【作者】 余铎；

【导师】 夏永旭；

【作者基本信息】 长安大学 ， 桥梁与隧道工程， 2011， 硕士

【摘要】 在岩体中开挖隧道,围岩受到施工扰动不断地进行应力释放,从而引起围岩的变形发展,而支护结构也随着时间的增长对围岩的变形产生越来越明显地抑制作用。本文介绍了岩土材料时空效应研究现状、流变理论以及混凝土支护结构徐变等时间特性。利用依托工程万丈山等多个隧道的监测数据,通过归纳分析给出隧道施工不同时刻对应的围岩荷载释放率,然后选用弹塑性D-P模型和线性粘弹性广义开尔文模型,采用有限元方法对软岩隧道施工全过程的时空效应进行了数值分析研究。首次尝试同时考虑围岩流变和混凝土支护强度增长特性,动态模拟分析了施工过程中隧道围岩和支护结构的力学特性。主要得出以下结论：(1)对依托工程等多个隧道的监测资料进行分析,得出Ⅳ级围岩隧道洞周收敛在20天内基本达到稳定。并通过归纳分析给出了不同施工时间段对应的围岩压力释放率。(2)运用弹塑性本构模型,不考虑围岩流变和支护强度增长过程进行分析时,围岩各特征部位计算位移值均偏小,与实际监测结果偏差很大；而考虑围岩流变及不同时刻支护结构对应不同强度特性时,计算结果与实测数据吻合较好,能反映出施工过程的时间空间效应。因此,在进行软岩隧道设计和施工模拟时要计入时间因素对结构的影响。(3)三维数值分析研究结果显示,隧道开挖时掌子面附近监测点位移收敛速率较大,但由于开挖面附近空间支撑作用,各项应力值均较小,开挖面附近围岩的时间效应不明显；离掌子面远端处(1.5D以上),各特征部位应力值较大,而周边收敛速率却较小,开挖面的空间效应基本在距开挖面约1.5D～2.0D后消失。(4)在隧道施工初期,隧道各特征点位移变化值较为剧烈,位移最大变化速率基本都出现在前3天,其变形累计值占到总量的一半左右。支护结构在前3～4天内的各项应力值增长也较快。而在这个阶段,喷射混凝土有效弹性模量却不足最终值40%,显然最不利断面出现在进行支护后的第3天左右。因此,建议加强对距掌子面0.5D～1.0D断面处的施工管理和监测。更多还原

【Abstract】 Excavating in the rock tunnel, it is continue to be disturbed by the construction of stress release, causing the deformation of surrounding development, and strength of support grow with time, the deformation of the rock getting more and more obviously inhibition.This article introduced the effects of temporal and spatial of geotechnical materials, rheological theory and time characteristics of concrete retaining structure (creep and elastic modulus change with time and other factors).Relying on construction works and other monitoring data tunnel to draw out the rock at different times with different load release rate, then choosing viscoelastic D-P and generalized Kelvin style model, using the finite element method soft rock tunnel construction process of the temporal and spatial effects of the numerical analysis. And the first attempt in the calculation taking into account the rheological properties of rock and concrete support growth characteristics of strength, dynamic simulation of the upper and lower level construction method steps. Main draw the following conclusions:(1) Relying on the tunnel projects, analyzed and gradeⅣRock Tunnel in the first 20 days in the week convergence of basically stable. Summarized by the construction offering time period corresponding to the different rock pressure release rate.(2) Using elastic-plastic constitutive model, ignoring strength rock rheology and supporting analysis of the growth process, the surrounding parts of the characteristic values calculated displacement is small, a large deviation of the actual monitoring results; and considering the rheology of rock and structure at different times corresponding to different strength characteristics, the calculated results agree well with the measured data can reflect the effect of the construction process of the time and space. Therefore, when soft rock tunnel design and construction of the simulation time factor to be included on the structure.(3) Dimensional analysis show that the tunnel excavation tunnel face displacement monitoring points near the convergence rates were higher, but the supporting role of space near the excavation face, the stress values are small, the flow surrounding the cutting face effect is not obvious; remote from the working face at (1.5D above), the characteristic part of the stress is large, and the surrounding convergence rate is smaller, the spatial effect of the basic excavation face away from the excavation face about 1.5D～2.0 D disappearing.(4) In the earlier tunnel construction, the value of each feature point displacement is more severe, the maximum rate of change in displacement basically appear in the first 3 days, the cumulative value of the deformation accounted for about half of the total. Support structure within the first 3 or 4 of the stress of rapid growth. In this stage, the effective elastic modulus of sprayed concrete was less than 40% of final value, obviously the worst cross-section support occurs during the first 3 days after. Therefore, it is recommended to strengthen the cross-section from the tunnel face 0.5D～1.0D at the construction management and monitoring.更多还原