隧道坍方处治的数值模拟与优化分析

发布时间：2018-01-30 19:33

本文关键词： 隧道坍方支护机制力学行为数值模拟优化途径　出处：《成都理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：我国西南地区山区分布广泛，地形地貌条件极为复杂，在这些地方修筑公路或者铁路，隧道工程往往占有很大的比重，而在隧道修建的过程中遇到的围岩稳定性问题日益突出，隧道坍方是其中最常见的灾害现象之一。它具有高危性、高频性以及高突发性等特点，若治理不当，不但延缓工期，而且增加建设成本，还会留下重大安全隐患。因此，对坍方事故的影响因素和处治方法进行总结，对以后隧道的快速、安全施工具有较大的实际意义。本文采用理论分析总结与数值模拟手段，对隧道坍方类型及处治方法、隧道坍方处治典型措施作用机制及隧道坍方处治施工过程力学行为进行了研究，最后总结了隧道坍方处治设计的基本原则和优化途径，获得的主要成果如下：（1）通过对诸多隧道坍方事故案例的分析，总结出隧道坍方的影响因素主要有不良的地质条件、地下水、设计因素、施工和管理因素。并从规模大小、机理、控制因素和坍方位置的角度对隧道坍方进行系统分类。（2）结合隧道坍方预支护原理，采用理论分析和力学推导方法研究了超前小导管注浆、管棚和喷锚支护等典型支护措施的作用机制，建立了管棚在隧道开挖中的力学模型，采用FLAC3D软件对不同工况钢拱架支护下的围岩应力、位移情况进行数值模拟分析，研究得出：1）钢拱架的设置，对拱脚应力集中现象有抑制作用，同时能够减少拱顶出现低应力区的范围，并可以有效抑制拱顶和底板的竖向位移；2）随着钢拱架设置间距的加大，其拱内最大轴力和弯矩值均有增加；3）钢拱架的最大轴力主要发生在拱顶处，最大弯矩主要发生在拱腰和拱顶处，拱脚处弯矩很小。（3）以广甘高速公路沈家山隧道坍方事故为依托，通过FLAC3D数值计算软件模拟分析坍方段施工力学行为引起的围岩应力场、位移场和塑性区变化规律，得出：1）拉应力最大主应力出现在拱顶60°范围以及底板中央，压应力最大主应力出现在隧道中间部分的拱脚处；2）拱顶下沉最大位移主要分布在拱顶60°范围内，底板隆起最大位移主要分布在底板中央1/3处；3）随着开挖的进行，坍腔中央也开始出现塑性区（以拉伸屈服为主），拱脚塑性区（以剪切屈服为主）范围明显增大，且向围岩深处发展，若不加以控制，拱脚部位可能会发生剪切破坏。4）结果表明处治措施在整个坍方治理过程中发挥了积极的作用，且拱脚和拱顶60°范围是本次坍方处治施工中应当重点支护的部位。（4）隧道坍方处治一般应遵循“先治水、后加固、防扩大、再处理”的基本原则，在有条件的前提下“宁早勿迟”，以达到安全、快速、经济的工程目的。并从开挖手段和方法的选择、支护方式的选取、信息化指导施工、施工管理水平的提高等方面阐述隧道坍方处治优化设计的基本途径。
[Abstract]:The mountainous areas in southwest China are widely distributed, and the terrain and geomorphology conditions are very complex. In these places, tunnel projects often occupy a large proportion in the construction of highways or railways. In the process of tunnel construction, the surrounding rock stability problem is increasingly prominent, tunnel collapse is one of the most common disaster phenomenon. It has the characteristics of high risk, high frequency and high sudden, if not treated properly. Not only delay the construction period, but also increase the construction cost, but also leave a major safety risk. Therefore, the factors affecting the landslide accident and treatment methods are summarized, and the tunnel in the future is fast. Safety construction is of great practical significance. By means of theoretical analysis and numerical simulation, this paper studies the types and treatment methods of tunnel collapse, the action mechanism of typical measures of tunnel collapse treatment and the mechanical behavior of tunnel collapse treatment construction process. Finally, the basic principles and optimization approaches of tunnel collapse treatment design are summarized. The main results obtained are as follows: 1) through the analysis of many tunnel collapse cases, it is concluded that the main influencing factors of tunnel collapse are poor geological conditions, groundwater, design factors, construction and management factors. The mechanism, controlling factors and the angle of collapse position are systematically classified for tunnel collapse. Combined with the principle of tunnel collapse pre-support, the mechanism of typical supporting measures, such as small pipe grouting, pipe shed and shotcrete anchor support, is studied by theoretical analysis and mechanical derivation. The mechanical model of pipe shed in tunnel excavation is established, and the surrounding rock stress and displacement of steel arch support under different working conditions are numerically simulated and analyzed by FLAC3D software. It is concluded that the steel arch structure can restrain the stress concentration of arch foot, reduce the range of low stress area, and effectively restrain the vertical displacement of arch roof and bottom plate. 2) with the increase of the distance between steel arches, the maximum axial force and bending moment increase; 3) the maximum axial force of the steel arch is mainly at the top of the arch, and the maximum bending moment mainly occurs at the arch waist and the arch top, and the bending moment at the arch foot is very small. Based on the collapse accident of Shenjiashan Tunnel in Guanggan Expressway, the stress field of surrounding rock caused by mechanical behavior in construction of collapse section is simulated and analyzed by FLAC3D numerical calculation software. The variation of displacement field and plastic zone shows that the maximum principal stress of tensile stress appears in the 60 掳range of arch top and the center of bottom plate, and the maximum principal stress of compressive stress appears at the arch foot in the middle part of tunnel. 2) the maximum displacement of the dome subsidence is mainly distributed in the range of 60 掳of the arch top, and the maximum displacement of the floor uplift is mainly distributed in the center of the floor 1/3; 3) with the excavation, the plastic zone (tensile yield is the main part) in the center of the cavern, and the plastic zone (shear yield is the main area) at the arch foot increases obviously, and develops to the deep surrounding rock, if not controlled. The results showed that the treatment measures played an active role in the whole process of treatment. And the arch foot and the arch roof 60 掳range should be the key support in the treatment of the landslide. 4) the treatment of tunnel collapse should generally follow the basic principle of "treating water first, then strengthening, preventing expansion, and treating again", and under the precondition of conditions, "better early than late", in order to achieve safety and speed. From the aspects of the selection of excavation means and methods, the selection of supporting methods, the guidance of information construction and the improvement of construction management level, this paper expounds the basic ways of optimal design of tunnel collapse treatment.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U458.3

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