Abstract Sandy cobble stratum has little cohesion and poor self-stability capacity, and is very prone to collapse during tunnel construction, making it difficult to control the ground surface settlement. In order to study the ground surface settlement pattern and relevant control measures when a shield is driving under sensitive areas in sandy cobble stratum, this paper uses the Chengdu Metro Line 5, which passes under the throat area of Baocheng Railway, as the engineering context for the study. Through comparison of construction methods, numerical simulation and feedback from site monitoring, this paper proposes the control measures for and elucidates the pattern of the ground settlement, and verifies the effectiveness of the settlement control measures. The study results show that it is reasonable and effective to use the reinforcement measures such as the double-layered large pipe roof in combination with the ground tracing grouting method to control the ground settlement during the shield construction in sandy cobble stratum; calculations show that the ground surface settlement is reduced by 61.16% after consolidation of the strata compared to that without consolidation; using fully automatic monitoring system for real-time feedback and early warning of ground settlement, the monitoring data show that the maximum ground settlement during construction is 1.29 mm and the maximum heaving is 0.72 mm, which verifies the effectiveness of the ground reinforcement measures and ensures the safety of shield tunnelling and railway operation.
Abstract：
Sandy cobble stratum has little cohesion and poor self-stability capacity, and is very prone to collapse during tunnel construction, making it difficult to control the ground surface settlement. In order to study the ground surface settlement pattern and relevant control measures when a shield is driving under sensitive areas in sandy cobble stratum, this paper uses the Chengdu Metro Line 5, which passes under the throat area of Baocheng Railway, as the engineering context for the study. Through comparison of construction methods, numerical simulation and feedback from site monitoring, this paper proposes the control measures for and elucidates the pattern of the ground settlement, and verifies the effectiveness of the settlement control measures. The study results show that it is reasonable and effective to use the reinforcement measures such as the double-layered large pipe roof in combination with the ground tracing grouting method to control the ground settlement during the shield construction in sandy cobble stratum; calculations show that the ground surface settlement is reduced by 61.16% after consolidation of the strata compared to that without consolidation; using fully automatic monitoring system for real-time feedback and early warning of ground settlement, the monitoring data show that the maximum ground settlement during construction is 1.29 mm and the maximum heaving is 0.72 mm, which verifies the effectiveness of the ground reinforcement measures and ensures the safety of shield tunnelling and railway operation.
QIU Wenge WAN Shifu GAO Ganggang ZHAO Hailin QI Xingxin
.tudy on the Control Measures against Ground Settlement Induced by Shield Tunnel Construction underneath Railway Throat in Sandy Cobble Stratum[J] MODERN TUNNELLING TECHNOLOGY, 2021,V58(5): 37-45
2021, Vol. 58 