Research Of Foundation Soil Consolidation Settlement Laws Under Material Accumulation Loading Around Yangtze River

The Yangtze River Economic Belt is based on the golden waterway of the Yangtze River and plays the core role of Shanghai,Wuhan and Nanjing.The engineering geological characteristics of soft soil along the river have gradually become the key and difficult problems of engineering construction in this area.The muddy silty clay under the raw material yard of Masteel has engineering characteristics such as large void ratio,high compressibility,high water content and low shear strength.It is widely distributed along the river and has a great impact on local regional development and engineering construction.Therefore,it is particularly important to study the variation of physical and mechanical indexes and engineering characteristics of muddy silty clay in the site.On the basis of previous studies,this paper takes the muddy silty clay exposed in the survey of Masteel raw material yard as the research object.Firstly,the conventional physical index test,triaxial test and consolidation test of muddy silty clay are carried out.Then,the physical and mechanical index statistics are carried out by mathematical statistics method,and the regression equation of physical and mechanical index is established.The correlation coefficient is introduced to evaluate the correlation between physical and mechanical indexes.On this basis,through the stress analysis of Masteel raw material yard,the strength characteristics and deformation characteristics of soft soil foundation in the process of bulk material loading are analyzed.Three kinds of foundation settlement calculation methods are used to calculate and predict the settlement of soft soil foundation in the muddy silty clay layer in the site.Based on the finite difference method,a three-dimensional digital model of raw material yard is established for numerical analysis.Through this study,the following conclusions can be drawn:（1）The average value of natural water content（w）,natural void ratio（e）,compression coefficient(a_v1-2)and compression modulus（E_s）of the original foundation mucky muddy silty clay in Masteel raw material yard is 40.45%,1.14,0.68 MPa^-1 and 3.22 MPa.It is a kind of soft soil with large void ratio,high water content and high compression.（2）By analyzing the strength characteristics of muddy silty clay in the study area,it is found that it has strong structural characteristics.Therefore,the rational use of the structural characteristics of foundation soil can reduce construction costs and improve safety.（3）Through the statistical analysis of physical and mechanical indexes,it is found that the correlation of water content fitting curve in the physical indexes of silt in the study area is good,the variability of mechanical indexes is high,and the correlation between compression coefficient(a_v1-2),cohesion（c）,unconfined compressive strength（q_u）and void ratio（e）is good.（4）Combined with the raw material yard project of Masteel,the stress analysis of muddy silty clay is carried out.The settlement calculation and settlement prediction of soft soil foundation are carried out by layered summation method and standard method.The final settlement calculation results are 1.854 m,2.033 m and 2.025 m respectively.Therefore,the secondary consolidation amount of muddy silty clay in the site is large,and the secondary consolidation settlement of soft soil should be fully considered in the construction of the project in this area.（5）Through the analysis of compression coefficient and compression modulus in each stage of raw material yard,the engineering characteristics of silt muddy silty clay under the raw material yard of Masteel have changed after treatment and raw material loading,and the soft soil layer has changed from high compression soil to medium compression soil.（6）According to the finite difference method,the soft foundation is modeled in three dimensions,the bulk loading is simulated,the pore water pressure in the soft soil under graded loading and the settlement deformation analysis of the soft foundation are analyzed to reveal the stress-strain law that the maximum stress to the soft foundation under long-term loading is concentrated in the load center and the maximum strain is located on the surface of the foundation.