基于岩块渐进破碎效应的干碎屑流运动-堆积全过程多尺度分析方法研究

Rock avalanche is defined as a type of downslope flowage of rock fragments, which is typically characterized by progressive breakage of rock fragments, high speed, long run-out and destructive power. Its kinematics or underlying mechanism has been the focus of many researchers in the field of landslides. However, there is no well accepted conclusion until now on the significance and effects of the progressive breakage of rock fragments on the macro-scale sliding and depositing behavior. The work in this proposal is fundamentally aimed at the interaction between the meso-scale progressive fragmentation of discrete rock particles and the overall macro- sliding motion. Abundant series of physical and numerical test studies are to be undertaken for a deeper investigation into the sturzstrom, which should be considered as a complex multiscale system. The main content of the proposed research is as follows: Firstly, physical test study, including compression tests on assembly samples made up of a number of rock fragments with particle breakage mobilized, and a series of centrifuge tests for modeling downscaled rock avalanche instances, are to be conducted. These tests results can serve as a strong basis for understanding the fragmentation mechanism of rock particles within a sturzstrom, and the effects of key factors on the macro-scale load-deformation as well as meso-scale particle breakage behavior. Secondly, a multiscale numerical approach is to be developed, which is capable of direct considerations of the progressive breakage of rock fragments within the flowing sliding rock mass, the vertical redistribution of fine particle content as well as the complete sliding-depositing process. The approach is to be verified by the lab test results. Finally, the capability of the developed numerical approach in reproducing prototype sturzstrom sliding-depositing response is to be checked through comparison with field data, and an in-depth numerical investigation into the Hongshiyan sturzstrom and its induced landslide dam is to be conducted, which can provide technical support for the long-term engineering treatment and utilization activities.

高速岩质滑坡—碎屑流具有速度高、滑程远、破坏力强等特点，往往引发灾难性后果，其动力学机理的研究一直是滑坡灾害领域的前沿热点。目前关于碎屑流中岩块的动态渐进破碎对其宏观运动—堆积全过程的影响机制和规律尚未取得公认的成果。本项目拟以揭示细观尺度岩块的渐进“碎屑化过程”和宏观尺度滑体动力响应的相互作用机制为核心，对这一复杂多尺度系统开展物理和数值模型探索。首先开展系列岩块堆积体压载试验和离心机滑坡模型试验，揭示碎屑岩块堆积体试样的变形与渐进破碎机理，研究岩块堆积体细观组构特征对岩样渐进破碎模式和变形力学行为的影响规律，探求典型要素对碎屑流滑坡宏观运动—细观渐进破碎相互作用机制的影响规律；其次发展和建立统一描述碎屑岩块沿程动态渐进破碎、竖向沉积与运动—堆积全过程的多尺度模拟理论和方法；最终结合典型碎屑流滑坡现场特征进行验证和预测，并为红石岩堰塞坝的工程整治措施提供依据。

岩质滑体在解体、破碎后的粒径分布规律在一定程度上影响远程运动形式，如何分析碎屑岩块的沿程动态渐进破碎，以及动态更新的粒径分布规律，并将其与宏观滑体的运动学特征联系，是亟需进一步研究的课题。本项目基于数值和物理试验手段，深入调研相关国内外相关研究成果，针对岩块渐进破碎效应对岩质高速远程滑坡的机制进行了深入研究。主要研究内容包括两个方面：一是开展了系列压载试验，研究颗粒堆积体的受压动态渐进破碎机制及其对宏观变形力学行为的影响规律；二是发展和建立考虑岩块渐进破碎效应的干碎屑流滑坡多尺度模拟方法。基于本项目研究工作，一方面在常规有限元，块体离散元和颗粒离散元数值方法基础上分别构建了表征岩块从完整到渐进断裂破碎全过程的数值力学模型，另一方面通过系列仿真研究，探索了单一球形颗粒以及变化粒径级配条件下的渐进变形与破碎响应机制，并系统探讨了岩块渐进破碎效应对于碎屑流滑坡运移速度和最终滑程的影响规律。本项目研究一方面在理想岩块（即球形颗粒）的细观渐进破碎机制和响应规律方面取得了更为深入和翔实的物理和数值试验数据，另一方面也初步构建了模拟碎屑流滑坡的双尺度模拟框架，研究结果认为岩块的渐进破碎行为在一定程度上有利于滑体运移位移的显著增加，但应该不是岩体碎屑流高速远程特征的主导机制。