Variations of the Susceptibility of Rock Samples before and after Fracture under Uniaxial Compression

Abstract

Piezomagnetic measurements have been performed on seven different kinds of rocks collected in the Beijing-Tangshan area of China. The measurements involve examination of the variations in the magnetic susceptibility before and after fracture of the rocks under high stress conditions. The results show that changes in the magnetic susceptibility depend upon the stress applied and are very weakly influenced by changes of volume and the processes of microfracturing and dilatation. In these experiments the range of the stress coefficient of susceptibility was approximately (0.4-2.75)×10^-4 bar^-1. Piezomagnetic curves were also obtained subsequent to fracture.