On Safety in Dismantling Temporary Strut of Super-large Tunnels with Double-layer Primary Support
(1 Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, Chengdu 610031; 2 China Railway Southwest Research Institute Co., Ltd., Chengdu 611731; 3 China Railway Siyuan Survey and Design Institute Group Co., Ltd., Wuhan 430063)
Abstract：
More and more multiple-track tunnels and super-large section tunnels have been built, and disman? tling of temporary strut is a weak point of the whole structure during force transfer when the secondary lining is constructed. It is significant to guarantee structure safety during dismantling of temporary strut. Little systematic research on safety in dismantling of temporary strut of the super-large section tunnel with double-layer primary support has been conducted, so the internal force and security of the two-layer primary support of the Xinkaotang tunnel were analyzed by a numerical analysis and site measurement, and it proves the effect of two-layer primary support on the safety during strut dismantling. The research results indicate that: (1) with constant support thickness and one-time longitudinal dismantling length, the safety factor of secondary primary support is larger than that of the first primary support, and the safety factor of the first primary support is larger than that of the single layer primary support. Change range of safety factor for the first primary support is smaller than that of the single-layer primary support, and the safe factor for the single-layer primary support is smaller than that of the secondary primary support; (2) with the same support pattern, the safety factors increase firstly and then decrease with an increase of the onetime dismantling length. The calculated results of various cases show that the reasonable one-time dismantling length for this project is about 9 m.
.On Safety in Dismantling Temporary Strut of Super-large Tunnels with Double-layer Primary Support[J] MODERN TUNNELLING TECHNOLOGY, 2018,V55(6): 108-116
2018, Vol. 55 