【作者】 王迎超；

【导师】 尚岳全；

【作者基本信息】 浙江大学 ， 防灾减灾工程及防护工程， 2010， 博士

【摘要】 山岭隧道建设过程中,塌方灾害频繁发生,造成重大经济损失和人员伤亡。随着我国经济的快速发展和高速公路的大力建设,投入到塌方治理的费用呈逐年增加趋势。开展隧道塌方机制和防灾方法研究具有重大现实意义。本文采用数值模拟和理论分析为主要研究手段,结合现场调查和监控量测,研究山岭隧道塌方机制和预防措施,探索有效预测方法。运用层次分析法,研究塌方影响因素的敏感性。开展隧道塌方范围的压力拱理论研究,分析不同应力场下潜在塌方范围。探索新的围岩分级方法,建立有效的围岩失稳风险预警模型。研究断层破碎带对围岩稳定性的影响及塌方处治方案优化思路,探讨山岭隧道复合式衬砌在围岩蠕变过程中的受力规律。揭示山岭隧道出洞口塌方机制,并提出相应处治措施。基于突变理论,分析降雨对浅埋隧道塌方的影响。研究隧道出洞口段衬砌结构安全性的评价方法。探索隧道出洞口塌方的时空预测方法。研究取得以下主要成果和认识：(1)分析了塌方的主要影响因素,指出围岩自身属性及地下水对塌方的影响最大,并按塌方发生部位对塌方灾害进行了系统分类。(2)通过压力拱理论研究,计算出不同应力场下的压力拱线。指出不同地应力模式下,隧道压力拱存在差异,压力拱和判断标准关系密切,从工程安全角度出发,宜以最小主应力受拉为判断标准。(3)基于特尔菲-理想点法和集对分析理论,建立了新的围岩分级模型,为隧道塌方风险评价提供依据。将功效系数法应用于隧道围岩稳定性评价中,建立了切实可行的围岩危险性预警模型。(4)提出断层破碎带地区隧道塌方段施工方案优化思路。基于粘弹性有限元理论,分析了复合式衬砌结构在围岩蠕变过程中的受力规律,确立了断层破碎带围岩流变特性明显洞段隧道衬砌设计和施工的合理思路。(5)指出隧道出洞口塌方破坏机制为掌子面失稳和洞顶松散介质垮落共同作用所致,出洞口应采用初期支护紧跟和超前支护。建立了降雨作用下浅埋隧道塌方的尖点突变模型,推导出围岩为不同岩土介质组合时的松散围岩失稳判据。提出隧道出洞口段衬砌工作状态的合理评价方法。(6)建立了隧道出洞口塌方的时空预测模型。基于应力传递思想,推导出隧道出洞口松散围岩失稳判据,得到塌方发生时进入松散围岩段的临界距离。结合灰色理论和协同理论,预测塌方发生时间。通过实际工程案例证明所建时空预测模型具有较高的预测精度。更多还原

【Abstract】 Collapse frequently occurres in the construction of mountain tunnel, which leads to great economic loss and heavy casualties. With the rapid development of the economy and construction of expressways, the cost of collapse treatment increases year by year. It has great realistic significance to do research on the mechanism and control measures of collapse of mountain tunnel.By means of numerical simulation and theoretical analysis, combining with geological survey and in-site monitoring, the mechanism and prevention measures of tunnel collapse were studied, and a method of collapse prediction was explored. The sensitivity of influence factors of tunnel collapse was studied by analytical hierarchy process. The pressure-arch theory of collapse scope was studied and pressure-arches in various stress fields were analyzed. New effective methods of surrounding rock classification and a early-warning model of instability risk were put forward. Here, the influence of fault fracture zone on surrounding rock stability and optimized treatment schemes of collapse in such a zone were researched. At the same time, the mechanical rules of double-lining in creeping surrounding rock were studied. Meanwhile, the mechanism and prevention measures of collapse at tunnel exit were analyzed. Based on catastrophe theory, the influence of rainfall on collapse which occurred in shallow tunnel was discussed in the thesis. A method was put forward to evaluate the safety and stability of lining at tunnel exit, and a method of time and space prediction of collapse in loose wall rock of tunnel exit was proposed. Finally. the main results and new ideas of this study are as follows:(1) The main factors of collapse are analyzed. The conclusion is presented that the properties of surrounding rock and groundwater are the most important influence factors of collapse. Tunnel collapses are systemically classified according to the occurrence position.(2) Based on the pressure-arch theory, pressure-arch lines in different stress fields are computed. The research shows that pressure-arches in different stress fields are different. which is related to judge criterion. Considering the engineering safety. the judge criterion that the minimum principal stress is tensile stress should be selected to analyze pressure-arch.(3) Based on the delphi-ideal point method and set pair analysis, new surrounding rock classification models are established, which can provide evidence for evaluating the risk of tunnel collapse. An efficacy coefficient method is applied to evaluate the stability of surrounding rock, and an early-warning model of instability risk for tunnel surrounding rock is established.(4) Optimized construction scheme of tunnel collapse in fault fracture zone is presented. Based on viscoelastic infinite element theory, the rules of double-lining in creeping surrounding rock are studied, which can provide experiences and references for lining design in fault fracture zone.(5) Collapse at tunnel exit is caused by instability of tunnel face and loose rock together with soil mass collapse at tunnel roof. The primary support should be constructed timely and advanced support is necessary. Cusp-catastrophic models of shallow tunnel under rainfall action are established. The instability criterions are derived when surrounding rock is combined with different rock and soil mass. A method is presented to evaluate the working state of lining at tunnel exit.(6) A new model which is used to predict the occurrence time and position of collapse is established. Based on stress-transferring theory, the instability criterion and critical distance in loose wall rock of tunnel exit when collapse occures are derived. Based on the grey theory and synergetic theory, occurrence time of collapse can be predicted. The prediction model is highly accurate which has been proved by a practical project.更多还原