Investigation of the shear failure of rock joints using the four-dimensional lattice spring model
Date
2022
Authors
Pratomo, F.Y.
Wei, X.
Zou, C.
Zhao, G.-F.
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Journal article
Citation
International Journal of Rock Mechanics and Mining Sciences, 2022; 152:105070-1-105070-18
Statement of Responsibility
Fauzan Yudho Pratomo, Xindong Wei, Chunjiang Zou, Gao-Feng Zhao
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Abstract
This research adopts the four-dimensional lattice spring model (4D-LSM) to investigate the shear strength and failure mechanism of irregular rock joints and the influence of rock heterogeneity. The 4D-LSM has been used for a wide range of rock engineering applications, however its ability for simulating direct shear tests has not been investigated in detail. The material strength parameters were calibrated using uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS) tests on granite specimens while the joint parameters were calibrated from direct shear tests on saw-cut UCS specimens and rock joints containing a single triangular asperity. From UCS tests, a calibration method is proposed to adjust the excessive machine deformation due to the high brittleness of granite, which is further applied to the direct shear test results. It was found that the strength of rock joints is strongly influenced by the intact rock properties. To investigate the influence of joint geometry and rock heterogeneity, three joint asperity angles and five heterogeneous models were simulated using the calibrated 4DLSM model. Simulation results were able to capture the influence of different joint asperity angles on the shear strength and failure mechanism as reported in previous experimental and numerical studies. With larger asperity angles, higher shear strengths were obtained. Meanwhile, rock heterogeneity represented by particles with lower strength will reduce the shear strength and alter the failure mechanism, especially at a high porosity. This strength reduction was observed to be greater for steep-angle asperities and becomes less significant for flatter asperities. Similar conclusions were also obtained based on the simulations of natural joint profiles. From these findings, it is suggested that the characterisation of rock heterogeneity is crucial to estimate the strength of rock joints. In addition to the roughness parameters, heterogeneity parameters such as porosity are fundamental for rock engineering applications.
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Available online 24 February 2022
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© 2022 Elsevier Ltd. All rights reserved.