Soft rock triaxial strength evaluation method and system

Abstract

The soft rock triaxial strength evaluation method and system provided by the present invention can capture the nonlinear behavior of the rock, include few independent parameters and the parameters are easy to obtain, and can be "tailor-made" for soft rock (can cover brittleness and continuous damage at the same time) and lead to evaluation High precision. The soft rock triaxial strength evaluation method includes: Step 1. Obtain the rock block uniaxial strength σ of the rock block in the soft rock mass to be measured ci ; Step 2. Obtain the joint coefficient f(joint) about joints in the soft rock mass to be measured; Step 3. Calculate the uniaxial strength σ of the rock block ci Substitute the joint coefficient f(joint) into the formula to calculate the triaxial strength σ of soft rock 1 (where, σ 3 is the minimum principal stress, σ 2 is the intermediate principal stress, σ * for σ 2 The turning stress corresponding to the turning point, b is a dimensionless parameter, and B is a dimensionless parameter used for true triaxial calculation).

Description

technical field [0001] The invention belongs to the field of rock mechanics and soft rock engineering, and in particular relates to a soft rock triaxial strength evaluation method and system. Background technique [0002] Such as figure 1 As shown, since the uniaxial test is far simpler than the triaxial test and the uniaxial strength is positively correlated with the triaxial strength, the rock mechanics community is more inclined to use the uniaxial strength for the sake of engineering practicality (simple, fast, and cost-saving). to characterize rock mechanical properties. However, such simplification brings a series of problems: [0003] (1) The rocks buried underground are usually in a complex triaxial stress state, rather than a simple uniaxial stress state. Simplifying triaxial to uniaxial cannot fully reflect the rock stress state. [0004] (2) For the previous shallow rock engineering, due to the confining pressure (minimum principal stress σ 3 and intermediate ...

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Problems solved by technology

[0003] (1) The rocks buried underground are usually in a complex triaxial stress state, rather than a simple uniaxial stress state. Simplifying the triaxial to uniaxial cannot fully reflect the rock stress state

[0004] (2) For the previous shallow rock engineering, due to the confining pressure (minimum principal stress σ 3 and intermediate principal stress σ 2 ) is low, the error caused by simplifying the triaxial to a single axis is usually acceptable to engineering; for future deep rock engineering, due to the high confining pressure, the error caused by the above simplification is usually not acceptable to engineering

[0007] (1) The linear failure criterion represented by the Mohr-Coulomb criterion cannot capture the nonlinear behavior of rock, which leads to evaluation errors that are sometimes unacceptable to engineering

[0008] (2) The nonlinear failure criterion represented by the Hawke-Brown criterion contains too many parameters (independent parameters ≥ 3) and the parameters are generally difficult to obtain, and the relationship between these parameters and the existing index parameters of rock mechanics has not been established. relationship, which makes it difficult to use in engineering

For this reason, failure criteria applicable to hard rock cannot be directly applied to soft rock

[0012] (2) Compared with hard rock engineering (less potential disasters and low construction difficulty), soft rock engineering (more potential disasters and greater construction difficulty) appeared later, so the existing triaxial strength evaluation methods are usually "tailor-made" for hard rock "(Only cover brittle failure, not ductile failure), without considering whether it can be applied to soft rock

[0016] What needs to be explained is that the reason why the existing true triaxial method is "not easy to use" is rooted in: the true triaxial method is usually developed on the basis of the false triaxial method, so different true triaxial methods will inherit Corresponding to the advantages and disadvantages of the pseudo-triaxial method; because the existing pseudo-triaxial method is "not easy to use" (low evaluation accuracy, including many parameters and difficult to obtain parameters, and not suitable for soft rock), it is developed on the basis of it The true three-axis method is usually "not easy to use"

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