Method for determining crack initiation strength of rock under compressive conditions

A technology for crack initiation strength and determination method, which is applied in the direction of applying stable tension/pressure to test material strength, etc., can solve problems such as interference with accurate identification of crack initiation strength values, and achieve easy popularization and application, uniqueness, and simple and reliable methods Effect

Inactive Publication Date: 2015-03-25
BEIJING RES INST OF URANIUM GEOLOGY
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  • Description
  • Claims
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Problems solved by technology

However, due to the high sensitivity of the acoustic emission monitoring signal to the mechanical response of the rock and the interference of background noise, the rock may also detect a st...

Method used

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  • Method for determining crack initiation strength of rock under compressive conditions
  • Method for determining crack initiation strength of rock under compressive conditions
  • Method for determining crack initiation strength of rock under compressive conditions

Examples

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Embodiment 1

[0028] In this embodiment, the crack initiation strength of the rock is determined under uniaxial compression conditions, and the following operations are performed now:

[0029] (1) Process the complete core drilled in the preselected area of ​​the high-level radioactive waste geological repository in Beishan, Gansu Province, and prepare a cylindrical rock specimen with a height-to-diameter ratio of 2:1. The diameter of the rock specimen used in this example is 50mm , the height is 100mm.

[0030] (2) Install the rock specimen on the sample table of the press, the model of the press is: MTS815 (manufactured by MTS Company of the United States).

[0031] (3) Install axial and circumferential extensometers in the middle of the rock sample.

[0032] (4) Use the load control mode of the press to perform a uniaxial compression test on the specimen, with the loading rate set at 0.75MPa / s, until the specimen is destroyed, and the test ends.

[0033] (5) if figure 1 shown, accordi...

Embodiment 2

[0040] In this embodiment, the determination of rock crack initiation strength under triaxial compression conditions is performed as follows:

[0041] (1) Process the complete core drilled in the preselected area of ​​the high-level radioactive waste geological repository in Beishan, Gansu Province, and prepare a cylindrical rock specimen with a height-to-diameter ratio of 2:1. The diameter of the rock specimen used in this example is 50mm , the height is 100mm.

[0042] (2) Install the rock specimen on the sample table of the press, the model of the press is: MTS815 (manufactured by MTS Company of the United States).

[0043] (3) Install axial and circumferential extensometers in the middle of the rock sample.

[0044] (4) Apply confining pressure to the rock sample through the surrounding rock system of the press, and the confining pressure value used in this example is 20MPa.

[0045] (5) Use the load control mode of the press to perform a triaxial compression test on the...

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Abstract

The invention relates to a method for determining the crack initiation strength of a rock under compressive conditions. The method includes the following steps: 1, processing a rock sample; 2, arranging the rock sample on the sample bench of a press; 3, axially loading the sample in a load control mode until the sample is destroyed; 4, calculating the volumetric strain of the sample; 5, determining the crack damage strength in a volumetric strain-axial stress curve; 6, connecting a zero point with the crack damage strength point in the volumetric strain-axial stress curve to form a reference line; 7, calculating a difference between the strain value in the volumetric strain-axial stress curve and a strain valve corresponding to the reference line under a same stress level from the zero point to the end of the crack damage strength; and 8, making a volumetric strain and axial stress relation point diagram, and determining the stress corresponding to the peak of the volumetric strain difference as the crack initiation strength of the rock. The method is suitable for mechanical test of the rock, serving for underground engineering.

Description

technical field [0001] The invention relates to a method for determining the crack initiation strength of rocks under compression conditions, in particular to a method for determining the crack initiation strength of rocks under compression conditions by using volumetric strain difference, which is suitable for rock mechanics tests serving underground engineering. Background technique [0002] The mechanical failure process of rock is the process of initiation, expansion and penetration of internal micro-cracks. The damage and failure process under compression can be divided into several important stages: (1) crack closure; (2) elastic deformation; (3) crack initiation; (4) crack stable development; (5) crack penetration; (6) Unsteady fracture development; (7) Destruction; (8) Post-destruction stage. Among them, the stress level corresponding to the initial crack is called rock crack initiation strength. Crack initiation strength (σ ci ) is one of the important characteri...

Claims

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Application Information

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IPC IPC(8): G01N3/08
Inventor 赵星光马利科谢敬礼宗自华苏锐王驹
Owner BEIJING RES INST OF URANIUM GEOLOGY
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