| Catastrophe behavior of tunnel, forced dynamic response and cracking destruction mechanism of structure, anti-breaking control of supporting structure system under the condition of active fault stick-slip movement are the key scientific issues to be addressed during tunnel contruction and operation. Facing the problem of metro tunnel construction in the active fault site, it is frequently recommended to adopt avoidance scheme. For unable to avoid around the tunnel engineering, our country does not develop a set of reasonable and complete design methods. In order to research the design parameter reasonability of tuunel support structure in different level of movement, metro line 1 of Urumchi is taken as the research object in this paper with many approaches, such as information research, theoretical studies and numerical simulation. The following aspects were studied mainly:(1) Based on exsisting engineering technology, the paper put forward five design concepts for anti-breaking measures of metro tunnel, for example, segmentation design, over-excavation design, energy dissipation structure, strengthening stiffness and new material application. For the deformation of segmentation design, three different structure forms and simplified model of mechanism were discussed. According to research relative position among deformation and fault rupture surface, the mechanical diffeerances and clearance expanding volume were comparaed analyzed.(2) By using the finite element program ansys, the ground-structure model of integral metro tunnel is established to analyze mechanical response characteristics of supporting structure, and to summarize anti-breaking strengthening length of tunnel. The strengthening length defined main control area and impact area by the mechanical characteristics of primary support.(3) The interaction-spring stiffness calculation formula between primary support and secondary lining are deduced initially by using elastic mechanics analysis method. According to actual engineering parameters, the theoretical value of spring stiffness is calculated. For the waterproof partition design of deformation joint, three-demensional load-structure model of sectional tunnel is established to analyze deformation characteristics, stress, fracture distribution and typical section internal force by different thickness and section length of lining under effect of stick-slip fault, which can evaluate safety in various fault momentum and obtain grading evaluation of supporting structure. In the end, related parameters of supporting structure are obtained comprehensively in metro line 1 of Urumchi cross BangGang-ShiHua reverse fault.(4) On the basis of related parameters of metro tunnel structure in fortified area, considering distributed steel requirement of lining, separate type load-structure model of segmented tunnel is established. Numerical simulation was conducted to study crack width and distribution of segmented lining, which microanalyzed crack state of lining in main control area and impact area. Further combing with the damage form of metro tunnel under the effect of fault, maintenance and reinforcement measures are presented after earthquake. |
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