云南保山金鸡剖面丁家寨组及其古水温问题的讨论

保山金鸡剖面丁家寨组下部含砾层的双层结构特征与不同的地质作用有关:下部砾岩层为滨海相砾岩;上部角砾状灰岩由碎屑流产生。所产遗迹化石指示滨海相环境。根据保山地区丁家寨组的颗粒成分、胶结物及地球化学特征,对丁家寨组冷温水成因的观点提出了质疑     

基于GIS的滑坡、泥石流灾害危险性区划关键问题研究

随着GIS技术的引入,滑坡、泥石流灾害危险性区划的效率和准确性得以大大提高。依据工程地质类比原则,在灾害学理论指导下,结合专家打分、层次分析、人工神经网络、信息量、Logistic回归、统计量等模型方法,以MAPGIS软件为平台,利用C++语言开发了滑坡、泥石流灾害危险性区划评价分析系统;并重点探讨了GIS支持下的滑坡、泥石流灾害危险性区划过程中的因子分析、模型选取、模型复合、单元划分、系统集成、结果评价等关键问题,建立了一整套基于GIS的滑坡、泥石流灾害评价方法体系。应用该系统对长江三峡库区和辽宁省鞍山市分别开展了滑坡、泥石流灾害危险性区划研究,取得了较好的效果。     

基于弯道超高计算泥石流流速的探讨

泥石流流速是难以实测和准确推算的重要参数。在分析既有各类弯道超高计算公式的基础上,探讨适用于各类泥石流的弯道超高计算模式,进而改进基于弯道超高的粘性泥石流、稀性泥石流和泥流的流速计算公式,用实例加以验证。     

北京市泥石流灾害临界雨量研究

降雨是泥石流灾害的主要诱发因素。文章根据北京市历史上泥石流灾害发生时的前期雨量与当日激发雨量,建立了临界雨量判别模型。通过对北京地区泥石流灾害与降雨频率的分析,计算了不同时段的临界雨量;经验证明,计算结果是可信的。基于灾害与降雨频率分析来确定北京地区泥石流发生的临界雨量是一种新的尝试。该方法可用于计算不同泥石流沟道发生泥石流的临界雨量。     

Experimental study of the woody debris trapping efficiency of a steel pipe,open sabo dam

In recent years, the damage caused to human settlements in Japan by large woody debris (LWD) has been increasing. For example, the 2013 Izu Oshima typhoon resulted in a large number of fatalities and missing persons, and the Kagoshima Typhoon Disaster and Northern Kyusyu torrential downpour caused vast infrastructure damage due to the associated LWD. Current countermeasures for preventing LWD are insufficient to maintain the safety of residential areas. One type of protective barrier, the open sabo dam, has been constructed in Japan during the past 30 years. The primary function of open sabo dams is to block the flow of boulders, thereby also reducing sediment flow by reducing the gap size. However, because Japanese open sabo dams are designed specifically for boulder-trapping, the ability of these dams to trap LWD remains uncertain. In particular, many problems have been reported with respect to sediment trapping by driftwood with roots in an open sabo dam setting. The objective of this study was to examine the trapping efficiency of open sabo dams for LWD and sediment. The experimental approach clarified the influence of driftwood, without and with roots, on sediment trapping for a straight-channel flume. The flexible roots of the driftwood were shown to have a significant effect on the sediment trapping efficiency of the dam.     

黄山第四纪泥砾沉积物分形结构特征与成因机制分析

黄山第四纪泥砾沉积物粒度组成的分维值介于２７０８～２７３５之间,非常接近古泥石流堆积物粒度组成的典型分维值２７５．结合沉积特征,表明该沉积物属第四纪间冰缘环境下的稀性泥石流沉积,其形成过程与季风型冰缘环境有关     

泥石流的结构两相流模型：I.理论

泥石流的运动既有类似于固液两相流之处,又在很程度上不同于固液两相流。在泥石流滨汉体模型,膨胀体模型,粘塑体模型及颗粒流模型研究的基础上,本文提出了一种新的模型－泥石流的“结构两相流模型”这种模具有以往各类模型的优点,同时又便于对不同类型的泥石流进行描述,在理论上,它比现行各类模型更加严密,在应用上,它较现行各类模式更加方便,能够适用于更加广泛的各类条件,泥石流的结构两相流模型中将现行模型的作为特例     

Large debris avalanches and associated eruptions in the Holocene eruptive history of Shiveluch Volcano, Kamchatka, Russia

 Shiveluch Volcano, located in the Central Kamchatka Depression, has experienced multiple flank failures during its lifetime, most recently in 1964. The overlapping deposits of at least 13 large Holocene debris avalanches cover an area of approximately 200 km² of the southern sector of the volcano. Deposits of two debris avalanches associated with flank extrusive domes are, in addition, located on its western slope. The maximum travel distance of individual Holocene avalanches exceeds 20 km, and their volumes reach ∼3 km³. The deposits of most avalanches typically have a hummocky surface, are poorly sorted and graded, and contain angular heterogeneous rock fragments of various sizes surrounded by coarse to fine matrix. The deposits differ in color, indicating different sources on the edifice. Tephrochronological and radiocarbon dating of the avalanches shows that the first large Holocene avalanches were emplaced approximately 4530–4350 BC. From ∼2490 BC at least 13 avalanches occurred after intervals of 30–900 years. Six large avalanches were emplaced between 120 and 970 AD, with recurrence intervals of 30–340 years. All the debris avalanches were followed by eruptions that produced various types of pyroclastic deposits. Features of some surge deposits suggest that they might have originated as a result of directed blasts triggered by rockslides. Most avalanche deposits are composed of fresh andesitic rocks of extrusive domes, so the avalanches might have resulted from the high magma supply rate and the repetitive formation of the domes. No trace of the 1854 summit failure mentioned in historical records has been found beyond 8 km from the crater; perhaps witnesses exaggerated or misinterpreted the events. Received: 18 August 1997 / Accepted: 19 December 1997     

The influence of organic debris on channel morphology and bedload transport in a New Zealand forest stream

The behaviour and form of, and bedload sediment transport through, a 3.5 m wide forest stream have been monitored for nearly three years. Bedload transport is highly episodic and spatially variable, and is controlled less by water discharge than by sediment availability. Organic debris in the channel creates temporary base levels and sites at which coarse sediment may remain stored for long periods; collapse or disruption of log and debris jams makes sediment available for transport in only a small proportion of the runoff events that are actually competent to move the material. Even then, sediment travels only a short distance before being redeposited, frequently behind debris accumulations further downstream. Rates of sediment transport during a given runoff event can vary markedly over short distances along the stream, again depending on whether sediment was made available for transport by log jam collapse upstream. Organic debris is therefore a major constraint on the application of physical laws and theories to explaining sediment movement in, and the morphology of, this stream.