Failure and post-failure characteristics of mine deposits in Korea

A series of ring shear tests were performed on waste rock materials collected from mine deposits in the mountainous region of Korea. The collected samples were classified as gravelly sand soils. After the samples were fully saturated, they were subjected to a normal stresses of 50–100 kPa for 300 s. The test program includes: A measurement of (1) shear stress for a given shearing speed, (2) shear stress as a function of normal stress and (3) strength behavior as a function of shear speed, which varied from 0.01–100 mm/s. A comparison was also made between clayey, sandy and waste rock materials. For the given materials, strain softening behavior was observed regardless of the drainage condition and shearing speed. From the grain size distribution results, we found that the larger grain sizes in the matrix, corresponded to greater fragmentation during shearing. At a relatively high shear speed condition, such as rapid mass movements, the grain crushing effect is more significant.