Abstract: The western region of Panzhihua city has abundant resources and will be the focus of development. Xigeda strata, which is distributed in this region, is a special soft rock with poor engineering properties. Research on Xigeda strata is of importance to the infrastructure construction and geologic disaster prevention in this region. Xigeda strata siltstone is planned to be used in the expansion project of Meizijing reservoir. In this paper we discuss the suitability of Xigeda strata siltstone as the filling material of earth-rock dam through a number of physical and mechanical tests by using large size test equipment. Test result reveals that Xigeda strata siltstone has good shear strength, good resistance to penetration deformation, with medium compressibility and permeability. It can be used as the filling material of earth-rock dam. The nature of Xigeda strata siltstone is close to that of silty soil in mechanical properties.

Key words: Xigeda strata, siltstone, filling material of earth-rock dam, geotechnical test, engineering property