Abstract
Understanding the deformation failure behavior of the composite rock strata has important implications for deep underground engineering construction. Based on the uniaxial compression laboratory test of the specimens of composite rock strata containing holes, the microscopic parameters in the particle discrete element simulation are firstly calibrated. Then, the mechanical properties and failure characteristics of the composite rock strata with holes under different confining pressures are studied. The results show that different dip angles and confining pressures have significant effects on the peak strength and elastic modulus of the specimens. Under the same confining pressure, the peak strength and elastic modulus decrease first and then increase with the increasing dip angle. As the dip angle is constant, both the peak strength and elastic modulus gradually increase with the increase in confining pressure. It shows that the first area to be damaged in composite rock strata transfers from soft rock to hard rock with the increase in dip angle. With the increase in confining pressure, the range of tensile stress concentration area decreases substantially, while the range of compressive stress concentration area changes less.
Highlights
With the advancement of underground engineering technology, more and more tunnels have been built in deep complex rock strata [1,2,3]
It is revealed that both the peak strength and the modulus obtained by experiment and simulation decreases first and increases with the increase of the dip angle of the rock strata, and the difference between them is small
Taking specimen with α = 0° as an example, with the increase of the confining pressure, the peak strength of the composite rock specimen with holes increased from 12.4 MPa to 16.6 MPa, an increase of 34%
Summary
With the advancement of underground engineering technology, more and more tunnels have been built in deep complex rock strata [1,2,3]. Zhou et al [12] conducted uniaxial compression tests on hard rock with four types of cavities, and the influence of the shape of the holes on the rock mechanical properties and the evolution of fracture failure are studied. Wu et al [13] conducted a series of uniaxial compression tests using digital image techniques and acoustic emission to study the mechanical properties, failure characteristics and fracture features of the specimens with cross-excavation formed holes. In this paper, based on the uniaxial compression test of the composite rock strata with holes in the laboratory, the PFC2D software is used to conduct the biaxial compression test on the specimen of the composite rock strata with holes at different dip angles, and the influence of rock dip angle and confining pressure on the mechanical characteristics and failure modes of the specimen is studied
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