岩土环境恶化下黄土滑坡孕灾和成灾机制及支护技术研究

The environment of geotechnical engineering has being deteriorated and geological disasters frequently occur due to the influence of global extreme climate and seismic active, which caused people to pay attention to the living environment. In view of the frequent occurrence of loess landslide and the complication of geological environment, and based on the fact that engineering environment changes induce landslide disasters, the investigation of intrinsic mechanism of landslide disaster induced by the deterioration of geotechnical environment has important scientific research value and meaning. According to the investigation, experiment and numerical analysis, the mechanics characteristic of landslides mass and the influrence factors of geo-environment are coupled. A non-linear stress strain constitutive model considering engineering environmental factors is established. Based on the unified strength theory, the determination of residual strength parameters and unified yield criterion are proposed under different geo-environment. The instability criterion of slope induced by disoperation of residual pore water pressure of cohensive under the dynamic loading is determined. In order to prevent the deterioration of geo-environment, combining with the site large-scale model experiment, the support of micropiles and the mechanism of interaction of pile and soil are investigated. The influences of the shape, soil characteristic, and top loading on the slip planes are analyzed. The quantity and optimal set of micropiles are reasonably determined to prevent the occurrence of landslides. The research achievements have innovation and application prospect, which can provide an important basis for the construction and the geo-environment assessment of the western area in China.

受全球极端气候和地震活跃期的影响，岩土工程环境急剧恶化，地质灾害的频发引起人们对生存环境的高度忧患。针对黄土滑坡灾害多、地质环境复杂的实际，基于工程环境变化造成滑坡灾害频发的事实，深入研究岩土环境恶化诱发滑坡灾害的内在机制具有重要的科学意义和研究价值。本项目通过调查、试验和数值分析，基于大量的现场和室内试验，将滑坡体破坏时土的力学特性与工程环境变化因素耦合起来，建立工程环境因素与滑坡体土的强度变形间关系的非线性本构模型；基于统一强度理论，提出不同工程环境下土的残余强度参数确定的合理方法和屈服准则；揭示动载下粘性土中残余孔隙水压力消散造成边坡失稳判据；为预防岩土环境的恶化，结合现场大型模型实验，研究微型桩支护边坡的作用机理，分析边坡形状、土性、坡顶堆载对滑裂面的影响，合理确定微型桩数和优化设置，防治地质灾害的发生。研究成果具有创新性和应用前景，可为西部基本建设规模与岩土环境评估提供重要依据。

受全球极端气候和地震活跃期的影响，岩土工程环境急剧恶化，地质灾害的频发引起人们对生存环境的高度忧患。针对黄土滑坡灾害多、地质环境复杂的实际，基于工程环境变化造成滑坡灾害频发的事实，深入研究岩土环境恶化诱发滑坡灾害的内在机制具有重要的科学意义和研究价值。本项目首先对黄土地区人工开挖边坡、临水边坡及高填土边坡进行野外地质灾害实地调查，进行了工程环境变化与地质灾害发生诱因的分析，进行了地质灾害综合评价。然后从滑坡现场取回黄土试样，进行了一系列试验。基于试验研究对饱和、非饱和土黄土对环境影响因素的敏感程度进行分析，揭示了工程环境影响和含水率变化孕育黄土地质灾害成灾机制。基于大量的现场和室内试验，进行了环境地质效应与岩土材料的强度-变形特性的关系及边坡稳定性分析研究。将滑坡体破坏时土的力学特性与工程环境变化因素耦合起来，进行了基于参数敏感性及强度折减有限元法的土质边坡可靠度分析，为边坡在不确定环境因子的风险评估提供理论依据。基于统一强度理论，建立了边坡稳定性分析中黄土的三维非线性统一弹粘塑性本构模型。通过人工切坡和高填土边坡工程实际，进行了滑坡的孕灾和成灾机制和边坡稳定性分析，提出了合理的支护措施。为预防岩土环境的恶化，进行了支护边坡加固技术的理论和模型试验研究。基于统一强度理论，建立了加筋土挡墙三维应力状态下的土压力计算式并进行实测值验证。结合现场大型模型试验，研究了微型桩和锚杆抗滑桩支护边坡的作用机理和桩土受力变形特性，揭示了微型桩和锚杆抗滑桩在支护边坡中的强度发挥机制。合理确定微型桩数和优化设置，防治地质灾害的发生。研究成果具有创新性和应用前景，可为西部基本建设规模与岩土环境评估提供重要依据。