Expreimantal Research On Mechanical Properties Of Exapansive Soils In Chengdu Area

With the structures large-scale built in the expansive soil of Chengdu area, the buildings are higher, their basements are more deeply and the pit excavation depth of their foundations in the expansive soil region come bigger. It is still happen that the foundation pit slope craze and collapse. Expansive soil slope stability in Chengdu area has become one of the main factors of the project safety and economic benefit. Based on the foundation construction projects of Longtanshi Kechuang Center and Wangjiangjin Garden, the experimental research of physical mechanical properties and engineering properties on the expansive soil of Chengdu area were carried on in this paper. The contents are including:(1)The distribution of the expansive soil in Chengdu area, their characteristics, cause type, material composition and structure characteristics are introducted firstly. The physical mechanical and engineering properties of the typical expansive soil in Longtanshi Kechuang Center are test in the laboratory. Furthermore, in order to determine the most adverse related parameters of it stability, the yellow clay and the gray clay in the fissure of expansive soil are tested respectively.(2)The choice in the engineering of the direct shear tests in field is discussed. The direct shear tests in the Longtanshi Kechuang Center and Wangjiangjin Garden are carried on and the method include the large shear instrument and the horizontal shear at once. The tests in field are carried on in different conditions, such as natural state, saturated state, and different depth. Their shear strength parameters are obtained including the local expansive soil and the strong weathering mudstone at he same position. At the same time, the shear surfaces are described, the failure mode and characteristics of the expansive soil in the region are determined.(3)Based on the data about the shear strength obtained in the above tests, the relationship among the parameters in differet conditions are analysised, the main influencing factors of the shear strength are obtained and the the shear strength suggested-value of the region expansive soil are determined.