本文以小寨隧道工程大变形问题为背景，采用模型试验和三维快速有限差分软件

本文以小寨隧道工程大变形问题为背景，采用模型试验和三维快速有限差分软件对泥质岩隧道中不同大变形产生时间对隧道结构安全性的影响进行研究。探讨了在上下台阶法施工中大变形产生在不同施工阶段，隧道结构的受力状态及其位移变化规律和围岩的稳定性的变化规律。
通过探究得出如下结论：
1. 在支护刚度和强度足够时，大变形产生时间对洞周变形趋势影响不大，在支护及时时最终均收敛，但对其量值有影响，大变形产生时间越早，变形值越大。
2. 在支护刚度和强度足够时，大变形产生时间对二衬内力分布特征影响不大，墙脚往往是危险截面；但对二衬安全系数有影响，大变形发生在二衬施做之前，大变形产生时间越晚，安全系数整体越大，大变形发生在二衬施做之后，二衬安全系数整体又会减小。
3. 在支护刚度和强度足够时，大变形产生时间对塑性区分布特征影响不大，均在隧道横断面呈蝴蝶状，但对进入塑性区的围岩面积有影响，大变形产生时间越早塑性区面积越大，极差在300m2左右，且向拱顶两侧延伸最明显。
4. 在V级围岩条件下采用当前规范推荐支护设计，能够保证隧道结构体系安全；由于围岩强度低，初支虽对洞周变形有明显控制效果，但变形有较明显不收敛趋势，不能保证长时间的隧道安全，二衬需做承载结构考虑，施工时应严密进行监控量测，及时施作支护。
关键词：软岩大变形隧道、数值模拟、室内模型试验、大变形产生时间

結果 (中文) 3:

In this paper, with the background of Xiaozhai tunnel large deformation problems by model test and the three dimensional finite difference software of argillaceous rock tunnel in different deformation produced the effect of time on the safety of tunnel structure is studied. The change of the mechanical state of the tunnel structure and its displacement variation and the stability of the surrounding rock during the different construction stages are discussed..
by that explore the conclusions are as follows:
1. In the supporting stiffness and strength enough, large deformation time of deformation around the tunnel has little effect on the developing, supporting and always eventually converges, but the amount of the value of, large deformation time sooner.The bigger the deformation value.
2. In supporting stiffness and strength enough, large deformation time of secondary lining internal force characteristics had little influence on the distribution, skirting is often dangerous section; but the safety coefficient of the second lining, large deformation occurs in the secondary lining construction before, large deformation in the later time, the safety coefficient is bigger and bigger whole, large deformation occurs in the secondary lining construction after, the second lining safety coefficient will be reduced. . in supporting stiffness and strength enough, large deformation time of plastic zone distribution have little impact, in the cross section of tunnel is shaped like a butterfly, but to enter the plastic zone of surrounding rock area and.The bigger the time of the deformation, the bigger the plastic zone area, the range is about 300m2, and the extension of the arch crown is obvious..
4. in grade V surrounding rock under the condition of the current recommendations for supporting design, to ensure the safety of tunnel structure system; due to the low strength of surrounding rock, primary support although the deformation around the tunnel has obvious control effect, but the deformation is obviously not convergence trend, can not guarantee long tunnel, secondary lining for bearing structure considering, construction should be closely monitoring and measurement, promptly applied for support. Keywords: soft rock large deformation tunnel, numerical simulation, indoor model test, large deformation time