EVALUATION OF IN-SITU SHEAR STRENGTH OF NATURAL SLOPES VULNERABLE TO HEAVY RAINFALL BY LIGHTWEIGHT DYNAMIC CONE PENETROMETER

摘要

Shallow slope failures, induced by torrential rainfall, are common in the western Japan, where Masado, a regional soil made of decomposed granite, is widely distributed in natural slopes. There is quite a few information on the geotechnical conditions, because of the difficulty of ground investigation on steep slopes with lush vegetation. The lightweight dynamic cone penetration test (LWDCPT) has been used for geotechnical survey of natural Masado slopes in the region. Based on the results of direct shear tests and the laboratory calibration tests of LWDCPT, a method of determining shear strength parameters from the data of qd was proposed. The applicability of the proposed method was examined by comparing the strength parameters predicted by of qd values and those measured in the laboratory shear strength test with undisturbed samples at the same sites.