基于随机介质理论的公路黄土暗穴稳定性评价

【作者】 陈党民；

【导师】 彭建兵； 李炳乾；

【作者基本信息】 长安大学 ， 地质工程， 2005， 硕士

【摘要】 随着我国西部黄土地区基础建设的发展,发育在黄土浅层的暗穴对公路建设和安全运营构成了严重威胁,有的已造成严重后果,因此研究有效的公路黄土暗穴稳定性评价方法对于黄土地区的公路路基处理和设计具有非常重要的指导作用,本文应用随机介质理论,对公路黄土暗穴的稳定性进行了探讨性的分析和评价。 本文提出了基于随机介质理论评价黄土暗穴稳定性的一种新方法,建立了黄土暗穴的简化几何模型和等效力学模型。应用该方法计算并分析了不同形状、大小及埋深的黄土暗穴引起的地表变形和影响范围;计算了不同参数下黄土暗穴的临界安全厚度;分别以地表变形和顶板结构强度作为评价黄土暗穴稳定性的依据,分析了洞形参数对地表变形和临界安全厚度的影响,对黄土暗穴的稳定性进行了探讨性地研究;定性分析了安全系数、地面荷载与临界安全厚度的关系;将该方法与其它几种方法的计算结果进行了比较,讨论了各种方法的适用性和合理性;设想了基于随机介质理论方法在实际工程中应用的工作步骤。 通过本文研究,得到以下主要结论: (1) 暗穴引起的地表下沉量的大小和分布不仅与暗穴埋深有关,而且与暗穴断面大小、地层特性有关。 (2) 暗穴引起的地表最大下沉量随着地层主要影响角、暗穴断面尺寸、暗穴半径收敛值等参数的增大而增大,随着暗穴埋深的增大而减小。 (3) 暗穴临界安全厚度随着暗穴断面尺寸、暗穴半径收敛值、安全系数、地面荷载等参数的增大而增大。暗穴临界安全厚度对地层影响角的变化不敏感。 (4) 地表影响范围随暗穴埋深、断面尺寸的增加而增加,随地层影响角的增大而减小。更多还原

【Abstract】 With the development of infrastructure construction in loess regions of western China, shallow hidden cavities in loess are the high risk to the highway construction and transportation safety. So, working out effective methods of highway hidden cavity stability assessment is of great importance for highway foundation treatment and design. In this paper, the stability of highway hidden cavity in loess area is discussed and assessed based on the stochastic media theorv.A new method for loess hidden cavity assessment is presented on the basis of stochastic media theory. A simplified geometric model and an equivalent dynamic model of loess hidden cavity assessment are developed. With this method, the ground deformation resulted from the hidden loess cavities of different shapes, sizes and depths and their affected range are calculated and analyzed. The critical safety thickness of loess hidden cavity with different parameters is calculated. Using surface deformation and intensity of top layer structure as criterion of loess hidden cavity stability assessment, the effects of cavity shape parameters on surface deformation and critical safety thickness are analyzed, and the stability of loess hidden cavity is studied. The qualitative analysis on the relation of safety coefficient and ground loading with critical safety thickness is made. The results of this research are compared with the calculated results obtained by other different methods. Practicability and rationality of different methods are discussed. Operational procedure of the stochastic media theory and method in practical engineering is conceived.The following conclusions are got in this research: 1. The magnitude and distribution of ground subsidence due to hidden cavity are related not only with depth of hidden cavity but alsowith the size of cavity section and characteristics of stratum.2. The magnitude of maximum ground subsidence caused by hidden cavity increases with the augment of principle influence angle of stratum, cavity section size and cavity radial constringency and diminishes with the decrease of hidden cavity depth.3. The critical safety thickness of hidden cavity increases with the augment of hidden cavity section size, radial constringency, safety coefficient and surface loading. The critical safety thickness of hidden cavity is not sensitive to influence angle of stratum.4. The influence range on ground surface increases with the augment of hidden cavity depth and section size and decreases with augment of influence angle of stratum.更多还原