Mechanical properties and failure characteristics of sandstone under ramp loading paths

Abstract

The revelation of the mechanical behaviors of rock in complex stress conditions is of vital importance for the safe exploitation of underground resources. In this paper, the ramp loading path was designed to elaborate the mechanical properties and failure characteristics of sandstone under the compound action of linear loading path and cyclic loading and unloading path. The strength, deformation, AE and failure characteristics of sandstone under ramp loading paths were obtained. The research achievements indicate that with the increase of the amplitude and decrease of the stress change rate, the peak stress decreases. Elastic modulus is more greatly affected by the linear path stress than by the cyclic disturbance. The irreversible strain curve is L-shaped under a single loading and unloading cycle. Under lower amplitudes and higher stress change rates, the loading and unloading response ratio fluctuates largely and decreases slightly. Under lower amplitudes and higher stress change rates, the deformation and failure of sandstone caused by stress growth under the linear path is the leading cause for total deformation and failure of sandstone. Under higher amplitudes and lower stress change rates, cyclic loading and unloading are the dominant factor for the failure of sandstone. The research results are of scientific value for evaluating rock failure.