【作者】 裴建中；

【导师】 胡长顺； 王秉纲；

【作者基本信息】 长安大学 ， 道路与铁道工程， 2004， 博士

【摘要】 青藏公路北起青海省格尔木，南止西藏拉萨，全长逾1100km。青藏公路承担着85％以上的进出西藏物资运输任务，对西藏的政治稳定、经济发展和国防建设具有特别重要的意义，是保障西藏200多万各族人民生活、生产和国防安全的重要生命线。 青藏公路自昆仑山口至桑雄进入青藏高原腹地，平均海拔4500m以上。高原气候条件恶劣，全年气候负温期长，昼夜温差变化大，寒冷干燥，空气稀薄，太阳辐射强烈，路基阴阳坡温度差异明显。沿线地质条件复杂，地表广泛分布着各种成因的第四纪松散沉积物，特别是沿线550km的路段下分布着多年冻土。 恶劣的自然条件和复杂的地质状况，导致该路出现大量路基纵向裂缝。这些纵向裂缝不仅规模巨大、数量繁多，而且发展迅速、难以养护，导致路面行驶质量每况愈下，运输效益常年偏低。过去常规的以小修保养的养护方法，治标不治本，且呈现出病害日渐严重的趋势，不能确保该地区道路的畅通，严重威胁着车辆的行驶安全，成为制约当地经济快速发展的瓶颈。 为此，论文以青藏公路为依托，以解决重大工程问题为出发点，着手进行多年冻土地区路基纵向裂缝形成机理与防治对策研究。整个论文分为两大部分。第一部分为多年冻土地区路基纵向裂缝形成机理研究，对纵向裂缝的形成过程进行数值仿真，着重阐释纵向裂缝形成的深层原因；第二部分为青藏公路纵向裂缝防治对策研究，从工程实际出发，研究提出经济合理、技术可行的处治对策，服务于西部大开发中的公路基础设施建设。 论文研究首先对青藏公路路基纵向裂缝进行了现场勘察，通过全线普查和典型路段详细调查，对这种病害的发育性状及分布规律进行了研究。瑞雷面波仪对于勘探浅层工程地质问题具有优势，本研究利用其进行了路基病害原因的测试分析。 在纵向裂缝形成机理研究中，首先根据多年冻土上限变化规律、多年冻土地区路基温度场特征和青藏公路纵向裂缝特点构建了分析模型，然后利用有限元方法进行数值仿真，研究纵向裂缝的形成过程。分析结果显示，路基纵向裂缝形成过程十分复杂，经历了三个阶段：初始变形阶段、强度破坏阶段和变形失稳阶段；与此相对应，形成过程在力学性质上呈现三个区域：发育区、抑制区和诱发区。 据实际路况调查分析，影响纵向裂缝的因素很多，本研究择其主要影响因素进行了分析，其中包括多年冻土融化区参数、季节活动层参数和路基参数，以掌握路基纵向裂缝的形成及其规模随这些因素的变化规律。 在上述分析的基础上，论文对影响纵向裂缝的内在条件，外界环境因素进行研究，提出了纵向裂缝的防治原则与分类分级评价方法;并有针对性的提出多年冻土地区新建路基的防治对策和基于纵向裂缝分类分级的既有路基纵向裂缝的处治措施。根据不同的防护原则，提出了三种防护对策:保温隔热稳定技术、通风散热稳定技术和综合防护措施。基于现场勘察资料，按照纵向裂缝发育性状和形成原因的相似性和工程整治的方便性，将纵向裂缝分为直线型和边坡弧型两种类型。对直线型纵向裂缝，按照开裂程度分为轻微、严重和非常严重三个等级。 对于直线型纵向裂缝，论文研究提出可以采用的基本对策主要有:单层土工格栅处治技术、柔性枕梁处治技术和柔性枕梁与土工合成材料复合处治技术。针对边坡弧型纵向裂缝，一般采用土工格栅分层加筋技术进行处治。论文通过对处治结构设计参数分析、处治路面结构的力学分析和不同处治结构之间的对比分析，研究了这几种结构的可行性和适应性，提出了相应的设计方法。其中柔性枕梁处治技术在国内外属首次提出并系统研究。最后结合实体工程试验研究，提出了处治结构的施工工艺。更多还原

【Abstract】 The Qinghai-Tibet Highway amounts to 1100km from Germod to Lasha. It plays important roles for Tibet in political stabilization, economic development and defense construction. At the same time, it is an important line that makes sure the lives, work, and safety of more than 2 million local people.The Qinghai-Tibet Highway lies in the areas of Tibet Plateau with the 4500 average attitude. The weather is so bad with longer winter, colder and drier, fewer air, and stronger solar radiation that there is big temperature difference in slopes of subgrade. In addition, there are very complex geology conditions, especially permafrost along line.Due to the above reasons, there are many longitudinal cracks occurring in the line. These cracks are too huge to be maintained with ordinary methods. As a result the performance of road is very low. In recent years, these cracks become more severe and have a threat to the riding safety.Therefore, the paper, depending on the Qinghai-Tibet Highway, begin to study. The paper has two main parts; the first part has analyzed the forming mechanics of longitudinal cracks through FEM, and the other part has studied the treating structures according to the different types and classes.First of all, the paper has investigated the longitudinal cracks in the fields, and analyzed the characteristic and distributing laws of the crack. At any more, the paper also tests the reasons of crack through Reiligh Wave Instruction.In the mechanism analysis part, the paper has established the model through analyzing the changing laws of permafrost upper limit, temperature field characteristic and the longitudinal crack traits, and solved through FEM. The results has revealed that the forming process of crack have three different phases: the initial deforming phase, the strength destroying phase and deforming destroying phase; and there are three different area in mechanics aspects: development area, restrict area and urging area. At the same time, a lot of factors, including thawing zone of permafrost, seasonal active layer and subgrade, are considered to study forming course of the longitudinal cracks.On the basis of the above analysis, the paper has put forward the protectingprinciples and classifying and grading methods of the longitudinal cracks. According to the protecting principles, three protecting methods are suggested to use; and according to the classifying and grading methods of cracks, the longitudinal crack is divided into two types: the linear crack and the slope arc crack. In addition, the linear crack is further divided into three grades: light, severe and much severe. Though studying, there are three basic maintain methods on the linear crack, including single layer geogrid, the flexible beam and the composite structure of geogrid and flexible beam, and the geogrid of many layers to used to treat the slope arc crack.The paper has studied the design parameters of the treating structures and mechanics characteristic after treating through FEM, analyzed the feasibility and adaptability of these structures, and brought forward the corresponding design methods. Among these, the flexible beam is firstly introduced and studied.In the end, combined with the field test project, the paper has studied the construction techniques.更多还原