A study of saw-cut shear strength

Abstract

It is necessary to determine the shear strength of intact rock to analyze the stability of excavations. The strength of rock and rock mass are important parameters for design of mine excavation and its stability. Shear strength of the rock is one of those. It is carried out to determine the cohesion and angle of friction of the rock material. Determination of direct shear strength value of rock in the field is very difficult due to direct shear testing machine is bulky which is difficult to carry to the site and experiment is only possible at laboratory as it requires a constant power for application of consistent horizontal force. A conventional shear-box testing machine is unsuitable due to high strength of rock and it minimizes the bending stresses of rock specimens. However the procedure of direct shear strength is complex and often require varying machine characteristics. Saw cut shear is a process which incorporates punching action so that the ends of the sample experience shear. This investigation reports the experiments carried out to correlate the conventional shear and saw cut shear data. Thin dolomite plates of were cut from core with rock cutting machineand tested in double shear by a linear punching action. Saw-cut shear strength of dolomite is determined for the differentthickness of plates and optimum value is found to be 14.7 MPa and a relation between saw-cut shear strength and thickness is established.