A Method of Determining the 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

Active Publication Date: 2020-10-30
WUHAN UNIV
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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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  • A Method of Determining the Initiation Stress Index of Damaged Rock
  • A Method of Determining the Initiation Stress Index of Damaged Rock
  • A Method of Determining the Initiation Stress Index of Damaged Rock

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Embodiment

[0042] Larger microcrack damage can be generated inside the rock through heat treatment, and this example is illustrated by the experimental data of thermally damaged rocks undergoing different times of high-temperature heat treatment. The rock used is granite, and the high-temperature treatment temperature is 600°C. After high-temperature treatment, cooling to room temperature is called primary heat treatment. Figure 4 to Figure 6 It is the triaxial compression test curve of the selected granite after 0, 1 and 2 heat treatments.

[0043] Step 1: Determine the damage stress index of the rock. The determination of the damage stress index is obtained by drawing the volume strain-axial stress curve and determining the inflection 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 In the middle curve data acquisition, in this embodiment, it is determined that the damage stress indicators after 0...

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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 in particular relates to a method for accurately determining the crack initiation stress index of rocks subjected to micro-crack damage. Background technique [0002] The strength and deformation characteristics of rock are the basis of rock mechanical properties. Accurately grasping the mechanical properties of rock under complex conditions is the basis for evaluating the deformation and stability of rock mass engineering, and it is an important guarantee to ensure the safety of large-scale rock mass engineering construction. It has an important impact on the long-term safety and stability of structural engineering. Numerous rock mechanics experiments 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 instability propagat...

Claims

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Application Information

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Patent Type & Authority Patents(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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