Abstract
Excavation-damaged zones (EDZs) induced in underground mining and civil engineering potentially threaten tunnel safety and stability, and increase construction and support costs. In this paper, an investigation of the excavation damaged zone (EDZ) around roadways in Fankou lead-zinc mine in Guangzhou, China is performed by applying a seismic velocity method accompanied by SET-PLT-01 nonmetallic ultrasonic detector. Meanwhile, the in situ stress in the mining area was measured based on the stress relief method with the Swedish high-precision LUT system. The results indicate that the stress field is dominated by the maximum horizontal tectonic stress, and the extents of the EDZ on the roof-floor region are greater than that on the sidewall. In addition, both of the in situ stresses and EDZs show an increasing trend with an increase of depth. Analytical solutions of EDZ around circular openings in the brittle rock mass subjected to non-hydrostatic stress fields are presented in terms of the Mohr–Coulomb and generalized Hoek–Brown criteria, and validated by several cases mentioned above. The extents of EDZ solved by closed-form solutions were found to be in a great agreement with those obtained in the field. Finally, a series of parametric studies are conducted to investigate the effects of cohesion (c), friction angle (φ), geological strength index (GSI), mi, uniaxial compressive strength (σc), and disturbance factor (D) on EDZ. It is shown that the effects of c, φ, GSI, and σc are significant; however, more attention should be paid to consider the dynamic disturbances induced by mechanical drilling, blasting, and seismic waves in tunnel excavations or operations.
Highlights
The supply of energy is related to the lifeblood of global economic development
In this paper, closed-form solutions based on the Mohr–Coulomb and Hoek–Brown failure criteria are derived for predicting the extent of Excavation-damaged zones (EDZs) in the surrounding rock mass around a circular opening subjected to a non-hydrostatic stress field
The results indicate that σh-max, σh-min, and σv of the mining area increase approximately linearly with the depth, and the in situ stress field is dominated by maximum horizontal tectonic stress, followed by vertical principal stress
Summary
The supply of energy is related to the lifeblood of global economic development. As one of the important components of energy, mineral resources are rapidly decreasing in the shallow crust.in order to ensure sustainable human production activities, a number of mines are gradually shifting to deep mining around the world. The supply of energy is related to the lifeblood of global economic development. As one of the important components of energy, mineral resources are rapidly decreasing in the shallow crust. It is well known that in situ stress redistribution will be generated during the excavation progress of a man-made opening, the tangential stress gradually increases while radial stress on the surrounding rock mass decreases. Both of them reach an extreme state on the surface of the openings and stress concentrations occur in the surrounding of the openings. Once the concentrated stress exceeds the failure strength of the surrounding rocks, excavation-induced cracks are initiated and gradually expand deep into the rock mass until the stress
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