Study on damage characteristics and crack evolution properties of different types of sandstones based on multi-physics field monitoring

Abstract

Complete rock and cracked rock will produce different forms of new cracks under cyclic loading. It is of great significance to study the crack evolution process of different types of rock to ensure the safety and stability of rock mass structure. Based on acoustic emission(AE), resistivity and DIC monitoring technology, the evolution process of rock cracks is monitored from the perspective of acoustic, electrical and optical multi-physical fields. The results show that the peak strength of intact rock under uniaxial compression is basically the same as that under uniaxial cyclic loading and unloading. The failure mode of the former is tensile failure and the latter is shear failure. The peak strength of pre-cracked rock under cyclic loading decreases with the increase of the number of cracks. The failure mode of single and double crack rock is tensile failure. In the cyclic process, the acoustic emission count reflects the initiation state of rock cracks from a microscopic point of view. It is more in the loading stage and less in the unloading stage, which indicates that the initiation of microcracks basically occurs in the loading stage. Rock resistivity reflects the connectivity state of rock cracks from a macro perspective, which has a certain correlation with rock strain, that is, the peak value of resistivity corresponds to the valley value of strain and the valley value of resistivity corresponds to the peak value of strain. At the same time, the evolution process of new cracks in different types of rocks was obtained based on DIC monitoring. Based on a variety of monitoring angles, the crack evolution process of rock under cyclic loading is explored, which is of positive significance for the subsequent study of rock damage characteristics.

Keywords

cracked rock / crack development / resistivity / acoustic emission(AE) / digital image correlation(DIC)