Micro computer control of direct shear tests

In many instances, tests are more a function of equipment capabilities than an attempt to simulate field conditions. For example, direct shearing of rock joints in which dilation is restricted normal to the joint plane is more representative of underground deformation than a constant normal load test. Yet, shearing with restricted normal deformation is rarely conducted because, among other things, available equipment is best suited for the more common constant normal load test. This paper describes the interfacing of a general purpose micro computer to a MTS system and its subsequent use in shearing rock joints under conditions of controlled normal deformation. The use of micro computer control greatly reduces the cost of performing such tests. Results of selected tests are presented to demonstrate the effectiveness of the procedure.