【作者】 王志斌；

【导师】 李亮；

【作者基本信息】 中南大学 ， 岩土工程， 2007， 博士

【摘要】 近年来，山区高等级公路得到迅猛发展，而在山区修建高等级公路时，不可避免会遇到大量岩质斜坡地基上的填方路堤。目前，对于岩质斜坡路堤的破坏机理、稳定性计算方法及设计方法尚缺乏系统的研究。因此，开展岩质斜坡路堤稳定性研究具有重要的现实意义。论文以常(德)-吉(首)高速公路为依托，运用大比例模型试验、数值计算和理论分析等手段，对岩质斜坡路堤的工作性状、变形特性、破坏模式、稳定性计算方法及设计方法等内容进行了系统研究，取得了如下创新性成果：1、在国内首次采用1：20的大比例室内模型试验对岩质斜坡地基上高填方路堤工作性状与稳定性进行研究。形成了一套可供借鉴的大比例室内模型试验的设计、数据测试和分析方法。通过对岩质斜坡路堤在外荷载作用下的应力、应变特性的分析，得出了岩质斜坡路堤极限承载力的大小、整体破坏模式以及与现行规范不同的折线型破坏模式。其中，折线由填筑层之间的交界面和斜坡坡面组成，交界面一般出现在路堤填筑高度的2／3处。2、运用数值计算的方法，首次系统地分析了各种岩质斜坡路堤的破坏模式，并与模型试验的结果进行对比分析，得出了各种破坏模式与岩质斜坡地基和填土条件之间的关系。分析了斜坡地基坡度、填方路堤高度、填方路堤宽度、填方路堤斜坡坡度对岩质斜坡路堤极限承载力的影响。针对岩质斜坡路堤整体破坏模式，提出了台阶的宽度设置为1m的建议。3、基于极限分析上限法的基本原理，首次建立了岩质斜坡路堤在不同破坏模式下的机动容许速度场，并推导出其极限承载力的计算公式。在此基础上，采用Visual Basical可视化语言编制了相应的计算程序，利用该程序的计算结果与FLAC的数值计算结果对比分析表明：上述计算方法具有一定的工程应用价值。4、本文首次将极限平衡水平条分法应用于岩质斜坡路堤稳定性计算，推导出了岩质斜坡路堤极限承载力的计算公式。在此基础上，采用Visual Basical可视化语言编制了相应的计算程序，利用该程序的计算结果与FLAC的数值计算结果对比分析表明：该法计算结果属下限解，计算成果较稳定性系数的真值略低。综合利用极限分析上限法与极限平衡水平条分法得出了岩质斜坡路堤极限承载力的计算公式，为山区岩质斜坡地段高速公路建设提供了合理的指导。5、在综合模型试验、数值计算及稳定性分析成果基础上，针对山区岩质斜坡地段高速公路建设中存在的问题，提出了岩质斜坡路堤的设计原则及加固措施，对山区高速公路建设具有一定的指导意义。更多还原

【Abstract】 Since Western Area Development policy was issued by the government, mountainous highways have expanded rapidly. Fill embankments on rock slope foundations are the common problems in the construction of mountainous highways. Up to the present, the system research of the stability of the fill embankments on rock slope foundation, the relevant engineering measures and design methods are not developed. Therefore, to study stability of fill embankments on rock slope foundation is of practical significance in engineering construction.Based on the project of the working character of embankments on rock slope foundation in the railway from Changde to Jishou, the dissertation is dominated by the work performance, deformation, failure mechanism, stability calculation method and construction application. The stability of fill embankment on rock slope foundation is studied by means of full scale of model experiments, numerical and theoretical analysis. The major research findings are as follows.The First, According to the practical experiences in the expressway construction on the mountain region, full scale model experiments are carried to analyze the embankments performance on rock slope. The test design and instrumentation were introduced. During the experiments, the vertical force distribution, displacements of slope, the shape and location of the slip surface in the embankments were also investigated. The failure location, shape, stress distribution, displacements and settlement regulations were found out when the fill embankment on slope foundation is under unstable condition.The Second, FLAC software is used to analyze the major failure models of fill embankment on rock slopes. There are surface failure (whole failure), curve failure (partial failure) and zigzagging curve failure (partial failure). Studies are focused on various kinds of failure models and grades of slope, proportion of embankment heights and width and physical mechanical properties of earth filling, specific shapes of sliding surface under various kinds of conditions. Meanwhile, works are carried to determine various inclination angles of the slopes, various heights of earth filling and different widths of embankment fillings. Impacts on ultimate carrying capacity are analyzed for the high fill embankment foundation at different angles of roadbed. Effects of excavation steps on stability of fill embankment on rock slope foundation are discussed preliminarily. Proper shape of excavation steps is proposed.The Third, based on numerical results and model experiments, using upper bound theorem of limit analysis, velocity fields are established for different failure models. Equaling external power rate to internal energy dissipation, ultimate beating capacity formula of fill embankment on rock slope foundation was obtained. The corresponding program is coded with Visual Basic. The upper bound solution is easy to obtain, and physical meaning is clear without redundant presumptions. The numerical results show that the upper bound solutions are slightly bigger than those using FLAC method. Therefore, the upper bound method of limit analysis is precise and reliable, and can be used in stability analysis for foundation on rock slopes.The Forth, limit equilibrium method is used in the dissertation. Based on experimental and numerical results, formulas of limit equilibrium of horizontal slice method are derived, and are programmed correspondingly by Visual Basic for different failure models of rock slope embankment. The results show that the solution of bearing capacity of embankment is reasonable with the limit equilibrium of horizontal slice method. Limit equilibrium of horizontal slice method is much closer to actual solution than vertical slice method, because it not only satisfies strength equilibrium but also moment equilibrium between slice filling of embankment. The solution with limit equilibrium method is lower than the actual solution. For practical engineering, the two methods are considered so that the solutions upper bound theorem of limit analysis and limit equilibrium slice analysis are determined. The safety coefficient or ultimate beating capacity usually can be restrained within a small range. Thus, proper solutions are likely to be obtained.Finally, according to construction experiences, generalized are technical principles of engineering design of high fill on rock slope foundation based on the experimental results, rock slope embankment failure mechanism analysis and stability calculation method. Consolidation design and construction applications of high fill on slope foundation under different construction conditions are introduced. These are of instructive significance for design and construction of high fill on slope foundation in mountainous area so as to ensure safe and expedite traffic.更多还原