盾构隧道管片结构承载能力评估方法研究

Bearing Capacity Evaluation Method for Segment Lining Structure of Shield Tunnel

摘要:

承载性能是盾构隧道管片衬砌结构重要的力学特性之一，其准确评估是保障结构受力安全的关键，然而目前尚无成熟的评价方法。首先基于管片衬砌结构中管片和管片接头的受力及变形特征，建立了基于管片承载力和管片接头承载力的管片衬砌结构承载性能评估方法，提出了管片衬砌结构承载性能评估指标，然后分别开展了单环和组合环管片衬砌结构破坏加载原型试验对所提出的方法进行检验，最后结合现场实测对实际工程中管片衬砌结构的承载状态进行了定量评估和分析。研究结果表明：单环结构破坏试验中，管片接头破坏现象更为明显，其先于管片达到抗弯承载力极限值，组合环结构破坏试验中，管片破坏现象更为明显，其先于管片接头达到抗弯承载力极限值；单环和组合环管片结构试验中，结构破坏与理论计算方法中管片或接头达到承载力极限的荷载一致，表明所提出的结构承载状态评估方法是合理的；所选取监测断面管片结构中管片和接头的承载安全系数分别为4.27和4.86，可见其承载状态良好。该研究方法和结论可为类似盾构隧道管片结构承载安全评估提供重要支撑。

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.