Abstract
The initial stresses have a strong effect on the mechanical behavior of underground rock masses, and the initial stressed rock masses are usually under strong dynamic disturbances such as blasting and earthquakes. The influence mechanism of a blasting excavation on underground rock masses can be revealed by studying the propagation of stress waves in them. In this paper, the improved Mohr-Coulomb elasto-plastic constitutive model of the intact rock considering the initial damage was first established and numerically implemented in Universal Distinct Element Code (UDEC) based on the variation of the experimental stress wave velocity in the initial stressed intact rock, and the feasibility of combining the established rock constitutive model and the BB (Bandis-Barton) model which characterizes the nonlinear deformation of the joints to simulate stress waves across jointed rock masses under initial stress was validated by comparing the numerical and model test results subsequently. Finally, further parameter studies were carried out through the UDEC to investigate the effect of the initial stress, angle, and number of joints on the transmission of the blasting stress wave in the jointed rock mass. The results showed that the initial stress significantly changed the propagation of the stress waves in the jointed rock mass. When the initial stress was small, the transmission coefficients of the stress waves in the jointed rock were vulnerable to be influenced by the variation of the angle and the number of joints, while the effect of the angle and the number of joints on the stress wave propagation gradually weakened as the initial stress increased.
Highlights
The initial stressed underground rock masses are under strong dynamic disturbances, and the underground structure can be damaged by the stress waves generated during the excavation process
This paper presents a numerical exploration of blasting stress wave propagation in the initial stressed jointed rock mass
P17 and P18 stress measurement points in each model test sample under different biaxial pressures were relatively similar in form and amplitude, and the stress wave amplitude decreased as the biaxial pressure increased
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Besides discontinuous interfaces, intact rocks are the other part of the rock mass Due to their long geological age and various complex tectonic effects, intact rocks inevitably contain a certain number of defects such as microcracks and micropores; intact rock can be considered as an initial damaged medium [31–33]. Based on the variation of the stress wave velocity in the intact rock under different equal biaxial static loading in the model test, the initial damage variable was determined, and the Mohr-Coulomb elasto-plastic constitutive model. Based on the variation of the stress wave velocity in the intact rock under different equal biaxial static loading in the model test, the initial damage variable was determined, and the Mohr-Coulomb elasto-plastic constitutive model of the rock considering initial damage was established and subsequently imof the rock considering initial damage was established and subsequently implemented in plemented in the UDEC.
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