盾构隧道管片结构设计几个问题的探讨

由于国内盾构隧道结构现有计算方法考虑因素不全面、部分计算方法不合理,造成盾构管片配筋量偏大,对管片预制及工程造价都带来很大影响。为提高现有盾构隧道结构设计方法的准确性和可靠性以及优化管片配筋,通过大量的盾构隧道结构计算和工程经验,对多个设计问题进行分析,结果表明:深埋等复杂地质条件下长大盾构隧道结构计算需要考虑管片的环、纵向接头作用;极限状态法没有区分施工和运营工况受力特点等。通过研究提出以下解决方案:(1)采用改进管片接头单元的梁-弹簧模型,结合接头试验对抗弯刚度等取值进行优化;(2)考虑盾构隧道施工阶段为短暂设计工况,运营阶段为持久设计工况进行安全校核;(3)提出纤维梁单元模型,对管片配筋进行校核;(4)提出多种管片配筋优化设计方法,减少钢筋用量。

Discussion on Several Problems in the Design of Shield Tunnel Segment

As the existing calculation methods of shield tunnel structure in China are not comprehensive and some of them are not reasonable, the quantity of reinforcement of shield tunnel segments is relatively large, which has a great impact on the prefabrication and engineering cost of the segments. In order to improve the accuracy and reliability of the existing shield tunnel structure design method and optimize the reinforcement of the segments, a number of design problems are analyzed based on a large number of shield tunnel structure calculation and engineering experiences. The results show that the toroidal and longitudinal joint action of segments should be considered in the calculation of long shield tunnel structure under complex geological conditions such as deep burial, and the limit state method fails to distinguish the stress differences caused by the construction and the operation. The following solutions are proposed through research: 1)The beam-spring model of the improved segment joint unit is adopted to optimize bending stiffness and so on through joint test; 2)The shield tunnel construction stage is taken as a short-term design condition and the operation stage as a permanent design condition for safety check; 3)A fiber beam element model is proposed to check the reinforcement of the segment; 4)A variety of tube reinforcement optimization design methods are put forward to reduce the amount of steel.