崂山龙潭水库坝址渗透试验分析

文章针对崂山龙潭水库坝址区采取工程地质钻探、压水试验等手段,查明了坝址区的工程水文地质特征,经过对不同位置3个钻孔12个试验段的压水试验结果分析得出,坝基渗透性等级属微透水—弱透水。     

青藏高原东缘水库绕坝基渗流化学溶蚀研究

研究了青藏高原东缘某大坝基础遭受渗流场与化学场破坏的过程。通过氯离子示踪、温度电导示踪以及人工示踪方法,确定混凝土防渗墙中存在缺陷,库水通过非全封闭式防渗墙绕坝基渗漏,渗水通过坝后区的反滤层排泄;酸溶解试验和X射线荧光分析证明,坝后区地表的白色颗粒物主要是CaCO_3;结合化学反应过程,确认析出物来自于防渗墙中的水泥,渗漏水中的CO_2与水泥中的Ca(OH)_2发生反应生成可溶性Ca(HCO_3)_2,然后被渗漏水带到地表,并在常温下分解形成CaCO_3。通过地表水中CO_2含量的测试分析发现,参与水岩反应的CO_2具有除大气降水之外的其他来源。结合地质构造推断来自深部碳库中的CO_2通过断裂带进入到了地下水与库水中,并参与了水岩反应,对大坝的侵蚀速度大幅度增加。研究表明深部CO_2进入地下水并参与渗流过程,对大坝及水工建筑物的化学侵蚀作用将大幅度增强。     

虚拟热源法研究坝基裂隙岩体渗漏通道

利用虚拟热源法研究坝基裂隙岩体中存在的集中渗漏通道。水库底部通常为低温水,而基岩温度随着深度的增加而升高,坝后温度异常区域可能存在库水渗漏。渗漏水与周围地层将进行热量的交换。低温的渗漏水从地层中吸收热量,而地层则释放出热量,根据能量守恒原理,这两个热量是相等的。将集中渗漏通道看作是一个虚拟线热源,通道以外地层温度的分布仅与渗漏带最外层的温度有关,与渗漏通道内部的温度分布无关,渗漏通道内部的温度是由水流带来的,其外部的温度是靠热传导进行。根据热传导及能量守恒理论,可以推导出温度在地层中的分布趋势,通过温度分布曲线可以确定渗漏范围,建立堤坝渗漏量的虚拟热源法模型;同时,对具体工程实例进行了定量计算。     

Controlling the Artesian Boreholes of the South Lincolnshire Limestone

This paper describes (i) a long-established, serious and growing problem in a part of the Anglian Region of the National Rivers Authority due to uncontrolled leakage of groundwater from old artesian boreholes ('wild bores') in the South Lincolnshire Limestone aquifer, and (ii) a remedial project recently undertaken by the Authority. The paper discusses (a) the nature of the problem and its implications for water resources, (b) the means employed to carry out the work, (c) environmental considerations, and (d) the results of the project.     

某水库大坝除险加固帷幕灌浆工程施工工艺

针对某水库大坝由于蓄水压力逐渐增大,出现渗漏而危及大坝安全的严重问题,分析研究和采取了科学有效的帷幕灌浆工艺方法,对水库大坝进行了除险加固,有效地解决了大坝渗漏问题,确保了水库大坝的安全。     

双塔水库大坝渗流反演分析与特征水位渗流计算研究

结合双塔水库大坝现场检查以及地质勘探情况,通过渗流观测资料分析对坝体渗漏成因进行了分析,通过Auto Bank软件建立平面典型断面有限元模型,通过参数渗流参数反演分析调整了本次计算的渗透系数,计算得到浸润线规律符合一般均质坝分布。并进行了特征水位下稳定渗流计算分析,计算结果表明心墙下游侧出逸点偏高,并未自心墙与坝基接触部位形成出逸,坝脚出逸处渗透坡降满足要求。     

冲击试验在堤坝渗漏通道探测中的应用研究

 利用冲击试验测量平面中某一点渗透系数的特点,第一次将冲击试验应用到堤坝渗漏通道的探测的工程应用之中。以岭澳水库工程为例,通过一系列冲击试验的测量,判断得到桩号0+275～295区间的坝段存在渗漏通道。运用温度示踪以及电导率探测的方法,分析得到渗漏通道的位置范围,与冲击试验测量结果基本一致。对0+275～295坝段区域进行灌浆处理以后,通过记录水库库水位及坝后量水堰流量变化,发现灌浆效果明显,证明冲击试验的测量结果的正确性。冲击试验在寻找渗漏通道以及对土石坝进行检修加固等方面有明显的实际工程意义和广阔的应用前景。     

Geological and geotechnical characteristics of Karameh dam site, north of the Dead Sea, Jordan

This paper describes a feasibility stage geotechnical evaluation carried out at the Karameh dam site. The 45 m high, 2,150 m long dam will be built across the Wadi Mallaha on Quaternary lacustrine deposits and store fresh water from the King Abdullah Canal. A confined highly saline aquifer was identified at a depth of 25 m, the saline groundwater migrating naturally through the Lisan Formation. Stability analysis of the foundation indicates that the slopes are just stable under dry conditions and may become unstable under wet conditions. The most important problem is the presence of the active main Jordan Valley Fault crossing both the dam body and reservoir. Electronic Publication     

The Effect of Borehole Sealing on the Southern Lincolnshire Limestone Catchment

The Southern Lincolnshire Limestone is an important groundwater resource; however, for many years water has been lost from the aquifer system through uncontrolled artesian flow from wild-bores in the Fenland area. During 1991–92, there was an extensive programme of sealing or controlling the wild-bores, and compensation flows for ecological and farming purposes were provided at some sites.
This paper describes a field study which was designed to identify the important features of part of the catchment; this was followed by the development of an existing groundwater model to provide an improved representation of the uncontrolled and controlled wild-bores. The model is used to assess the consequences of controlling or sealing the wild-bores.     

Evaluation of seismic hazard,local site effect,liquefaction potential,and dynamic performance of a world example of an embankment dam characterized by very complex and unique foundations conditions: Karameh dam in the Jordan Valley

The geologic structures associated with the site of a 55·10⁶ m³ Karameh embankment dam (under construction in Jordan Valley) and the tectonic effects on dam foundation and reservoir margins were reviewed. The regional seismicity and history of events were analyzed and a design earthquake was established. At Karameh dam site, the geotechnical conditions for the foundations formations (including liquefiable sands) and materials to be placed, the presence of the major Jordan Valley fault crossing the site, the hydrogeological conditions with salty artesian aquifers and soluble soils make this site a unique, very complex one at the limit of feasibility. The under construction Karameh dam is situated in the Dead Sea Rift (32.00°N, 35.50°E), the boundary between the Arabian and African-Sinai plates. The primary seismic source contributing to the hazard at the Karameh dam site is the active Jordan Valley fault which extends from the Dead Sea to the Sea of Galilee with an expected maximum earthquake magnitude of 7.8, and passes under the right abutment of the dam body. A probabilistic method is used to evaluate the seismic hazard at the dam site. The Peak Ground Acceleration (PGA) is selected as a measure of ground motion severity. Analysis is carried out for 50%, 90% and 95% probability that is not being exceeded in a life time of 50, 100, and 200 years. According to guidelines of ICOLD, PGA for a Maximum Design Earthquake (MDE) was 0.50 g and for an Operating Basis Earthquake (OBE) it was 0.17 g. Local site effect analysis was carried out using the computer code SHAKE (Schnabelet al., 1972). The performance of the dam under dynamic loading was analyzed. The factor of safety was evaluated for different cases of dam operation. Newmark sliding block on a plane method was used to evaluate the displacement of the dam body considering liquefaction potential. A PGA of 0.50 g associated with the MDE will trigger liquefaction of the sand layers existing in the dam foundation. Similarly, liquefaction may occur in the dam foundation layers in case of 7.8 magnitude earthquake which is expected to result in a crest settlement of 4.4 m. The event horizontal rupture displacement for an earthquake of this magnitude will be about 12 m. To safely resist large earthquake events, it is recommended to have the following safety measures for the design of the dam: (1) free board should be increase at least to 7.0 m instead of the 5.0 m of the final design; (2) the foundation of the dam should be stabilized against liquefaction hazard; and (3) the embankment internal zoning should be designed to accomodate damage resulting from earthquakes of intensity greater than the OBE event. Critical elements of the embakment regarding safety are the core, downstream fine filter, chimney drain and drainage blanket. The downstream critical filter zone had a horizontal width of 5.0 m, enhanced to 7.0 m in the vicinity of the main fault. Stability analysis indicated that embankment side slopes as flat as 1(V):8(H) were required.     

Characterization of transient groundwater flow through a high arch dam foundation during reservoir impounding

Even though a large number of large-scale arch dams with height larger than 200 m have been built in the world, the transient groundwater flow behaviors and the seepage control effects in the dam foundations under difficult geological conditions are rarely reported. This paper presents a case study on the transient groundwater flow behaviors in the rock foundation of Jinping I double-curvature arch dam, the world’s highest dam of this type to date that has been completed. Taking into account the geological settings at the site, an inverse modeling technique utilizing the time series measurements of both hydraulic head and discharge was adopted to back-calculate the permeability of the foundation rocks,which effectively improves the uniqueness and reliability of the inverse modeling results. The transient seepage flow in the dam foundation during the reservoir impounding was then modeled with a parabolic variational inequality(PVI) method. The distribution of pore water pressure, the amount of leakage, and the performance of the seepage control system in the dam foundation during the entire impounding process were finally illustrated with the numerical results.     

土石坝坝坡稳定分析浅议

土坝稳定分析的目的是保证土坝在自重、渗漏压力、孔隙压力和其他外荷载的作用下,具有足够的稳定,不致发生通过坝体或坝基接触面的整体剪切破坏。本文详细论述求解土石坝坝坡稳定过程,明确坝坡抗滑稳定求解的意义和目的。     

某水库大坝渗漏勘察实例分析

某重点工程的供水水库发生严重渗漏,经多种手段的勘察论证和分析,查明了渗漏部位、渗漏模式和渗漏强度,为工程堵漏提供了准确的地质依据,试验段的堵漏效果明显,为一次成功的水库渗漏勘察。     

灌浆技术在惠阳沙田水库防渗工程中的应用

根据惠阳沙田水库在工程投入使用后出现渗漏现象、防渗体系不完善、存在安全隐患的实际情况,介绍了灌浆技术的设计要点、施工控制方式和处理效果,解决了大坝多处渗漏和涌水的现象,以供参考。     

厦门坂头水库运行管理和调度探讨

厦门是个海岛型水资源十分短缺的城市,坂头水库是该市重要的水源之一,如何做好水库的运行调度,将直接影响到厦门市的经济发展。本文结合水库的管理现状,运用水情自动测报系统、洪水风险图、库容曲线率定和大坝鉴定结果四个科技手段,对水库运行调度管理进行了进一步的探讨,总结出一套科学的、系统的优化调度办法。     

碾压混凝土坝体析出物及其对材料耐久性的影响

碾压混凝土坝在材料、结构等方面均不同于普通混凝土坝,因而在坝体表面常出现较为复杂的析出物。本文以一座位于我国南方的碾压混凝土坝作为实例,从现场调查、试样测试、水质特征以及坝体结构等方面探讨了此类析出物的基本性状、形成机理以及对于坝体材料耐久性的影响。分析表明：(1)坝体析出物系坝体渗水对于坝体材料的物理一化学侵蚀作用所致;(2)不同颜色的析出物具有不同的主化学成分;(3)坝体的微结构(如孔、缝、隙等)特征决定了坝体内与形成析出物有关的组分的迁移方式。因而认为,在具较好连通性的缝、隙等部位,有关组分以相对集中的渗漏方式而迁移,由此形成的析出物对于坝体材料的耐久性具有较明显的不利影响。     

基于流固耦合模型分析库水位对尾矿坝的影响

尾矿库水位是影响坝体安全的重要因素之一,针对库水位变化对尾矿坝稳定性的影响问题,建立考虑超孔隙水压力作用下的流固耦合数学模型,利用有限差分程序FLAC3D进行数值求解.模拟了某尾矿库在不同库水位时的稳定性,得出库水位的升高对尾矿坝影响规律.即随着库水位的升高,尾矿坝浸润线升高,安全系数降低,尾矿坝坝体中部的剪应力逐渐增...     

生活垃圾填埋场应急库区工程方案设计研究

随着生态城市的建设对城市环境提出了新的挑战,环境问题与人们的生活密不可分,其中生活垃圾填埋问题不可忽视,现在许多旧的垃圾填埋场服务年限较长,因此填埋场应急库区的新建势在必行,我们以漳州某生活垃圾填埋场为实例,进行生活垃圾填埋场应急库区工程方案设计,根据现有地形地势以及库容的需要,合理设计坝体位置、高度及其他相关参数,防止渗滤液对地下水的污染,有效进行雨污分流,实现与现有填埋场的设计完美结合。     

浅谈小型水库除险加固处理技术的应用

阐述了渗漏严重的均质土坝除险加固工程中采取的防渗、防浪、既防渗又防浪的处理措施,对复合土工膜的应用进行了初步了解,指出对渗漏严重的均质土坝宜通过坝体和坝基防渗来保证大坝的渗流安全稳定,采用土工合成材料处理小型水库有推广价值。     

水库岩石坝基防渗设计

结合某水库存在大坝渗漏严重的病险隐患,通过工程特点的分析,研究了塑性混凝土防渗加固的设计理论和施工方法,对类似工程的补强加固有重要的借鉴作用。