灾变破坏的临界幂律前兆及预测处理方法研究

Catastrophic rupture such as earthquake is a low-probability but high-consequence event. Exploring reliable precursors is a way to understand the underlying mehanism and predict it. It was found that, in heterogeneous brittle material, some responses may grow drastically and present a power law singularity prior to rupture. This results are verified by theoretical results and observations in laboratory and field conditions. But it is still lacking of knowledge about its application that intend to predict time-to-rupture. In this project, we focus on methods for near-real-time prediction of catastrophic rupture by using the power law singularity precursor. Based on the condition trigering castastrophic rupture, we will explore the the underlying fundamental principle implied by the critical parameters of the power law expression and the relationship between them, and then derive a more simple and straightforward expresion. For the application in practice, we will develop two method: Graphical method and recursion method, to predict time-to-rupture. We will compare the prediction quality of these two methods to understand the key points impacting the prediction. Furthermore, we will try to test the methods in the earthquake prediction and explore the effects based on two cases of Wenchuan and Ya’an earthquakes. It is different from the study for testing precursors, this project directly study the method to recognize the catastrophic precursor in advance and the method to predict rupture. So, the work has considerable significance for the understanding and interpretation of catastrophic rupture and its prediction.

前兆研究，是应对地震等灾变破坏这类概率低后果严重事件的一个重要方法。已有实验室结果和理论模型分析揭示，非均匀脆性介质在灾变破坏发生前，响应量会呈现临界幂律奇异性前兆。但是，该结果目前还主要集中于后验验证，缺少正向预测的探索。本研究将从研究灾变破坏临界幂律前兆的物理本质入手，探索据此进行灾变破坏预测的处理方法。基于灾变破坏的触发机理，研究临界幂律前兆中临界参数的物理意义和参数之间的关联；在此基础上，从临界幂律关系出发，推导更简单的数学表达。基于实际观测数据的特点，发展利用临界幂律前兆预测破坏时间的递推和几何算法；通过预测效果比较分析，理清实际应用中的关键问题。并以汶川和雅安地震为案例，探索进行地震预测的检验，分析地震预测中的应用效果和关键因素。本项目突破对灾变破坏前兆的验证，着重于临界参数的物理意义和预测灾变破坏的方法。因此，本项目对于理解灾变破坏机理和探索灾变破坏预测具有理论和实际意义。

临近破坏时，响应量呈现得临界幂律奇异性加速过程，是一个被广泛证实得有效前兆。但是，大多结果主要集中于后验验证，缺少有效的实时预测手段。本项目从灾变破坏临界幂律奇异性前兆的物理本质入手，探索据此进行灾变破坏预测的处理方法。基于实验、理论、数值计算和现场监测数据分析，本项目取得了如下主要研究成果：(1) 阐明了临界幂律奇异性加速前兆中临界参数的物理意义及其分散性的物理机理，表明了灾变破坏临界幂律奇异性指数并不是一个定值，澄清了临界奇异性指数分散性不仅仅来源于实际测量数据的误差，其关键物理本质是，临界奇异性指数的取值受损伤对局部真应力的非线性依赖特征控制。(2) 基于三种典型加载实验证实了临界幂律奇异性前兆，并基于地震、火山、滑坡等实测数据验证了其可观测性。(3) 给出了单参数破坏过程表达式，发展了外推法、递推计算法、几何法3种预测处理方法，并通过实验室数据、火山和滑坡等实测数据进行了预测检验，说明了影响实际预测结果的主要因素。(4) 建立了刻画完全自持式灾变破坏的理论模型, 在实验室，设计和实现了完全自持式灾变破坏过程的实验观测，阐明了其触发宏观灾变破坏的条件，揭示了其机理。(5) 基于汶川地震GNSS监测数据，从灾变破坏的力学原理上，给出了震前与同震变形关联性的对照认识，初步提取了震前加速前兆，并据此进行了探索性预测验证。这些成果对于正确理解自然灾害破坏过程及其预测探索方面，从力学原理与监测方法上，给出了新认识，为进一步基于实验室观测和实地测量数据进行临灾预测提供了实践基础和理论借鉴。