考虑微结构特性的黄土斜坡强震失稳演化机理及稳定性预测

In the background of being prone to strong earthquake in Loess Plateau and the sturcure characteristic of porous and weekly conslidated of loess, based on hotspot of seismic disasters researches at home and abroad in loess areas and actual demand of the urbanization construction site safety, the mechanism of loess slope instability under strong earthquake and the prediction of its stability in view of microstructural characteristics will be studied in this project. Through investigating earthquake disaster characteristics of different types of slopes in Loess Plateau, the relationship will be discussed between slope instability and other factors such as the local site conditions, loess structure characteristic, geological environment and the hydrogeology conditions. Combining with dynamic characteristics tests of loess and scanning electron microscopy experiments, the influencing rule of micro-structure characteristic parameters of loess on its dynamic constitutive relation will be illustrated. Moreover, large-scale shaking table model tests of seismic response and slope instability in typical loess slopes will be carried out to explain the occurrence and evolution mechanism of instability disaster of loess slopes under strong earthquake. Based on analysis of strength-deformation of soil dynamic stability, the kinetic mechanism of the loess slope instability under strong earthquake will be analyzed by digital simulation methods and the analysis model of loess slope stability will be established to predict seismic stability of loess slopes. The results of this project will provide scientific foundation for slope earthquake disasters prevention and mitigation and construction engineering sites planning in Loess Plateau where strong earthquakes are very active.

本项目拟结合目前国内外黄土地震灾害研究的热点问题和黄土高原地区城镇化建设场地安全的实际需求，针对黄土高原强震多发的背景和黄土的多孔隙、弱胶结的结构特性，开展考虑黄土微结构特性的斜坡强震失稳机理与稳定性预测研究。通过对黄土高原不同类型斜坡地震灾害特征的调查，探讨局部场地条件、黄土结构特性、工程地质和水文地质条件等因素与斜坡失稳之间的联系；结合黄土动三轴和微结构电镜实验，揭示黄土微结构特性参数与其宏观动力本构的指标关联；开展典型黄土斜坡的动力响应和变形失稳破坏的大型振动台模型试验，阐明强震作用下黄土斜坡的变形失稳发生和演化机制；基于土体动力稳定性的强度-变形分析方法，利用数值仿真剖析黄土斜坡强震失稳的动力学机理，建立稳定性分析模型，开展黄土斜坡的地震稳定性预测。研究成果可为我国地震活动强烈的黄土高原地区的斜坡地震灾害防护治理和建设工程场地规划选址提供科学依据。

项目针对我国黄土高原强震多发的背景和黄土的多孔隙、弱胶结的结构特性，以黄土地区斜坡强震变形失稳破坏特征调查为出发点，开展了现场地形地貌调查、探井取样、原位测试、面波勘探等野外测试，调查了场地土体基本物理性质和土层分布状况，揭示了黄土高原不同地区内不同类型斜坡地震诱发变形失稳灾害的特征，给出了局部场地条件、黄土结构特性、工程地质和水文地质条件等因素与斜坡失稳之间的关联；以黄土微观结构特性分析评价为基础，对现场所取原状土样，在室内开展动本构和强度、颗分、扫描电镜等测试，综合利用MATLAB和IPP软件，系统研究了不同类型斜坡灾害发生场地的黄土微结构特征，揭示了黄土微结构特性参数与其宏观动力本构的指标关联，建立了考虑黄土微结构特性的动本构模型；以相似理论为基础，开展了黄土层内斜坡、黄土-基岩接触面斜坡和黄土塬边裂隙发育斜坡等三种典型黄土斜坡的动力响应和变形失稳破坏的大型振动台模型试验，阐明了强震作用下黄土斜坡的变形失稳发生和演化机制；基于土体动力稳定性的强度-变形分析方法，利用有限元模拟方法，揭示了黄土斜坡强震失稳的动力学机理，建立了考虑微结构特性的黄土斜坡稳定性预测模型，并对已有地震诱发失稳斜坡进行了反演验证。研究成果可为黄土高原内高烈度地区的斜坡地震灾害防治、减轻和建设工程场地规划选址提供科学依据。