重建莫拉克台风引致台湾小林村堰塞湖坝体几何形状

<正>2009年8月莫拉克台风造成于台湾小林村献肚山大山崩,于旗山溪形成堰塞湖后在很短时间内发生溢顶破坏。该研究由航照图、灾前与溃坝后DTM、土壤物性试验与野外调查,根据崩塌与坝体堆积平衡,结合堰塞湖溢流时间,重建小林村天然坝地形与水文参数,并进行坝体稳定性分析。结果显示小林村堰塞湖天然坝主要由透水性低、易冲蚀的细颗粒组分组成,坝体积为15.34×10~6m~3,溢流点坝高及最大坝高分别为44m及60m,坝长与坝     

滑坡堰塞坝越顶溢流破坏的物理模型实验

滑坡堰塞坝作为结构松散的堆积物,随着上游水位的不断上涨,其稳定性不断降低,并存在突然溃坝的风险。以唐家山滑坡堰塞坝为研究对象,基于相似原理,开展符合坝体颗粒级配的室内水槽物理模型实验,模拟了不同坝后蓄水量、不同水位和不同颗粒物质组成条件下坝体渗流、漫顶破坏的整个过程。监测结果显示：堰塞坝漫顶溃坝主要分为渗流、漫顶、冲刷和溃决4个过程;坝体堆积颗粒级配越差,坝体允许渗流坡降越小;相同材料配比的坝体,上游水位相同时,坝体底部水平位移最大,且漫顶溃坝时溃口尺寸与蓄水量正相关。该研究结果揭示了堰塞坝漫顶破坏规律,可为堰塞坝溃坝防治提供理论参考。     

退役尾矿坝的环境安全问题分析

退役后的尾矿坝是否安全,主要决定于坝体和坝基的渗漏、坝体土的渗透变形和坝体的稳定性。本文主要从这三个方面出发,以东北地区754矿尾矿坝为例,对退役尾矿坝的环境安全问题进行了分析。结果表明,在对退役尾矿坝的环境安全问题进行分析时,渗流计算可不考虑正常情况下的渗流问题。鉴于尾矿坝与普通坝的不同,坝体稳定性分析的计算方案应增加地震叠加洪水时的情况,在对一些组成复杂含有夹层的土层进行参数分区时,应遵循"就粗"原则。     

南京江宁区某退役小型硫铁矿尾矿库的治理方法

针对江宁区某退役小型硫铁矿出现的不良地质现象,对该尾矿坝进行了抗滑以及抗渗稳定性计算和分析,指出坝体处于不稳定状态,并提出具体治理方法。治理的方案包括降低坝体高度减载,在坡脚处反压坝体增加坝体稳定性,设置排渗设施降低浸润线高度,修筑排水沟阻止地表水停留在库区表面。最后需验证治理后尾矿坝在地震作用下的稳定性,运用时程分析法对设计后的坝体进行了动力有限元的分析,结果表明坝体内部和整体处于较稳定的状态。     

坝后淤积条件下泥石流冲击拦挡坝动力响应研究

拦挡坝有效库容和泥石流冲击力是泥石流实体拦挡坝设计的重要指标,现有实体拦挡坝在泥石流反复冲击作用下淤积甚至填满,会对坝体调控能力产生重要影响.为此,基于理论分析和物理模型试验,开展坝后淤积条件下泥石流冲击实体拦挡坝动力响应研究,推导坝后淤积条件下泥石流速度衰减率、坝体拦挡率的无量纲计算公式,并建立考虑空间分布特性的坝后淤积条件下泥石流冲击力计算模型.结果表明：泥石流速度衰减率和坝体拦挡率与淤积体高度/淤积长度比值和泥石流相对容重呈正相关;泥石流冲击力静动荷载组合计算模型能较好反映坝后淤积条件下泥石流冲击力的组成和分布特征.上述研究可为泥石流实体拦挡坝工程设计提供理论及技术支持.     

陡坡水库大坝渗透稳定性及渗透变形分析

陡坡水库存在大坝质量差、坝体发育大量裂缝、背水坡出现散浸现象、坝后沼泽化并形成一上升泉以及排水渠和鱼池有絮状析出物、渗漏量增大等问题,这些异常现象都是由坝体及坝基渗流引起的。在阐述坝体和坝基地质、水文地质条件情况下,分析了大坝渗漏成因及大坝的渗透稳定性,指出坝体实际浸润线及坝体渗漏量是不正常的,特别是1987年后当库水位高于194 m,同一库水位呈上升趋势,这是反常的。坝基实际渗漏量异常,存在管涌和接触冲刷问题,尤其库水位低至 193.84 m,坝后上升泉仍有沙沸现象。上述现象表明大坝渗流是危险的,并分析了散浸、析出物、上升泉及沼泽化、坝肩及绕坝渗漏等现象的成因。     

水库土坝劈裂式灌浆施工技术

某水库主坝为均质土坝,劈裂灌浆施工前,坝体出现多条裂缝,坝坡及坝坡脚等多处渗漏水,坝土体渗透系数为6.41×10-4cm/s,坝体稳定性差。经采用劈裂灌浆施工后,其渗透系数降低至2.62×10-8cm/s,帷幕泥墙厚度及其连续性达到设计要求;坝坡及坝坡脚的渗漏水点已消除,坝体未出现新的裂缝,达到除险加固的目的。     

某尾矿坝扩容抗滑稳定性分析

用瑞典圆弧法对某尾矿坝的抗滑稳定性进行了计算分析,得到了不同坝体高程和不同运行情况下尾矿坝的抗滑稳定性安全系数。结果表明浸润线对坝体稳定性的影响很大,当浸润线位置较高,坝体趋于饱和状态时,坝体稳定性降低很多。同时根据抗滑稳定性的计算分析结果,对尾矿坝的治理提出了一些建议。     

龙都尾矿库地下渗流场的数值模拟分析

利用2D-FLOW计算软件,对龙都尾矿库在不同条件下的渗流进行了模拟计算。其中,初期坝按透水和堵塞两种情况,干滩面长度分100,200,300 m三种情况考虑;同时,首次考虑了大气降雨对尾矿坝渗流场的影响,分别计算了50,100,200 mm/d三种雨型。通过计算,获得了龙都尾矿库在不同条件下地下渗流的变化规律。从计算结果中发现,如果初期坝被堵塞,则坝体浸润线会抬高,与尾矿堆积坝坝面相交,并从坝面溢出,对坝体的稳定性产生不利影响;干滩面距离的长短对坝体浸润线有影响,但均不会与堆积坝坝面相交,不会从坝面溢出;大气降雨对坝体的渗流影响较大,从模拟计算中可以看出,大气降雨越大,浸润线抬升越高,对坝体的稳定越不利。     

上向弯曲双向槽孔排渗管技术在新厂沟尾矿库的应用

为了满足矿山生产需要,凉山矿业公司经过综合比较后,对即将达到原设计坝高的新厂沟尾矿库进行加高扩容改造,以延长尾矿库的服务年限。由于该尾矿库在使用过程中,坝体浸润线一直偏高,在堆积坝坡面上经常有水渗出,坝坡面出现沼泽化、局部坍塌等。现场勘察揭示坝体浸润线埋深较浅。因此,在实施加高扩容前,需要对坝体过高的浸润线进行治理。综合考量后,决定采用上向弯曲双向槽孔排渗管技术,分别在初期坝坝顶、第5级和第8级子坝处施工三排上向弯曲钻孔,孔内安置双向槽孔排渗管,实施坝体排渗加固。2009年底排渗工程竣工后,经过两年多时间的检验,经现场踏勘和坝体浸润线观测,结果表明,该项排渗工程效果显著,使该尾矿库能够满足加高扩容的要求。     

Gypsum-karst problems in constructing dams in the USA

Gypsum is a highly soluble rock and is dissolved readily to form caves, sinkholes, disappearing streams, and other karst features that typically are also present in limestones and dolomites. Gypsum karst is widespread in the USA and has caused problems at several sites where dams were built, or where dam construction was considered. Gypsum karst is present (at least locally) in most areas where gypsum crops out, or is less than 30–60 m below the land surface. These karst features can compromise on the ability of a dam to hold water in a reservoir, and can even cause collapse of a dam. Gypsum karst in the abutments or foundation of a dam can allow water to pass through, around, or under a dam, and solution channels can enlarge quickly, once water starts flowing through such a karst system. The common procedure for controlling gypsum karst beneath the dam is a deep cut-off trench, backfilled with impermeable material, or a close-spaced grout curtain that hopefully will fill all cavities. In Oklahoma, the proposed Upper Mangum Dam was abandoned before construction, because of extensive gypsum karst in the abutments and impoundment area. Catastrophic failure of the Quail Creek Dike in southwest Utah in 1989 was due to flow of water through an undetected karstified gypsum unit beneath the earth-fill embankment. The dike was rebuilt, at a cost of US $12 million, with construction of a cut-off trench 600 m long and 25 m deep. Other dams in the USA with severe gypsum-karst leakage problems in recent years are Horsetooth and Carter Lake Dams, in Colorado, and Anchor Dam, in Wyoming.     

库鲁克塔格地区巷古勒塔格组瘤状灰岩及其沉积环境

新疆库鲁克塔格地区巷古勒塔格组发育瘤状灰岩,是一种深水沉积序列.本区瘤状灰岩形成于台缘斜坡带,滑塌重力流改造原岩形态,并分为富泥型、过渡型及富灰型3种类型.富泥型瘤状灰岩沉积在CCD线之下,受深度海水溶解作用改造.过渡型瘤状灰岩形成在CCD附近,受海底底流和深度海水溶解的双重作用改造.富灰型瘤状灰岩形成在CCD之上,受周期性的重力流作用的改造和海底底流的溶解作用.岩性组合表明,早奥陶世库鲁克塔格地区处于迅速海侵阶段.     

数字化形变仪器环境改造方案实施

“九·五“期间 ,厦门地震台实施 95 - 0 1 - 0 2项目 ,安装DSQ水管倾斜仪、SS -Y伸缩仪、VS型垂直摆和DZW重力仪等四台套数字形变仪器。众所周知 ,台址与环境改造、仪器设备和良好的管理是获得优秀的观测成果不可缺少的三个重要因素。而良好的台址条件与环境改造又是三要素之首。在台址确定之后 ,环境改造必须科学地、精心地组织设计与施工 ,以使工程质量达到最佳效果。本文阐述的即是该项目设计、施工的做法与经验     

某磷石膏尾矿库堆积坝渗透稳定性分析

随着尾矿库堆积坝高度的增加,库内的地下水渗流场将发生改变,当尾矿堆积坝处的实际水力梯度大于临界水力梯度时,尾矿库堆积坝将产生渗透变形或失稳破坏。为了预测某已建磷石膏尾矿库堆积坝的渗透稳定性,本文运用地下水位计水位恢复试验去确定磷石膏尾矿渗透系数并计算水力梯度,同时采用Geo-studio软件中的SEEP/W模块分析磷石膏堆积坝在不同工况下的渗透稳定性。计算和分析结果表明当堆积坝处于945m堆积高程,在无干滩和100m干滩情况下,实际水力梯度分别为0.784和0.583;当堆积坝处于960m堆积高程,无干滩情况下,实际水力梯度为0.692,在以上两种情况下,堆积坝渗出点高程高于初始坝高程,堆积坝将出现流土变形,坝体处于不稳定状态。当堆积坝处于960m堆积高程100m干滩时,堆积坝上无渗出点,堆积坝处于稳定状态。分析研究结果对该尾矿库的安全运行和维护管理提供技术依据,同时为同类型尾矿库堆积坝渗透稳定性评价提供参考。     

小型土石坝加密抗液化离心机振动台试验研究

地震作用下土石坝液化易导致坝坡失稳滑移等严重后果,加密法是常用的抗液化手段之一。针对坝趾压重与坝壳翻压两种坝身加密加固方法,开展了离心机振动台试验,分析了不同加密型抗液化处理的小型土石坝坝坡地震响应规律。试验结果表明,由于高水头作用下坝坡底部土体软化,未处理坝坡加速度放大系数沿高程先减小后增大,而加密坝坡加速度放大系数沿高程逐渐增大,且坝坡表面处加速度存在表面放大现象。坝趾压重和坝壳翻压提高了坝身有效应力,降低地震产生的超静孔压比,有效防止土体液化。未处理坝坡在峰值加速度为0.24g地震作用下即发生坝趾液化现象,而加密坝坡在峰值加速度为0.24g和0.45g下均未发生液化。未处理坝坡整体侧向位移大,加密处理后,在峰值加速度为0.24g下坝坡整体表现为竖向位移。坝趾压重区坝趾水平位移明显减小,坝壳翻压区坡顶沉降减小了50%。试验结果验证了坝趾压重和坝壳翻压的抗液化效果,为小型土石坝抗震加固设计提供了参考。     

Effect of Construction Material on Dam Type Selection of the Büyük Karaçay Dam (Hatay, Turkey)

This paper covers the investigation of construction materials and selection of the dam type for the Büyük Karaçay Dam, which was planned to be constructed on Büyük Karaçay River 20 km to the SW of Hatay (Southern Turkey). The purposes of the dam are irrigation, domestic water supply, and producing energy. Auxiliary structures locations have been determined during the study of detailed geological maps of the dam axis and reservoir area. Quality, quantity and hauling distance of natural construction materials were effective to select different dam types. For engineering geological studies exploration boreholes were drilled at the dam site; pressuremeter tests were performed in order to determine bearing capacity and elasticity properties of rocks; pressured water tests were also performed to determine permeability of the dam site. Moreover, physical and mechanical properties of rocks were determined by the laboratory test. In the feasibility stage, the dam type was chosen as the central core rock-fill dam, depending on state of natural construction materials. In design stage dam type was changed as faced symmetrical hardfill dam. Finally, the dam type was revised again during the design stage as concrete face rockfill dam.     

Dam-break risk analysis of the Attabad landslide dam in Pakistan and emergency countermeasures

The Attabad landslide dam caused significant property losses and many human casualties in Pakistan, and also greatly affected the operation of the China-Pakistan Karakoram Highway (KKH). This paper discusses the risk of dam breach and hazards to the KKH project construction site following a dam breach. The paper examines the following three topics. (1) The geomorphologic dimensionless blockage index (DBI) and the analogy method were used to analyze the stability of the Attabad landslide dam. The long-term behaviors of landslide dams downstream of the Attabad landslide dam indicate that the risk of a dam breach exists, but the probability of a total dam failure is low. (2) The peak discharge of a potential breach of the Attabad landslide dam was calculated for scenarios in which 1/4, 1/3, 1/2, and total failure of the dam was breached. The potential breach discharge decreases with the downstream distance. (3) The potential impacts of the landslide dam breach on the KKH project construction site were analyzed. Based on the composition of the landslide dam, the probability of a 1/3 dam breach is high. To ensure the safety of downstream areas, disaster preparedness plans that correspond to the 1/2 dam breach scenario should be developed. Based on experience in addressing the landslide dam that was caused by the Wenchuan Earthquake, artificial controlled drainage measures are suggested and provide a technical reference for addressing the Attabad landslide dam and achieving recovery and normal operation of KKH.     

Changes to dam safety management in British Columbia triggered by failure of a small earth dam

The Testalinden earth dam in southern British Columbia failed in June 2010 and created a huge debris flow. Homes were destroyed and property was damaged. The failure of this small dam resulted in a comprehensive review of over 1000 dams in the province, evaluation of dam safety management practices, changes to the Water Act and improvements in how data on dams are collected, archived and communicated. The provincial dam inventory was re-evaluated to ensure that appropriate consequence classification, and therefore attention, is assigned to dams. Increased scrutiny was placed on dam owners to ensure they complied with dam safety policies and to ensure they submitted annual inspection reports and formal dam safety reviews in a timely manner. Dam owners and professionals engaged in dam safety activities have received new guidelines and better education and training.