Estimation of Crack Initiation Stress Based on Axial Crack Strain Expansion Rate

Crack initiation stress (sigma(ci)) can be used to estimate the spalling strength of rock mass for engineering applications. Its accurate identification is of great significance for analyzing the long-term stability and brittle failure mechanism of rocks. This paper presented an error analysis of various crack initiation stress determination methods and proposed a new method for the identification of crack initiation stress by the expansion rate of axial crack strain. The comparison of the crack initiation stresses calculated by this method with those calculated by the crack volumetric strain method, lateral strain response method, and lateral strain interval response method through tests on three types of rocks showed that the results for marble obtained by all four methods were similar. However, the crack initiation stresses of granite and sandstone calculated by the lateral strain response method were significantly smaller, While the results obtained by the other three methods were similar. The results showed that the sigma(ci) determined by the method proposed by this paper is accurate. This method can accurately identify the crack initiation stress and its application in engineering practice is convenient.

Automated summary

This paper presents an error analysis of various crack initiation stress determination methods and proposes a new method for the identification of crack initiation stress by the expansion rate of axial crack strain. The results show that the proposed method can accurately identify crack initiation stress.