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| Mechanism of splitting failure and stability analysis of the loosening zone in deep surrounding rock |
| GUO Wei1, CHEN Haoxiang2*, LI Jie1, XU Tianhan1, LI Chao1, JI Yuguo1
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1. State Key Laboratory of Disaster Prevention and Mitigation of Explosion and Impact, Army Engineering University of PLA, Nanjing 210007, Jiangsu, China;
2. School of Civil and Transportation Engineering, Beijing University of Civil Engineering and Architecture, Beijing 100044, China |
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Abstract The deformation control mechanisms in underground caverns were investigated through systematic analysis of splitting phenomena within the surrounding rock's loosened zone. An elastic-brittle-plastic constitutive model was developed to formulate stress and deformation field expressions, enabling the derivation of a quantitative characterization for loosened zone dimensions. Stress relaxation mechanisms at rock mass discontinuities were analyzed, leading to systematic characterization of deformation and splitting processes within the loosened zone. Clear logical relationships between shear failure and splitting failure mechanisms were established, with a stress criterion for splitting failure in the loosened zone being proposed. Critical external load conditions were identified for four typical failure modes: shear failure, shear fragmentation, slab fracturing, and splitting in the maximum support pressure zone. Key findings revealed that radial unloading induced localized tensile stress fields in surrounding rock. Plastic shear deformation was confirmed as a prerequisite for internal rock mass splitting failure. A positive correlation was observed between modulus differences during loading-unloading cycles and splitting susceptibility. Comparative analysis demonstrated that the occurrence threshold for shear fragmentation significantly exceeded that of splitting failure, suggesting limited practical occurrence of shear fragmentation in engineering applications. These findings provide theoretical foundations for predicting and controlling surrounding rock stability in underground excavation projects.
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Published: 18 June 2025
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