弯曲河流斜槽裁弯模式与发育过程

结合遥感影像、野外调查和形态统计,深入分析斜槽裁弯现象,将其划分为切滩冲刷、串沟冲刷和主流顶冲3种模式。切滩模式发生于洪水期间主流水流动力轴线偏向凸滩后,形成漫流水流冲刷,极可能在边滩形成新的斜槽。切滩裁弯的形态统计表明,弯道曲率半径与平均河宽之比约2.92,分流角约54.8°。串沟模式是前期洪水漫过河湾内侧洪泛平原,漫滩水流冲刷形成若干串沟,后续洪水沿串沟继续冲刷,串沟逐步横向展宽和向下游侵蚀,直至形成新的河槽。主流顶冲模式是水流顶冲河湾内侧河岸,形成湾状缺口,后续洪水持续顶冲湾状缺口,直至上下游水流贯通,形成斜槽裁弯。     

Formation Mechanism and Sedimentary Pattern of Abandoned Channels

Accurately identifying and quantitatively describing abandoned channels in meandering rivers are of great significance for improving hydrocarbon recovery. By using modern deposition analogy, field outcrop analysis, a dense well spacing, core observations and a review of the literature, this paper studied the formation process and space–time amalgamation of abandoned channels in meandering river. The results reveal that formation mechanisms of abandoned channels include chute cutoff patterns(shoal-cutting, ditch-scouring and embayment-eroding patterns) and neck cutoff patterns. The chute cutoff pattern forms a gradually abandoned channel, while the neck cutoff pattern forms a suddenly abandoned channel. From upstream to downstream, the sedimentary pattern of the abandoned channel transforms from a chute cutoff pattern to a neck cutoff pattern, where the main controlling factors transition from the grain size and gradient to the flow and vegetation. An abandoned channel formed by a chute cutoff pattern consists mainly of siltstone, fine sandstone and thin gravel layers, which form a lithological-physical barrier. The abandoned channel formed by a neck cutoff pattern consists mainly of mudstone and argillaceous siltstone, forming a lithological barrier. Based on the amalgamation and structure of the reservoir architectural elements, the abandoned channel can be divided into three planar sedimentary patterns(crescent, semilune and horseshoe) for a single channel and five vertical sedimentary patterns for composite channels.     

钢管爆炸破坏的数值模拟分析与试验研究

在三峡工程二期下游围堰拆除爆破中,其难点问题为混凝土防渗墙的一次性爆破拆除成功。由于混凝土防渗墙内有预埋的灌浆钢管及固定钢管的保持架,这种结构在以往的围堰水下防渗墙爆破拆除工程中是没有先例的。如果混凝土防渗墙爆破拆除仅仅只将混凝土爆碎,而钢管不炸断、保持架不松散则会使爆渣的水下开挖无法进行,因此将混凝土预埋灌浆钢管炸断及保持架炸散是关系到二期下游围堰拆除爆破成败的关键问题。针对这一问题,利用ANSYS/LS-DYNA计算软件和现场试验,研究了不同装药结构、药包直径等因素对钢管爆炸破坏效果的影响,讨论了钢管爆炸炸断破坏形态与装药结构之间的关系,在此基础上确定钢管爆炸炸断破坏的合理爆破参数及装药结构形式。二期围堰爆破拆除结果表明研究成果是可靠的。     

越过截渗墙渗流自由面的求解

对于越过截渗墙的剖面二维含自由面的渗流,应用保角变换方法求解,通过引入速度矢端平面和应用Schwarz-Christoffel变换,推导出了物理平面Z(x,y)和复势平面ξ(Φ,Ψ)的映射关系式.主要的待求参数和积分常量有4个,提出了相应的联立求解关系式.算例表明所提出的求解方法是可行的.     

重金属作用下改性水泥系隔离墙化学相容性研究

水泥系隔离墙被广泛应用于工业污染场地修复工程,但其防渗性能有待改善,且在高浓度、毒理性重金属污染作用下的化学相容性有待研究。通过室内试验研究了不同粒化高炉矿渣（GGBS）掺量、膨润土掺量和固化剂总掺量对水泥系隔离墙的强度和渗透特性的影响;综合考虑成墙效果和成本,选出固化剂掺量为20%（水泥、粒化高炉矿渣和膨润土掺量分别为8%、8%和4%）作为改性水泥系竖向隔离墙的最优配比。通过柔性壁渗透试验研究了重金属锌、铅污染作用下改性水泥系隔离墙试样的化学相容性。结果表明,重金属溶液作用下试样防渗性能的下降由重金属种类、重金属浓度以及试样孔隙液pH值三者共同决定。重金属种类对防渗性能的不利影响为：硝酸锌-硝酸铅>硝酸锌>硝酸铅。锌、铅溶液作用下试样的渗透系数为自来水作用下渗透系数的1.49～10.10倍,且重金属溶液的浓度越高渗透系数越大。在满足防渗要求前提下,该配比墙体材料能阻挡50 mmol/L的硝酸锌污染液、100 mmol/L的硝酸铅污染液和10 mmol/L硝酸锌-硝酸铅污染液。     

根治黄河断流的基本途径

本文介绍了影响河流造福或致灾的因素,分析了黄河致灾的原因,指出了根治黄河断流的基本途径在于提高黄河的流域调节功能,对黄河进行综合治理     

Factors controlling landslide frequency–area distributions

A power-law relation for the frequency–area distribution (FAD) of medium and large landslides (e.g. tens to millions of square meters) has been observed by numerous authors. But the FAD of small landslides diverges from the power-law distribution, with a rollover point below which frequencies decrease for smaller landslides. Some studies conclude that this divergence is an artifact of unmapped small landslides due to lack of spatial or temporal resolution; others posit that it is caused by the change in the underlying failure process. An explanation for this dilemma is essential both to evaluate the factors controlling FADs of landslides and power-law scaling, which is a crucial factor regarding both landscape evolution and landslide hazard assessment. This study examines the FADs of 45 earthquake-induced landslide inventories from around the world in the context of the proposed explanations. We show that each inventory probably involves some combination of the proposed explanations, though not all explanations contribute to each case. We propose an alternative explanation to understand the reason for the divergence from a power-law. We suggest that the geometry of a landslide at the time of mapping reflects not just one single movement but many, including the propagation of numerous smaller landslides before and after the main failure. Because only the resulting combination of these landslides can be observed due to a lack of temporal resolution, many smaller landslides are not taken into account in the inventory. This reveals that the divergence from the power-law is not necessarily attributed to the incompleteness of an inventory. This conceptual model will need to be validated by ongoing observation and analysis. Also, we show that because of the subjectivity of mapping procedures, the total number of landslides and total landslide areas in inventories differ significantly, and therefore the shapes of FADs also differ considerably. © 2018 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.     

基于核磁共振双截止值的致密砂岩渗透率评价新方法

对比分析致密砂岩岩心在完全含水状态和束缚水状态下的核磁共振T₂谱,明确了致密砂岩孔隙中流体的赋存状态和渗流规律,指出常规核磁共振方法预测渗透率的局限性并提出核磁共振双截止值的概念.基于核磁共振双截止值,将储集空间细分为完全可动、完全束缚、部分可动等三部分,分析不同孔隙组分对渗透率的影响,并应用三组分法建立了核磁共振渗透率表征新模型.研究表明：致密砂岩渗透率与完全可动流体饱和度、部分可动流体T₂几何平均值、核磁孔隙度成正比,与完全束缚流体饱和度成反比.在此基础上,结合完全含水核磁共振T₂谱的二阶差分得到了双截止值的自适应确定方法,可以连续地计算储层双截止值.将该研究成果应用于生产实践,渗透率计算精度有较大的提高.     

隐伏铁矿床封闭不良钻孔井下止水技术及应用

苍绎铁矿带会宝岭铁矿床为大型隐伏沉积变质岩型铁矿床,矿山涌水量大、排水成本高,且对矿山安全生产构成了威胁。治水前,矿山正常涌水量约530m³/h,其中已探明的封闭不良钻孔涌水量163.5m³/h,占矿山涌水的重要组成部分。本文针对封闭不良钻孔的涌水量、水压、充水水源等特征进行分析,首次在深隐伏铁矿床中提出了孔底点注浆、分段泄压注浆、截水墙注浆止水3种井下注浆止水技术,建立了隐伏铁矿床封闭不良钻孔井下注浆止水体系,并取得了较好的止水效果,对类似矿山的封闭不良钻孔的止水工作具有重要指导意义。     

五甲渡裁弯工程主要效益与负面的影响

五甲渡裁弯工程是显著提高曹娥江中、下游河道行洪能力的防洪工程,也是浙江省迄今最大的河道裁弯工程。在简述五甲渡裁弯工程与曹娥江中、下游水文及河床演变主要特性的基础上,分析了该裁弯工程显著的防洪效益、节省标准塘建设巨大投资费用等的经济效益,并对由于裁弯使河道长度缩短而造成咸水上朔距离有所增加等负面的影响进行了介绍。