【作者】 王瑞钢；

【导师】 闫澍旺；

【作者基本信息】 天津大学 ， 岩土工程， 2004， 博士

【摘要】 公路灾害研究与公路发展密切相关。随着我国山区高速公路的修建，高填土路基不断出现。能持续一定时间的暴雨能给公路带来很大的破坏，产生滑坡等诸多灾害。本文从复杂渗流条件下的土坝稳定分析入手，从不同方面、运用多种理论分析了高填土质路堤在降雨渗流作用下的稳定，研究了降雨作用下的土质公路边坡的稳定机理和破坏模式。1. 针对白石土坝的复杂渗流条件编制了有限元程序。对自由面的求解，在计算中提出了弃单元法算法。用有限元方法对渗流量进行了计算。分析了实测水位和理论计算水位有较大差别的原因并提出相应的渗流稳定措施。此外，对大坝在库水位骤降情况下的稳定进行了分析。本文中所提供的相关方法为白石大坝的设计、运行提供了计算依据。2. 建立了降雨入渗渗流作用下的高填土路堤稳定计算模型，并根据所建模型编制了极限平衡法路堤土坡稳定分析程序；通过对比分析，提出了符合实际的路堤入渗深度计算公式，并计算了在不同条件下公路路堤的降雨入渗深度；用编制程序对现行的各种高填土路堤的稳定进行了计算和分析；用渗流有限元和弹塑性有限元程序计算了高填土路堤的稳定性，验证了本文所建立的路堤稳定计算模型和稳定分析程序。3. 本文基于非饱和渗流数学模型，设计了二维非稳定渗流程序。选取了适合SWC曲线，用Corey-Green方法预测了土体的渗水性系数。针对现行的高路堤边坡，模拟了因雨水入渗引起的暂态渗流场，分析了土体中含水量、基质吸力的变化规律。然后将计算得到的孔隙水压力作为输入条件，采用了适用于非饱和土的Mohr -Coulomb破坏准则对路堤边坡进行了弹塑性有限元分析，进而得出降雨后不同时刻的应力场。通过在边坡滑弧上进行线积分，得出边坡在不同时刻的整体安全系数,进而提出了路堤边坡降雨作用下“小弧滑动”的概念。分析了不同的降雨重现期、参数φb的变化对边坡稳定的影响。对由路堤施工所引起的土体渗水性系数的各向异性对边坡的渗流稳定影响进行了分析。4. 基于平均降雨量概念，考虑了降雨的随机性，用改进的JC法和Monte-Carlo模拟方法（MCSM）对公路路堤结构边坡进行可靠度稳定<WP=4>对比分析，且编制了相应程序，考虑了随机变量为相关任意分布的情况；根据实测数据，定量分析了路堤边坡土体因降雨而引起的饱和度变化对土体强度参数的影响；此外，对路堤稳定敏感性因素及其可靠度的一些规律进行了一些研究。更多还原

【Abstract】 The studying of highway hazards is closely connected with the development of highway constructions. Large-scale Highway subgrades are booming in mountain regions with more and more highways being constructed in our country. The heavy rain with certain duration can cause serious damages to the highway, such as slope sliding. This paper, firstly, analyzed the stability of BaiShi earth dam with complicated seepages, and then calculated extensively the stability of the highway subgrade due to rainfall infiltration with different theories. The slope stability mechanism and failure mode are deeply dealt with in the paper. 1. A FEM program is made to calculate the complicated seepage of the earth dam of BaiShi reservoir and a new finite element algorithm called abandoned element method is developed to solve the free surface of the unconfined seepage. This method is verified to have good precision and convergence by the comparison of calculation results with electrical resistance simulation method, and can be applied to all kinds of unconfined seepage. The unit discharges are calculated by FEM method. In addition, the difference between calculated and measured water levels is dealt with. Accordingly, the measures of seepage stability are proposed in this paper. At last, the stability of the earth dam is analyzed under the rapid drawdown. The calculating method proposed in the paper provides a good reference for the design and running of the BaiShi earth dam. 2. In this paper, a seepage model of infiltration into unsaturated highway subgrades was proposed and the corresponding analyzing program of stability of the bank was made on the basis of the simplified Bishop’s method, which can calculate the different depths of infiltration into the subgrade. The stabilities of popular highway subgrades are calculated with the program easily, and the finite methods of seepage and elasto-plasticity verified the results calculated by the limit equilibrium program. Some valuable conclusions have been drawn for <WP=6>the design and construction of the highway subgrade.3. A two-dimensional unsteady seepage FEM program was developed on the basis of a saturated-unsaturated seepage mode. A suitable SWC curve was applied and the unsaturated hydraulic conductivity was predicted with Corey-Green method. Transient seepage fields due to rain infiltration were computed for popular highway subgrades and the water content and matric suction in the slope was analyzed. The computed transient pore water pressures were then used for subsequent elasto-plastic FE program. An extended Mohr-Columbia failure criterion was used to allow for shear strength variations as a result of changes in matric suction and the FE stress fields were gained accordingly. The global safety factors were calculated by the stress integration along a slip line and a concept of “small slip failure” was introduced in stability of the embankment slope. Effects of various rainfall events, angleφb and the anisotropic permeability ratio caused by construction of the embankment on the seepage and stability were analyzed. 4. In this paper, reliability analysis of highway subgrades is presented using two methods of uncertainty adapted “JC” method and Monte Carlo simulation method (MCSM) based on the view of “mean rainfall” and the corresponding program was developed which can account for relative randomly distributed variables. According to published data, the effect of changes of saturation due to rainfall infiltration on soil strength parameters is dealt with. In addition, the sensibility factors affecting the slope stability are analyzed, and also the rules of reliability of soil slope stability are researched a little more deeply. At last, a reference reliability index is proposed for the highway subgrade stability.更多还原