【作者】 李文江；

【导师】 朱永全；

【作者基本信息】 西南交通大学 ， 道路与铁道工程， 2012， 博士

【摘要】 软弱围岩隧道的稳定性及变形控制一直是界内关注的焦点之一,而软弱围岩隧道工程的设计理念、稳定性判别方法和变形控制技术又是控制隧道施工安全、施工造价以及施工周期的决定因素。经过了多年来隧道界的共同努力,虽然在某些方面取得了长足发展,但还远未形成一个成熟的理论体系。本文在借鉴和传承国内外现有理论研究成果的基础上,根据我国铁路隧道施工分部开挖的特点,针对软弱围岩山岭隧道,采用数值模拟和典型工程现场试验的方法,在施工变形特征、施工过程稳定性判别以及变形控制技术等方面进行了系统研究,并形成以下主要成果：(1)软弱围岩隧道空间变形一般均包括三个部分,即掌子面前方的先行变形、掌子面变形和后方收敛变形。先行变形影响范围约为掌子面前方1.5D以内；对于软弱围岩隧道,掌子面前方先行变形中,拱顶下沉较水平收敛更加明显。(2)软弱围岩隧道,围岩掌子面挤出变形、上台阶拱脚沉降变形均相对显著。隧道开挖后铁路单线隧道以收敛变形为主,铁路双线隧道拱顶沉降变形亦相对显著。(3)软弱围岩隧道产生较大变形的根本原因在于围岩软弱和地应力值相对较大,施工过程中洞周围岩塑性区分布范围和深度大,隧道变形的主方位一般为塑性区主发展方位。(4)定义了软弱围岩隧道体系的极限状态。软弱围岩隧道稳定可定义为：施工中围岩不发生坍塌,洞周位移协调发展且收敛,支护结构不产生影响承载能力的开裂和破损。当围岩和支护系统一起,或其一部分达到上述临界状态为隧道的稳定性极限状态。(5)将突变理论引用到隧道,形成了基于塑性应变突变理论的围岩稳定性分析方法,并确定了未支护隧道的极限位移。(6)根据钢架和混凝土喷层不同的材料特性和支护作用效果,研究中考虑了二者的不同作用时机,并在支护结构极限状态定义的基础上,确定了不同围岩级别、不同埋深下的支护后隧道体系相应的极限位移。(7)采用面内非线性屈曲模型,对支护结构的承载极限和失稳模式进行了分析研究。分析结果显示,锚杆抗力在20～100MPa/m之间时,支护结构的承载能力为0.5～1.0MPa,说明在深埋软弱围岩隧道条件下,支护结构发生整体压溃的可能性很大。同时,支护结构在发生整体失稳时,一般变形是不协调的,这一点也符合工程实际情况。(8)在数值分析和现场试验的基础上,形成了软弱围岩隧道变形控制技术体系。具体包括：开挖技术、支护技术、掌子面稳定技术、拱脚稳定技术、支护补强技术、超前支护技术以及空间变形监测及反馈技术等。(9)根据软弱围岩隧道施工过程中各工况下隧道变形的计算统计结果、典型隧道现场测试统计结果以及计算极限位移和支护结构承载能力等,同时借鉴了相关工程的成功经验,提出了软弱围岩隧道变形控制基准。(10)综合前述研究成果,并借鉴国内外相关工程经验,针对不同工况提出了软弱围岩施工变形控制措施方案,并将研究成果应用于依托工程,在实际过程应用中效果良好。更多还原

【Abstract】 The problem of stability and deformation control for weak rock tunnel is one of the focus in the tunnel field. During the constructing, the design concept, the stability analysis method and deformation control technology are usually becoming control factors, which affect the safety of tunnel construction, construction cost and construction period in finally. In the past years, by the means of collaboration, many hard works had been done, and a considerable progress has been made in some areas, but it is still far away from forming a mature theory system in soft weak surrounding rock tunnel. In this paper, based on the domestic and foreign existing research results, and considering of the actual situation of the partial excavation during the constructing of railway tunnel in China, a systematic research was carried out, including of the deformation characteristics, stability identification and deformation control technology during excavation of soft weak surrounding tunnel. By the means of numerical simulation and field test in typical engineering, the following results were put forword:(1)The tunnelling deformation consists of the prior deformation before excavation, the deformation of woring face and the later deformation after excavation. The range of prior deformation before excavation is within1.5D ahead working face. For the prior deformation of weak rock tunnel, the crown settlement more obvious than horizontal convergence.(2)For the soft weak surrounding rock tunnels, the displacements such as the squeezing deformation of working face and the arch springing settlement afer excavation are obvious. After the excavation, the main directional displacement is horizontal convergence for single track railway tunnel, and crown settlement for double-track tunnel.(3)The essential reason of large deformation in weak rock tunnel is the weak of surrounding rock and high of in-situ stress value, the plastic zone distribute range and depth of surrounding rock around the tunnel is relatively large during construction process, and the main directional displacement is along with the main development orientation of plastic zone in generally.(4)The limit state of tunnel system was defined. The tunnel stability of soft weak surrounding rock was defined that the surrounding rock during the construction does not collapse, the tunnel displacement harmonious develops and converges, supporting structure does not appear the cracking and breakage of affecting the bearing capacity. When the surrounding rock and supporting system get together, or part of it be to the limit state above, the state is looked as the stability limit state of the tunnel.(5)Introduced the catastrophe theory into the tunnel engineering, and an analysis method of surrounding rock stability was put forword, basing on catastrophe theory by plastic strain. At the same time, the corresponding limit displacement is obtained.(6)Based on the different material properties and support effects of the spray concrete and steel frame, two different action time were considered. Acorrding to the definition of the limit state of supporting structure, the corresponding limit displacement of supported tunnel for different surrounding rocks, different buried depth is obtained.(7)A nonlinear buckling model was applied to analyze limit load and unstable mode of supporting structure. The result shows that the limit load of supporting structure are within1.0MPa, when the reaction coefficient of bolts are between20-100MPa/m. It reveals that in the condition of high ground stress, it is likely that the supporting structure take place the whole crushing damage. At the same time, when the supporting structure is in instability, its deformation is discordant development. This is mached with actual project.(8)Combined with numerical analysis and field test results, the deformation control technology system of soft weak surrounding rock tunnel was proposed, which Including excavation control techninology, supporting control techninology, control techninology of working face and arch springing stability, supporting reinforcement technology, advance support technology and space deformation monitoring and feedback technology, and so on.(9)According to the statistical results of numerical analysis and field test, the calculating ultimate displacement, the limit load of supporting structure during the construction process, as well as referencing the successful experience of related projects, the deformation-control standard for was proposed.(10)Based on the all research results above, and drawing lessons from related engineering experience of domestic and foreign, different deformation controlled measures of soft weak surounding rock tunnel was proposed, for different conditions. And the research results are applied in the related projects and the operation performance were excellent.更多还原