岩溶空腔对大断面公路隧道稳定性的影响研究

发布时间：2018-05-30 09:35

本文选题：大断面隧道 + 数值分析　；参考：《西南交通大学》2017年硕士论文

【摘要】：我国西部山区山高谷深,沟壑纵横的岩溶溶蚀地貌给城市快速路网的建设带来了施工难题,尤其大、特大断面隧道穿越岩溶地层往往为该线路的控制性工程,隧道在岩溶地层的施工难题成为整条线路的控制性难题。岩溶地层因岩溶发育而形成的岩溶空腔,造成岩溶地层围岩的应力场分布与普通地层有很大区别,在岩溶空腔附近有较强的应力集中区,当隧道开挖后,这种应力分布的不均匀性还会加剧。岩溶地层的复杂性(尤其隧道临近岩溶空腔时),加之受季节性、周期性、阵发性降水影响,隧道运营期衬砌受力极为复杂。因此研究岩溶空腔对隧道施工及运营期稳定性的影响极为必要。本文依托重庆市快速路网中"三横线"的重要组成部分——双碑隧道,采用数值分析的方法研究岩溶空腔对隧道施工期及运营期稳定性的影响,主要对隧道施工期隧道开挖稳定性及运营期二次衬砌受力特性、安全性进行了研究,主要研究内容和结论如下:1)采用二维平面应变模型,当隧道背后存在隐伏岩溶空腔时,考虑空腔大小、位置、与隧道间距三种因素不同的所有工况,模拟隧道开挖并监测洞周位移、初期支护内力,研究了岩溶空腔对于隧道洞周围岩及支护结构的稳定性的影响规律。2)采用三维有限元模型,模拟岩溶空腔的三维空间结构与隧道沿纵向掘进完整的开挖工序、施工循环,选取岩溶空腔沿纵向空间尺寸变化的三个典型断面,监测并分析隧道洞周位移及围岩位移场、初期支护内力、塑性区,研究岩溶空腔对隧道纵向开挖稳定性的影响规律。3)采用渗流结构模型,监测二衬外水压力、二衬结构内力,研究临近隧道岩溶空腔的存在对隧道渗流场的影响;在设计排水系统下,得出二衬结构内力分布特征并评价其安全性。
[Abstract]:The karst dissolution geomorphology with deep mountains and high valleys and deep gullies in the western mountainous areas of China has brought construction difficulties to the construction of the urban expressway network, especially in the case of large cross-section tunnels passing through the karst strata, which are often the controlling projects of the railway line. The construction problem of tunnel in karst formation becomes the control problem of the whole line. The karst cavity formed by karst formation is very different from the ordinary strata in the distribution of stress field in the surrounding rock of karst stratum, and there is a strong stress concentration area near the karst cavity, when the tunnel is excavated, The inhomogeneity of the stress distribution will also be aggravated. The complexity of karst strata (especially when the tunnel is near the karst cavity, plus the influence of seasonal, periodic and paroxysmal precipitation), the tunnel lining force is extremely complex during the operation period. Therefore, it is necessary to study the influence of karst cavity on the stability of tunnel construction and operation. In this paper, the influence of karst cavity on the stability of the tunnel during construction and operation is studied by using the method of numerical analysis, which is an important part of "three horizontal lines" in Chongqing Expressway Road Network. In this paper, the stability of tunnel excavation during tunnel construction, the stress characteristics and safety of secondary lining during tunnel construction are studied. The main contents and conclusions are as follows: 1) the two-dimensional plane strain model is used, when there is a concealed karst cavity behind the tunnel, Considering all working conditions different from the three factors of cavity size, location and tunnel spacing, the tunnel excavation is simulated and the displacement around the hole is monitored. The influence of karst cavity on the stability of surrounding rock and supporting structure of tunnel is studied. The three-dimensional finite element model is used to simulate the three-dimensional space structure of karst cavity and the complete excavation procedure along the longitudinal tunnel. Three typical sections of karst cavity changing along longitudinal spatial size are selected to monitor and analyze the displacement field around tunnel and surrounding rock, the initial supporting internal force and plastic zone. The influence of karst cavity on the stability of tunnel excavation is studied. (3) the seepage structure model is used to monitor the external water pressure and the internal force of the two-lining structure, and the influence of the karst cavity in the adjacent tunnel on the seepage field of the tunnel is studied. Under the design of drainage system, the internal force distribution characteristics of two-liner structure are obtained and its safety is evaluated.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U451

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