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汶川震区典型小流域泥石流发育特征及危险性
引用本文:孟华君, 张向营, 张春山, 王鹏, 李焕彬. 2017: 汶川震区典型小流域泥石流发育特征及危险性. 工程地质学报, 25(s1): 349-356. DOI: 10.13544/j.cnki.jeg.2017.s1.055
作者姓名:孟华君  张向营  张春山  王鹏  李焕彬
作者单位:1.中国地质科学院地质力学研究所 北京 100081;;2.国土资源部新构造运动与地质灾害重点实验室 北京 100081;;3.中国地质大学 北京 100083
基金项目:国家自然科学基金(41502339),中国地质科学院基本科研业务专项经费(YYWF201523),中国地质调查局项目(DD20160267)资助
摘    要:银洞子泥石流沟是典型的地震区小流域泥石流沟,是汶川地震和震后强降雨共同作用的结果,从2009年雨季开始到2013年雨季结束共发生14次泥石流事件。研究银洞子沟泥石流的演化过程对进一步认识震区泥石流的长期活动性、危险性具有重要意义。本文通过现场调查、采样测试、历史泥石流事件资料分析,揭示了该泥石流沟的物源特征、激发条件的变化,计算了泥石流密度、流速等相关参数;最后依据现存物源动储量评估了该泥石流沟潜在危险性,提出了相应的防灾减灾对策,能够为地震区泥石流防灾减灾工作提供参考。结果表明:(1)震后初期,银洞子泥石流暴发频率达到3.5次年-1,泥石流容重1.5~1.6tm-3,说明银洞子沟是一条由地震活动触发的高频稀性泥石流沟。(2)经过震后7a的流水侵蚀,银洞子沟物源总量明显减少12.92104m3,但物源动储量减少不明显,导致泥石流危险性居高不下;物源中小于10mm的细颗粒含量由地震初期的27.04%衰减到了18.22%,说明该沟未来泥石流事件仍以稀性泥石流为主。(3)短历时强降雨是银洞子沟泥石流的主要激发方式,当雨量过程超过8h,银洞子泥石流沟的激发暴雨强度为11.53mmh-1时,泥石流危险性较高;在100年一遇暴雨条件下流速接近3.8ms-1,一次冲出量可达8.64104m3。目前该泥石流仍为高度危险性泥石流沟。

关 键 词:地震区  小流域  泥石流  特征  危险性分析
收稿时间:2017-05-31
修稿时间:2017-07-05

RISK ANALYSIS AND CHARACTERISTICS OF TYPICAL SMALL WATERSHED DEBRIS FLOW IN WENCHUAN EARTHQUAKE STRICKEN AREA
MENG Huajun, ZHANG Xiangying, ZHUANG Chunshan, WANG Peng, LI Huanbin. 2017: RISK ANALYSIS AND CHARACTERISTICS OF TYPICAL SMALL WATERSHED DEBRIS FLOW IN WENCHUAN EARTHQUAKE STRICKEN AREA. JOURNAL OF ENGINEERING GEOLOGY, 25(s1): 349-356. DOI: 10.13544/j.cnki.jeg.2017.s1.055
Authors:MENG Huajun  ZHANG Xiangying  ZHUANG Chunshan  WANG Peng  LI Huanbin
Affiliation:1.Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081;;2.Key Laboratory of Neotectonic Movement and Geohazard, Ministry of Land and Resources, Beijing 100081;;3.China University of Geosciences, Beijing 100083
Abstract:Yindongzi gully is a typical small watershed debris flow in earthquake stricken area where 14 debris flow events happened from 2009 rainy season beginning to the end of rainy season in 2013,which is the result of Wenchuan earthquake and subsequent heavy rainfall for several years. Therefore, it is very significantly to study the mechanism and procession of debris flow for understanding its long-term activities and riskness in earthquake disturbed area. The characteristics of material supplies and rainfall condition have been analyzed by filed investigation, experiment and collecting antecedent rainfall events reference, and calculating some parameters of debris flow, such as density, velocity, etc. Finally, the riskness of Yindongzi gully is analyzed according to the volume of material supplies presently and,providing some advices for debris flow prevention. The conclusion are that(1):After Wenchuan earthquake, Yindongzi debris flow is a frequently and diluted debris flow, and frequency is 3.5 times a year while density is 1.5~1.6tm-3.(2)During 7 years of water erosion the total volume of material supplies decreased from 35.93104m3 to 23.02104m3, and the percentage of fine particles that smaller than 10mm reduced from 27.04%to 18.22%,which indicate that Yindongzi debris flow events will be diluted debris flow type.(3)When rainfall duration more than 8 hours, the mean rainfall intensity will be 11.53mmh-1 that less than the average value of the whole Wenchuan earthquake striken area. Therefore, Yindongzi gully in high dangerous condition presently.
Keywords:Earthquake stricken area  Small watershed  Debris flow  Characteristic  Risk analysis
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