Triaxial rheological test process and method for hard and crisp rock

Abstract

The invention relates to a triaxial rheological test process and method for a hard and crisp rock. The method comprises the following steps of: 1, determining an instantaneous triaxial compressive strength of the hard and crisp rock and loading by adopting a triaxial rheological mode; 2, determining the size of a confining pressure of a test and test loading grades and adopting a loading mode of circularly loading and unloading; 3, sealing a rock sample by using a heat-shrinkable sleeve and a stainless steel tube hoop so as to prevent oil from leaking; 4, applying the confining pressure to a set value, applying a first stage of axial load after the confining pressure is stable, and reasonably setting a time interval of recording data; 5, after the deformation is stable, continuously applying axial stresses in a grading mode until the test is completed; and 6, determining the long-term strength of the rock by adopting a residual strain method. In the invention, a reasonable value of the confining pressure is provided so as to furthest avoid deformation mutation caused by local fracture of the rock; the test loading grades are reasonably determined so as to not only obtain a threshold value of the creep stress of the rock, but also obtain an accelerated creep curve; and the scheme of determining the long-term strength of the hard and crisp rock by using the residual strain method of the loading and unloading rheological test is provided.

Description

technical field [0001] The invention relates to a triaxial rheological test technique and method for hard and brittle rocks. Background technique [0002] With the vigorous development of underground resources and the rapid development of hydropower engineering construction, the long-term stability of underground cavern structures and hydropower engineering has attracted more and more attention and attention. The sites of large-scale hydropower projects and underground caverns are selected on hard rock foundations, such as granite, marble, diabase, etc., in consideration of the purpose of safety and stability. These high-strength rocks are often accompanied by brittle characteristics, such as granite and diabase. In order to effectively evaluate the long-term stability of the surrounding rock after the excavation of large-scale underground projects, in addition to using theoretical research and numerical calculation methods, it is necessary to rely more on indoor rheologica...

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Problems solved by technology

This method adopts the uniaxial rheological method, which cannot avoid the discreteness of the results caused by the brittleness of the rock, and because the data is recorded by the dial gauge, the data of the accelerated creep stage cannot be collected

[0007] (3) "Rock and Soil Mechanics" No. 4, 2005 introduced a triaxial rheological test method for greenschist. This method adopts the method of constant confining pressure and axial pressure, but it does not clearly explain how to determine the number of loading stages

[0008] (4) "Rock and Soil Mechanics", No. 1, 1980, introduced a method for the rheological properties of weak rock mass and a long-term strength measurement method. There are many human factors, and the accuracy of the results cannot be guaranteed

[0009] (5) "Rock and Soil Mechanics" No. 5, 2006 introduced a rheological property method and long-term strength measurement method of red sandstone. This method proposes to determine according to the threshold stress of rock entering lateral stable creep, but this method does not The rock can be regarded as a whole, only from the perspective of axial strain or lateral strain, and the uniformity of the overall deformation cannot be guaranteed

[0010] (6) Hohai University's doctoral thesis "Experimental Research on Rheological Mechanical Properties of High Arch Dam Spand Shoulder Groove and Analysis of its Long-term Stability" introduces a method for determining the long-term strength of rock by steady-state creep rate. The applicability of high-hardness rocks with insignificant state creep is poor, and the accuracy of the results cannot be guaranteed

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