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   CN 44-1745/U

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Tunnel Construction >

2021 , Vol. 41 >Issue 1: 67 - 76

DOI: https://doi.org/10.3973/j.issn.2096-4498.2021.01.008

Safe Thickness and Fracture Evolution Law Determined for Hydraulic Fracturing of WaterResistant Rock Mass with Hidden Karst Based on GDEM

  • LI Tao ,
  • ZHANG Li ,
  • JIANG Qing ,
  • FENG Chun ,
  • ZHAO Ran
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  • (1. Shandong Hispeed JiLai Intercity Highway Co., Ltd., Jinan 250014, Shandong, China; 2. Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China)

Online published: 2021-02-08

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Abstract

To analyze the influence of hydraulic fracturing in hidden karst structures on the safe thickness and fracture evolution of a waterresistant rock mass, a highperformance GDEMDAS based on the continuumdiscontinuum element method is used to conduct threedimensional numerical simulation. The critical thickness of the rock mass is determined on the basis of the displacement evolution law of the tunnel face, and the fracture degree, a dimensionless index, is introduced to quantitatively describe the fracture evolution law of the rock mass during the excavation process. The results show that the changing curves of displacement and fracture degree are obtained at water pressures of 1, 2, and 3 MPa. The safe thicknesses of the rock mass under different water pressures are almost the same, at 7 m. In addition, the curves of displacement and fracture degree show inflection points of fracture degree 6 m in front of the inflection point of displacement, showing that displacement mutation will occur when the internal damage of the rock mass reaches a catastrophic level. Moreover, under the same simulation conditions, the inflection points of displacement and fracture degree under different water pressures in the karst cave are consistent, indicating that the water pressure is not the primary factor affecting the stability of the waterresistant rock mass.

Key words： karst tunnel; waterresistant rock mass; fracture degree; safe thickness; GDEM; numerical simulation

Cite this article

LI Tao , ZHANG Li , JIANG Qing , FENG Chun , ZHAO Ran .

Safe Thickness and Fracture Evolution Law Determined for Hydraulic Fracturing of WaterResistant Rock Mass with Hidden Karst Based on GDEM

[J]. Tunnel Construction, 2021 , 41(1) : 67 -76 . DOI: 10.3973/j.issn.2096-4498.2021.01.008

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