Effects of the compressible layer on the long-term stability of secondary lining in a squeezing tunnel

• Published in: Tunnelling and underground space technology Vol. 149; p. 105787
• Main Authors: Hongming, Tian, Zheyuan, Zhang, Weizhong, Chen, Xianjun, Tan, Dong, Wang, Jianxian, Yu
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2024
• Subjects: Compressible layer; Long-term stability of tunnel; Squeezing ground; Yielding support; Yielding support; Compressible layer; Squeezing ground; Long-term stability of tunnel
• ISSN: 0886-7798; 1878-4364
• DOI: 10.1016/j.tust.2024.105787

•Polyethylene foam layer is firstly used by the yielding support in a squeezing tunnel.•Verify the effectivity of polyethylene foam layer for the long-term stability of squeezing tunnel.•Proposed optimum thickness and filling materials of the compressible layer. The long-term deformation behavior of squeezing rock often results in damage to the secondary lining during tunnel operation. To prevent such damage, a compressible layer filled with foamed materials that possess high deformation capacity, is constructed between the primary support and the secondary lining. This study investigated the effects of a polyethylene (PE) foam compressible layer on the long-term stability of the squeezing tunnel through field monitoring and numerical simulation. Results demonstrate that the PE foam compressible layer can absorb approximately 90% of the time-dependent deformation of the squeezing rock during tunnel operation, and the compressible layer significantly reduces the hoop stress and plastic zone of the secondary lining, indicating the substantial benefits of the PE foam compressible layer for the long-term stability of squeezing tunnels. Based on the influences of thickness and filling materials on the performance of the compressible layer, optimization suggestions for the design parameters of the compressible layer are proposed for the squeezing tunnel.