干湿循环条件下煤系土强度特性及边坡致灾风险分析

The cutting slope landslides are often occurred after excavating in coal bearing formation,because the weathering speed increases, water softening and strength decreaseing rapidly. In view of research about meso-scopic strength parameters and unsaturated characteristics of coal-bearing soil hasn’t started, by geological survey of cutting landslide along the typical Highway of coal-bearing formation, slope deformation damage causes and the type of coal-bearing formation are proposed; Then, through wetting-drying cycle simulation and used scan electric mirror test (ESEM), fine views structure features parameter of coal-bearing soil in different water content is analyzed . Second, unsaturated soil mechanics tests of the coal-bearing soil are carried out, analyzing water state changes impact on coal-bearing soil strength index parameters, revealing the characteristic parameters of coal-bearing soil structure and the relationship between intensity index, establishing different water content (moisture content, changing the path of moisture), coal-bearing soil, the soil-water characteristic curve. Finally, specific risk analysis for a typical coal-bearing soil slope engineering stochastic finite element analysis model for analysis of coal-bearing soil slope stability under different conditions of wet and dry cycles, combined with intensity the statistical parameters of indicators and environmental change responses, establishment of risk assessment model for soil slope stability of coal. The results of the research not only improves the soil strength theory of coal bearing soil, can also further promote the risk assessment theory of coal-bearing soil water loss and disease, has high academic value and significant economic and social benefits.

煤系地层开挖后风化速度快、遇水易软化、强度衰减常致路堑发生滑坡。鉴于煤系土强度变化的细观研究、煤系土非饱和特性等研究尚未展开，拟对典型高速公路沿线煤系地层路堑滑坡进行地质调查，探讨煤系地层边坡破坏成因及分类；在此基础上采样通过干湿循环模拟，采用扫描电镜试验(ESEM)分析不同含水状态下土体细观结构特征。其次，开展煤系土非饱和土力学试验，分析含水状态改变对煤系土强度指标统计参数的影响，揭示煤系土结构特征参数与强度指标之间的关系，建立不同含水状态（含水率及其路径变化）下煤系土的土水特征曲线。最后采用风险分析理论针对典型煤系土边坡，建立随机有限元分析模型求解不同干湿循环条件下煤系土边坡稳定状态；结合强度指标的统计参数和环境变化情况，建立煤系土边坡稳定状态风险评估模型。该研究成果不仅完善了煤系土强度理论，还可推进煤系土边坡水损灾害的风险评估理论和方法，具有较高的学术价值和显著的经济效益、社会效益。

煤系地层开挖后风化速度快、遇水易软化、强度衰减常致路堑发生滑坡，有必要开展对赣西煤系土在干湿循环条件下强度衰减特性及其边坡致灾风险分析做深入研究。目前有关煤系土强度变化的细观研究、煤系土非饱和特性等研究成果为数不多见，该项目通过对南昌至上栗高速公路K145、K207地段石炭系—三迭系（C—P）煤系地层崩解性和软化性及路堑滑坡进行现场调研，探讨煤系地层边坡破坏的成因及分类；在此基础上通过采样开展干湿循环试验，采用扫描电镜试验(ESEM)分析不同含水状态下土体细观结构特征。其次，开展了煤系土非饱和土力学试验，分析了含水状态改变对煤系土强度指标统计参数的影响，揭示煤系土结构特征参数与强度指标之间的关系，建立了不同含水状态（含水率及其路径变化）下煤系土的土水特征曲线。最后采用风险分析理论针对典型煤系土边坡，建立随机有限元分析模型求解不同干湿循环条件下煤系土边坡稳定状态；结合强度指标的统计参数和环境变化情况开展了煤系土边坡稳定状态风险评估；还探讨了合理的煤系土边坡加固措施，提出了针对煤系土堑边坡的基于桩-土效应的微桩组合抗滑结构计算方法。该研究成果不仅完善了煤系土强度理论，还可进一步推动煤系土边坡水损灾害的风险评估理论，具有较高的学术价值和显著的经济效益、社会效益。