出渗对均匀大粒径泥沙附近水动力特性影响

为探讨出渗对均匀大粒径泥沙颗粒周围水流特性的影响,基于粒子图像测速技术（PIV）对出渗影响下的均匀大粒径泥沙颗粒群周围水流结构进行测量,并对不同出渗强度下颗粒群周围立面二维流场结构进行了分析。试验结果表明:出渗能够减小颗粒群周围原水流运动方向的流速,而增大垂直向上的流速,且两者均随着出渗强度的增强而对流速的影响愈加明显;根据实测数据,拟合出考虑出渗影响下的均匀大粒径泥沙周围纵向流速分布公式,相关性较好;出渗能增强颗粒群附近的紊动强度,加剧周围水体的能量耗散;随着出渗强度的增强,颗粒群周围的涡量值随之减小。     

水动力学条件对复氧过程的影响研究

通过水槽实验对紊动水体复氧规律进行了研究.将氧通量理论应用于紊动水体复氧过程的研究,得到了紊动水体表面传质系数.数值模拟研究了实验流场分布和紊动特性,得出了紊动水体表面传质系数与流速和紊动动能的关系式.不同工况的实验资料验证表明了紊动复氧理论的合理性和可靠性.     

坡面流层流区动力学特性

为完善坡面水流的基础理论研究,基于定床水槽试验,以甘油溶液为试验流体,采用超声波测量技术,进行了4种粗糙度、5种坡度和13种单宽流量条件下的组合试验,研究了坡面流层流区的动力学特性及滚波特征。研究结果表明:在雷诺数为8~160的范围内,流态指数在理论值0.33附近波动,且随粗糙度的增大呈现先增大后减小的变化趋势,在粗糙度为0.10 mm附近达到峰值;阻力系数受坡度和粗糙度影响显著,可较好地由坡度、粗糙度和雷诺数的关系式表示;随着雷诺数的增大,滚波波速和波峰均呈幂函数形式递增,滚波周期大小无明显变化;坡度的增大会使层流失稳临界单宽流量减小,粗糙度的增大会使临界弗劳德数的均值减小。     

Analytical solution for transient groundwater flow during slug test in vertical cutoff walls

An analysis method for transient groundwater flow during slug tests performed in vertical cutoff walls is presented. The analytical solution for evaluating hydraulic conductivity of vertical cutoff walls is derived by applying the method of images to the previously developed analytical solution that is exclusively applicable to an infinite aquifer. Two distinct boundary conditions are considered to account for the configuration of the vertical cutoff wall: the wall‐soil formation interfaces with or without the existence of filter cakes, that is, constant‐head boundary and no‐flux boundary conditions. A series of type curves is constructed from the analytical solution and compared with those of a partially penetrated well within an aquifer. The constant‐head boundary condition provides faster hydraulic head recovery than the aquifer case. On the other hand, the no‐flux boundary condition leads to a delayed hydraulic head recovery. The greater the shape factor and well offset from the center of the cutoff wall, and the smaller the width of the cutoff wall, the greater the effect of the boundary condition observed in the type curves. This result shows the significance of considering proper boundary conditions at the vertical cutoff wall in analyzing slug tests. Copyright © 2014 John Wiley & Sons, Ltd.     

新型开孔桥墩水动力特性的PIV试验

基于粒子图像测速技术（Particle Image Velocimetry,PIV）对新型开孔桥墩周围的水流结构进行试验研究。通过分析开孔桥墩中轴面（y/b=0）处的立面流场和桥墩周围不同水深位置处的平面流场,探究开孔桥墩周围水流动力结构。试验结果表明,矩形开孔桥墩周围水流呈明显的三维结构特点。在桥墩上设置方孔,能有效地抑制墩前部分下降流的形成、降低墩前壅水的高度和改善墩侧水流流态,同时明显改变墩后尾流结构。方孔所在水深位置处（z/h=0.45）,墩侧低速区最大相对宽度以及墩后尾流区最大相对宽度与相对孔宽比（w/b）呈二次曲线关系,且相关关系密切。近水面处（z/h=0.75）,w/b=0.5条件下墩后旋涡对的相对长度为无孔时的70%;相反,近床面处（z/h=0.15）旋涡对的相对长度略有增加,但旋涡对的相对宽度一直保持在1左右。     

On the maximum width of oil stringers under hydrodynamic flow conditions

An analysis is presented of the maximum thickness of a stationary buoyant oil-mass, trapped under an angled incline, when subjected to hydrodynamic, surface tension and buoyancy forces. For high water-flow speeds down the aquifer, with upward buoyancy forces dominantly combating hydrodynamic pressure, it is shown that the maximum oil thickness occurs at about 60% of the length of the oil stringer measured from the upward end. The length of the oil stringer then is roughly proportional to the square root of the oil-mass contained, as is the maximum thickness. For low water-flow speeds, in which buoyancy and surface tension are dominantly balanced (with only lesser contributions from hydrodynamic pressure), the oil length is effectively constant, whereas the maximum thickness grows proportionately to the 3/4 power of the contained oil mass at low oil masses, and proportionately to the oil mass at high mass values. As the water-flow velocity increases, the shaping of the oil stringer shifts from the small bubble form to the long oil stringer form. Analytic formulae are given to provide approximate methods from which to estimate oil and gas accumulations under more complex conditions.     

水文地质概念模型的水动力场研究方法——"流场分析法"

水文地质概念模型建立的正确与否是地下水资源评价计算的关键,水文地质概念模型的水动力场研究方法——“流场分析法”是以地下水动力学和水均衡原理为基础,通过对水头函数的时空分布特征分析,判断出地下水系统的结构和功能,据此,科学概化出地下水系统的水文地质概念模型,为地下水资源的正确评价计算奠定基础。     

An integration-based estimation approach for the determination of slug test parameters under various flow geometries

A simple parameter estimation procedure, designated as integration-based estimation (IBE), was introduced to determine the hydraulic properties of an aquifer using slug test models subjected to certain flow geometries such as radial and spherical flows. The basic idea behind the proposed IBE approach is to link an integration value at pre-defined normalized head levels for field data with that of a theoretical type curve. The IBE method removes the need for the implementation of the classical graphical matching process which would be ineffective to acquire aquifer parameters for non-ideal aquifer conditions. As the second aspect of this study, a new decision tool was suggested to determine the suitable slug test model to be utilized for the site data since diagnosing the flow character properly is of crucial importance for following a convenient analysis procedure. The estimation performance and limitation of the proposed IBE method were tested for several slug test scenarios including radial and spherical flow models with a number of synthetically generated data sets as well as a field application. Results reveal that the IBE together with the identification methodology not only is able to retrieve aquifer parameters as reliable as the existing techniques in the literature but also diagnoses the flow character precisely as demonstrated in this study.     

通风路基通风管管内空气流动特性研究

基于青藏高速公路试验工程的实测资料,利用数值模拟系统分析了通风路基通风管内的空气流动特性和变化规律.研究表明,当外界环境风速一定时,通风管内不同区域流动特征显著不同,表现为较为明显的三段性：在入口扰动区段,管内空气紊流强度最大;中部为完全湍流区,紊流强度最弱;出口射流影响区的紊流强度介于入口扰动区和完全湍流区之间.随着外界环境风速的增加,管内空气流速相对环境风速增加的量值随之增加,总体呈现非线性快速增加的趋势;入口扰动响应的长度和紊流强度增加最显著;尾部射流影响区由于受到空气流动惯性等因素影响,其长度以非线性加速减小,其空气运动轨迹的振动幅度以非线性加速提高.管内各区域空气流动特性的不同是造成通风管不同部位局部换热量差异的根本原因,这些流动特性的存在进一步叠加,或是导致通风管路基阴阳坡效应的重要因素之一.     

一维向上渗流作用下多层地基有效应力性状研究

研究了一维向上渗流作用下多层地基有效应力的计算问题,推导了有效应力的计算公式,讨论了有效应力性状。定义了渗流有效应力的概念。渗流作用下土层有效应力由两部分组成：一部分是自重有效应力,它由重力引起,体现了静水压力的影响;另一部分是渗透有效应力,由土层水头差产生,体现超静水压力的影响。一维向上渗流作用使土层的有效应力减小。一维向上渗流作用下多层地基有效应力沿土层厚度呈线性分布,在土层层面处发生转折。多层地基有效应力计算的关键是确定土层层面处的有效应力,而确定土层层面处的有效应力的关键是计算各土层的水头差。文后给出了实例计算。     

黏度时变性注浆材料流动特性与应用研究

浆液的流动性对于浆液的扩散与运移具有重要的影响。通过开展黏度时变性注浆材料流动性正交试验,并选择不同可泵时间黏度时变性浆液进行流动度测试,分析了水灰比、外掺剂对浆液流动性能的影响规律,揭示了黏度时变性浆液流动度时间变化特征,从外掺剂对浆液水化硬化影响基础上,对浆液的流动变化机制性进行了探讨,并以碎裂岩体注浆为例,研究浆液流动性在注浆中的应用。研究结果表明:对于浆液的流动度的影响,随着水灰比、助剂1~#、助剂2~#、助剂3~#量的增加,浆液的流动度增加,水灰比是影响流动度的最大的因素,其次为助剂2~#、助剂3~#、助剂1~#;对于浆液黏度的影响主次关系为助剂3~#、助剂1~#、水灰比、助剂2~#;浆液流动度的变化具有缓慢期、快速期、稳定期3阶段特征,浆液临近可泵时间时,浆液流动度变化具有显著的突变性。碎裂岩体注浆应用结果表明:运用浆液的黏度时变特性进行注浆,减少了普通水泥浆待凝、复灌所带来的工时延长,缩短了注浆时间,节省注浆材料。     

波浪环境下多孔射流水动力特性试验

为了研究波浪对多孔射流运动和稀释过程的影响,采用粒子图像测速（PIV）及激光诱导荧光（LIF）量测系统对波浪环境下多孔射流的速度场和浓度场进行了测量。结果表明:在波浪环境下多孔射流可分为3个区域,即初始区、过渡区和混合区。在初始区,各孔射流保持各自的射流特征,相互影响较小;在过渡区,各孔射流发生分叉,并在孔与孔之间相互叠加,形成若干个汇流点,平均速度和平均浓度的峰值从射流轴线位置向汇流点处偏移;在混合区,多孔射流相互融合,其平均速度和平均浓度呈现单一的“坦峰”分布,形式上表现为单孔射流的水动力特征。通过对比分析发现,波高和周期的增大以及射流初始速度的减小可使汇流点的位置向下偏移,多孔射流将更快地进入过渡区和混合区。     

水流交汇区污染物输移扩散特性

为分析水流交汇区污染物输移扩散规律,开展了交汇区污染物浓度分布规律的实验和数值模拟研究。建立了交汇区污染物扩散的水气两相流数学模型,并采用实验结果进行验证,对交汇区不同流量、动量和交汇角情况进行实验和数值模拟研究。结果表明:含高浓度污染物的支流汇入干流后,在交汇口下游支流侧形成较长的污染带,且支流与干流的交汇角和流量比(动量比)越小,污染带越狭长;在污染带范围内,污染物浓度梯度较大;污染物分布主要受随流输移和扩散的综合作用影响,其中在交汇区污染物的扩散作用明显。     

明渠恒定紊流的总流控制方程与能量损失特性

为进一步深化对明渠总流控制方程的认识,探究总流能量损失的构成与分布特点,通过理论分析,在黏性流体力学理论的框架下构建了描述明渠恒定紊流总体特性的总流积分模型与总流微分模型的控制方程,其模型参数能直接通过流动统计特征量在过流断面上的分布来获取,由此实现明渠流的流场特性描述与总流描述的统一,并得到了总流能量损失的显示表达式。同时指出,总流能量损失由黏性耗散与维持紊动两部分构成,在矩形明渠恒定均匀流紊流的分类能量损失构成中,壁面上以黏性耗散部分为主,维持紊动部分的能量损失密度随着离开壁面距离的增加而快速增加,且随着雷诺数的增大,其增加速度也越快。     

明渠恒定紊流的总流控制方程与能量损失特性

为进一步深化对明渠总流控制方程的认识,探究总流能量损失的构成与分布特点,通过理论分析,在黏性流体力学理论的框架下构建了描述明渠恒定紊流总体特性的总流积分模型与总流微分模型的控制方程,其模型参数能直接通过流动统计特征量在过流断面上的分布来获取,由此实现明渠流的流场特性描述与总流描述的统一,并得到了总流能量损失的显示表达式。同时指出,总流能量损失由黏性耗散与维持紊动两部分构成,在矩形明渠恒定均匀流紊流的分类能量损失构成中,壁面上以黏性耗散部分为主,维持紊动部分的能量损失密度随着离开壁面距离的增加而快速增加,且随着雷诺数的增大,其增加速度也越快。     

过水巷道中骨料起动力学机制及两相流耦合模拟

为研究动水巷道中骨料堆积状态与巷道倾角的内在关系,建立动水环境不同倾角巷道中骨料颗粒的起动判据,基于计算流体力学和离散元法建立描述骨料灌注过程的固液两相流耦合模型（CFD-DEM）,对5~10 mm、10~30 mm、30~50 mm骨料颗粒组在不同堆积厚度下的起动速度和水流携砂能力进行测试,并模拟各粒径颗粒组在不同倾角巷道中的静水休止角和动水运移规律。结果表明：起动速度在上山巷道、水平巷道、下山巷道依次减小,3种工况下骨料起动速度的平方之比值为：（tanΩcosθ+sinθ）：tanΩ：（tanΩcosθ-sinθ）;堆积体形态由流场与灌注能力的动态平衡状态所决定,当流场的携砂能力远小于灌注能力时接顶容易,反之接顶困难;巷道倾角对堆积体相对于水平线的休止角没有影响,在相同流速条件下骨料在下山巷道中堆积形态被“拉长”不易接顶,上山巷道中被“压缩”相对容易接顶;上山段截流可降低施工难度,截流位置确定后应根据巷道倾角实时调整灌注参数,下山巷道骨料粒径适当增加,上山相应减小,使堆积长度和高度同步“生长”实现快速截流。研究成果对截流工程选址和骨料灌注参数设定具有重要指导意义。     

基于HBP本构模型的泥石流动力过程SPH数值模拟

本构模型是描述泥石流流变特性的关键,也是决定其动力过程数值模拟准确性的核心问题之一。泥石流流体属多相混合物,现有的研究已证实其存在剪切增稠或剪切变稀的现象,传统基于Bingham及Cross线性本构关系的数值模型难以准确描述泥石流流变特性。文中探讨了Bingham模型在低剪应变率下的数值发散问题,在光滑粒子流体动力学（SPH）方法框架上建立了整合Herschel-Bulkley-Papanastasiou(HBP）本构关系的稀性泥石流动力过程三维数值模型。相比传统基于浅水波假设的二维数值模型,所述方法从三维尺度建立SPH形式下的泥石流浆体纳维?斯托克斯方程并进行数值求解,可获取泥石流速度场时空分布及堆积形态,同时采用HBP本构关系描述泥石流流变特性,能在确保数值收敛的前提下反映泥石流流体在塑性屈服过渡段及大变形状态下应力?应变的非线性变化。为验证提出方法的合理性,结合小型模型槽实验观测进行了对比,结果表明数值模拟与实测结果基本吻合。     

大渡河次级支流斯合沟泥石流特征研究

泥石流作为地质环境较差、的山区的主要自然灾害之一，对它的研究尤其是泥石流规律方面的研究已取得了较大的成绩。但是对于泥石流的研究思路却有待进一步发展和完善，这在很大程度上将对山区的工程建设有很重要的指导意义。论文从工程地质研究思路的角度出发，对位于大渡河支流官料河上某水电站下闸址区的斯合沟泥石流进行了研究。文中采用工程地质分析的方法对大渡河次级支流斯台沟泥石流的形成环境(地层岩性条件、构造条件、地貌条件、气象条件、植被发育及人类活动)、基本特征(泥石流沟的基本特征、泥石流的堆积特征)进行了系统的研究，提出了该泥石流的形成演化过程及其机制模型(初期是堰塞式沟谷型泥石流，后期逐渐转向汇聚式沟谷型泥石流)。并在此基础上对泥石流沟沿岸的岸坡稳定性(可能泥石流的物源)等进行了评价分析。将定性分析和定量分析相结合，对泥石流的活动趋势以及可能泥石流的体积(未来泥石流形成将主要是在面蚀和沟蚀作用下的坡面泥石流。泥石流规模较小，且由于沟谷中下游坡降的进一步减缓，形成的泥石流物质一般将沿途停积．实际进入官料河内的体积很小)做出了较为科学的评价预测。经过这样的系统分析对工程建设中的泥石流防治有着积极的指导意义。     

基于地貌扩散和水动力扩散的流域瞬时单位线研究

流域汇流是地貌扩散和水动力扩散共同作用的结果。用宽度函数描述地貌扩散,用河道响应函数描述水动力扩散,从而导出了流域地貌瞬时单位线的表达式。建立了长江三峡区间沿渡河流域的数字高程模型(DEM),由此自动生成了该流域水系,并提取了流域地貌瞬时单位线公式所需的地貌信息。23场洪水的检验结果表明:所建议的流域地貌瞬时单位线公式用于流域汇流计算具有较高的精度。     

Reconstructing hydrodynamic flow parameters of the 1700 tsunami at Cannon Beach, Oregon, USA

Coastal communities in the western United States face risks of inundation by distant tsunamis that propagate across the Pacific Ocean as well as local tsunamis produced by great (M_w?>?8) earthquakes on the Cascadia subduction zone. In 1964, the M_w 9.2 Alaska earthquake launched a Pacific-wide tsunami that flooded Cannon Beach, a small community (population 1640) in northwestern Oregon, causing over $230,000 in damages. However, since the giant 2004 Indian Ocean tsunami, the 2010 Chile tsunami and the recent 2011 Tohoku-Oki tsunami, renewed concern over potential impacts of a Cascadia tsunami on the western US has motivated closer examination of the local hazard. This study applies a simple sediment transport model to reconstruct the flow speed of the most recent Cascadia tsunami that flooded the region in 1700 using the thickness and grain size of sand layers deposited by the waves. Sedimentary properties of sand from the 1700 tsunami deposit provide model inputs. The sediment transport model calculates tsunami flow speed from the shear velocity required to suspend the quantity and grain size distribution of the observed sand layers. The model assumes a steady, spatially uniform tsunami flow and that sand settles out of suspension forming a deposit when the flow velocity decreases to zero. Using flow depths constrained by numerical tsunami simulations for Cannon Beach, the sediment transport model calculated flow speeds of 6.5?C7.6?m/s for sites within 0.6?km of the beach and higher flow speeds (~8.8?m/s) for sites 0.8?C1.2?km inland. Flow speed calculated for sites within 0.6?km of the beach compare well with maximum velocities estimated for the largest tsunami simulation. The higher flow speeds calculated for the two sites furthest landward contrast with much lower maximum velocities (<3.8?m/s) predicted by numerical simulations. Grain size distributions of sand layers from the most distal sites are inconsistent with deposition from sediment falling out of suspension. We infer that rapid deceleration in tsunami flow and convergences in sediment transport formed unusually thick deposits. Consequently, higher flow speeds calculated by the sediment model probably overestimate the actual wave speed at sites furthest inland.