Failure Mechanism and Energy Damage Evolution of Deep Sandstone Anchored by Carbon Fiber

Abstract

Deep rock mass engineering usually needs anchoring after excavation, and the strength and deformation characteristics of anchored rock mass will directly affect the safety and stability of underground engineering. Aiming at the state of deep surrounding rock after bolt shotcrete support, this paper takes the sandstone of a tunnel under construction in Guangxi as the research object, innovatively uses carbon fiber to anchor the sandstone in the circumferential direction, so as to simulate the bolt shotcrete support state of deep surrounding rock, and systematically studies the mechanical properties, failure mechanism and energy damage evolution law. The results show that: In this paper, carbon fiber was used as the anchoring material, and the anchoring effect was ideal, which can approximately simulate the bolt shotcrete support state of tunnel surrounding rock; With the gradual increase of anchorage area, the anchorage strength provided by carbon fiber gradually increases, the strength and deformation parameters, shear strength parameters and characteristic stress of anchored sandstone gradually increase, and the failure form gradually changes from single shear failure to shear failure, supplemented by cross through tension cracks, and the dissipated energy, elastic strain energy and total energy corresponding to the peak strength of anchored sandstone gradually increase, while the proportion of elastic and dissipated energy gradually decrease, and the damage variable gradually decreases; Based on the energy dissipation theory, the energy damage evolution equation considering the anchoring effect of carbon fiber was established. The rationality of the energy damage equation was verified by comparing test curves and theoretical curves of different anchoring areas. The research conclusion can provide a reliable theoretical basis for bolt shotcrete support of surrounding rock in deep underground engineering.