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。     

秦山核电站邻近水域的流况分析

本文分析了秦山核电站邻近水域各测站的实测流、潮流和佘流分布及季节变化。结果表明:测区内潮流为非正规丰日浅海潮流,其运动形式呈往复流。核电站二期工程取水口附近(L_1,18站)为一大流速区,而一期工程出水口周围(L_2,L_2′站)有一相对小的流速区。大流速区落潮流历时大于涨潮流历时,而相对小流速区则相反;大流速区的余流较小,而小流速区的余流大。在四个季节中,涨潮流速秋季最大,春季次之,夏季最小;落潮流速秋季最大,夏季次之,春季最小。余流冬、秋两季较大。在实测流中以潮流为主,径流和季风的作用也相当显著。     

Hierarchically nested river landform sequences. Part 2: Bankfull channel morphodynamics governed by valley nesting structure

River corridors exhibit landforms nested within landforms repeatedly down spatial scales. In Pasternack et al. ( 2018 ), a new, scale‐independent, hierarchical river classification was developed that uses five landform types to map the domains of a single fluvial process – flow convergence routing – at each of three–five spatial scales. Given those methods, this study investigated the details of how flow convergence routing organizes nested landform sequences. The method involved analyzing landform abundance, sequencing, and hierarchical nesting along the 35 km gravel/cobble lower Yuba River in California. Independent testing of flow convergence routing found that hydraulic patterns at every flow matched the essential predictions from classification, substantiating the process–morphology link. River width and bed elevation sequences exhibit large, nonrandom, and linked oscillations structured to preferentially yield wide bars and constricted pools at base flow and bankfull flow. At a flow of 8.44 times bankfull, there is still an abundance of wide bar and constricted pool landforms, but larger topographic drivers also yield an abundance of nozzle and oversized landforms. The nested structure of flow convergence routing landforms reveals that base flow and bankfull landforms are nested together within specific floodprone valley landform types, and these landform types control channel morphodynamics during moderate to large floods. As a result, this study calls into question the prevailing theory that the bankfull channel of a gravel/cobble river is controlled by in‐channel, bankfull, and/or small flood flows. Such flows may initiate sediment transport, but they are too small to control landform organization in a gravel/cobble river with topographic complexity. Copyright © 2018 John Wiley & Sons, Ltd.     

北京门头沟区涧沟泥石流危险性调查评价

涧沟泥石流位于北京市门头沟区潭柘寺镇西北,本文分析了涧沟泥石流的基本特征和形成条件,预测了不同暴雨频率下的泥石流流量,结合泥石流的易发程度及可能造成的损失,评价了泥石流隐患的危险性,并提出了防治建议。     

Optimisation de la quantification des flux de matière en suspension d'un cours d'eau alpin : l'Isère à Grenoble (France)

This study seeks to determine suspended-matter flux of the Isère at Grenoble, one of the most important rivers of the northern French Alps. Since 1994, and especially 1996, systematic samplings of the left bank make it possible to follow in one point the variations of suspended particles and matter (SPM) of this river. But from a single measurement, sometimes not very representative of the whole observable concentrations within the section, it remains still difficult to estimate precisely the SPM flux. The results of this study show in particular the successive appearance of several turbidity gradients, whose occurrence is explained mainly by the hydrological and hydro-sedimentary dynamics of this river. The estimate of these gradients thus makes it possible to extrapolate specific measurements more easily and consequently to daily define the quantities of suspended matter exported by the Isère. Since 1996, the results show a very high flow, specific of the Isère at Grenoble, variable between 124 and more than 460 t km^?2 yr^?1. To cite this article: D. Dumas, C. R. Geoscience 336 (2004).     

青海涩北一号气田流动单元研究

以青海涩北一号气田为例,探讨了气藏储层流动单元研究方法。通过对各种储层参数分析,选择了自然电位相对幅度(ΔSP)、自然伽马相对幅度(ΔGR)作为流动单元划分参数,将研究目的层段储层划分为5类流动单元。其中Ⅰ、Ⅱ类流动单元储层物性最好,主要发育在高能滩坝相;Ⅲ类流动单元储层物性较好,主要分布中能滩坝相;Ⅳ类流动单元储层物性差,为低能滩坝相;Ⅴ类流动单元为泥岩层,其实质上为渗流屏障。通过综合分析,建立了研究区流动单元的分布模式,并分析了其对流体分布的控制作用。     

山地灾害研究的发展态势与任务

泥石流、滑坡等山地灾害已成为世界各国十分关注的自然灾害问题。据最近几年的国际学术会议,泥石流、滑坡研究的前沿领域是：泥石流、滑坡活动的地带性与全球气候变化的规律;泥石流、滑坡起动机理、动力学模型;泥石流、滑坡等山地灾害风险分析、发生时间预报;成灾机理与减灾防灾关键技术。国内研究较晚,但发展很快。经过近50 a的研究,涉及上述诸多研究颁域。但研究不深,还存在不少差距。据国内外研究态势,针对山地所实际,提出了在泥石流、滑坡理论创新和防治关键技术等研究方面12条任务。     

俯冲-增生型造山带增生楔流体研究进展

俯冲－增生型造山带弧前增生楔流体的特点为：盐度低、氯化物含量异常低，并含有丰富的CO2和CH4。流体以扩散式或沿断层带渠道式活动；泥火山、张裂隙充填脉、碳酸盐壳、深海生物群是流体活动的直接体现；流体活动影响着增生楔的内部结构和构造样式；增生楔中流体活动特征的研究对研究造山带的地质演化及矿床成因具有重要意义。     

高拱坝施工初-中期导流风险模型及应用

面向工程设计阶段,采用高拱坝施工动态仿真技术获取施工初-中期挡水度汛面貌数据,综合考虑水文、水力随机性因素,构建高拱坝施工初-中期导流风险模型,提出采用Monte Carlo方法耦合挡水度汛面貌数据和主要随机因素进行风险模型求解的方法。基于风险分析原理提出了导流洞设计的风险判别方法,给出导流洞尺寸设计优化的数学模型和具体步骤。通过金沙江上游某高拱坝工程案例分析的结果表明:所提风险模型及求解方法是适用的、有效的,该模型能够得到整个施工初-中期导流风险率,较为客观地反映高拱坝施工中期度汛可能存在的两种挡水情况,克服了初期导流风险模型的局限性;施工中期导流风险率随导流洞尺寸增大而减小,导流洞尺寸设计的可行方案集存在界限,即优化方案。研究成果可为高拱坝施工导流的风险决策和设计优化提供理论支撑。     

孔隙尺度多孔介质流体流动与溶质运移高性能模拟

深入探究孔隙尺度下的流体流动特性和溶质运移规律对石油开采、农田养分管理、地下水污染修复有着重要意义。以人工构建的多孔介质结构和同步辐射X射线显微CT扫描的土壤团聚体(分辨率3.7μm)为研究对象,在空间节点数多达64 000 000的情况下,基于格子Boltzmann模型和GPU并行技术计算得到多孔介质流体运动和溶质运移过程的关键参数,并据此探究多孔介质空间异质性对水力学特性的影响。通过对3组不同结构的多孔介质比较发现,结构复杂程度最高的土壤样品和不规则堆叠的圆球结构的渗透率在100 mD(即10^-13m^2)量级,远低于规则堆叠的圆球结构(>20 000 mD);土壤的迂曲度为1.40~1.60,明显高于规则堆叠的圆球结构。研究结果表明,渗透率大的样品具有较小的迂曲度,这与结构的空间异质性有较强的关系;土壤的渗透率和迂曲度呈现各向异性;在水力梯度一定的前提下,渗透率较大的样品,纵向弥散系数也较大;同时,结构的异质性也会影响溶质的穿透曲线。本研究提出的模拟方法可在土壤结构中进行高效的水流运动和溶质运移模拟,可用于土壤多孔介质在孔隙尺度下的水力学特性研究。