胡凯衡+马超

基金项目：中国科学院重点部署项目(KZZDEW0501)；国家自然科学基金重点项目(41030742)；中国科学院水利部成都山地灾害与环境研究所青年百人团队项目(110900K235)

摘要：传统的泥石流预警方法多基于前期和实时降雨量等间接指标，但实际上直接影响泥石流启动的关键物理参数是土体含水量，通过分析土体含水量的变化来判断泥石流启动更为直接可靠。首先定义了泥石流启动的临界土体含水量的概念，然后基于国内外泥石流启动的观测试验数据，采用逐步回归分析方法，建立了临界土体含水量与土体渗透系数、孔隙度和颗粒曲率系数的经验关系，进而提出一种基于临界土体含水量和实时降雨的泥石流预警方法。最后，以云南东川蒋家沟1999年7月16日发生的一场泥石流为实例进行演算和验证。结果表明：该方法在可靠性和准确性上优于传统利用临界线和暴发线判别泥石流的预测模型。

关键词：泥石流；预警；临界土体含水量；孔隙度；渗透系数；曲率系数；降雨

中图分类号：P642.23文献标志码：A

Critical Soil Moisture for Debris Flow Initiation and Its Application in Forecasting

HU Kaiheng1,2, MA Chao1,2,3

(1. Key Laboratory of Mountain Hazards and Earth Surface Processes, Chinese Academy of Sciences, Chengdu 610041,

Sichuan, China; 2. Institute of Mountain Hazards and Environment, Chinese Academy of Sciences

and Ministry of Water Resources, Chengdu 610041, Sichuan, China; 3. University of

Chinese Academy of Sciences, Beijing 100049, China)

Abstract: Most of traditional debris flow forecasting methods are based on indirect variables such as antecedent and realtime rainfalls. But the key factor influencing directly the debris flow initiation is soil moisture, which is more reliable for debris flow forecasting. Firstly, the concept of critical soil moisture for debris flow initiation was defined; secondly, based on the experimental and observation data of debris flow initiation at home and abroad, the empirical relationships between critical soil moisture and permeability coefficient, porosity, coefficient of paritcle curvature were obtained by the means of stepwise regression analysis; finally, the forcasting method for debris flow based on critical soil moisture and realtime rainfall was proposed. The method was tested and verified by the debris flow happened at Jiangjiagou of Dongchuan, Yunnan on 16 July, 1999. The results show that the reliability and accuracy of new forcasting method is better than the traditional forecast method for debris flow based on critical line and occurrence line.

Key words: debris flow; forecasting; critical soil moisture; porosity; permeability coefficient; coefficient of curvature; rainfall

0引言

自然界中，泥石流往往由上游沟岸或坡面的固体物质失稳进入沟道，并在沟道水流的动力作用下形成。初始形成的泥石流规模不大，在运动过程中通过侵蚀、裹挟松散物质，规模才逐渐增长［12］。

一般而言，坡面土体要达到一定的含水量(体积比，下同)才能启动形成泥石流。坡面土体的含水量是反映泥石流形成的直接参数。目前常用的前期降雨和当期降雨量预警指标，间接体现了降雨使土体含水量增加，抗剪强度和土体稳定性降低，从而使泥石流发生的可能性增大［36］。……