Research On The Properties Of Unsaturated Red Clay In Chenzhou Distract And Its Application

Engineering practice and research results show that:The engineering and physical properties of unsaturated soils have a distinguish difference from saturated soils because of the existence of suction in the soil. Because of this, unsaturated soils can not be easily regarded as saturatd soils. Located in the Lingnan region, Chenzhou has a wide distribution of red clay which is always in an unsaturated circumstance. Slopes constituted by red clay can keep stable with a rather steep gradient and cconsiderable height when there is no rain. While, even a very gentle slope can slide after a rainfall. Due to the insufficient understanding of the unsaturated properties of red clay, slopes often slide after reinforced and reinforced again after a second slide, which cause a huge economic lost to Chenzhou. As a result, research on the unsaturated properties of red clay in Chenzhou and its influences on the stability of slopes and foundation pits have a important theoretical and practical meaning. In order to understand the unsaturated properties of red clay in Chenzhou and its influences on the stability of slopes and foundation pits, following research works were done in this paper.1、By measuring the suction of the red clay in Chenzhou in different water content through the filter method and fitting the results with a function, a simple form of soil-water characteristic curve (SWCC) was require, which forms the foundation for the research of unsaturated seepage and the strength of red clay2.Through the unconsolidated and undrained triaxial tests, the variation of the total shear strength parameters of red clay in different water content was researched and the mechanism how water content influences the total shear strength parameters was analysed as well. By fitting the results with a function, the relationship between the total shear strength parameters and water content was presented in this paper.3. Combining the one-dimensional unsaturated seepage theory, the SWCC and the relationship between the total shear strength parameters and water content required by tests, the stability of a foundation pit in Chenzhou was analysed in the different rainfall intensity. The analysis reveals the relationship between the safe factor and rainfall intensity and provides a simple and practical method to evaluate the stability of slopes and foundation pits constituted by unsaturated red clay in Chenzhou.