Method for determining initiation stress index of damaged rock

Abstract

The invention discloses a method for determining an initiation stress index of damaged rock. The method comprises the following steps of firstly, carrying out triaxial compression test on the damagedrock, and recording corresponding test data; secondly, marking a point corresponding to an axial stress-lateral strain curve as a point N according to a damage stress index of the rock; thirdly, determining an initial point of the lateral strain according to a point of inflection of the axial stress-lateral strain curve, and marking as a point M; and finally, connecting the point N and the point Min the axial stress-lateral strain curve to obtain a reference line NM, and obtaining a lateral strain difference value by computing a difference value between the actually measured lateral strain and the reference line, wherein the maximum value of the lateral strain difference value is the initiation stress of the rock. According to the method, an initial fracture section of the lateral strainof the damaged rock at the microstructure of the initial stage is removed, and the accuracy of determining the crack initiation of a new crack in the damaged rock corresponding to the initiation stress is ensured; according to the method, the influence of human factors can be removed, the method has strong objectivity and is also easy to program and realize batch work.

Description

Technical field [0001] The invention belongs to the field of rock mechanics and geotechnical engineering, and particularly relates to a method that can accurately determine the initiation stress index of a rock undergoing microcrack damage. Background technique [0002] The strength and deformation characteristics of rock are the foundation of rock mechanics. Accurately grasping the mechanical properties of rock under complex conditions is the basis for evaluating the deformation and stability of rock mass engineering. The long-term safety and stability of structural engineering has an important impact. Numerous rock mechanics test studies have found that the progressive failure process of rock can be divided into the following stages: crack closure and compaction stage; linear elastic deformation stage; crack initiation stage; crack unstable growth stage; post-peak deformation stage. Different stages correspond to different rock characteristic stress values, which are crack clo...

AI Technical Summary

Problems solved by technology

However, rocks in complex geological environments (high temperature, high ground stress, etc.) often have certain microcrack damage, which may lead to positive values ​​of lateral strain (Poisson's ratio is negative) at the initial stage. At this time, the lateral strain response method is difficult to accurately determine the crack initiation stress, so new methods that can be used to determine the crack initiation stress of damaged rocks are needed

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