![]() ![]() ![]() including rock masses, intact rocks, fractured rocks and rock joints. The y-intercept of the curve which fits the test results is the cohesion, and the slope of the line or curve is the friction angle. Direct shear tests were conducted on these joint specimens. The results of the tests on each specimen are plotted on a graph with the peak (or residual) stress on the y-axis and the confining stress on the x-axis. Several specimens are tested at varying confining stresses to determine the shear strength parameters, the soil cohesion (c) and the angle of internal friction, commonly known as friction angle ( Ï). The load applied and the strain induced is recorded at frequent intervals to determine a stressâstrain curve for each confining stress. A confining stress is applied vertically to the specimen, and the upper ring is pulled laterally until the sample fails, or through a specified strain. of the rock material (intact rock), but also on the discontinuities. A specimen is placed in a shear box which has two stacked rings to hold the sample the contact between the two rings is at approximately the mid-height of the sample. Hence, in-situ direct shear tests are conducted to find out the shear strength. Procedure of the direct shear test Direct shear tests were carried out according to. The test is performed on three or four specimens from a relatively undisturbed soil sample. The half-half notched specimen test is used when the shear strength of an intact rock has to be determined.
0 Comments
Leave a Reply. |