Experimental Study On Consolidation And Strength Characteristics Of Dalian Red Clay

In recent years,the economy of Liaodong Peninsula is developing rapidly,the passenger flow is increasing day by day,and the existing traffic network has been overloaded.In order to improve the transportation capacity,Dalian began to reclaim some areas of Jinzhou Bay,and plans to build a maritime international airport.The non-uniform settlement and salinization of the marine fill significantly affect the reliability of the project construction and the safety operation in the later stage.Moreover,the marine fill is fil ed with red clay which is widely distributed in Dalian area.Red clay is a kind of special soil,which is particularly sensitive to the change of environment.It is easy to disintegrate when encountering water and losing water,which is an important aspect to test the engineering performance of airport fill.According to the existing consolidation theory,the coefficient of consolidation remains unchanged in the process of compression,which is in contradiction with the actual situation.Therefore,the study of the consolidation and strength characteristics of red clay in the process of filling has a fundamental role in the prediction of settlement and the stability of fil.In this paper,the consolidation and strength characteristics of red clay in the marine environment are studied by means of experiments.The main work is as follows:(1)The research status of related fields at home and abroad is analyzed.The physical indexes such as natural moisture content,specific gravity,density and liquid plastic limit of red clay were measured,which provided the basis for the subsequent study of the consolidation and strength characteristics of red clay.(2)The shear strength parameters of red clay with different salt content and water content were obtained by direct shear test in laboratory.The results show that appropriate salt content can improve the shear strength index of red clay,and water content is the main factor affecting the shear strength index of red clay.(3)Compression tests were carried out on four kinds of red clay samples with different initial water content to explore the influence of water content on the compression characterist ics of red clay.Based on the compression data,the parameters of the model are determined,and the accuracy of the fitting results is evaluated.Based on the concept of pore index I_v and the principle of least square,the I_v-lnp compression model considering water content is established.(4)Based on a new type of three-dimensional strain testing device,the evolution law of internal strain state of saturated soil during one-dimensional consolidation is studied.It is found that the strain state of red clay tends to be stable gradually in the consolidation process,and the soil shows obvious anisotropic characteristics in the loading and unloading process.The resistivity method is used to quantitatively analyze the density distribution of red clay in the height direction during one-dimensional consolidation.