Abstract: Practical engineering activities are closely related to engineering properties of soil-rock materials under low confining stress. Cases of landslides of Levees and dams due to earthquake were summarized and analyzed; and it revealed that the depth of landslides was usually less than 7m, and the effective overburden stress was usually not more than 100 kPa. 106 cases of the foundation liquefaction were analyzed; and it is revealed that the foundation liquefaction occurred mostly at where the effective overburden stress below 100 kPa. In the present study, only the properties of soil-rock materials under high confining stress are paid great attention, and in applications the parameters of soil-rock materials under low confining stress are assigned the same as those under medium to high confining stress; while the reliability of this parameter selection method is disputable for the properties of soil-rock materials are seriously dependent on the stress. Therefore, study of the engineering properties of soil-rock materials under low confining stress and discussing the corresponding parameters selection method in numerical simulation have great significance both to engineering practice and scientific research.

Key words: earthquake damage of hydraulic projects, earthen structures, damages under low confining stress, cases of landslide and liquefaction