Location of acoustic emission events and changes of spatial correlation length in rock during uniaxial compression

Abstract

Acoustic emission (AE) location technique was applied to study the three‐dimensional spatial evolutionary process of microcracks initiation, propagation and coalescence during rock failure process under uniaxial loading. Changes of spatial correlation length of AE events during fracture process of granite and marble specimens were acquired using the single link cluster method. Stiffness obtained by the moving point regression technique can clearly reflect the plastic phase. Two factors may influence the change of spatial correlation length in plastic phase: stress release, which leads to a decrease in correlation length, and stress redistribution, which leads to an increase in correlation length. During the rock fracture process, long range correlations are established by the redistribution of stress from smaller to larger scales. In this regard, the change of spatial correlation length reflects the long range transfer of stress field. The different characteristics of spatial correlation length during elastic and plastic phases may be used as an indicator for predicting failure of rock.

Keywords:

• Rock failure
• Acoustic emission location
• Spatial correlation length
• Single link cluster
• Plastic phase

This work was financially supported by the National High‐Tech Research and Development Program (‘863’ program) of China (grant no. 2007AA06Z107), the National Natrual Science Foundation of China (grant no. 50974031), the National Key Technology R&D Program of China (grant no. 2008BAB34B02), the Program for New Century Excellent Talents in Chinese universities (grant no. NCET‐07‐0163), and the Fundamental Research Funds for the Central Universities (grant no. 90401006).