Prediction method for fracture mode of brittle rocks under long-term steady load function
A brittle rock, prediction method technology, applied in the direction of using stable tension/pressure to test the strength of materials, can solve problems such as lack of prediction methods, and achieve the effect of reducing engineering cost and saving engineering volume
Active Publication Date: 2013-01-23
POWERCHINA HUADONG ENG COPORATION LTD
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Problems solved by technology
During the test, the rock failure usually shows obvious microcrack propagation along the axial direction and shear slip along the inclined crack, and there has been a lack of a simple and easy-to-use prediction method for the final failure mode.
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[0015] The implementation steps of this embodiment are as follows:
[0016] a. Drill and process rock samples at the construction site to ensure the integrity and homogeneity of the rock samples and prevent the damage mode of the rock samples from being affected by other external factors.
[0017] b. Install the rock sample obtained in step a on the loading instrument. In this example, the loading instrument selects a triaxial tester, and simultaneously installs an axial displacement sensor, a circumferential displacement sensor, an acoustic emission probe and an acoustic wave probe on the rock sample. And can guarantee real-time transmission of data.
[0018] c. Load according to the displacement control mode until the first sudden increase of the detected acoustic emission signal occurs, such as figure 1 As shown, stop increasing the stress and maintain the stress level constant, the stress includes the axial pressure σ 1 and confining pressure σ 2 and σ 3 , and σ 2 = σ...
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The invention relates to a prediction method for a fracture mode of brittle rocks under a long-term steady load function. A technical problem to be solved by the invention is providing the prediction method for the fracture mode of the brittle rocks under the long-term steady load function to reliably predict the fracture modes of the rocks. A technical scheme for solving the problem comprises the following steps: a, drilling a rock sample at a construction site; b, mounting the rock sample on an uploading instrument, and mounting axial and circular displacement sensors, an acoustic emission probe and a sonic probe on the rock sample; c, uploading the rock sample according to a displacement control mode, until that an acoustic emission signal increases suddenly for the first time, keepingthe tress level unchanged, and recording the change of an axial displacement epsilon 1 and a lateral displacement epsilon 3 with variation of time of the rock sample under continuous steady load function, until that the acoustic emission signal forms a second peak; d, predicting the fracture mode of the rock sample according to a dilatancy index, or calculating the dilatancy index so as to predict the fracture mode of the rock sample. The prediction method for the fracture mode of the brittle rocks under the long-term steady load function is mainly used for optimization of stability evaluation and permanent support design of a deep-buried cavern.
Description
technical field [0001] The invention relates to a method for predicting the fracture mode of brittle rock under long-term stable load, which is mainly applicable to the stability evaluation of deep caverns and the optimization of permanent support design. Background technique [0002] The failure and instability of geotechnical engineering is always closely related to the time factor. Under the conditions of a long geological history, rocks have been subjected to various tectonic actions, resulting in structural planes of various shapes and sizes. When the load acts further, these rock mechanical properties are controlled by these structural planes to a certain extent, in other words, the strength properties of the rock weaken with time, and when the stress reaches a certain critical value, the original cracks in the rock will expand, or Induce new rock cracks, thus affecting the long-term stability of rock engineering structures. [0003] A large number of experiments hav...
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IPC IPC(8): G01N3/08
Inventor 张春生刘宁
Owner POWERCHINA HUADONG ENG COPORATION LTD