Time-dependent Aspects of Rock Behavior as Measured by a Servocontrolled Hydraulic Testing Machine.
Internat J Rock Mech Min Sci and Geomech Abs 1973 May; 10(3):235-246
The closed-loop, servocontrolled hydraulic testing machine was used to study the mechanisms of rock failure. It was found that applied load relaxes appreciably as soon as macrocracks initiated at the specimen surfaces. The behaviors of load relaxation were obtained for Berea sandstone, Tennessee marble, and Arkose sandstone. Load relaxation was used to establish the residual strength and creep behavior of the fractured specimens of Tennessee marble and Arkose sandstone. The load relaxation was also used to explain the experimental result that the negative slopes of the postfailure curves of all four rock types increased with a decrease in the applied deformation rate. In addition, a fast response visicorder was used to record the rapid fracture of charcoal granite and Berea sandstone. The result indicated that the testing machine was not able to follow the fracture processes owing to its slow response and the high crack propagation velocity.
Internat. J. Rock Mech., Min. Sci., and Geomech. Abs., V. 10, No. 3, May 1973, PP. 235-246