Abstract
A grain‐based rock model was developed and applied to study mechanical characteristics and failure micromechanics in thick‐walled cylinder and wellbore stability tests. The rock is represented as an assembly of tetrahedral blocks with bonded contacts. Material heterogeneity is modeled by varying the tensile strength at the block contacts. This grain‐based rock model differs from previous disk/sphere particle‐based rock models in its ability to represent a zero (or very low) initial porosity condition, as well as highly interlocked irregular block shapes that provide resistance to movement even after contact breakage. As a result, this model can reach higher uniaxial compressive strength to tensile strength ratios and larger friction coefficients than the disk/sphere particle‐based rock model. The model captured the rock fragmentation process near the wellbore due to buckling and spalling. Thin fragments of rock similar to onion skins were produced, as observed in laboratory breakout experiments. The results suggest that this approach may be well suited to study the rock disaggregation process and other geomechanical problems in the rock excavation.
Highlights
Massive underground caving operations are becoming ever more prevalent. e development of cave infrastructure in rock strata may lead to excavation instability problems
Investigation of the rock failure process is of great importance for rock stability in engineering exploitations and excavations [6]
In the 1990s, nonlinear elastic, plastic, and elastoplastic models were developed by McLean and Addis [14], McLellan and Wang [15], and McLellan [16]
Summary
Massive underground caving operations are becoming ever more prevalent. e development of cave infrastructure in rock strata may lead to excavation instability problems. E development of cave infrastructure in rock strata may lead to excavation instability problems. It is increasingly important to better understand the redistribution of induced stresses and the failure process near underground excavations, and for support design, it is necessary to better predict the related deformation characteristics of brittle failing rock. Ese joints or cracks significantly affect the rock mass mechanical properties such as deformability, strength, and failure process in different ways of providing the crack source for further failure of the rock mass, leading to the brittle failure of the rock mass by the stress concentration at the crack tips [4, 5]. Investigation of the rock failure process is of great importance for rock stability in engineering exploitations and excavations [6]. In the 1990s, nonlinear elastic, plastic, and elastoplastic models were developed by McLean and Addis [14], McLellan and Wang [15], and McLellan [16]
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