ANALYSIS OF MECHANISM OF MID-PARTITION ECCENTRIC COMPRESSION AND CONSTRUCTION EFFECT ON SUPER-LARGE SECTION MULTI-ARCH TUNNEL
XU Chongbang1，2，XIA Caichu1，3，WANG Hualao2
(1. Department of Geotechnical Engineering，Tongji University，Shanghai 200092，China；2. Research Institute of Highway，Ministry of Transport，Beijing 100088，China；3. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education，Tongji University，Shanghai 200092，China)
Abstract：The mid-partition of a multiple-arch tunnel is very important and attracts much attention in tunnel designing and constructing as it is a main support structure of tunnel，and affects the integrated stability of tunnel engineering. The mid-partition destabilization is eccentric compression instability in which the mechanics reason is unevenly stressing，so，controlling eccentric compression of the mid-partition control is critical to the control stability of mid-partition. The geological eccentric compression of tunnel engineering and the construction eccentric compression which come from asymmetric construction are the basic cause，and according to stress state of mid-partition，the condition and the position of eccentric compression from the geological eccentric compression and the construction eccentric compression are determined. The effects of construction procedure under the geological eccentric compression and the construction eccentric compression are analyzed through the computation simulation for different construction procedures of multi-arch tunnel by the finite element method. Optimum analysis for construction scheme according to the obtained law is completed. At last，the example of the multiple-arch tunnel with eight traffic lanes is given.
