Abstract

Based on the particle flow code, numerical models of vertical and horizontal orientations of holes with different shapes were established, and the effects of preexisting holes with different shapes and arrangement patterns on the mechanical behaviors and failure characteristics of rocklike materials were studied. The evolution trend of the stress field is discussed by taking a circular hole as an example. The results show that the existence of holes reduces the peak stress, peak strain, and elastic modulus of the sample, and different shapes of holes and different arrangement patterns have different effects on the mechanical properties and damage degree of the sample and significantly affect the horizontal orientation model. Before crack formation, the compressive stress and tensile stress concentration areas of each sample are located at the left and right ends and the upper and lower ends of the hole, respectively. After model failure, the compressive stress and tensile stress concentration areas of each sample are relatively scattered. In the vertical orientation model, the middle area of vertical holes is the main compressive stress concentration area, which is approximately “columnar” distribution. In the horizontal orientation model, the compressive stress concentration area between the holes is cross distribution and approximately “X” type distribution. The vertical orientation model sample forms a “columnar” distribution to bear the applied load with a more favorable bearing orientation.

Highlights

  • Most natural rock masses have various defect structures such as fractures and holes, affecting the mechanical properties of rocks [1,2,3,4,5]

  • Many studies have been conducted on the failure characteristics of circular holes and the coalescence mode of cracks, and some meaningful conclusions have been obtained [24,25,26,27,28,29]

  • Wong et al [30] conducted a series of uniaxial compression physical and numerical tests on singlehole specimens with different diameters and widths and studied the splitting failure, failure mode, and strength characteristics caused by crack propagation

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Summary

Introduction

Most natural rock masses have various defect structures such as fractures and holes, affecting the mechanical properties of rocks [1,2,3,4,5]. Huang et al [31] studied the strength failure behavior of three noncoplanar circular hole specimens under uniaxial loading using experimental and numerical simulation methods, determined four typical crack coalescence modes, and elucidated the crack evolution mechanism around preexisting holes in granite specimens. Gui et al [44] used mixed continuous discrete element method to conduct numerical studies on the effect of circular, rectangular, and triangular holes on rock mechanical behavior, proposed a simulation method that could reasonably reproduce the crack initiation and propagation, and better predicted the mechanical property changes caused by holes. Erefore, PFC2D program was used in this study to establish vertical and horizontal orientation models containing four types of holes with different shapes, studied the effect of hole shape and arrangement on the failure characteristics and mechanical properties of samples, and analyzed the evolution of the stress field in a circular hole model Various types of defective holes exist in the natural rock mass. ese defects pose a potential threat to the stability of rock mass. erefore, PFC2D program was used in this study to establish vertical and horizontal orientation models containing four types of holes with different shapes, studied the effect of hole shape and arrangement on the failure characteristics and mechanical properties of samples, and analyzed the evolution of the stress field in a circular hole model

Model Design and Determination of Microparameters
Test Results
Conclusions
Full Text
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