Experiments Studying the Instability Process of a Subway Tunnel in Soil–Rock Composite Strata Influenced by Defects

Subway tunnels excavated in soil–rock composite strata face great challenges due to the prevalence of inner defects. The instability of tunnels in these strata poses significant risks to construction safety. In this paper, indoor experiments are adopted to study the instability process of a subway t...

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Main Authors: Ruichuan Zhao, Yunfei Zheng, Yongjian Guo, Shaoshun Luan, Sulei Zhang
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Buildings
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Online Access:https://www.mdpi.com/2075-5309/15/6/878
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author Ruichuan Zhao
Yunfei Zheng
Yongjian Guo
Shaoshun Luan
Sulei Zhang
author_facet Ruichuan Zhao
Yunfei Zheng
Yongjian Guo
Shaoshun Luan
Sulei Zhang
author_sort Ruichuan Zhao
collection DOAJ
description Subway tunnels excavated in soil–rock composite strata face great challenges due to the prevalence of inner defects. The instability of tunnels in these strata poses significant risks to construction safety. In this paper, indoor experiments are adopted to study the instability process of a subway tunnel in soil–rock composite strata influenced by inner cavities. A total of six groups of tests are designed based on the location of the cavity and the distance of the cavity from the tunnel. High-resolution monitoring techniques are employed to capture the real-time deformation and failure process of strata. The results show that a cavity in the strata significantly affects the stability of the strata after the tunnel excavation. The existence of a cavity increases ground deformation, and a cavity at different locations affects ground deformation. The strata around the cavity are the first to experience failure by the upper loads applied after the tunnel is excavated. The location of the cavity changes the stress distribution state of the strata and thus alters the emergence of cracks, which finally disturbs the collapse process and pattern of the composite strata. The probability and collapse range increase when the tunnel excavation impact zone is connected with the cavity weakening zone. The findings can provide technical support for the collapse prevention and safety control of subway tunnels in composite strata with internal defects.
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spelling doaj-art-d62d6dd476024f13981023f2a3bcdcb02025-08-20T02:11:15ZengMDPI AGBuildings2075-53092025-03-0115687810.3390/buildings15060878Experiments Studying the Instability Process of a Subway Tunnel in Soil–Rock Composite Strata Influenced by DefectsRuichuan Zhao0Yunfei Zheng1Yongjian Guo2Shaoshun Luan3Sulei Zhang4CCCC HIGHWAY CONSULTANTS Co., Ltd., Beijing 100010, ChinaSchool of Civil Engineering, Qingdao University of Technology, Qingdao 266033, ChinaQingdao Conson Second Jiaozhou Bay Subsea Tunnel Co., Ltd., Qingdao 266071, ChinaSchool of Civil Engineering, Qingdao University of Technology, Qingdao 266033, ChinaSchool of Civil Engineering, Qingdao University of Technology, Qingdao 266033, ChinaSubway tunnels excavated in soil–rock composite strata face great challenges due to the prevalence of inner defects. The instability of tunnels in these strata poses significant risks to construction safety. In this paper, indoor experiments are adopted to study the instability process of a subway tunnel in soil–rock composite strata influenced by inner cavities. A total of six groups of tests are designed based on the location of the cavity and the distance of the cavity from the tunnel. High-resolution monitoring techniques are employed to capture the real-time deformation and failure process of strata. The results show that a cavity in the strata significantly affects the stability of the strata after the tunnel excavation. The existence of a cavity increases ground deformation, and a cavity at different locations affects ground deformation. The strata around the cavity are the first to experience failure by the upper loads applied after the tunnel is excavated. The location of the cavity changes the stress distribution state of the strata and thus alters the emergence of cracks, which finally disturbs the collapse process and pattern of the composite strata. The probability and collapse range increase when the tunnel excavation impact zone is connected with the cavity weakening zone. The findings can provide technical support for the collapse prevention and safety control of subway tunnels in composite strata with internal defects.https://www.mdpi.com/2075-5309/15/6/878soil–rock composite stratainner defectinstability processground deformationindoor experiment
spellingShingle Ruichuan Zhao
Yunfei Zheng
Yongjian Guo
Shaoshun Luan
Sulei Zhang
Experiments Studying the Instability Process of a Subway Tunnel in Soil–Rock Composite Strata Influenced by Defects
Buildings
soil–rock composite strata
inner defect
instability process
ground deformation
indoor experiment
title Experiments Studying the Instability Process of a Subway Tunnel in Soil–Rock Composite Strata Influenced by Defects
title_full Experiments Studying the Instability Process of a Subway Tunnel in Soil–Rock Composite Strata Influenced by Defects
title_fullStr Experiments Studying the Instability Process of a Subway Tunnel in Soil–Rock Composite Strata Influenced by Defects
title_full_unstemmed Experiments Studying the Instability Process of a Subway Tunnel in Soil–Rock Composite Strata Influenced by Defects
title_short Experiments Studying the Instability Process of a Subway Tunnel in Soil–Rock Composite Strata Influenced by Defects
title_sort experiments studying the instability process of a subway tunnel in soil rock composite strata influenced by defects
topic soil–rock composite strata
inner defect
instability process
ground deformation
indoor experiment
url https://www.mdpi.com/2075-5309/15/6/878
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