Method and device for determining rock softening curve in bonding crack model

Abstract

The invention provides a method and a device for determining a rock softening curve in a bonding crack model, which can completely and accurately reflect the three-section change of the rock softeningcurve, can be simultaneously suitable for soft rock and hard rock, and are high in fitting precision and free of human factor interference in the whole process. The rock softening curve determinationmethod comprises the following steps: step 1, acquiring peak stress, peak strain, residual stress and residual strain of a rock to be measured; 2, dividing rock uniaxial tensile test data into soft rock and hard rock according to different rock brittleness indexes B; 3, normalizing the post-peak stage of the rock stress-strain curve; 4, fitting the normalized data by adopting a power-exponentialsoftening function, and determining fitting parameters suitable for soft rock and hard rock respectively; 5, substituting the fitting parameters into the power-index softening function to obtain a rock softening curve in the bond crack model;

Description

technical field [0001] The invention belongs to the field of rock mechanics and rock engineering, and in particular relates to a rock softening curve determination method and device in a bonding crack model. 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 conservancy....

AI Technical Summary

Problems solved by technology

[0010] ③ Regardless of whether it is soft rock or hard rock, each softening function uses the same fitting parameters (the soft rock and hard rock cannot be distinguished "different from rock"); this is consistent with the real situation of the rock (soft rock, the stress drop is more gentle ; hard rock, the stress drop is steeper) does not match, especially when simulating composite formations (soft rock-hard rock mixed formations), the error is huge

For this reason, there is no softening function that can be applied to soft rock and hard rock at the same time: part of the softening function has high fitting accuracy when characterizing soft rock, and low fitting accuracy when characterizing hard rock; the other part of the softening function is vice versa.

Images