Measurement of SWCC of Xiamen Residual Soil by Filter Paper

Soil suction is one of the most important parameters for unsaturated soils. An experimental program was carried out to measure the maric suction of soil specimens of a residual soil in Xiamen by filter paper method. Initial water content, soil structure, and stress state were taken into account to investigate the hysteresis loop of SWCC. The air-entry value of test soil is about 140kPa and residual saturation is about 18%. The soil specimen at wet of optimum has the largest hysteresis loop for a relatively uniform pore-size distribution. However, the soil specimen at dry of optimum has the smallest hysteresis loop. The soil specimen at optimum lies between them. For specimens subjected to different stress states under various applied loads, the higher the applied load on the specimen, the smaller the size of hysteresis loop. In drying or wetting process, there is a significant difference in matric suction though soil specimens are at same water content. Therefore, for this kind of soil, it should be attention that the shear strength may be greatly reduced during rainstorms.