Field test on engineering characteristics of karst breccia

Abstract

Karst breccia is a special kind of rock related to karst action with wide distribution. The karst breccia in the dam site area of a hydropower station in the Three Gorges reservoir is very representative. Field tests are carried out on the karst breccia at the dam site of the hydropower station, including in-situ deformation test, direct shear test, triaxial compressive test, large density test and particle analysis test. The test results show that the engineering characteristics of karst breccia in the dam site area is close to that of soil, and moisture content, gravel content and lateral pressure are important factors affecting deformation modulus. Water content has a weakening effect on the mechanical properties of karst breccia, and the higher the water content is, the lower the deformation modulus of the same kind of lithology is. The shear strength parameters of karst breccia determined by triaxial compression test are higher than that of the direct shear test.