Effect of Axial In-Situ Stress in Deep Tunnel Analysis Considering Strain Softening and Dilatancy

Kang Yi, Zhenghe Liu, Zhiguo Lu, Junwen Zhang and Shuangyong Dong
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Kang Yi: School of Energy & Mining Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
Zhenghe Liu: Key Laboratory of In-situ Property-improving Mining of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China
Zhiguo Lu: Mining and Designing Branch, China Coal Research Institute, Beijing 100013, China
Junwen Zhang: School of Energy & Mining Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
Shuangyong Dong: Mining and Designing Branch, China Coal Research Institute, Beijing 100013, China

Energies, 2020, vol. 13, issue 6, 1-14

Abstract: In many previous tunnel analyses, the axial in-situ stress was ignored. In this work, its effect on the deformation and failure of the surrounding rock of a deep tunnel was revealed, considering the objective strain softening and dilatancy behavior of the surrounding rock. Analysis based on the incremental plastic flow theory was conducted, and C++ was used to write a constitutive model for numerical simulation to verify and further analyze this effect. Then, the results were validated by the field monitoring data of a coal mine gateway. Results show that the effect of the axial in-situ stress σ a0 is more significant when strain softening is considered, compared with the results of a perfectly elastoplastic model. When the axial stress σ a is σ 1 or σ 3 at the initial yield, an increase or decrease in σ a0 intensifies the deformation and failure of the surrounding rock. When σ a is σ 2 at the initial yield, 3D plastic flow partly controlled by σ a may occur, and an increase in σ a0 intensifies the deformation and failure of the surrounding rock. The effect of σ a0 will be amplified by considering dilatancy. Considering both strain softening and dilatancy, when σ a0 is close to the tangential in-situ stress σ t0 or significantly greater than σ t0 (1.5 times), σ a will be σ 2 or σ 1 at the initial yield, and then 3D plastic flow will occur. In the deformation prediction and support design of a deep tunnel, σ a0 should not be ignored, and the strain softening and dilatancy behavior of the surrounding rock should be accurately considered.

Keywords: deep tunnel; axial in-situ stress; strain softening; dilatancy; constitutive model (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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