声发射矩张量反演

地震矩张量反演是获取震源过程的有效方法.岩石变形过程中的声发射与地震类似，均是弹性应变能快速释放.如假设条件得到满足，矩张量反演方法同样可用于了解声发射震源过程.声发射矩张量反演可使用P波位移进行计算.当样品尺寸远大于声发射波长，且声发射由微破裂产生，声发射源的尺度很小时，P波矩张量反演可采用远场近似.本文首先针对声发射的特点，实现根据远场P波反演声发射矩张量的算法，并通过人工声发射实验对算法的正确性和可靠性进行了检验.最后，用声发射矩张量反演方法对花岗岩单轴压缩实验的声发射源特征进行了分析.结果表明：对于纯剪切破裂模式，声发射矩张量反演可得断层面；对于非纯剪切破裂模式，如纵向挤压导致的横向张性劈裂，由于存在多解性不能得到断层面，但可通过矩张量的迹区分破裂模式.

Moment tensor inversion of acoustic emission

Seismic moment tensor inversion is an effective method to get the process of earthquake sources. Acoustic emission (AE) during the deformation of rock is resulted from the rapid release of elastic strain energy, which is similar to earthquakes. The method can also be applied to calculate the process of AE sources if the assumptions are met. AE moment tensor inversion can be calculated by the displacement of P-wave. And the far-field approximation can be used to P-wave moment tensor inversion when the sample size is much larger than the wavelength of AE produced by the micro-fractures of enough small sizes. The algorithm of AE moment tensor inversion is developed by use of P-waves of the far field on the base of the features of AE, and its accuracy and reliability is tested through the experiments of artificial AE sources. Finally, the moment tensor inversion method is applied to analyze the properties of AE sources in granite sample under uniaxial compression. The results show that a fault plane can be well obtained by the AE moment tensor inversion for the pure shearing fracture mode, but not for non-pure shearing fracture mode because of multiple solutions, such as the transverse splitting micro-fractures caused by vertical compression, etc. However, the fracture mode can be distinguished easily according to the traces of AE moment tensors.