Path loading method used in determination of rock triaxial strength after failure

Abstract

The invention discloses a path loading method used in the determination of rock triaxial strength after rock failure. The method comprises the following steps that: first, samples of engineering rock mass requiring testing are collected; the collected samples are prepared into cylindrical samples; upper and lower rigid loading terminals of the samples closely contact a pressure head of a testing machine; hydrostatic pressure is applied to the cylindrical sample, such that an initial confining pressure to the sample is loaded to a designed value; with the initial confining pressure maintained, axial load is then applied to the cylindrical sample, and the pressure to the sample is loaded to a control point after a peak value intensity, such that a rock failure sample is formed; hydrostatic pressure is then applied to the rock failure sample, such that final confining pressure to the sample is loaded to a higher value; with the final confining pressure maintained, axial load is then applied to the rock failure sample, such that a yielding failure is occurred to the rock sample. With the testing method, mechanical characteristics of rock re-failure after failure can be researched, triaxial strength characteristics of rocks after failures can be acquired, and corresponding technical measures can be provided for the problems in failed surrounding rock reinforcing in the field of deep underground engineering.

Description

technical field [0001] The invention relates to a loading path method for measuring the triaxial strength of rocks after cracking, and is especially suitable for simulating the experimental process in which the supporting object of deep underground engineering is the strength of cracked rock mass. Background technique [0002] All kinds of rock engineering, such as underground engineering, dam foundation engineering, joint slope engineering, nuclear waste disposal engineering, etc., are usually in a three-dimensional stress state, so the strength characteristics of rocks in a three-dimensional stress state are important for rock engineering stability evaluation. important mechanical parameters. At present, the triaxial strength of rock is usually obtained by gradually increasing the axial load under constant confining pressure to induce yield failure of the rock sample (conventional triaxial compression path), or loading the rock sample to a certain level under high confinin...

AI Technical Summary

Problems solved by technology

However, in 1986, Xu Dongjun and Geng Naiguang analyzed the influence of loading paths on the strength and deformation and failure characteristics of hard and weak rocks, and the results showed that the strength of rocks affected by conventional triaxial and confining pressure stress paths is related to the test lithology: The strength of hard rock under the path of unloading confining pressure is slightly lower than that under conventional triaxial compression; the opposite is true for weak rock; in 2008, Wang Bin et al. analyzed the impact of conventional triaxial compression and The influence of rock strength parameters, the analysis shows that the strength of marble under the path of unloading confining pressure is lower than that of marble under conventional triaxial compression

To sum up, how the loading path affects the rock strength characteristics is still controversial, and its influencing mechanism is still not very clear

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