equivalent Modified Cam-clay Parameters For Cement Mixing Pile Composite Foundation Of Expressway In West Dongting Lake Area

The soft soil is widely distributed in the West Dongting Lake area,and the settlement and deformation characteristics of soft foundation should be considered in the construction of expressways in this area.For the treatment of soft soil foundation with cement mixing pile composite foundation,it is necessary to analyze the influence of various parameters of cement mixing pile composite foundation on the control effect of soft foundation settlement deformation.In this paper,the finite element software ABAQUS is used to simulate and calculate the equivalent modified Cam-clay parameters M,λ and κ of cement mixing pile composite foundation.The comparison and analysis of numerical simulation and field monitoring results verify the effectiveness of the equivalent modified Cam-clay parameters.The influence of pile length,pile spacing and pile diameter of cement mixing pile on the equivalent modified Cam-clay parameters is studied by orthogonal analysis method and SPSS data analysis software,and the corresponding regression equation is obtained,which provides reference for the optimal design of cement mixing pile composite foundation of expressway in West Dongting Lake area.The main research contents are as follows:(1)The general situation of soft soil foundation engineering in West Dongting Lake area is investigated and analyzed.According to the field settlement deformation monitoring data,the settlement deformation control of cement mixing pile composite foundation is analyzed,which provides data support for the validity verification of equivalent modified Cam-clay parameters of cement mixing pile composite foundation.(2)The finite element software ABAQUS is used to simulate the consolidation drainage triaxial test and consolidation test.The failure constant M,consolidation parameter λ and rebound parameter κ of homogeneous cement mixing pile composite foundation are obtained.The relationship between pile length,pile spacing and pile diameter and equivalent modified Cam-clay parameters M,λ and κ is analyzed.The results show that the failure constant M increases with the increase of pile length and pile diameter,and decreases with the increase of pile spacing.λ and κ decrease with the increase of pile length and diameter,and increase with the increase of pile spacing.(3)The equivalent modified Cam-clay parameters M,λ and κ are introduced as the model parameters to establish the composite foundation model of cement mixing pile for expressway in line with the engineering practice.The numerical simulation results and field monitoring data are compared and analyzed to verify the effectiveness of the equivalent modified Cam-clay parameters of cement mixing pile composite foundation.The finite element simulation of consolidation settlement has 15.53%error compared with the field monitoring data,and the simulation results are more accurate.It is feasible to use the equivalent modified Cam-clay parameters of cement mixing pile composite foundation to simulate the consolidation settlement of cement mixing pile composite foundation of expressway in West Dongting Lake area.(4)Based on orthogonal analysis method,SPSS data analysis software was used to explore the influence level of basic parameters of cement mixing pile on equivalent modified Cam-clay parameters,and the non-standardized coefficient regression equation of equivalent modified Cam-clay parameters of cement mixing pile composite foundation on pile length,pile spacing and pile diameter was obtained.The correlation coefficient R2 of the regression equation is above 0.93,and the fitting degree is high.It can accurately calculate and analyze the equivalent modified Cam-clay parameters of cement mixing pile composite foundation.