基于离心模型试验的沟谷型泥石流沿程沟道侵蚀规律研究

The gully debris flows are one of the disasters that occur most widely and have the highest degree of disaster. Channel erosion along the path after the formation of debris flow are important physical processes for the catastrophe gully debris flows. In this project, the erosion process along the channel is going to be researched through a centrifugal model test system which is self-developed. The centrifugal model tests for channel erosion of debris flow are carried out on different channel features and debris flow properties. The research of centrifugal model tests will focus on: (1) the influence of channel features and debris flow properties on the erosion morphology of channel surface and the channel erosion rate; (2) the relationship between channel erosion rate and pore water pressure in gully bed; (3) the effect of channel erosion on velocity and discharge of debris flow with different characteristics. Based on the centrifugal model test research, the main controlling factors of channel erosion are determined and a quantitative expression is established between these the main controlling factors and the channel erosion rate. Based on the fluid mechanics theory, the control equations that considers the interaction of the erosion momentum are deduced, and the complex boundaries that account for erosion rates are proposed. Then, based the proposed debris flow erosion model, a high-performance SPH numerical simulation method than can consider the effects of channel erosion is proposed to reveal the erosion law of gully debris flow. The present research can provide a reliable and powerful scientific basis for the prevention and control of debris flow disasters in mountainous regions of China.

发生在山谷流域的沟谷型泥石流是世界范围内分布最广、致灾程度最严重的自然灾害之一。泥石流形成后的沿程沟道侵蚀是沟谷型泥石流灾变的重要物理过程。本项目针对沟谷型泥石流的沿程沟道侵蚀过程，通过自主研发的泥石流沟道侵蚀离心模型试验系统，开展不同沟道特征和泥石流性质的泥石流侵蚀离心模型试验；研究沟道特征和泥石流性质对沟道侵蚀形态及侵蚀速率的影响，研究侵蚀速率与沟床孔隙水压力的变化关系，研究沟道侵蚀作用对泥石流流速、流量等的影响，从而确定泥石流沟道侵蚀作用的主控影响因素并建立定量表达。在此基础上，以流体力学理论为指导，推导考虑侵蚀动量交互作用的控制方程，研究考虑侵蚀速率的复杂边界表征，构建泥石流沟道侵蚀动力模型，提出可考虑侵蚀作用的沟谷型泥石流光滑粒子流体动力学（SPH）高性能数值模拟方法，全面揭示沟谷型泥石流的沿程沟道侵蚀规律。项目研究成果可为我国山区泥石流灾害防治提供可靠、有力的科学依据。

沟谷型泥石流是山区常见的一种多发性快速地貌灾害过程，广泛分布于世界各地。这类特殊洪流因群发性高、突发性强、破坏性大、灾害链效应明显等特性，成为近十年来我国西部山区致灾程度最严重的自然灾害之一，造成了大量的人员伤亡、经济损失和环境破坏。本项目针对沟谷型泥石流的沟道侵蚀和冲击致灾过程，综合灾害地质学、工程地质学、岩土工程学、计算流体力学等学科理论，开展泥石流现场资料分析、室内模型试验研究、以及SPH高性能数值算法研，开发了适用于泥石流沟道侵蚀和冲击致灾模拟的模型试验系统，构建了大规模泥石流运动过程的SPH高性能数值算法，并进一步构建了沟谷型泥石流灾害危险性定量评估模型，相关研究成果在国际高水平期刊上发表SCI论文3篇，授权国家发明专利1项，此外，项目责人以第五完成人获教育部科技进步一等奖。本项目研究成果可为此类地质灾害的临灾预案和减灾工程设计提供科学依据，对防灾减灾规划和方针政策的制定具有极为重要的现实意义。