大型水电站不良地质段大断面导流隧洞围岩稳定与施工技术研究

发布时间：2018-03-04 02:02

  本文选题：导流隧洞　切入点：不良地质　出处：《天津大学》2015年博士论文　论文类型：学位论文

【摘要】：大型水电工程的导流隧洞大多为浅埋、大断面洞室,在施工过程中,隧洞与进口边坡的施工及安全性相互影响、相互制约,一旦工程发生围岩稳定事故,不仅造成施工人员生命财产的损失,而且严重影响施工进度,因此大型水电站导流隧洞施工期的隧洞围岩及洞口边坡的稳定性一直是岩土工程界关注的重点问题。对于大型水电站导流隧洞,考虑进口洞段边坡与隧洞相互影响的结构设计与施工是一个受众多因素影响的复杂过程,无规范可循,工程类比少,且不良地质洞段的施工技术及其安全性在隧洞施工过程中直接影响工程的整体进度,因此有必要针对不良地质大断面隧洞的施工技术及围岩力学行为特征进行深入研究,以指导工程实际施工。本文结合我国西南某大型水电站为工程实例,采用岩石力学和数值分析方法等技术手段,通过分析不良地质大断面隧洞围岩及边坡的力学行为特征,研究隧洞围岩与边坡作用机制及隧洞施工技术,探讨安全、合理的施工方法。具体研究内容和成果如下:(1)在依托工程地质条件和背景下,分析了大断面地下洞室中的超前支护措施、喷锚支护机理与效果、拱架及钢筋网支护机理。超前支护主要改良地层特性和预支护作用。喷混对隧洞围岩进行加固主要有支承围岩、卸载作用、填平补强围岩、覆盖围岩表面、防止松动和分配外力等作用,采用混凝土喷层加固隧洞可有效地控制围岩变形,能有效遏制岩体塑性区的发展,防止围岩松动失稳。提高喷层厚度可有效减小隧洞顶拱塑性区范围,但厚度过大有可能造成拱脚处塑性区范围因应力集中而增大,采用标号较高的混凝土作为喷层材料对于限制围岩顶拱变形具有一定的作用,但效果不明显。(2)总结了隧洞进口围岩—边坡作用体系类型与力学模型,考虑隧洞—边坡的耦联作用机制,深入研究了隧洞施工对边坡的影响及边坡施工对隧洞围岩稳定性的影响,探讨了隧洞围岩与边坡体系稳定性演化特征,并提出了合理的进洞顺序。具体内容涉及四方面:(1)探讨了隧洞进口围岩与边坡相互作用的平行、正交和斜交三种体系类型,建立了相应的地质力学模型,并讨论了边坡与隧洞变形相互作用的顺滑型、剪切型、扰动型和顺滑剪切复合型等几种力学模型;(2)考虑隧洞进口围岩—边坡正交作用体系,深入研究了隧洞施工对边坡的影响及边坡施工对隧洞围岩稳定性的影响;(3)考虑隧洞进口围岩与边坡的三维效应及相应的动态施工过程,研究了隧洞围岩与边坡体系稳定性的时空演化特征;(4)通过拟定多个隧洞进洞方案,研究了隧洞围岩与边坡相互作用体系下的进洞顺序。(3)在总结不良地质大断面隧洞施工组织过程与施工技术的基础上,研究了大断面隧洞围岩的力学行为,提出了隧洞合理的施工方法和断层穿越顺序。在隧洞I层开挖中,研究了左右两幅开挖法和核心土开挖法下的围岩力学行为,综合考虑左右两幅开挖法具有施工速率更快,工序更简单,塑性区分布范围更小等特点,建议选择左右两幅开挖法。在隧洞II、III层开挖中,对比研究了半幅薄层和半幅厚层开挖法下的围岩力学行为,从结果来看,选择薄层开挖方案更利于围岩稳定。结合数值模拟方法研究了不良地质大断面隧洞在顺层开挖和逆层开挖方式对围岩稳定性的影响,通过探讨不同穿越方式下的围岩力学行为特征,提出了合理的不良地质断层穿越方式。在逆层开挖方式下,顶拱、底板和边墙的变形程度更大,塑性破坏区范围更广,因此选择顺层开挖方式更有利于围岩稳定。(4)考虑隧洞施工过程信息的时变特性,探索了不良地质段大断面隧洞耦合施工进度的实时安全分析方法。根据隧洞工程的二维设计信息和工程地质信息,建立常规三维几何模型(3D模型),以此为基础,考虑施工过程的进度信息,利用4D信息建模技术,建立隧洞施工期4D信息模型。基于SQL数据库搜索引擎的强大搜索功能,快速找到隧洞工程信息改变区域在计算模型中对应的单元,对ABAQUS数值计算软件进行二次开发,自动读取单元的搜索结果,并对其力学参数进行相应修改,实现隧洞数值计算模型信息的实时动态更新。利用参数反演技术将当前的监测信息与相应部位的计算值进行对应,从而实现4D监测信息模型与4D仿真模型的耦合。通过数值的实时计算判定隧洞各部位的安全稳定特征,从而及时判定施工方案的安全有效性和合理性,并对下一步的安全稳定状态进行预测。
[Abstract]:The diversion tunnel of large hydropower projects are mostly shallow and large section tunnels, in the construction process, the construction and the safety of the tunnel and the inlet side of mutual influence, mutual restraint, once the engineering stability accident surrounding rock, not only caused loss of life and property of the construction personnel, but also seriously affect the construction schedule, so the stability of tunnel surrounding rock and slope the diversion tunnel construction of large hydropower station has been the focus of attention in the field of geotechnical engineering. For diversion tunnel of large hydropower station, considering the structural design and construction of tunnel slope and tunnel interaction is a complex process with many factors affecting an audience, no rules to follow, the engineering analogy, construction technology and safety and the bad geological tunnel section directly affects the overall progress of the project in the tunnel construction process, so it is necessary for the construction technology of large section tunnel adverse geological Study on rock mechanics and behavior characteristics, to guide the actual construction project. The combination of China's hydropower station as an example, by using the rock mechanics and numerical analysis techniques, through the analysis of the adverse geological section of tunnel surrounding rock and slope of the mechanical behavior of tunnel surrounding rock and slope, mechanism of action and tunnel construction technology, safety, reasonable construction method. The main research contents and results are as follows: (1) based on the engineering geological conditions and background, analysis of underground cavern with large cross section in advance support measures, shotcrete supporting mechanism and effect of arch and steel net supporting mechanism of forepoling mainly. The formation characteristics of improvement and advance support effect. Spraying mixed reinforcement of tunnel surrounding rock are supporting the surrounding rock, loading, reinforcing surrounding rock fill, covering the surface of surrounding rock, prevent loosening and force distribution etc., The shotcrete tunnel reinforcement can effectively control the deformation of surrounding rock, can effectively curb the development of plastic zone in rock mass, rock loose to prevent instability. To improve the spray layer thickness can effectively reduce the tunnel top arch plastic zone, but the thickness is too large may cause the arch foot of the plastic zone due to stress concentration increases with the higher grade, the concrete spray layer as material for limiting the rock arch deformation has certain effect, but the effect is not obvious. (2) summarizes the tunnel surrounding rock slope system type and mechanical model, considering the tunnel slope coupling mechanism, in-depth study of the influence on the slope and tunnel construction slope construction on tunnel stability, discusses the tunnel surrounding rock and slope stability of the system evolution, and puts forward the reasonable hole sequence. The specific content involves four aspects: (1) to investigate the tunnel surrounding rock imports With slope interaction in parallel, orthogonal and oblique three system types, a geomechanical model is established accordingly, and discussed the slope and tunnel deformation interaction of sliding type, shear type, disturbance type and slip shear composite type several mechanical models; (2) considering the tunnel surrounding rock slope orthogonal import the role of the system, in-depth study of the influence on the slope of the tunnel construction and construction of the slope of the tunnel surrounding rock's stability; (3) considering the three-dimensional effects of tunnel surrounding rock and slope and the corresponding dynamic construction process of tunnel surrounding rock and slope stability of space-time evolution characteristics; (4) through the development of multiple hole tunnel study on the scheme, tunnel and slope interaction system under the hole in order. (3) based on summarizing the process and construction technology of large section tunnel construction geological bad organization, study the surrounding rock of large section tunnel. The mechanical behavior, put forward the construction method and the reasonable order of crossing tunnel in fault. In the I layer in the excavation of tunnel surrounding rock, study on mechanical behavior of about two amplitude excavation method and core soil excavation method, considering about two pieces of excavation method has the construction speed is faster, simpler process, plastic zone distribution range etc. about two pieces of advice, selection of excavation method in tunnel. II, III layer excavation, a comparative study of the half and half thin thick layer excavation of rock mechanical behavior under the law, from the results, the excavation scheme selection layer is more conducive to the stability of the surrounding rock. Based on the adverse geological tunnel large section excavation method for inverse effect the stability of the surrounding rock in the bedding excavation and numerical simulation method, the mechanical behavior of surrounding rock through the characteristics of different modes, put forward reasonable adverse geological fault crossing mode. In the inverse layer excavation method, arch, The degree of deformation of the base plate and the side wall is bigger, plastic zone range, so the choice of bedding excavation method is more conducive to the stability of the surrounding rock. (4) considering the tunnel construction process information time-varying, explore a real-time security analysis method of unfavorable geological section of large section tunnel coupling. According to the construction schedule of tunnel engineering the two-dimensional design information and engineering geological information, establish regular three-dimensional geometric model (3D model), on the basis of considering the progress of information construction process, using 4D modeling technology of information, establish 4D information model of tunnel construction period. The powerful search function of SQL database based on search engine, quickly find the information in the area of tunnel engineering change calculation model the corresponding unit of ABAQUS numerical calculation software development of two times, the automatic reading unit of the search results, and corresponding modification of the mechanical parameters to achieve the numerical model of tunnel Real time dynamic updating of the information. Using the parameter inversion calculation of monitoring information of current and the corresponding parts of the corresponding value, so as to realize the coupling of 4D monitoring information model and 4D simulation model. Through the numerical calculation to determine the safety and stability of the real-time characteristics of various parts of the tunnel, so as to timely determination of construction scheme is safe and effective and reasonable, and to predict the stability of the next step.

【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TV554
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本文编号：1563635