参加巴东国际地质灾害学术论坛记

岳中琦

应中国地质大学副校长唐辉明教授邀请，我在今年8月25日-28日，前往湖北省巴东县，参加了Badong International Geohazards Symposium（巴东国际地质灾害学术论坛）。巴东县城位于三峡大坝上游西偏北70公里处。巴东县是三峡水库区，到处都是高山峻岭和沟谷地貌，地表海拔高差可达2000米，滑坡等地质灾害频发。这次论坛总体情况可参见相关报道：http://info.cnhubei.com/gd/201708/t3896156.shtml；http://www.mlr.gov.cn/xwdt/jrxw/201708/t20170829_1584744.htm。

在26日和27日上午和中午进行的学术论坛上，我认真地听取了11位来自海外和9为来自内地的专家学者的20场精彩学术报告，了解到国际国内地质灾害调查、成因和预防的最新进展。

我在论坛上用英文做的大会报告题目是“Mechanism of Giant Rock Ejection at Donghekou during 2008 Wenchuan Earthquake”《汶川地震瞬间东河口巨大山体抛射高速溃流的机理分析》。我用造成地震的地下深部快速运移到东河口山坡岩体的极高压气体的体积膨胀能力，定量地计算和分析了，体积为1千6百万立方米（质量为38亿公斤）的相对平缓（倾角28度）山坡岩体被水平抛射千米的动力学过程（下图）。报告摘要参见附录。

在26日和27日下午（15：00-18：00），我参加了野外滑坡防治工程考察（下图）。沿着巴东县城的长江南北两岸，考察了史家坡滑坡的库区地质灾害防治与库岸再造工程和黄土坡滑坡的大型水库滑坡野外综合试验场。这些山峡水库库岸滑坡防治工程和研究让我看到、感受到内地相关科技人员的不懈努力、不畏艰苦和求真精神。

同时，我也参加了在26日和27日晚间（19：00-23：00）举行的《第七届青年工程地质学术研讨会》，认真地听取和点评了20位青年学者的20场精彩学术报告，了解到内地青年科技人员在地质灾害调查、成因和预防的最新工作和研究成果。我被他们的科研热情、兴趣和努力所感动。

在25日，从香港乘大巴、高铁、再乘大巴去巴东县城，我经历了15个小时的旅途劳累（早上4：30到晚上19：30）。在26日和27日两天，从早上8：00到晚上23：00的学术和考察活动，使得我在精神上收获极大。这种抓紧时间，从早上8点到晚上11点，进行学术交流和考察的会议形式是我第一次遇见和参加。这充分体现了会议领导和组织人员的渴望学术交流和相互学习的精神和努力。同时，在会场和野外参观，处处可见会议组织者的精心准备和投入的充沛人力和物力。也遇到了不少新老朋友，交谈起来喜气洋洋，增进了感情和友谊。特别地，会议期间提供的自助中餐和晚餐具地方特色和多样丰盛。美味的清炒小青菜更使得我想起了在长江下游家乡宣城的往事。

在此，我再次向论坛组织单位和工作人员表达由衷的感谢！

2017年9月6日18:31写成于香港大学602办公室

附录：报告的英文摘要

Mechanism of Giant Rock Ejection at Donghekou during 2008 Wenchuan Earthquake

Zhongqi Yue

Department of Civil Engineering, The University of Hong Kong, Hong Kong, P. R. China

Abstract

This presentation gives a quantitative dynamic examination of the ejection of a giant rock mass at Donghekou during the M_w 7.9 Wenchuan earthquake of May 12, 2008. The ejected rock mass is part of the upper mountain with a slope angle of 28°, about 3 km to  the town of Donghekou in Qingchuan County, Sichuan Province, China. The ejected rock mass has a volume of 6×10⁶ to 24×10⁶ m³and has a flying distance of 750 m to 1000 m. After the flying, the rock mass impacts the mountain slopes two times and slides further one gentle ground surfaces. The overall travel angle of the rock mass debris is about 14°. The ejected rock mass rapidly travels to a maximum horizontal distance of 2.4 to 2.6 km. The rock debris covers an area of 1.1×10⁶ m², destroys and buries four villages and a primary school and results about 800 fatalities. Under the hypothesis of highly compressed methane gas cause of the earthquake, a dynamic model is proposed and developed to back-calculate the giant rock mass ejection. The horizontal flying distances of 750 m and 1000 mare, respectively, used as the lower and upper ejection limits.  For these lower and upper limits, the giant rock mass would have to be accelerated heavily within the initial 0.1 second.Within the initial 0.5 to 0.6 seconds, the giant rock mass has to the highest upward vertical velocity of 27 to 39 m/s and the corresponding horizontal velocity of 57 to 77 m/s. The peak upward vertical acceleration has to be between 360 to710 m/s² (38g to 71g) within the initial 0.012 seconds. The peak forward horizontal acceleration has to be between 660 to 1250 m/s² (65g to 125g) within the initial 0.012 second.  The total flying time of the giant rock mass is about 12 to 14 second. The rock mass can have the high speed of 100 to 130m/s before the impacting. After the impacts, the rock mass can rapidly slide over the ground surface of gentle hillside slopes and stream course with the common ground frictional resistance angle of 30°.

Abstracts of Badong International GeohazardsSymposium, Part 1: Keynote Speech, pp. 7