湿陷性黄土隧洞开挖施工的数值模拟
发布时间：2018-08-04 22:02
【摘要】：湿陷性黄土是一种特殊土，具有遇水产生强湿陷性的特点。这种土体作为基础是非常不利于工程建筑物的，在常规工程建设中应该尽量避免选用湿陷性黄土作为基础。但是，我国许多地区天然地质条件并不理想，黄土覆盖层较厚、较广，多数黄土为湿陷性黄土，这就为工程建设带来了巨大的挑战。湿陷性黄土隧洞工程由于其特殊地质条件限制，建设数量少，施工难度大，因此原有施工技术已不能完全应用于湿陷性黄土隧洞工程，拓展与创新施工技术来改变湿陷性黄土隧洞施工难、易发生事故的情况正是我们需要面对的问题。只有进一步的研究与完善湿陷性黄土隧洞工程的施工技术，才能弥补湿陷性黄土隧洞研究成果少、施工经验凌乱的问题，补充湿陷性黄土隧洞工程的开挖施工分析，了解湿陷性黄土隧洞的开挖前应力场与位移场分布，对其开挖后及衬砌后应力场与位移场分布与开挖前进行对比研究，以便于合理安排施工安全、施工质量与施工进度三个方面，为湿陷性黄土隧洞建设能够具有安全性、快捷性带来指导意义。 结合某引水隧洞工程实例，采用FLAC3D有限差分软件建立了湿陷性黄土段隧洞的模型，分别对全断面开挖法、上下台阶开挖法、CD法、CRD法进行了施工模拟。湿陷性黄土隧洞开挖施工模拟主要内容包括三个方面： （1）整理与总结湿陷性黄土的工程地质特点与湿陷性黄土隧洞开挖施工的要求。根据引水工程湿陷性黄土段隧洞的地质条件、断面大小，进行了计算网格划分。然后，对隧洞开挖部位、隧洞周围岩体及隧洞衬砌部位建立模型。 （2）利用FLAC3D有限差分软件对隧洞周围进行了边界设定、参数选择等，对其计算网格模型进行了边界条件设置，获得模型初始平衡状态，加载模型的自重应力场； （3）对湿陷性黄土隧洞在不同开挖方法作用下进行工程开挖的响应分析，，处理一系列计算步后达到问题的解。通过计算结果得到的隧洞开挖过程中，岩体竖直与水平两个方向的应力场与位移场的分布图，以及竖直方向与水平方向应力与位移的计算结果。 通过对这四种开挖方法引起湿陷性黄土隧洞地层围岩的水平应力与竖向应力及水平位移和竖向位移进行比较，得出CRD法是一种有效控制湿陷性黄土隧洞围岩变形的施工方法。
[Abstract]:Collapsible loess is a special soil with strong collapsibility in water. This kind of soil is very unfavorable to the engineering building, and the collapsible loess should be avoided as far as possible in the conventional engineering construction. However, the natural geological conditions in many areas of China are not ideal, the loess overburden is thicker and wider, most of the loess is collapsible loess, which brings great challenges to the engineering construction. Because the collapsible loess tunnel project is limited by its special geological conditions, the quantity of construction is small and the construction is difficult, so the original construction technology can not be completely applied to the collapsible loess tunnel project. Expansion and innovation of construction technology to change the collapsible loess tunnel construction is difficult, prone to accidents is the problem we need to face. Only by further studying and perfecting the construction technology of collapsible loess tunnel engineering, can we make up for the problems of less research results and messy construction experience of collapsible loess tunnel, and supplement the excavation construction analysis of collapsible loess tunnel engineering. The distribution of stress field and displacement field before excavation of collapsible loess tunnel is understood, and the distribution of stress field and displacement field after excavation and lining is compared with that before excavation, in order to arrange the safety of construction reasonably. Three aspects of construction quality and construction schedule can provide guidance for the construction of collapsible loess tunnel with safety and rapidity. Combined with an example of a diversion tunnel, the model of collapsible loess section tunnel is established by using FLAC3D finite difference software. The construction simulation of full section excavation method and upper and lower step excavation method / CD method is carried out respectively. The main contents of the construction simulation of collapsible loess tunnel include three aspects: (1) the engineering geological characteristics of collapsible loess and the requirements of construction of collapsible loess tunnel are summarized. According to the geological conditions and section size of the tunnel in the collapsible loess section of the diversion project, the computational grid is divided. Then, the model of tunnel excavation site, surrounding rock mass and tunnel lining is established. (2) the boundary setting and parameter selection around the tunnel are carried out by using FLAC3D finite difference software. The initial equilibrium state of the model is obtained and the self-gravity stress field of the model is loaded. (3) the response of the collapsible loess tunnel excavation under different excavation methods is analyzed. Processing a series of computational steps to reach the solution of the problem. The distribution map of stress field and displacement field in vertical and horizontal direction of rock mass and the calculated result of stress and displacement in vertical and horizontal direction of rock mass during tunnel excavation are obtained. By comparing the horizontal stress with vertical stress, horizontal displacement and vertical displacement of the surrounding rock of collapsible loess tunnel caused by these four excavation methods, it is concluded that CRD method is an effective construction method to control the deformation of surrounding rock of collapsible loess tunnel.
【学位授予单位】：甘肃农业大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU444;TV554
本文编号：2165305
[Abstract]:Collapsible loess is a special soil with strong collapsibility in water. This kind of soil is very unfavorable to the engineering building, and the collapsible loess should be avoided as far as possible in the conventional engineering construction. However, the natural geological conditions in many areas of China are not ideal, the loess overburden is thicker and wider, most of the loess is collapsible loess, which brings great challenges to the engineering construction. Because the collapsible loess tunnel project is limited by its special geological conditions, the quantity of construction is small and the construction is difficult, so the original construction technology can not be completely applied to the collapsible loess tunnel project. Expansion and innovation of construction technology to change the collapsible loess tunnel construction is difficult, prone to accidents is the problem we need to face. Only by further studying and perfecting the construction technology of collapsible loess tunnel engineering, can we make up for the problems of less research results and messy construction experience of collapsible loess tunnel, and supplement the excavation construction analysis of collapsible loess tunnel engineering. The distribution of stress field and displacement field before excavation of collapsible loess tunnel is understood, and the distribution of stress field and displacement field after excavation and lining is compared with that before excavation, in order to arrange the safety of construction reasonably. Three aspects of construction quality and construction schedule can provide guidance for the construction of collapsible loess tunnel with safety and rapidity. Combined with an example of a diversion tunnel, the model of collapsible loess section tunnel is established by using FLAC3D finite difference software. The construction simulation of full section excavation method and upper and lower step excavation method / CD method is carried out respectively. The main contents of the construction simulation of collapsible loess tunnel include three aspects: (1) the engineering geological characteristics of collapsible loess and the requirements of construction of collapsible loess tunnel are summarized. According to the geological conditions and section size of the tunnel in the collapsible loess section of the diversion project, the computational grid is divided. Then, the model of tunnel excavation site, surrounding rock mass and tunnel lining is established. (2) the boundary setting and parameter selection around the tunnel are carried out by using FLAC3D finite difference software. The initial equilibrium state of the model is obtained and the self-gravity stress field of the model is loaded. (3) the response of the collapsible loess tunnel excavation under different excavation methods is analyzed. Processing a series of computational steps to reach the solution of the problem. The distribution map of stress field and displacement field in vertical and horizontal direction of rock mass and the calculated result of stress and displacement in vertical and horizontal direction of rock mass during tunnel excavation are obtained. By comparing the horizontal stress with vertical stress, horizontal displacement and vertical displacement of the surrounding rock of collapsible loess tunnel caused by these four excavation methods, it is concluded that CRD method is an effective construction method to control the deformation of surrounding rock of collapsible loess tunnel.
【学位授予单位】：甘肃农业大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU444;TV554
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