高密度电阻率法在探测水坝隐患中的应用

与其它方法相比较，在进行水坝隐患探测时，只有地球物理方法能够实现快速、无损探测，为分析研究坝体渗漏的原因以及采取相应的治理措施提供依据。本文以江西某水库土质坝体的隐患探测为例，介绍了高密度电阻率法在坝体隐患探测中的实际应用。     

工程物探方法在探测坝体隐患中的应用

针对锦西化工集团皂化渣场存在的防渗大坝渗水现象,采用综合物探方法对坝体进行渗漏检测.检测工作选择充电法、高密度电阻率法和浅震反射波法,准确地圈定了坝体内部的渗漏部位.经防漏施工后有效地制止了坝体渗漏.由此证实工程物探方法是一种经济、高效的坝体渗漏检测手段.     

综合物探在水库渗漏探测中的应用

受右坝肩正断层F2的影响,某水库岩溶发育,一直存在渗漏问题,经多处防渗处理,问题依然存在且日趋严重。本文综合采用流场法、自然电场法、高密度电阻率法对该水库渗漏进行了探测。发现老隧洞封堵质量较差,存在渗漏问题,并导致其下游侧坝体集中渗漏和大面积散浸;大坝坝体中部存在从上游坝坡至下游渗漏通道,是坝体下游二级坝坡出现散浸的主要原因;大坝右岸低矮山体存在渗漏入口,并可能与下游山脚的泉水点相连通;大坝右坝肩F2断层带防渗性差,存在与下游断层露头集中渗漏点相通的渗漏通道。此次探测结果表明:综合物探法能较准确获得水库渗漏源、渗流通道等位置信息。     

浅论高密度电阻率法在工程勘测中的应用效果

以往在工程地质勘测中,电法勘探主要采用的是电测深法,而电测深法又存在测点密度不大、信息量小等缺点.对于某些探测物来说,存在着资料解释困难的现象.为了解决上述问题,我们引进了一种新方法-高密度电阻率法,经过近几年我们对不同探测物的勘探应用,认为高密度电阻率在工程地质勘察中,是一种简单易行,行之有效的方法.     

灰坝渗漏的地球物理探测方法

探讨了灰坝渗漏的探测方法、效果及其实施过程.在灰坝渗漏治理中,如何准确地测量浸润线和渗流在坝体内的分布及其与溢出点的关系,对分析灰坝的稳定性和确定加固处理方案至关重要.实践证明,自然电位、探地雷达和高密度电阻率方法可以确定坝前入水位置、坝体内的浸润状态和浸润线位置,是灰坝渗漏探测的有效方法.     

高密度电阻率法在丹江口水源区尾矿坝监测中的应用

以丹江口水源区某铁矿尾矿库为例,采用高密度电阻率法对尾矿库进行了拟三维探测,针对出现的疑似渗流通道开展了尾矿坝二维精细剖面探测,查明了4处尾矿坝结构薄弱区;同时,鉴于渗漏主要由地下水运移作用导致,在雨季前后对尾矿坝进行了三次监测研究,得到了坝体电性结构的动态响应,确定了1处疑似泄露点,验证了高密度电阻率法在尾矿坝监测应用中的可行性,为尾矿坝稳定性研究提供了一种技术手段。     

混凝土防渗墙在小仕阳水库中的应用

混凝土防渗墙是近年来应用广泛的一种地下连续式防渗措施,以山东省莒县小仕阳水库为实例,对混凝土防渗墙在水库除险加固工程中的应用进行分析讨论。通过对坝基除险加固前的渗漏情况和采用混凝土防渗墙成墙后的渗透系数进行对比,并采用高密度电法对成墙的连续性进行无损检测,通过渗透系数对比和高密度电法电阻率色谱图分析得出,混凝土防渗墙的使用能有效的解决水库坝基的渗漏问题。同时对混凝土防渗墙的更好应用进行了展望。     

高密度电阻率法在垃圾填埋场渗漏检测中的应用

为检测垃圾填埋场的渗漏污染问题,基于垃圾填埋场渗漏污染特征,对高密度电阻率法在垃圾填埋场渗漏污染检测中的应用进行了深入研究,提出了一套获取高分辨率检测结果的工作模式和技术方法。实例证明,高密度电阻率法对于检测垃圾填埋场渗漏是一种行之有效、值得推广的技术方法。     

基于电阻率成像技术的基坑渗漏探测方法

随着城市建设的不断发展和进步,地下工程规模越来越大,各种超大超深基坑不断出现,特别是在软土和地下水丰富、水位较高地区,由于基坑工程的渗漏问题导致的工程事故时有发生。基坑渗漏是基坑止水帷幕施工中常见的一种施工缺陷,所以预先对基坑围护体系的渗漏情况进行探测,若发现有渗漏区域在开挖之前及时进行处理与预防就显得尤为必要。这里阐述基坑围护体系发生渗漏时,基坑周围地下水流线的变化特征,流线向渗漏处聚集,渗流位置的水流线密集区域渗流阻力小,导致基坑周围土体的渗漏处电阻率变低。给出了基于电阻率成像技术,通过探测基坑周围土体在基坑降水前后的电阻率变化,进行基坑渗漏探测的方法,并通过两个工程实例说明该方法能探测出基坑渗漏三维位置,探测结果客观准确。     

三维高密度电法用于工程勘查的试验

国内三维高密度电法在工程上的应用,大都采用二维数据反演,通过三维成图软件把视电阻率剖面连成三维视电阻率分布立体图,而很少将三维数据拼接在一起,通过三维软件反演。结合管线探测,对真三维高密度电法进行了探测试验,并取得了良好的勘探效果,为三维高密度电阻率法的进一步推广提供了宝贵的实践经验。      

龙井水库大坝的渗流和稳定分析

本文以龙井水库大坝为例,运用有限单元法对粘土心墙坝的渗流进行分析计算,同时运用瑞典圆弧滑动法和简化Bishop法对粘土心墙坝的坝体稳定进行分析计算,在此基础上对水库大坝进行了渗流安全评价和稳定性安全评价。     

张家湾水库大坝的渗流和稳定分析

以张家湾水库大坝为例,运用有限单元法对除险加固后均质土坝的渗流进行分析计算,同时运用瑞典圆弧滑动法和简化Bishop法对均质土坝的坝体稳定进行分析计算,在此基础上对水库大坝进行了渗流安全评价和稳定安全评价.     

蓝洞水库大坝病险综合物探勘查

针对蓝洞水库均质大坝出现散渗等病险,根据区内各介质物理性质及地球物理特征,合理选择了高密度电阻率、探地雷达、瞬态瑞雷波和自然电场4种物探方法进行综合勘查,查明病险的水源来向,为评估坝体的稳定性和加固处理设计提供依据.     

高密度电法在水库坝基无损检测中的应用

某坝基为砂卵石基础,其下为强风化基岩,坝基渗漏和左右岸绕坝渗漏是该水库坝基存在的主要地质问题。为此,采取了塑性混凝土防渗墙与双排帷幕灌浆相结合的综合防渗措施。为了检测水库坝基及塑性混凝土防渗墙施工质量,防止水库正常蓄水后发生渗漏,选用了高密度电法进行无损检测。工程采用温纳施伦贝尔法观测,分别采用5m和10m电极间距,电极数60个,剖面数16。依据5m和10m道距实测视电阻率剖面与反演结果的解释,对水库坝基和防渗墙的工程质量进行了评价,认为-25m桩号塑性混凝土防渗墙可能存在渗漏问题,-80m桩号对应一低阻异常,坝体可能存在渗漏通道;其余部位未发现明显异常。     

Combined analysis of electrical resistivity and geotechnical SPT blow counts for the safety assessment of fill dam

Electrical resistivity survey and the geotechnical SPT blow counts (N value) method were simultaneously analyzed to investigate the stability of a center-core type earth-fill dam against the seepage phenomenon. The coupling of these heterogeneous field methods provided a chance to understand the status of underground material by comparing the geophysical and geotechnical view. The analysis shows that the zones with low resistivity value generally have low N value, which means low stiffness. However, some zones with a high resistivity pattern are not accompanied by an increase of its N value, and are even showing a lower N value. These results imply that one should be careful to directly correlate resistivity value with the real status of the core material of a fill dam. And a highly resistive zone may be in poor status due to the effect of increase of resistivity value as a result of the piping condition. Additional laboratory tests show that there is a deficiency of fine soil particles believed as the clay at the troubled region, which means an increase in resistivity value. Therefore, multiple explorations should be planned to reduce the uncertainty in application of geophysical methods to dam safety evaluation in order to compensate the resistivity information of core material.     

Dam break threshold value and risk probability assessment for an earth dam

In dam safety assessment, it is customary to focus on stability analysis, and the safety factor is regarded as an assessment index that cannot correctly reflect the effect of multi-factors and variable uncertainty. The factors that induce dam breaks are complex and uncertain; however, three primary ones can be identified: hydrological factors, seepage and bank slope instability. In this paper, the risk probability and the dam break threshold value for each factor individually, as well as coupled factors, are studied. The threshold value is acquired using the relationship formula between risk probability and dam type. The Dongwushi reservoir located in the Hebei province of China is taken as a case study. The results show that the dam break threshold values for hydrological factors, seepage and bank slope instability are 2.53, 2.02 and 2.69, respectively. The integrated dam break threshold value for the coupled factors is 1.25, which indicates that the dam is under serious stress according to the established risk assessment standard. The safety factor is calculated as 1.15 using the Bishop method, which indicates that the dam is under serious stress. The results obtained by the proposed method are consistent with those of the Bishop method. Finally, the proposed theory and method are introduced into a dam safety evaluation system (DSES) for convenient and efficient dam safety management.     

碾压混凝土重力坝全程综合仿真分析与安全评估

运用有限元方法对光照碾压混凝土重力坝进行施工期温度、渗流、应力应变的综合仿真分析,得出了温度场、渗流场及应力场的分布规律,在此基础上评价整个坝体与坝基系统稳定性的安全度,为坝体与坝基系统的温控、渗控和安全性评价提供参考依据。同时对光照碾压混凝土重力坝进行了不考虑温度、徐变、浇筑过程和蓄水过程的应力-应变和安全度计算,并对两种计算的结果进行了比较,结果表明：对碾压混凝土重力坝而言两者的位移相差最大,达70 mm;应力差别其次,达1.5 MPa;而整体稳定超载安全系数则没有本质区别。由于变形、应力和稳定安全系数在碾压混凝土重力坝设计中都是重要指标,所以综合仿真分析具有意义。     

Electrical resistivity imaging and dye tracer test for the estimation of water leakage paths from reservoir of Akdeğirmen Dam in Afyonkarahisar,Turkey

The seepage occurrence from the reservoir on the right bank of the Akde?irmen Dam located in Afyonkarahisar province in the Turkey has been investigated. When the reservoir began to fill with water, a large amount of water seepage occurred at the dam. The seepage developed at the base of the spillway and the right downstream slope of the dam. The various attempts have been made to reduce the seepage using grouting. Although the additional grouting operations was reduced the seepage at the base of the spillway, there has not been a reduction in seepage at the water outlet location at the downstream slope. Electrical resistivity measurements along the eight lines with the dipole–dipole array and dye tracer tests were performed in order to identify the seepage locations. The interpretation of electrical resistivity data showed the distribution of strata and the seepage zone along the right downstream of the dam. Groundwater flow rates calculated from dye tests indicated that there is an excessive seepage south-eastwardly on the downstream slope of the dam. Integrated interpretation of resistivity data and dye tests indicate that the seepage paths are in the direction from NW to E and SE.     

考虑饱和-非饱和渗流的土坡极限分析

给出了均质土坝的下游坝坡的安全系数的计算方法。均质土坝的下游坝坡有可能会通过滑裂面发生破坏。土坝中的土坡通常处于非饱和状态。非饱和土坡的安全系数计算需要考虑吸力对抗剪强度的贡献以及土坡中的非饱和渗流。给出处于饱和-非饱和渗流状态下的土坡的安全系数,有助于评价均质土坝的安全系数。下游坝坡的安全系数计算方法有：极限平衡法、上限解法和下限解法,该算法适用于非饱和土坡,且是在饱和土坡安全系数的计算方法上修正得到的。算例中非饱和土坡安全系数的计算考虑了吸力对抗剪强度的贡献。考虑非饱和渗流理论的土坡安全系数计算方法通常更加接近现场实际情况,并且对于同一坝坡,考虑非饱和渗流计算出的土坡安全系数要比饱和渗流理论计算出的安全系数大。