汶川震区“宽缓”与“窄陡”沟道型泥石流致灾机理研究

发布时间：2018-02-16 07:37

本文关键词： “宽缓”沟道型 “窄陡”沟道型泥石流危险性致灾机理 CFX数值模拟防治措施有效组合　出处：《西南交通大学》2016年博士论文　论文类型：学位论文

【摘要】：2008年“5.12”汶川特大地震极重影响区内的都(江堰)—汶(川)高速沿线两侧沟道,普遍存在“宽缓”和“窄陡”两种类型,“宽缓”沟道型往往具有沟道纵坡缓、平均宽度大、流域面积大的特点,而“窄陡”沟道型则刚好相反。受强烈地震作用,沟道内形成了大量的崩滑物源,在极端暴雨条件下,这两种沟道类型都极易在震区内形成大规模突发性泥石流灾害。一般情况下,“宽缓”沟道型泥石流因沟道“宽缓”适合人类工程活动(如修建水电站、安置工业及生活区等)、且沟口堆积扇通常有人类集中居住而备受人们重视,对“窄陡”沟道型泥石流则因地形陡峭、流域面积小、沟内人类工程活动少,对其开展研究及重视程度相对较低。论文结合四川省都汶高速沿线2013年“7.10”特大型群发性泥石流爆发情况,在对桃关沟、磨子沟、七盘沟、福堂沟等13条泥石流的发育特征及其危害性进行调查分析的基础上,重点以“宽缓”沟道型的桃关沟、“窄陡”沟道型的磨子沟泥石流为实例,针对这两类泥石流对沟口段都汶高速、岷江等造成的冲击淤埋及堵塞问题进行了系统研究。通过现场调查泥石流形成条件和发育特征,深入分析研究了不同类型沟道泥石流的致灾机理,并利用大型流体动力学计算软件CFX模拟再现50年一遇暴雨频率下这两种沟道类型典型泥石流的动力学过程,分析泥石流速度场分布及其对沿沟建筑物的影响,重点研究了泥石流对都汶高速桥梁段桥墩的冲击力及危害性,评价其对都汶高速桥梁的冲击作用、对岷江的堵塞程度,以及回水淹没两岸居民安置点的破坏性影响。论文还针对不同类型泥石流的沟道特点及致灾机理,进行了防治措施的有效组合研究,分类提出了泥石流防治工程措施建议。论文从两类泥石流的形成机理、危险性预测、动力学过程数值模拟、灾害链研究及治理工程有效性分析等方面进行了系统的研究,得到以下主要认识:(1)根据野外地质调查和资料收集,针对都汶高速沿线两侧不同沟道的地形地貌、流域面积、沟道宽度等条件,提出了 “宽缓”和“窄陡”型沟道泥石流的分类概念。通过对都汶高速沿线2013年“7.10”爆发的13条典型泥石流沟的各项参数的统计分析,提出“宽缓”和“窄陡”沟道型泥石流的定义及分类标准。(2)采用基于优化理论和最大熵原理的优化组合赋权法,建立了都汶高速沿线2013年“7.10”泥石流的危险度评价数学模型,对这13条泥石流沟进行危险性评价,评价结果与泥石流的现状及发展趋势相吻合。(3)以桃关沟为例,通过分析其物源条件、地形条件、降雨条件,对“宽缓”沟道型泥石流的致灾机理进行研究。结果表明,沟道内崩滑物源因洪水侧蚀直接参与补给,沟床物源因洪水或泥石流下切淘刷补给,而坡顶震裂物源在降雨作用下以溯源侵蚀参与泥石流活动已经成为地震灾区泥石流一种新的物源补给形式。(4)针对“窄陡”沟道型泥石流,以磨子沟为例,通过分析其物源条件、地形条件、降雨条件,研究该种类型泥石流灾害的致灾机理。结果表明,磨子沟“7.10”泥石流是大型崩塌堆积体在暴雨条件下的沟道堵塞溃决所致,放大效应和级联效应极为明显。(5)在两种沟道类型泥石流灾害的动力学过程研究中,采用CFX大型流体计算软件,模拟再现了 2013年“7.10”桃关沟、磨子沟泥石流的动力学过程、危险范围,利用数值模拟得到的流速、流量等动力学参数,计算出桃关沟泥石流对都汶高速桥梁段桥墩的冲击力,预测出磨子沟泥石流堵塞岷江的危险程度及堰塞坝溃决的回水淹没范围。(6)依据“宽缓”和“窄陡”沟道型泥石流的致灾机理及其危害性,在阐明泥石流常规治理工程措施类型及其适用性的基础上,以桃关沟和磨子沟为例,分别针对其沟道特点及治理目标,并结合已经实施的治理工程运行效果,分别提出了两种沟道类型泥石流沟的有效治理工程措施。
[Abstract]:2008 "5.12" Wenchuan earthquake affected area are very heavy (Jiang Yan) - Wen (Sichuan) high speed along both sides of the channel, widespread "relief" and "narrow" two types of "Leniency" channel often has a channel with gentle slope, the average width of large river basin the area is large, and the "narrow" channel type is just the opposite. Under strong earthquake, the channel in the formation of a large number of landslide source in extreme storm conditions, these two kinds of channel types are very easy to form a large burst of debris flow in the earthquake region. In general, "wide slow channel type debris flow channel for" relief "for human engineering activities (such as the construction of a hydropower station, for industrial and living area, etc.) and Mizoguchi accumulation fan usually has attracted more and more attention to human living, on the" narrow "channel type debris flow due to steep terrain, small catchment area, ditch human engineering Less activity, to carry out research and importance is relatively low. Combining with the Sichuan province Timor speed along the 2013 "7.10" large mass of debris flow in the outbreak, peach Guangou, Mozigou, seven disc groove, the basis of investigation and analysis of the development characteristics and hazards of Futang 13 debris flow ditch on the key to "lenient" channel type Guangou "Mozigou peach, narrow and steep gully type debris flow" as an example, for these two types of debris flow on Duwen Mizoguchi high-speed, makes a systematic research on the impact caused by the blockage and buried Minjiang. Formation conditions and development features through field investigation the debris flow, analyze the disaster mechanism of different types of debris flow gully, and calculation software CFX to simulate 50 years of a rainstorm frequency dynamics of the two channel types of typical debris flow process using the fluid dynamics analysis The debris flow velocity field distribution and its influence on the buildings along the ditch, focuses on the research of debris flow on the Timor high-speed bridge section pier impact and harm, to evaluate the impact of Duwen highway bridge, the blockage of Minjiang River, and the resettlement of residents on both sides of the backwater inundation destructive impact point. The paper also channel characteristics according to the different types of debris flow and damage mechanism, studied the effective combination of prevention and control measures, the classification proposed engineering measures of debris flow control. This paper from the two types of debris flow formation mechanism, risk prediction, numerical simulation of dynamics process, carried out a systematic study of disaster chain research and control engineering effectiveness analysis. Results are as follows: (1) according to the field geological survey and data collection, the Timor speed along both sides of different channel topography, drainage area, channel width, Put forward the "classification relief" and "narrow" type of debris flow gully. Through statistical analysis of the parameters of 13 typical debris flows on Duwen Expressway in 2013 "7.10" the outbreak of the proposed definition of "Leniency" and "narrow" channel type debris flow and classification (. 2) the optimal combination weighting method and optimization theory based on maximum entropy principle, established the Duwen high speed along the 2013 "7.10" debris flow risk assessment model for the risk assessment of the 13 debris flow, current situation and development trend of debris flow and the evaluation results coincide. (3) in Guangou peach for example, through the analysis of the source conditions, terrain conditions, rainfall conditions, to research the disaster mechanism of "Leniency" gully debris flow. The results show that the channel landslide source for flood lateral erosion directly involved in the supply of gully bed source due to flooding or mudslides Cut the scouring supplies, and shattered the source of slope under rainfall on debris flow activity has become involved in the headward erosion earthquake debris flow a new source form. (4) according to the "narrow" gully type debris flow, with Mozigou as an example, through the analysis of the source conditions, terrain conditions the rainfall conditions, disaster mechanism study of the types of debris flow. The results show that the Mozigou "7.10" is a large debris flow collapse accumulation trench under storm conditions blockage caused by burst, amplification and cascade effect is very obvious. (5) to study the dynamic process in two types of debris flow channel in using CFX numerical simulation software, simulated the 2013 "7.10" peach Guangou, dangerous range kinetics, Mozi gully debris flow, the velocity obtained by using numerical simulation, flow dynamics parameters, calculate the peach Guangou debris Flow impact on Timor high-speed bridge pier, predict the degree of risk and backwater weir dam outburst debris flow Mozigou Minjiang River blocked flooded area (6). On the basis of the "cause and hazard of disaster relief mechanism" and "narrow" gully type debris flow, debris flow based on expounding the conventional measures project types and their applicability, and with the peach Guangou Mozigou for example, respectively according to the channel characteristics and the goal of governance, governance and combined with the engineering operation effect has been implemented respectively, and put forward some effective governance engineering measures two channel type debris flow.

【学位授予单位】：西南交通大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P642.23

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