【作者】 程晔；

【导师】 赵明华； 曹文贵；

【作者基本信息】 湖南大学 ， 岩土工程， 2005， 博士

【摘要】 岩溶区路桥基础稳定性分析与评价是目前国内外岩溶区高速公路建设的重大技术难题之一。本文结合湖南省交通厅重大科研课题“高速公路岩溶及采空区路、桥基础设计施工与质量监控方法研究”,基于系统理论的观点,分别从确定性和非确定性两方面对其展开深入研究,最后通过工程应用的反馈,形成一套较系统的岩溶区路桥基础下溶洞稳定性的分析与评价方法。 本文首先在深入分析已有评价方法的基础上,分别提炼出11个和9个影响路基和桥基下溶洞稳定性的主要因素,结合层次分析法分别建立出岩溶区路桥基础下溶洞稳定性的模糊二级评判模型,采用隶属函数曲线和隶属函数表建立了连续型和离散型因素的隶属度函数,并引入灰色关联分析和Dephi法给出了相应的权重分配方法,从而建立出岩溶区路桥基础下溶洞稳定性的模糊二级评判方法。 进而基于极限平衡分析理论,考虑到溶洞顶板稳定性分析参数和评价的模糊性,分别建立出路桥基础下岩溶顶板稳定性的模糊平衡分析模型;基于分解定理,导出了岩溶顶板稳定性安全系数的计算公式;并考虑到决策者的不同偏好建立出从隶属度值到可能性评价的转换标准及其评价方法,从而建立出系统的岩溶区路桥基础下溶洞顶板稳定性的模糊极限平衡分析方法。 通过对已有模糊集排序方法的深入研究,提出了一个既融合模糊序关系和序函数,又可同时考虑模糊极大集和模糊极小集作用的模糊集排序指标;并在前人工作基础上导出可有效提高效率的三角模糊数运算近似公式;结合模糊多属性决策方法和层次分析方法,提出了模糊多层次多属性决策的概念及方法,进一步建立出岩溶区路基稳定性的模糊多层次多属性决策模型,并解决了模糊属性集、模糊权集、模糊决策技术和模糊集排序等关键问题,从而形成了较完整的岩溶区路基稳定性的模糊多层次多属性决策方法。 此外还基于三角形有限单元的弹塑性数值流形方法,针对开挖模拟问题进行深入研究,解决了数值流形方法在开挖模拟中的网格智能化生成、释放荷载分析、荷载移置方法及开挖物理覆盖处理等难题。将其与强度折减技术结合,提出分析溶洞顶板稳定性的强度折减流形元法,并基于Visual C++编制了二维弹塑性流形元应用程序。通过大量数值分析得到了岩溶区高速公路路基下溶洞顶板的最小安全厚度。 考虑到基桩下溶洞稳定性分析难以简化为一个二维问题,本文还采用成熟的商业有限元软件,通过建立合理的分析模型,确定有效的破坏准则,并在求解安全系数过程中引入二分法思想,分别建立出高速公路路基和桥基下溶洞顶板稳定更多还原

【Abstract】 It is one of the important technique problems of expressway construction to analyze and evaluate the stability of roadbed and bridge foundations in karst region at home and abroad. In this paper, combined with the research project "Study on the design, construction and quality monitoring of foundations in karst and mined-out region along expressway" financed by the Department of Communication of Hunan Province, based on system theory, a deep analysis has been made by deterministic and non-deterministic methods. At last a series of analyzing and evaluation methods for roadbed and bridge foundation’s stability are set up by feedback of engineering application.Firstly, based on known methods, eleven and nine factors of the karst cave’s stability under roadbed and bridge foundation are respectively abstracted and the models of two stages fuzzy synthetic judgment are set up by using analytic hierarchy process (AHP). Then fuzzy function curves and tables are adopted to establish membership functions for continuous index factors and discrete index factors respectively. And the weight of each factor is established by grey correlation coefficient analysis, AHP and Delphi method respectively. Accordingly, the two stage fuzzy synthetic judgment evaluation methods of the cave stability under roadbed and bridge foundation are found.According to limit equilibrium analysis theory, considering parameters and appraises’ fuzzy quality, the fuzzy limit-equilibrium-analysis models of roof stability of cave under roadbed and bridge foundation are developed. Calculation formulas of stability safety factor of karst roof are derived by using decompose theorem. Considering decision-makers’ respective preference, conversion standard and evaluation methods from the value of subjection degree to probability evaluation are put forward. Accordingly the fuzzy limit-equilibrium-analysis methods of roof stability of cave under roadbed and bridge foundation are set up.A new fuzzy set taxis index is put forward by thoroughly researching known methods which not only contain order relation and order function but also consider the effect of fuzzy maximum set and minimum set at the same time. Based on others work, approximate calculation formulas of triangular fuzzy number are derived to improve calculation efficiency. Combined with fuzzy multiple attribute decisionmaking (FMADM) and analytic hierarchy process (AHP), the conception and method of fuzzy multiple hierarchy multiple attribute decision making (FMHMADM) is put forward and the FMHMADM models of roof stability of caves under roadbed are developed in this paper. Then fuzzy attribute sets, fuzzy weight sets, fuzzy decision technique and fuzzy sets taxis method are set up and the FMHMADM method of roof stability of cave under roadbed is advanced.Introduced numerical manifold method (NMM), the elastic-plastic NMM which based on triangular limit cover is established. Nets intelligentized formation, release loads calculation, loads displace method and physics cover digging for dig simulation are dealt with and the program for dig simulation by elastic-plastic NMM was worked out by using Visual C++ as well. Combined with strength reduction technique, stability evaluation of karst cave roof by strength reduction NMM is proposed. The safety thickness of cave roof under roadbed in karst region is found by large numbers of numerical analysis.It is difficulty to predigest model of stability analysis of cave under bridge foundation to a two dimensions model. So the stability evaluation of karst cave roof under roadbed and bridge foundation by strength reduction FEM are put forward by using commercial soft ware of FEM, reasonable models, effective failing rule and dichotomy idea respectively in this paper. And the safety thickness of cave roof under roadbed is found by large numbers of numerical analysis in karst region which accords with the result of NMM analysis.Lastly, the two deterministic methods (Strength Reduction NMM and Strength Reduction FEM) and three of non-deterministic methods (Fuzzy Synthetic Judgment, Fuzzy Limit-Equilibrium-Analysis and Fuzzy Multiple Hierarchy Multiple Attribute Decision Making) are used in the supported engineering and fed back by the results. Accordingly, a series of analyzing and evaluation methods for roadbed and bridge foundation’s stability are set up and proved be feasible and effective by it’s engineering application.更多还原