Method and device for determining rock softening curve through brittleness index

Abstract

The invention a method and the device for determining a rock softening curve by utilizing a brittleness index. The method and the device provided by the invention have the following five characteristics that: (1) a rock common index parameter (rock brittleness index B) is used as a fitting parameter, and physical significance is clear (easy to obtain); (2) the fitting bottleneck caused by extremely few rock uniaxial tensile test data can be thoroughly avoided, and one-to-one correspondence between rock and curves is realized; (3) no human factor interference exists in a whole process; (4) thefitting precision is high, and the maximum characteristic of the last two sections (rapid reduction-gentle reduction) in the three-section change of the rock softening curve can be accurately reflected; and (5) the method is suitable for natural rocks and rock-like materials. The method for determining the rock softening curve by using the brittleness index comprises the following steps of: step 1, acquiring the rock brittleness index B of rock to be measured; and 2, substituting the rock brittleness index B into a softening function based on the brittleness index to obtain the rock softeningcurve.

Description

technical field [0001] The invention belongs to the field of rock mechanics and rock engineering, and in particular relates to a method and a device for determining a rock softening curve by using a brittleness index. Background technique [0002] With the discovery of strain softening in the post-peak stage of the stress-strain curve of rocks (see Figure 1(a)), a bond crack model suitable for brittle materials such as rocks was proposed. By simplifying the mathematical relationship, the bonded crack model clearly defines the two criteria of crack generation and crack propagation, and provides a method for simulating the rock fracture process by numerical calculation methods such as the finite element method (FEM) and the finite element-discrete element hybrid method (FDEM). Simpler and more reliable means. For this reason, as a general model, it is widely used in numerical simulation analysis and prediction of rock engineering such as tunnels / roadways, mining, and water co...

AI Technical Summary

Problems solved by technology

[0006] Unfortunately, existing softening functions, whether they are linear softening functions (single linear, bilinear, trilinear, multilinear) (see Figure 2(a)), or nonlinear softening functions (see Figure 2(b) ), the fitting parameters generally have no physical meaning, and the connection between the fitting parameters and the common index parameters of rocks (for example, rock brittleness index) has not been established

In addition, there are other shortcomings in the existing method: there are many human factors in the whole process; the fitting accuracy is low, and the three-stage change of the rock softening curve cannot be well reflected (nearly parallel-rapid decrease-smooth decrease, see Figure 1( b)), especially the single linear softening function, the biggest feature of the last two stages (rapid drop-smooth drop) in the three-stage change cannot reflect

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