【作者】 张晅；

【导师】 杨成永；

【作者基本信息】 北京交通大学 ， 环境工程， 2008， 硕士

【摘要】 隧道施工中,利用支护位移的监控量测数据及时地进行支护结构的安全性评价是隧道动态设计的关键,对保证隧道结构的安全具有重要意义。在隧道监控量测参数中,支护位移由于测量方便、花费低和可信度高,在工程实践中被广泛采用。本文针对以位移为基础的隧道支护结构安全性分析方法,探讨了喷射混凝土的收缩和徐变变形对隧道安全性的影响。叙述了喷射混凝土的干缩和徐变特性,推导了考虑干缩和徐变时支护内力的计算公式,给出了支护结构截面失效的功能函数,并进行了工程实例分析。分析结果表明,干缩与徐变均使隧道支护结构的可靠指标有所增加,不考虑干缩与徐变时的计算结果是偏于保守的。相比而言,干缩使可靠指标增大不多,一般情况下可忽略其影响。徐变对可靠指标的影响,在喷层受力不大时,影响不显著,实际工作中可以不考虑;反之,则建议考虑徐变的影响。本文的工作提高并完善了施工期隧道喷射混凝土支护安全性评价位移方法。更多还原

【Abstract】 To a tunnel under construction, a prompt assessment to the safety of the lining through in-situ measured data is of practical importance both for the dynamic design and to guarantee the stability of the tunnel. Among all the parameters measured during tunnel construction, displacement is widely used and thus accepted as a very essential quantity, due to its advantages in convenience, low cost and high credibility.In terms of the displacement-based method previously proposed to evaluate the safety of tunnel support structures, the influence of shrinkage and creep of shotcrete on the stability of tunnels is approached in this paper. The properties of shotcrete on shrinkage and creep are discussed, and the formulas to calculate the internal forces of the shotcrete lining with shrinkage and creep considered are derived out. Then a performance function for the failure of a cross section is given. At last, three case studies are done.The results show that the method gives larger reliability index when shrinkage and creep of the shotcrete are taken into account. That is to say, the reliability index was underestimated in the past. In comparison with creep, shrinkage doesn’t have much contribution to the increase of the reliability index, which means that shrinkage could be neglected in the analysis. The influence of creep depends on the dimension of the internal forces of the lining. When the forces are small, the influence of creep could be ignored. However, when the forces are big, the influence of creep should be taken into consideration.This work improves the accuracy of the displacement-based method.更多还原