Abstract For a mined large-span tunnel constructed through the double side drift method in soft, weak, broken and water-rich strata, the alternate bay construction is completely dependent on the "shed support effect" of the initial support to maintain the stability of the large-span structure after support dismantling, which is often in the dilemma of small support-dismantling step, high risk, low efficiency and high cost, and if an improper support-dismantling scheme is taken, safety accidents such as the collapse will be easily induced. To address this problem, this paper takes the Cuobuling Station of Qingdao Metro Line 4 as the engineering background and applies the combination of theoretical analysis and numerical calculation to demonstrate that the "spatial shed support effect" of the initial support after support dismantling is mainly composed of the "transverse arching effect" and the "longitudinal beam effect", both of which help maintain the safety and stability of the large-span structure. Also, this paper determines reasonable, safe, efficient and fast support-dismantling zone partition length and compart zone partition length, which are L=9 m and S=18 m respectively and have successfully passed the verification of on-site construction. The results show that the support-dismantling scheme of "comparting two partitions and dismantling one partition, constructing inside first and then portal" is practical and feasible for subsequent projects.
Abstract：
For a mined large-span tunnel constructed through the double side drift method in soft, weak, broken and water-rich strata, the alternate bay construction is completely dependent on the "shed support effect" of the initial support to maintain the stability of the large-span structure after support dismantling, which is often in the dilemma of small support-dismantling step, high risk, low efficiency and high cost, and if an improper support-dismantling scheme is taken, safety accidents such as the collapse will be easily induced. To address this problem, this paper takes the Cuobuling Station of Qingdao Metro Line 4 as the engineering background and applies the combination of theoretical analysis and numerical calculation to demonstrate that the "spatial shed support effect" of the initial support after support dismantling is mainly composed of the "transverse arching effect" and the "longitudinal beam effect", both of which help maintain the safety and stability of the large-span structure. Also, this paper determines reasonable, safe, efficient and fast support-dismantling zone partition length and compart zone partition length, which are L=9 m and S=18 m respectively and have successfully passed the verification of on-site construction. The results show that the support-dismantling scheme of "comparting two partitions and dismantling one partition, constructing inside first and then portal" is practical and feasible for subsequent projects.
GAO Xin WANG Wenjuan LI Qingfei FENG Shijie WU Qi
.Spatial Effect of Support Dismantling through Alternate Bay Construction Method in Shallow-buried Large-span Tunnels in Soft and Weak Strata[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(2): 111-121
2022, Vol. 59 