Seasonal factors controlling mineral precipitation in the acid mine drainage at Donghae coal mine, Korea

Monitoring over a 12 month period in the Sanae creek flow in acid mine drainage, Donghae coal mine area, demonstrates that the concentrations of dissolved metals and sulphate are highest during autumn when water flow in the creek is at its lowest. The highest pH values of the stream were measured in April and May, whereas the lowest pH was recorded in October. The Fe concentration of stream water rapidly decreased downstream due to the precipitation of Fe oxyhydroxide and/or oxyhydroxysulfate phases in the stream. Mineral precipitates in the creek in the Donghae mine area show various colours such as brownish yellow (Munsell colour 9.5 YR hues), reddish brown (Munsell colour 3.5 YR hues) and white depending on seasons and distance from the pollution source in the creek. Such phenomena are attributed to the variation in pH and chemical composition of stream water caused by seasonal factors. The measured pH ranges in stream water of the brownish yellow, white and reddish brown precipitates are pH 3.2-4.5, 4.5-6.0 and 5.3-6.9, respectively.     

李家峡大坝6号坝段坝基扬压力异常成因综合分析

针对李家峡大坝6号坝段坝基扬压力产生异常的现象,建立了该坝及坝基的三维渗流有限元模型。详细介绍了模型中防渗帷幕及坝基、坝体排水孔模拟的方法,并且利用人工神经网络反演了岩体的渗透系数张量,对坝基进行了渗流有限元分析,分析不同防渗、排水以及基岩地质条件下的坝基渗流场,评估了各种因素对坝基渗流场的影响,结合坝基钻孔取芯、水质分析等试验成果,分析了扬压力异常的物理成因。研究结果表明,引起扬压力异常的原因是防渗帷幕局部存在缺陷,且帷幕前浅部岩层存在强透水带。建议对右岸6号坝段坝基进行灌浆处理,以阻断渗漏通道,提高防渗帷幕的阻水效果,并加强对渗水的抽排工作,以有效地降低扬压力。     

小浪底缓倾角结构坝基的渗漏及示踪探测研究

小浪底水电站(以下简称小浪底)左岸具有缓倾角结构坝基，30^#排水洞中排水量偏大，防渗帷幕经补强加固后效果仍不明显，渗流十分复杂。从层状结构岩体的渗透性出发，应用现代示踪理论与方法，分析了小浪底左岸缓倾角结构坝基的渗透性，认为30^#排水洞中的排水存在不同的补给方式，排水洞北侧的排水量最大，库水通过切层裂隙贯穿相对隔水岩层T1^3-2。越流进入T1^3-1透水岩层，最后从排水洞排出，己形成了由裂隙网络组成的集中渗漏通道，并通过连通试验证实，30^#排水洞其他部位的排水量较小，由库水、尾水和黄河水经浅层渗漏补给。建议推广应用现代示踪理论与方法解决重大水工建筑物复杂的渗流问题。     

Performance of constructed evaporation ponds for disposal of smelter waste water: a case study at Portland Aluminum, Victoria, Australia

The construction of evaporative ponds and wetlands for the disposal of waste water high in ionic concentrations is a waste disposal strategy currently considered by many industries. However, the design, construction and management of these ponds and wetlands are not straightforward as complex chemical interactions result in both spatial and temporal changes in water quality. The effects of evaporation and drainage on the water quality in two constructed ponds, an adjacent man-made wetland and local groundwater at Portland Aluminium were investigated. The minimum volume of water entering the ponds during the study period was 0.96 +/- 0.16 ML per month. The predicted theoretical evaporative capacity of the two ponds was calculated to be 0.30 +/- 0.07 ML per month. More water enters the ponds than it is theoretically possible to evaporate under the ambient weather conditions at Portland, yet the ponds do not overflow, suggesting percolation through the pond lining. No spatial differences in solute concentrations (fluoride, sulphate, bicarbonate, carbonate, sodium, potassium, calcium, and magnesium ions) were found within the waters of either pond, although temporal differences were apparent. The results support the conclusion that the ponds are not impermeable, and that much of the waste water entering the ponds is being lost through seepage. The impacts on local groundwater chemistry of this seepage are addressed. Significant correlations exist between solute presence within and between the ponds. wetland and groundwater. Fluoride and sulphate concentrations were significantly higher in pond waters throughout the duration of the experiment. Pond sediments revealed a high degree of spatial and temporal heterogeneity in the concentration of all monitored ions resulting from the chemical heterogeneity of the material making up the pond linings. Adsorption isotherms for fluoride indicate that the adsorption capacity of the pond linings remains high for this ion. Implications for the management of waste water by this strategy are discussed.     

考虑注浆圈作用的体外排水隧道渗流场解析研究

体外排水方式在隧道工程中已得到逐步应用,但考虑注浆作用的体外排水隧道渗流场解析理论未见报道,导致理论滞后于工程实践。基于镜像法与渗流力学理论,提出了考虑注浆圈作用的体外排水隧道渗流场理论模型,通过解析退化、数值仿真两种方法共同验证了理论模型及解析公式的正确性,探讨了注浆圈渗透系数与厚度对涌水量、隧道外水压力的影响规律。分析结果表明：注浆圈渗透系数对体外排水隧道渗流场存在显著影响,随注浆渗透系数比值增大,涌水量可得到明显控制,但会引起外水压力的增长;注浆圈厚度影响相对较小,其影响主要在于厚度值越大时能一定程度上加强对底部结构外水压力的控制。提出了兼顾隧道限排要求与隧底水压力控制效果的合理注浆圈参数。研究成果以期为体外排水隧道注浆参数设计及施工实践提供参考。     

水下隧道渗流场解析解及其应用

 以复变函数和地下水水力学理论为基础,推导由围岩、注浆圈、衬砌混凝土组成的水下隧道渗流场解析解。以厦门海底隧道F4风化囊地段为工程背景,研究影响围岩、注浆圈、衬砌的渗流参数对衬砌外水压力和渗流量的影响。研究结果表明,注浆圈和初期支护施工效果对衬砌后水压力和渗流量的影响很大,应重视注浆圈和初期支护的施工。当排水系统堵塞,渗流量减小时,初期支护和二次衬砌的外水压力会重新分配。结合理论计算和现场实测水压力结果,提出在堵水限排情况下,初期支护水压力可降至静水压力的1/3。     

水布垭大岩淌滑坡非饱和渗流分析与渗控优化

根据水布垭大岩淌滑坡的地质条件，提出了水布垭滑坡渗流分析的模型。应用改进的饱和－非饱和渗流分析方法对水布垭滑坡渗流场进行数值模拟研究，得出了水布垭滑坡的地下水位因降和雾化雨而变化的规律。比较各种渗控措施的效果，提出了排水优化方案。     

金川水电站地下厂房裂隙围岩渗控效应数值模拟与评价

针对金川水电站工程区复杂的地质条件和渗控措施,分别建立基于排水孔等效模拟的坝基整体模型和基于密集排水孔"弃孔算法"精细模拟的左岸厂区子模型,采用Signorini型变分不等式和自适应罚函数相结合的稳定渗流分析方法对厂区围岩的长期渗控效应进行论证和敏感性分析。在数值模拟中,为了克服传统分析所采用的均质各向同性渗透系数不能反映裂隙岩体渗透特性的不足,首先根据两岸和坝基岩体优势裂隙组的空间展布情况,基于统计学方法初步确定其渗透系数张量并获得主值及主方向,再根据钻孔压水试验资料确定的等效渗透系数对其进行修正,并通过坝址区的地下水位反分析对该方法进行了验证。结果表明,运行期工况下防渗排水系统对山体地下水位具有控制作用,主变洞和发电机层底板处于自由面之上,厂房和调压室底板稍有承压性。帷幕的渗透特性、辅助排水孔幕以及排水孔间距对渗流场分布影响很小但能显著减小厂房洞室及排水廊道的渗漏量,因此应保证防渗帷幕的施工质量并建议设置辅助排水孔幕,建议中层廊道以下的排水孔间距设为3 m,中层廊道以上的排水孔间距放宽到4.5 m。     

Experimental study of water curtain performance for gas storage in an underground cavern

An artificial water curtain system is composed of a network of underground galleries and horizontal boreholes drilled from these galleries.Pre-grouting measures are introduced to keep the bedrock saturated all the time.This system is deployed over an artificial or natural underground cavern used for the storage of gas（or some other fluids） to prevent the gas from escaping through leakage paths in the rock mass.An experimental physical modeling system has been constructed to evaluate the performance of artificial water curtain systems under various conditions.These conditions include different spacings of caverns and cavern radii located below the natural groundwater level.The principles of the experiment,devices,design of the physical model,calculation of gas leakage,and evaluation of the critical gas pressure are presented in this paper.Experimental result shows that gas leakage is strongly affected by the spacing of water curtain boreholes,the critical gas pressure,and the number and proximity of storage caverns.The hydraulic connection between boreholes is observed to vary with depth or location,which suggests that the distribution of water-conducting joint sets along the boreholes is also variable.When designing the drainage system for a cavern,drainage holes should be orientated to maximize the frequency at which they encounter major joint sets and permeable intervals studying in order to maintain the seal on the cavern through water pressure.Our experimental results provide a significant contribution to the theoretical controls on water curtains,and they can be used to guide the design and construction of practical storage caverns.     

Sensitivity analysis of effective parameters on water curtain performance for crude oil storage in Iranian URC using the 2k factorial design and numerical modeling

Underground storage of hydrocarbons in unlined rock caverns (URC) has advantages over above-ground storage in terms of safety, environmental protection and economy. However seepage of products can cause many environmental and economical problems. Water curtain system is used as a part of hydrodynamic method to control seepage. Water curtains system is composed of a network of underground galleries and horizontal boreholes drilled from these galleries to establish groundwater pressure artificially. Iranian crude oil unlined storage caverns are to be excavated in Asmari limestone formation. This study aimed to clarify the effects of effective parameters on water curtains performance in the establishment of water pressure. To aim this purpose 2^k factorial statistical experimental design and numerical modeling using FLAC3D has been employed to evaluate the performance of artificial water curtain systems under various conditions include equivalent permeability and effective porosity of Asmari limestone, borehole pressure, borehole spacing and elevation, groundwater level and operation time of boreholes before the storage operation. The results showed that borehole pressure, permeability, borehole elevation and porosity have most significant effect in order of magnitude respectively. Regression model for 2^k factorial design was presented as well.     

基于几何测量法的裂隙岩体渗透性研究

基于某坝址区左岸灌浆平硐裂隙实测结果，建立了裂隙岩体渗透系数张量计算方法，并开发了渗透系数张量计算软件。运用该软件对某坝址区左岸灌浆平硐中裂隙的渗透性进行了计算，计算结果得到了现场的验证，故该软件可以作为压水试验反演分析的补充，可为岩体渗透性分区及防渗帷幕的优化提供科学依据。     

裂隙岩体基渗流分析

裂隙岩体坝基渗流分析成果是进行大坝工程设计的重要依据之一。采用非连续介质的裂隙网络渗流原理对裂隙岩体坝基进行渗流分析 ,计算工况包括设置灌浆帷幕和排水孔与否及其组合共四种情况。由计算结果可以看出 ,坝基总渗流量主要由灌浆帷幕的质量和帷幕区的渗透系数决定 ,坝基排水孔在排出渗水和降低渗透压力方面起到极其重要的作用。     

An investigation into efficient drainage layouts for the stabilization of tunnel faces in homogeneous ground

This paper investigates the effectiveness of various advance drainage schemes with respect to face stability. The latter is analysed through limit equilibrium computations taking account of the modified seepage flow conditions prevailing in the ground after the implementation of drainage measures. The seepage forces are determined numerically through steady-state, three-dimensional seepage flow analysis which takes account of the characteristics of a given drainage scheme. A suite of computations was carried out to quantify the effects of the geometric parameters for the drainage layout, i.e. the number, length, spacing and location of drainage boreholes or the diameter and location of the pilot tunnel used for drainage. The computational results provide useful indications about optimum drainage arrangement with regard to face stability. A dimensionless formulation of the required support pressure (or the required cohesion of the ground, respectively) is developed in order to produce dimensionless design nomograms, which can provide a quick assessment of face stability in cases involving partial or complete pore pressure relief in advance of excavation.     

三峡船闸高边坡裂隙岩体渗流监测成果分析

三峡船闸是三峡工程的主要工程之一。闸室区边坡高度一般为70～120m,最高约160m,地下水是影响岩体高边坡稳定的重要因素之一。介绍了船闸高边坡施工期地下水渗流监测的布置和实施情况,根据将近3 a的实际监测成果,分析了施工期船闸高边坡地表降雨、排水、水质、排水硐渗流渗压的变化规律和影响因素;监测成果分析认为,施工期船闸南北边坡地下水位均低于设计水位,与长江科学院计算成果基本一致,随着二期工程的实施,地下水位将随之缓慢降低,说明设计最后选定的渗控方案是基本合理的。     

基坑工程地下水渗流模型试验系统研究

设计了符合基坑工程条件的模型试验系统,可以模拟基坑地下水渗流。模型试验系统由土箱、排水箱、进水箱、上水箱、下水箱、测压装置等组成。通过给定进水箱与排水箱的水位可以实现基坑内外水头恒定,从而形成稳定的渗流。利用模型试验系统已经完成的试验为悬挂式截水帷幕基坑地下水渗流以及完整井条件下的层状含水层渗流,获得与实际工程相符的渗流流网形态,用来研究地下水渗流场的特征和规律。试验结果可指导实际工程设计,同时可用来修正基坑规程中地下水涌水量、坑外水位降深以及降水引起的沉降计算等。     

Application of seismic tomography for detecting potential seepage paths in Bakhtyari Dam, Iran

Bakhtyari Dam and Hydropower Plant Project is one of the largest hydroelectric projects in Iran. This dam is located in Lorestan, in southern Iran, on the Bakhtyari river, which is a headstream of the Dez River. Previous gallery surveying showed that some open joints were present in the abutments. These joints may act as a good conduit for seepage. Five galleries were used to carry out seismic tomography in the right and left abutments (GR1, GR2 and GR3, GL2–GL3, totally 765 m). The objective of the tomography was to detect these weak zones susceptible for seepage. Velocity images obtained by P-wave travel time tomography indicated that in the level of GR2 gallery upward there is a large zone of low velocity. But the rock mass quality seems better in the left abutment. In spite of unfavorable condition in R₂₃ block (GR2–GR3), the P-wave velocity between GR2 and GR1 galleries is in the range of undisturbed limestone. Despite the presence of these weak zones, the placement of the dam is where the rock mass quality is good, and the design of the grout curtain could help to bypass the reservoir water away from these seepage paths.     

海底隧道稳定性分析

本文采用有限元极限分析法分析了海底隧道的整体稳定性与存在局部破碎带下的整体稳定性。以某海底隧道为例,计算表明隧道整体是安全的。当存在局部破碎带时,必须做好破碎带的超前注浆堵水加固,以减少其渗水量,并对破碎带进行局部加固;计算还表明,有局部破碎带时,隧道安全度降低,破碎带越宽,堵水圈厚度越小,安全系数越小;隧道倾斜破碎带较垂直破碎带安全系数小。     

Tunnel waterproofing practices in China

Water ingress in transportation tunnels not only will shorten the durability of concrete lining and reduce the function of establishments in the tunnel, but also will worsen the tunnel surrounding so much that the traffic will be greatly affected. In this situation, therefore, high maintenance costs are compulsory. In many cases, a perfect appearance is strongly recommended to take measures in order to prevent leakage. However, in China, tunnel waterproof requirements and standards for various special uses are considerably different, such that the basis which engineers apply to design in water-control is insufficient. Especially in montanic region, unpleasant geological condition confines engineers in working out more reasonable methods to stop water seepage, even leakage. In this paper, the current waterproofing requirements and measures in different special tunnels adopted in China are reviewed. The limitations of the popular methods in several practical cases applied to prevent water leakage, such as watertight lining, drainage system, as well as grouting, are analyzed at length. Then, some available measures, regarding concrete lining, watertight layer, drainage establishments as well as casting watertight concrete, are proposed, which we think indispensable for tunnel engineering to efficiently control water seepage and even completely prevent water leakage. In the end, to analyze the seepage field in montanic tunnels, the finite element and boundary element coupling analysis method is presented. As an example, the seepage field in Zhenwushan tunnel of Chongqing is simulated. The calculation results coincide with the in-situ data well, and provide credible evidence for the waterproof measures which will be taken in that tunnel project. The method presented in this paper will save expenditures for surveying measures and will enable more reasonable and reliable waterproofing measures to be taken.     

高心墙堆石坝坝基廊道受力特性研究

在中国水资源最为丰富的西部地区,河床覆盖层厚达数十米甚至百米,一大批土石坝正在和将在这些大江大河上建设。坝体心墙与坝基防渗墙多采用廊道这种结构型式进行连接,廊道受力条件复杂,是工程成败的关键,但是有些已建工程却出现了廊道漏水的现象,廊道开裂和结构缝破坏成为亟待解决的问题。为了对廊道受力情况和开裂规律有一个清楚的认识,分析总结了几个工程廊道的监测资料,同时基于混凝土非线性本构理论,建立有限元模型对廊道进行了数值模拟。对监测结果和数值计算结果进行对比分析之后,探讨了廊道中的结构缝问题和廊道整体的受力规律,指明了廊道中需要重点关注的易开裂部位,为廊道合理配筋提供了指导,同时为类似工程的决策提供参考。     

水质模糊聚类及环境同位素在探测某堤基渗漏通道中的应用

利用环境同位素及地下水水质的分析 ,结合地质条件 ,对调查堤坝渗漏具有很重要的意义。在许多情况下 ,对孔或泉水的水化学和同位素成分分析可探测已存在的集中渗漏通道。文中以某堤段堤内管涌为例 ,以钻孔及江水水样的水质及同位素成分为研究对象 ,以模糊数学为工具 ,分析了堤后管涌的成因 ,对下一步采取工程措施具有科学的指导意义。