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Z-P Yield Criterion Based Analysis of the Element Safety Factor for the Stability of Surrounding Rock
(1 State Key Laboratory of Water Resources and Hydroelectric Engineering, Wuhan University, Wuhan 430072; 2 Chengdu Investigation and Design Institute Co. Ltd. of PowerChina, Chengdu 610072; 3 Changjiang Institute of Survey, Planning, Design and Research, Wuhan 430010)
Abstract The traditional failure evaluation criterion for the stability of surrounding rock can only be used for determining if surrounding rock failure will occur, but it can not quantitatively reflect the extent of damage to the surrounding rocks. By introducing the safety factor concept used in engineering, and based on the Z-P yield criterion and a unified expression of generalized Von Mises yield criterion, a 3D elastoplastic finite-element based element safety factor expression considering rock mass damage properties is deduced by a theory analysis, a quantitative index is established for the evaluation of stability of the tunnel surrounding rock, a tunnel excavation model is set up and a numerical simulation is carried out based on engineering case studies. The calculation results show that: 1) the closer to the excavation face, the greater the rock damage and the less safe the rock mass, and the greater the failure degree of the rock mass; and 2) when the element safety factor is less than one, its scope is approximately the same as the calculated surrounding rock plastic failure scope and damage area, which verifies the correctness of the deduced Z-P yield criterion-based element safety factor formula.
Abstract：
The traditional failure evaluation criterion for the stability of surrounding rock can only be used for determining if surrounding rock failure will occur, but it can not quantitatively reflect the extent of damage to the surrounding rocks. By introducing the safety factor concept used in engineering, and based on the Z-P yield criterion and a unified expression of generalized Von Mises yield criterion, a 3D elastoplastic finite-element based element safety factor expression considering rock mass damage properties is deduced by a theory analysis, a quantitative index is established for the evaluation of stability of the tunnel surrounding rock, a tunnel excavation model is set up and a numerical simulation is carried out based on engineering case studies. The calculation results show that: 1) the closer to the excavation face, the greater the rock damage and the less safe the rock mass, and the greater the failure degree of the rock mass; and 2) when the element safety factor is less than one, its scope is approximately the same as the calculated surrounding rock plastic failure scope and damage area, which verifies the correctness of the deduced Z-P yield criterion-based element safety factor formula.
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.Z-P Yield Criterion Based Analysis of the Element Safety Factor for the Stability of Surrounding Rock[J] MODERN TUNNELLING TECHNOLOGY, 2015,V52(5): 48-54
2015, Vol. 52 