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| Numerical Simulation Analysis of Construction Behavior for Metro Triplet Tunnels with Extremely Small Spacing |
| WAN Tao1，LIN Gang2，XI Shu - juan1 |
| (1. Shijiazliuang Institute of Railway Technology， Shijiazhuang，Hebei 050041， China; 2. China Railway Eryuan Engineering Group Co. Ltd，Chengdu，Sichuan 610031，China) |
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Abstract Abstract:Research purposes: With the aim to study the construction behavior of triplet tunnels group with extremely small spacing，the construction progress was numerically simulated by finite diferential software FLAC3D. Based on the numerical simulation，the construction behavior characteristics such as the ground surface， crown settlements，failure area distribution of surrounding soils and the influence on the as - built tunnels from subsequent construction are presented. The construction scheme is also evaluated according to the numerical simulation and then optimizing suggestions are proposed. Research conclusions ：( 1) During the excavation of two side tunnels，the ground settlement presents W - shape and the settlement centers are located above the central lines of the side tunnels. While the middle tunnel is excavated using CRDmethod，the ground settlement above the middle tunnel is much greater than the ground settlements above the side tunnels and the final ground settlement trough shows some skewnes. (2) In the construction progress of triplet tunnels group with extremely small spacing， the failure area of surrounding soils has been continuous when the side tunnel construction is completed. Grouting reinforcement can effectively prevent the expansion of the failure area. (3) The influence on the primary support structures of constructed tunnels from subsequence construction is significantly greater at the entrance section with extremely small spacing. Especially the compressive stress increases greatly. ( 4) The numerical simulations results agreed with site monitoring data very well which proves the reliability of numerical simulation computation. (5 ) The research result can provide a reference for the design and construction control of similar projects.
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Received: 05 September 2016
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2016, Vol. 33 
