Research On The Silt-sand Mixed Soil’s Engineering Characteristics And Comparison Of Its Treatment Methods

With the constantly development of the highway projects, the probability that we meet silt-sand mixed soil foundation will become higher, to study its engineering properties is good for selecting the reasonable and feasible soft foundation treatment methods. Although a lot of engineering properties research about soft soil have been done, the engineering properties research of soil-sand mixed soil is fewer and the silt -sand mixed soil is even fewer. Meanwhile, the studies of using the cement and lime to reinforce the soft soil are also rare, its mechanism of action, the variation of strength that influenced by many factors, and the choose of soft foundation treatment programs are still need further studied.This thesis is a part of research result about "The study of soft soil engineering properties and foundation treatment technology in granite area" (Jiangxi provincial communications department of science and technology projects). Based on the project of Jing-mu highway’s silt-sand mixed soil, through using the laboratory tests to conduct the related research of this kind of soft soil. The main contents of this study includes:(1) Studied the engineering properties of the silt-sand mixed soil by using laboratory tests. Designed the light compaction test to analyse its density variation; Meanwhile, launched a series of undrained triaxial tests, studied the law of shear strength, and pointed out the bounded sand content of this mixed soil is 40% to 70%. It provided the reference on technical and theoretical for the treatment of such kind of soft foundation.(2) Studied the intensity variation of this mixed soil that reinforced by cement and lime through the laboratory tests. Using cement and lime as curing agent to reinforce the silt-sand mixed soil, and designed the compressive strength test, studied the sand content, curing period, the mixture ratio of cement and lime, cement content and lime content, such factors that affect its strength and deformation characteristics. Found out the variation of deformation characteristics, failure characteristics and the law of compressive strength that influenced by these factors.(3) By listing the feasibly reinforcement methods about silt-sand mixed soil foundation that refer to the Jing-mu highway project, through technical analysis and economic comparisons to determine the best soft foundation treatment method. Research analysis have shown, cement deep mixing pile has many advantages, and it is the best treatment options, it has certain advantages to ensure the reinforcement effect and saving engineering economy.