Crack closing stress determination method based on axial stress response

A technology of axial stress and closed stress, applied in the direction of applying stable tension/pressure to test the strength of materials, measuring devices, instruments, etc., can solve the problem of inconclusive stress threshold reliability, and solve the problem of determining the compaction point , the effect of improving the accuracy

CN113567243AActive Publication Date: 2021-10-29CENT SOUTH UNIV
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2021-10-29

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Abstract

The invention discloses a crack closing stress determination method based on axial stress response. The method comprises the following steps: establishing a curve graph corresponding to an axial strain-axial stress relation of a rock sample based on a test data point set; selecting an initial point P (epsilon p, sigma p) in a linear elasticity stage of a curve graph corresponding to the axial strain-axial stress relationship of the rock sample; acquiring the slope of a connecting line of two points between each test data point (epsilon i, sigma i) and the initial point P (epsilon p, sigma p); obtaining an elastic modulus E; obtaining a reference straight line sigma = E epsilon corresponding to axial strain-axial stress; establishing a curve graph corresponding to axial strain-axial stress difference; and obtaining an inflection point in the curve graph corresponding to the axial strain-axial stress difference, wherein the axial stress corresponding to the inflection point is the crack closing stress sigma cc. According to the method, the problem in determining the compaction point is effectively solved, the accuracy of obtaining the crack closing stress sigma cc is remarkably improved, and the influence of man-made subjective assume on the crack closing stress in an existing method is eliminated.
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Description

technical field

[0001] The invention relates to the technical field of engineering structures, in particular to a method for determining crack closure stress based on axial stress response. Background technique

[0002] Affected by complex geological structures and environmental factors such as excavation disturbances, earthquakes, and microseisms, natural rock materials contain more or less primary microscopic microcracks. Initiation, extension, and penetration are closely related [1,2] , it is of great significance to study the corresponding characteristics between microcrack development and macroscopic stress threshold for the stability evaluation of deep tunnels, underground storages and other underground projects.

[0003] The mechanical properties of rocks under compression have been extensively studied over the past 60 years [3] . Generally speaking, if figure 1 As shown, there are four key stress thresholds in the process of rock compression failure, that is, the...

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Embodiment Construction

[0052] In order to further understand the features, technical means, and specific objectives and functions achieved by the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0053] figure 2 is a schematic flowchart of a method for determining crack closure stress based on axial stress response provided by an embodiment of the present invention, as shown in figure 2 As shown, the method for determining the crack closure stress based on the axial stress response specifically includes the following steps:

[0054] Step S1, carry out the compression test of the axial strain-axial stress relationship on the rock sample, and obtain the test data point set Based on the test data point set, the corresponding curve diagram of the axial strain-axial stress relationship of the rock sample is established, such as image 3 shown;

[0055] Step S2, select the initial point P(ε p ...