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Numerical Simulation Study on Loosened Zone of Surrounding Rock of Large-span Flat Caverns
(1. State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092; 2. Department of Geotechnical of Geotechnical Engineering, Tongji University, Shanghai 200092; 3. State Key Laboratory of Disaster Prevention & Mitigation of Explosion & Impact, Army Engineering University of PLA, Nanjing 210007)
Abstract From the perspective of the expansion law of cavern loosen zone, FLAC 2D software was adopted to carry out the numerical simulation of four different flat caverns with different spans and buried depths. The full-face excavation method was selected to simulate the construction. And the loosened zone of surrounding rock was estimated by the ultimate tensile strain criterion. After that the corresponding expansion pattern of loosened zone was analyzed.The research result shows that: (1) The loosened zone of the four caverns are mainly distributed at the arch part of surrounding rock, and the sidewall is not loose. When the span increases to 68 m, the scale of loosen zone increases significantly. (2) With the increase of buried depth of caverns, the range of loosened zone firstly increases, then decreases and increases again. (3) The increase of span and degree of flattening leads to higher requirement of buried depth for the decreasing stage of loosened zone. Four different caverns have different optimum buried depths, which can provide reference for the design and construction of practical projects.
Abstract：
From the perspective of the expansion law of cavern loosen zone, FLAC 2D software was adopted to carry out the numerical simulation of four different flat caverns with different spans and buried depths. The full-face excavation method was selected to simulate the construction. And the loosened zone of surrounding rock was estimated by the ultimate tensile strain criterion. After that the corresponding expansion pattern of loosened zone was analyzed.The research result shows that: (1) The loosened zone of the four caverns are mainly distributed at the arch part of surrounding rock, and the sidewall is not loose. When the span increases to 68 m, the scale of loosen zone increases significantly. (2) With the increase of buried depth of caverns, the range of loosened zone firstly increases, then decreases and increases again. (3) The increase of span and degree of flattening leads to higher requirement of buried depth for the decreasing stage of loosened zone. Four different caverns have different optimum buried depths, which can provide reference for the design and construction of practical projects.
LEI Zhongdai1,
2 KONG Xinli3 WANG Wenye3 YAN Zhiguo1,
2
.Numerical Simulation Study on Loosened Zone of Surrounding Rock of Large-span Flat Caverns[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(5): 41-46
2022, Vol. 59 