下穿隧道施工对高速公路路基变形影响研究

发布时间：2018-11-29 13:22

【摘要】：隧道作为一种十分重要交通构筑物形式,在高速公路和高速铁路的建设中不可避免,为了节约用地、保护既有建筑物或环境将会更多的采用隧道下穿的方式。隧道下穿既有高速公路成为近年来的一种常见形式,而隧道的顶部覆盖层较薄,围岩为路基填筑材料,稳定性差,极易产生较大的变形,甚至失稳,严重影响隧道施工与高速公路运营安全。因此,下穿隧道施工对高速公路路基变形的影响研究具有十分重要的意义。论文以贵州省某下穿既有高速公路的铁路隧道建设为研究背景,通过数值模拟、现场监测、理论分析,研究下穿隧道施工对高速公路路基的变形影响规律。主要研究的工作如下:(1)采用FLAC3D数值模拟方法对现场施工过程进行模拟,分析隧道开挖过程与路基变形的关系,得出了路基变形规律:(1)掘进深度越大对高速公路路基沉降变形的影响范围越大,纵向的影响深度普遍超过开挖面的掘进深度,横向影响范围随隧道掘进深度增加而逐渐增大,最大影响位置为隧道中轴线,监测断面影响最大的为断面S3,其扩散角为49°。(2)采用CRD法施工可以有效控制路基沉降,公路路基最大累计沉降为36.6mm,小于规范要求的40mm。(3)路基某一断面的变形速率随其与隧道的掌子面距离的增大而减小,在掌子面到达该断面时沉降速率快速增大,远离该断面时沉降速率快速趋于稳定。(2)采用现场监控对隧道下穿段路基变形的进行分析,得出下穿隧道施工引起的路基沉降的变化规律以及高速公路路基侧向滑移的变化规律:(1)CRD法施工对于上方高速公路路基的影响较小,沉降最大值不超过35mm,达到设计标准40mm。(2)高速公路路面沉降的变形分别经历超前隆起阶段或微小沉降阶段、沉降急剧变形阶段、沉降缓慢变形阶段、沉降稳定阶段。(3)数值模拟结果与现场监控结果差别较小,验证了数值模拟结果的可靠性。(3)基于线性M-C屈服准则及极限分析上限法,建立掌子面失稳导致高速公路路基失稳的破坏模式,推导出下穿隧道临界埋深的上限表达式,并运用非线性规划程序优化计算获得临界最优解,分析各种因素对临界埋深的影响规律及影响程度。
[Abstract]:As a very important form of traffic structure, tunnel is inevitable in the construction of highway and high-speed railway. In order to save land, to protect existing buildings or environment will be more adopted under the tunnel way. Tunnel underpass through existing highway has become a common form in recent years, but the top of the tunnel overburden is thin, surrounding rock is subgrade filling material, the stability is poor, it is easy to produce large deformation, even instability. The safety of tunnel construction and highway operation is seriously affected. Therefore, it is of great significance to study the influence of underpass tunnel construction on highway roadbed deformation. Based on the research background of the railway tunnel construction of an existing expressway in Guizhou Province, this paper studies the influence of the underpass tunnel construction on the subgrade deformation of the expressway through numerical simulation, field monitoring and theoretical analysis. The main research works are as follows: (1) FLAC3D numerical simulation method is used to simulate the construction process, and the relationship between tunnel excavation process and roadbed deformation is analyzed. The law of roadbed deformation is obtained as follows: (1) the greater the excavation depth, the greater the influence range on the settlement and deformation of expressway subgrade, and the longitudinal influence depth is generally higher than the excavation depth of excavated surface. The transverse influence range increases gradually with the increase of tunneling depth. The maximum influence position is the central axis of the tunnel, the section S3 has the greatest influence on the monitoring section, and the diffusion angle is 49 掳. (2) subgrade settlement can be effectively controlled by using CRD method. The maximum cumulative settlement of highway subgrade is 36.6 mm, which is less than 40mmm. (3) the deformation rate of a section of the roadbed decreases with the increase of the distance between the roadbed and the face of the tunnel, and the settlement rate increases rapidly when the surface of the roadbed reaches the section. The settlement rate tends to be stable rapidly when away from the section. (2) the deformation of the subgrade in the underpass section of the tunnel is analyzed by field monitoring. The variation law of subgrade settlement caused by underpass tunnel construction and lateral slip rule of expressway roadbed are obtained. (1) the influence of CRD construction on the roadbed of the upper expressway is small, and the maximum settlement is not more than 35mm. (2) the settlement of expressway pavement has experienced the stage of advance uplift or small settlement, the stage of rapid settlement, the stage of slow settlement, the second is that the settlement of freeway has reached the design standard of 40mmm. (2) (3) the difference between the numerical simulation results and the field monitoring results is small, which verifies the reliability of the numerical simulation results. (3) based on the linear M-C yield criterion and the upper limit method of limit analysis, The failure mode of roadbed instability caused by metacarpal instability is established, the upper limit expression of critical buried depth of underpass tunnel is derived, and the critical optimal solution is obtained by optimizing calculation with nonlinear programming program. The influence of various factors on critical burial depth is analyzed.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U416.1

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