Method for determining initiation stress index of damaged rock

A rock and stress technology, applied in the field of rock mechanics and geotechnical engineering, can solve problems such as micro-crack damage, achieve strong objectivity and ensure accuracy

Active Publication Date: 2019-07-19
WUHAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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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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  • Method for determining initiation stress index of damaged rock
  • Method for determining initiation stress index of damaged rock
  • Method for determining initiation stress index of damaged rock

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Embodiment

[0042] The heat treatment can cause large micro-crack damage to the inside of the rock. This embodiment illustrates the experimental data of the heat-damaged rock undergoing different times of high-temperature heat treatment. The rock used is granite, and the high temperature treatment temperature is 600℃. After high temperature treatment, cooling to room temperature is called a heat treatment. Figure 4 to Figure 6 To select the triaxial compression test curve of granite after 0, 1, and 2 heat treatments.

[0043] Step 1: Determine the damage stress index of the rock. The damage stress index is determined by drawing the volumetric strain-axial stress curve and determining the reverse bending point of the curve (see Figure 5 Shown), the volumetric strain is the axial strain plus twice the lateral strain, that is, by Figure 4 The middle curve data is obtained. In this embodiment, it is determined that the damage stress indexes after 0, 1, and 2 heat treatments are 120.94 MPa, 77....

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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...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/08
CPCG01N3/08G01N2203/0064
Inventor 彭俊刘泉声吴志军张晓平
Owner WUHAN UNIV
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