滑坡型泥石流形成机理

滑坡型泥石流是一种特殊的能量转换体运动类型。它是在很短时间内,由滑坡体的位能快速转化为动能的一次性滑动——流动堆积。滑坡型泥石流的活动是由块体在整个连续运动过程中发展的两个阶段(先滑坡,后泥石流)组成。滑坡型泥石流与一般的滑坡、泥石流不同,它兼具滑坡和泥石流的一些特征。滑坡型泥石流速度快,冲击力强,破坏性大。在理论上和国民经济影响方面有独特的研究意义。     

Disaster Reduction Decision Support System Against Debris Flows and Landslides Along Highway in Mountainous Area

Highways in mountainous areas are easy to be damaged by such natural disasters as debris flows and landslides and disaster reduction decision support system (DRDSS) is one of the important means to mitigate these disasters. Guided by the theories and technologies of debris flow and landslide reduction and supported by geographical information system (GIS), remote sensing and database techniques, a DRDSS against debris flow and landslide along highways in mountainous areas has been established on the basis of such principles as pertinence, systematicness, effectiveness, easy to use, open and expandability. The system consists of database, disaster analysis models and decisions on reduction of debris flows and landslides, mainly functioning to zone disaster dangerous degree, analyze debris flow activity,simulate debris flow deposition and diffusion, analyze landslide stability, select optimal highway renovation scheme and plan disaster prevention and control ergineering. This system has been applied successfully to the debris flow and landslide treatment works along Palongzangbu Section of Sichuan-Tibet Highway.     

6.16龙潭泥石流成因

６．１６松潘龙潭泥石流是一种典型的雨后饱和松散坡只物没坡堰塞泥石流。对该泥石流的形成条件、成灾情况及动力学、运动学特征进行了研究，提出了防治对策。     

基于野外监测的阿娘寨滑坡自愈合特征

滑坡在地震、降雨和坡脚开挖时会发生慢速滑动,部分滑坡直接失稳破坏,但是部分慢速滑坡会慢慢变得稳定,呈休眠状态。目前,滑坡恢复稳定的自愈合过程外在表现和内在机制还研究较少,尤其是坡脚侵蚀型慢速滑坡的自愈合特征研究。2020年6月17日,四川省丹巴县梅龙沟爆发的泥石流堵塞小金川,形成泥石流-堰塞湖-溃决洪水灾害链,且溃决洪水掏蚀坡脚,导致阿娘寨古滑坡复活。通过对阿娘寨滑坡应急监测数据发现,阿娘寨古滑坡初期存在大变形,但后期变形逐渐稳定,存在强度恢复的自愈合现象。另外,数据表明滑坡的两次突然启动和小金川流量增大侵蚀坡脚相关,和地震和降雨关系不大。通过现场监测数据分析,滑坡刚发生时变形速率高达118 mm/h,本文建立的预测模型表明,在没有外在触发因素条件下,滑体会在8月21日左右变形速率低至1 mm/h。本文以阿娘寨滑坡为例,分析滑坡的变形过程和自愈合特征,并基于野外监测数据建立自愈合过程预测模型,该方法对于科学评估滑坡稳定性,减小滑坡防治设计成本具有重要意义。     

新构造运动与城市减灾

指出了我国是新构造运动活跃的区域,新构造运动引发的活动断裂对城市密集建筑物构成了极大的潜在威胁,如何查明活动断裂、怎样有效避免活动断裂的这种危害是必须解决的课题·在分析新构造运动引发的活动断裂对城市之危害的基础上,论述了刚引入我国并被用来查明活动断裂的地质动力区划方法,然后,提出了城市楼寓、生命线系统的减灾措施·     

Onset of submarine debris flow deposition far from original giant landslide

Submarine landslides can generate sediment-laden flows whose scale is impressive. Individual flow deposits have been mapped that extend for 1,500 km offshore from northwest Africa. These are the longest run-out sediment density flow deposits yet documented on Earth. This contribution analyses one of these deposits, which contains ten times the mass of sediment transported annually by all of the world's rivers. Understanding how this type of submarine flow evolves is a significant problem, because they are extremely difficult to monitor directly. Previous work has shown how progressive disintegration of landslide blocks can generate debris flow, the deposit of which extends downslope from the original landslide. We provide evidence that submarine flows can produce giant debris flow deposits that start several hundred kilometres from the original landslide, encased within deposits of a more dilute flow type called turbidity current. Very little sediment was deposited across the intervening large expanse of sea floor, where the flow was locally very erosive. Sediment deposition was finally triggered by a remarkably small but abrupt decrease in sea-floor gradient from 0.05 degrees to 0.01 degrees. This debris flow was probably generated by flow transformation from the decelerating turbidity current. The alternative is that non-channelized debris flow left almost no trace of its passage across one hundred kilometres of flat (0.2 degrees to 0.05 degrees) sea floor. Our work shows that initially well-mixed and highly erosive submarine flows can produce extensive debris flow deposits beyond subtle slope breaks located far out in the deep ocean.     

白龙江流域全新世泥石流与环境演变的初步研究

根据黄土－古土壤沉积序列研究和野外考察资料并结合放射性＾１４Ｃ测年,初步确定嘉陵江上游白龙江流域全新世泥石流共分三期,时代分别为７０００－６０００ａＢＰ、４０００ａＢＰ和２０００ａＢＰ。研究表明,泥石流频繁爆发于古气候由寒冷向温暖转换的波动时期。     

耦合地貌信息熵和斜坡单元物质响应率的泥石流危险性分析

以粤西高州马贵镇为研究靶区,通过地貌信息熵法分析流域地貌发育演化阶段和泥石流沟谷危险性;提出流域单元物质响应率的概念,并结合遥感影像解译得到的松散物源分布,探讨泥石流沟谷的物源敏感性;在此基础上,将地貌信息熵值和流域单元物质响应率进行耦合,开展地形和物源复合作用下的泥石流危险性评价研究。研究结果表明：研究区子流域地貌信息熵值的变化范围为0.1398~0.8787,沟谷地貌演化从幼年期至老年期均有分布,60.57%的研究区面积处于幼年期—壮年期,泥石流沟谷比较活跃、危险性大;研究区子流域单元物质响应率变化范围为0~0.1716,53.46%的沟谷流域对物源较敏感,面积约为85.667 km2;基于地貌信息熵值和流域单元物质响应率耦合的泥石流危险性评价结果表明,43.87%的泥石流沟谷处于中等及以上危险区域,泥石流危险性较大。对比分析发现评价结果和实际情况较为吻合,评价结果合理,优于上述两种方法单独评价的结果。该成果可以为马贵河流域泥石流危险区规划和防灾减灾提供参考。     

丹巴县“6·17”阿娘寨村滑坡体特征及成因初步分析

2020年6月17日凌晨3点20分左右四川甘孜州丹巴县半扇门镇梅龙沟发生泥石流,阻断小金川河,形成堰塞湖,造成S303烂水湾段道路中断和阿娘寨村山体滑坡。通过现场勘查、无人机航拍和模型计算等方法,基于该区域地质环境和气象条件分析,揭示了阿娘寨滑坡体变形特征和成因,在此基础上预测滑坡发展趋势。研究结果表明:阿娘寨滑坡为土质滑坡,老滑坡体的复活与演变是内外动力综合作用的结果。频繁的地质构造活动破坏了岩土体稳定性,降雨和渗流降低了土体强度,泥石流冲刷淘蚀坡脚直接导致滑坡体启动。根据滑坡体变形特征,推测无重大地质构造活动和降水条件下,滑坡体会逐渐变形后渐趋于平衡。故汛期时应持续监测,及时预警,加强该地区防灾减灾措施。     

金沙江河谷——水系演化的崩滑外动力作用研究

在进一步研究金沙江河谷——水系发育的构造——气候机理基础上,认识到:山区深切河谷中普遍存在着大型堰塞现象:在青藏高原东南边缘地区,由于新构造运动强烈和地震频发及大暴雨等,在山高谷深的金沙江河谷中导致大型滑坡、崩塌或其他形式的外动力作用等,阻塞河谷水流,形成河谷堰塞湖,在堰塞体上游河谷形成静水沉积;在一定时间与条件下,堰塞坝溃决,在其下河谷中形成更大更急水流,加速河谷下切速率与深度,导致更大地形高差;新一轮新构造运动强烈和地震及大暴雨等,导致新一轮大型滑坡、崩塌等,形成新一轮河谷堰塞湖……如此多次重复,逐步加快与促进金沙江河谷——水系向现代形态演化,从而构成了金沙江河谷——水系演化的一种外力动力作用。这一认识对进一步研究山区深切河谷——水系形成与演化、工程建设选址评估和进行灾害防治等有普遍的参考价值与意义。