Bearing Capacity Evaluation Method for Segment Lining Structure of Shield Tunnel

Abstract:

Bearing capacity is one of the most important mechanical properties of the segment lining structure of shield tunnel, whoes accurate evaluation is the key to ensuring the safety of the structure under stress. However, there is currently no mature evaluation method. Based on the stress and deformation characteristics of segment and segmental joint， the evaluation method and index for evaluating the bearing capacity of segment lining structure with the bearing capacity of segment and segmental joint involved were established in this paper， the prototype failure tests of straight-joint assembly structure （STRS） and staggered-joint assembly structure （STGS） were preformed to verify the proposed evaluation method， in combination with the field monitoring tests， the bearing state of the segment lining structure in the actual project is quantitatively evaluated and analyzed. The results show that the failure phenomenon of segmental joint is more obvious in the failure tests of STRS， and the joint reaches its ultimate bearing capacity before the segment， while in the failure tests of STGS， the failure phenomenon of segment is more obvious， and the segment reaches its ultimate bearing capacity before the joint. In the failure tests of STRS and STGS， the failure of segment and segmental joint occur simultaneously with their internal forces reaching the ultimate bearing capacity， indicating that the proposed evaluation method is reasonable. The bearing safety factors of segment and segmental joint in the selected section are 4.27 and 4.86 respectively， indicating that the bearing state of the selected section is good. The research methods and conclusions of this paper can provide important support for bearing safety assessment of similar segment lining structure in shield tunnels.

Key words:shield tunnel;segment lining structure;bearing state;evaluation method;prototype test;field monitoring test