颗粒非均匀性对松散堆积体自组织临界性影响机理研究

Many studies have shown that magnitude–frequency distribution of slope disasters event exhibits power-law, while the exponent vary greatly in different regions. At present, scholars from various countries carried out a large number of statistical work on the power law relationship of landslides, but no one answered the reasons for the differences in power exponents. With Wenchuan, Lushan, Nepal earthquakes have occurred, some phenomena that reflect deep scientific rules are gradually revealed. A hypothesis begins to form, Which is "Non-uniformity structure is the main reason for the difference in self-organized criticality (SOC) behavior of slope system". In view of this, shaking table experiments of sand-pile will be carried out to reappear the collapse of loose deposit with different particle gradation; Aocustic emsision experiments of loose deposit samples will be carried out to watch the effect of particle interaction; Non-uniform cellular automata model will be built to explain the mechanism of influence of non-uniformity on SOC, in the condition of particles sizes assumed as physical property of cellular. The theoretical framework of three characteristics(power law, robustness, long-range correlation) in influence of non-uniformity geotechnical on self-organized criticality of slope system will be established, that will be applied in disaster prediction, such as landslides triggered by earthquake. The achievement of this program will accelerate development of slope disaster theory from phenomenology to precise science.

斜坡灾害往往呈现规模与频率的幂律分布规律，但不同区域的幂指数差异很大。目前各国学者开展了大量崩塌滑坡幂律关系的统计工作，但幂指数差异的原因尚无人回答。随着汶川、芦山、尼泊尔地震的相继发生，一些反映深层次规律的现象逐步展现，促使我们形成了“组构非均匀性是导致斜坡系统自组织临界性（SOC）行为差异的主要原因”的认识。鉴此，项目通过振动台沙堆模型实验，重现地震动力扰动作用下不同级配松散堆积体表层坍塌特性；通过大直剪—土体声发射实验，观察剪力作用下土体内部颗粒相互作用效应；通过将颗粒几何尺寸的大小概化为元胞物理属性差异的方式，研发非均匀元胞自动机模型，诠释组构非均匀性影响SOC的机理。从而建立颗粒非均匀性影响松散堆积体SOC动力学三大特性（幂律、稳健性、长程相关性）的理论框架，并以地震触发崩塌滑坡为例，探索理论研究在灾势预测中的应用。成果有益于推动斜坡灾害整体理论研究从唯象学向精确化科学迈进。

斜坡灾害往往呈现规模与频率的幂律分布规律，但不同区域的幂指数差异很大。目前各国学者开展了大量崩塌滑坡幂律关系的统计工作，但幂指数差异的原因尚无人回答。项目组通过现场考察野外斜坡松散堆积体，获得粒度分布特征，确定了以分形维数D作为颗粒组构非均匀性的的描述指标，并以此为参照制备了不同分形维数的多组沙堆模型。通过振动台沙堆模型实验，重现地震动力扰动作用下散粒体表层坍塌特性，研究散粒体坍塌量-频率之间的关系，获得了分形维数D与b值的关系，利用振动台实验具有地震波强度可变的特点，探究了系统的稳健性；通过大直剪-声发射试验，观察剪力作用下散粒体内部颗粒相互作用效应，研究声发射（Acoustic Emission, AE）信号-频率之间的关系，获得了D与b值的关系，利用实验具有高采样率的特点，一次可获得上百万次的AE信号，探究了系统的长程相关性。然后建立了非均匀元胞自动机模型，利用物理实验规律对模型进行修正与正确性检验，开展数值模拟，揭示系统组构分形维数D与系统SOC特性的关系。成果有益于推动斜坡灾害整体理论研究从唯象学向精确化科学迈进。