Abstract: A series of laboratory tests and plate load tests under different conditions of water immersion were conducted aim at solving a lack of researches on Xigeda formation siltcaused by lake deposit located in Zhaizi Village, Yunnan Province, China. The experimental data were then compared with the researches on widely distributed Xigeda strata situated at Panzhihua and Xichang regions. The results demonstrate that the Xigeda strata located in Zhaizi Village, Yunnan Province are mainly composed of silt granules and sand granules, and present horizontal bedding formation, which are semiforming rocks with poorer mechanical properties. Local shear failure plays a major role after plate loading for this kind of rocks. The strength indictors, elastic moduli and deformation moduliobtained from the tests on Xigeda formation silt are larger than those situated at Panzhihua and Xichang regions. The strength of these rocks decreases rapidly under the condition of fully immersion in water.

Key words: Geotechnical Engineering, Xigeda Formation, Plate Load Test, Bearing Capacity of Foundation Soils