黄土公路隧道结构工程性状研究

【作者】 赵占厂；

【导师】 谢永利；

【作者基本信息】 长安大学 ， 道路与铁道工程， 2004， 博士

【摘要】 鉴于黄土公路隧道土体及衬砌力学特性研究不足的状况，论文针对黄土公路隧道工程进行了土体和衬砌结构受力与变形性状分析、隧道施工过程和浸水影响数值分析、衬砌结构力学特性现场测试和围岩压力理论研究。 针对黄土公路隧道衬砌结构受力特性，根据埋深和土质情况，选取三座黄土公路隧道为依托工程，首次开展了大规模系统的现场测试，着重研究了一衬和仰拱围岩压力、格栅拱钢筋轴力、一衬和二衬接触应力以及二衬混凝土应变时间变化规律及分布特性。实测结果表明：现有浅埋隧道围岩压力公式计算结果与实测结果偏差较大，其分布呈“猫耳朵”形状；深埋隧道围岩压力属形变压力，其实测值与修正卡柯公式计算结果较为一致；深埋与浅埋隧道中仰拱的受力性态有所不同；格栅拱钢筋轴力以受压为主；黄土公路隧道二次衬砌受力相对较小。 根据隧道工程施工特性，研编了数值仿真有限元程序，该程序较客观的反映了隧道施工中的开挖效应及一衬和二衬之间的接触特性等。利用研编程序，分析了邓肯—张模型中土体参数、衬砌混凝土强度、衬砌尺寸、混凝土龄期和埋置深度对土体和衬砌结构性状的影响。分析结果表明：土体粘聚力、内摩擦角、刚度参数k和初始切线泊松比为计算敏感参数；混凝土强度提高对围岩和衬砌结构影响不大；存在一个“合理经济”的衬砌厚度；考虑混凝土龄期与否对衬砌轴力影响较大。在黄土公路隧道台阶法施工进尺范围内，研究了进尺因素对隧道周围土体受力及变形的影响差异。 利用研编程序，对依托工程施工过程进行了动态模拟，并将数值仿真结果进行综合对比，仿真结果较系统地反映了埋置深度和土体强度对土体和衬砌结构受力及变形的影响。以浅埋隧道为工程背景，采用两种数值仿真方法对土体浸水时隧道工程特性进行了计算分析，结果表明土体局部浸水导致围岩压力显著增大，衬砌结构安全状况恶化，是黄土隧道诸多病害之主因。 结合现场测试结果及埋置深度影响性状分析，指出了现有隧道深浅埋界定标准问题，以中心线土体侧压力系数变化规律为依据，首次提出了隧道深浅埋界定的新思路和方法，并用两个工程实例进行验证。针对现有方法计算浅埋隧道围岩压力偏差较大的问题，推导了浅埋土质隧道围岩压力计算公式，并与依托工程观测结果进行对比，验证了本文公式的可行性。更多还原

【Abstract】 In view of poor researches on stress characteristics of soil and lining in the loess highway tunnel, the paper analyses the performances of stress and deformation of soil and lining structure, the process of tunnel construction, and water infiltration influences, and makes field observation of stress features of lining structure and theory research of surrounding rock pressure.Directed against stress properties of lining structure of loess highway tunnel, the paper selects three loess highway tunnels as relying engineering according to buried depth and soil properties, and takes field observation synthetically for the first time, which pays more attention to researches on the change regulations of pressure acting on first lining and invert, axial force of lattice girder, contact stress between first and second lining, concrete strain of second lining verse the time and distributions in different positions. The observation results reveal the difference between surrounding rock pressures of shallow tunnel calculated by exiting methods and test results is large, pressure figure seems cat ear, surrounding rock pressure of deep tunnel belongs to clastic pressure, the test result is consistent with result by modified KAKE formula, the invert stress properties of shallow tunnel and deep tunnel are different, the axial force of lattice girder is at pressure in majority, and the stress of second lining is relatively small in loess highway tunnel.According to the properties of tunnel construction, the paper compiles the FEM program of numerical simulation, which reflects the excavation effects of tunnel construction and the contact properties between first and second lining. The paper analyses the influences of soil parameters in Duncan-Zhang model, lining concrete strength, lining size, concrete age and buried depth of tunnel on performances of soil and lining. The results show the calculating results are sensitive to soil parameters such as internal friction angel, cohesion, rigidity parameter k and initial tangential Poisson ratio, the influences of concrete strength on the soil and lining are not large, there is rational and economical thickness of the lining, concrete age has large effect on lining axial force. The paper researches the effect difference of excavation length at one time on surrounding soil within the possible range of bench cut method through the compiled program.By use of the compiled program, the paper dynamically simulates the construction process of relying engineering, and compares these results synthetically, the results comprehensively reveal the influences of soil strength and buried depth on soil and lining. Selecting the shallow tunnel as engineering background, the paper adopts two simulation methods to analyze tunnel engineering properties in the situation of water infiltration, The results show water infiltration results in the increase of surrounding rock pressure, and deteriorates the safety condition of the lining, which is the main reason of loess tunnel diseases.On the basis of field observation results and effect properties analysis of the buried depth, the paper points out some problems with the exiting demarcation criterions of buried depth when they are used to loess highway tunnel, and firstly puts forward new thought and method through change regulation of soil lateral pressure coefficient in the center line, which is proved feasible by two engineering cases. In view of the large difference among the surrounding rock pressures calculated by different methods in the shallow soil tunnel, the paper draws the calculating formula of the pressure, and compares the results by the formula with the observation results of relying engineering, which proves the formula feasible.更多还原