Abstract When the high-speed railway tunnel is excavated in the karst development area, the influence of large karst cave below on tunnel construction cannot be ignored. In view of construction difficulty in bottom large karst cave encountered in Wangzhuang Tunnel of Nanning-Chongzuo Railway, the "treatment-after-passing" construction technology was proposed to deal with the karst cave below by using the methods of numerical simulation and model test analysis on the basis of high bearing capacity characteristics of limestone, as shown below. The foot-locking bolts and arch anchor cables will be added after completion of upper bench, and the lower support structure will be lifted. The tunnelling process will continue, and the muck will be quickly used to backfill the karst cave below.When there is no interference between the construction area and the karst cave treament area the karst cave roof will be exposed in the lower bench and the permanent treatment will be conducted for the karst cave. Raft and pile foundation is adopted to treat the large karst cave below to form a "pile-slab structure" to reduce the impact of the karst cave on the tunnel operation. This karst tunnel construction technology effectively reduces the impact of karst tunnel treatment on construction progress and ensures construction safety and quality. So, it provides a useful reference for similar projects.
Abstract：
When the high-speed railway tunnel is excavated in the karst development area, the influence of large karst cave below on tunnel construction cannot be ignored. In view of construction difficulty in bottom large karst cave encountered in Wangzhuang Tunnel of Nanning-Chongzuo Railway, the "treatment-after-passing" construction technology was proposed to deal with the karst cave below by using the methods of numerical simulation and model test analysis on the basis of high bearing capacity characteristics of limestone, as shown below. The foot-locking bolts and arch anchor cables will be added after completion of upper bench, and the lower support structure will be lifted. The tunnelling process will continue, and the muck will be quickly used to backfill the karst cave below.When there is no interference between the construction area and the karst cave treament area the karst cave roof will be exposed in the lower bench and the permanent treatment will be conducted for the karst cave. Raft and pile foundation is adopted to treat the large karst cave below to form a "pile-slab structure" to reduce the impact of the karst cave on the tunnel operation. This karst tunnel construction technology effectively reduces the impact of karst tunnel treatment on construction progress and ensures construction safety and quality. So, it provides a useful reference for similar projects.
CHEN Wenyin
.Study on Treatment-after-passing Technology for Large Karst Cave below High-speed Railway Tunnel[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(4): 248-255
2022, Vol. 59 