强降雨条件下某铅锌矿尾矿堆积坝安全稳定性分析

强降雨是影响尾矿坝安全的重要因素之一,同时尾矿堆积坝在建造的过程中随着选矿工艺的改变堆坝尾砂的粒径分布也随之变化。为了研究不同组构尾矿堆积坝在强降雨条件下的稳定性,以湖南某铅锌矿尾矿堆积坝为研究对象,在分析该尾砂坝各级堆积子坝的尾矿砂物理力学性质的基础上,采用数值模拟方法研究了该尾矿坝在强降雨作用下不同时期堆积子坝的稳定性。研究表明:1)不同高度堆积子坝的尾砂组构不同,其不均匀系数、曲率系数以及黏聚力不同,尾矿堆积坝的安全系数与尾砂黏聚力呈正相关关系,与尾砂的不均匀系数呈正比,与曲率系数呈反比;2)相同降雨强度,降雨时长的增加对尾矿堆积坝整体稳定性影响小,但对坝坡表面及一定深度的尾砂有影响,其负孔隙水压力减小,坝体松散,影响坝坡稳定;3)尾矿堆积坝各部位能承受的最大剪应变与尾砂的黏聚力呈正相关关系,且黏聚力大的坝体的最大剪应变在各个区域都较黏聚力小的坝体有较大剪应变。实际堆积坝施工过程中可通过尾砂组构来分析坝体在强降雨作用下的稳定性。     

饱和尾矿稳态特性研究

饱和尾矿的稳态强度和变形特性是尾矿坝能否发生流滑破坏的关键因素,通过试验充分了解尾矿的稳态特性是尾矿坝稳定性评价的重要内容。以江西九江某尾矿坝体的尾矿为对象,进行三轴固结不排水剪切试验,研究饱和尾矿的稳态特性。结果表明：饱和松散尾矿的三轴固结不排水剪切曲线具有明显的软化特性,曲线软化程度随围压的增大而减小,同一围压下孔隙比越小软化现象越不明显。根据试验结果建立尾矿的稳态线,论证了稳态是尾矿的固有属性,即稳态线具有唯一性。指出稳态内摩擦角是尾矿变形最终可动用的有效内摩擦角,并求出尾矿稳态内摩擦角。     

细粒含量对高应力尾砂不排水剪切强度特性的影响

通过三轴固结不排水试验,对饱和尾砂的剪切强度特性和颗粒破碎特性进行研究,讨论了试验中尾砂在不同细粒含量和围压条件下的应力-应变关系、孔隙水压力特性、应力路径和颗粒破碎程度。试验结果表明：在细粒含量小于15%时,高应力尾砂的剪切强度和软化程度随细粒含量的增大而减小。增加细粒含量使得孔隙水压力达到更高值,不同细粒含量时应力路径均属于完全软化-剪缩模式。颗粒破碎程度随着细粒含量的增大而减弱,且颗粒破碎程度与围压之间呈幂函数型增长关系。为此,建议在实际工程中尽可能采用粗颗粒尾砂筑坝,或采取其他工程措施,以提高尾矿坝体的稳定性。     

Stability analysis of a copper tailings dam via laboratory model tests: A Chinese case study

The upstream method is a popular method for raising tailings dams. Currently in China there are more than 12,000 tailings impoundments and almost 95% of them use the upstream method for the construction of the dam. Statistical data has shown that the tailings impoundment is one of the main sources of risk in the mining industry. Failures of tailings impoundments have resulted in the loss of many lives, considerable property damage, and irreversible pollution in downstream areas. Therefore, the safety of tailings management facilities has been of increasing concern to governments and local communities. The management of a conventional tailings storage facility requires the maintenance of a high level of structural stability. Therefore, according to the relevant mine Acts, the mine operators are required to conduct stability analyses for all types of tailings facilities, whether they are new, active, or decommissioned. For the stability analysis of tailings dams, the accurate profile of the tailings dam is very important. The profiles are easily obtained for both active and decommissioned tailings facilities because their data can be collected through field investigations. However, collecting basic data from newly constructed tailings facilities is difficult. In this paper, a laboratory physical model test has been performed. The construction process for new tailings impoundment has been physically simulated in the laboratory, where the tailings particle composition and distribution below a beach, the change of phreatic surface of the dam, and the engineering properties of the tailings of the dam profiles have been measured. A new tailings facility, Yangtianqin tailings impoundment, owned by Tongchang copper mine of Yuxi Mine Co., was used as a case study to illustrate the physical modeling of the tailings dam. In the model test, the geometrical model of pond area was constructed according to the scale factor, λ_L, of 1:200 (model:prototype), and the tailings discharge system was also established, the tailings slurry then being discharged based on the design data. Finally, on the basis of the model test results on profiles, the stability analysis of the tailings dam at different heights was conducted under different conditions. The model test results and stability analysis show that the height of the tailings dam should be less than that originally planned. The original design of Yangtianqing tailings impoundment should therefore be revised for the safety of the tailings impoundment.     

Effects of Nonhomogenity of Permeability on Tailings Dams

This paper has the objective of showing the influence of the permeability gradient during the construction of tailings dams, built by the upstream method, using the hydraulic fill technique. During the hydraulic disposition, two mechanisms affect the tailings permeability: the hydraulic segregation and the consolidation due the staged construction procedure. These mechanisms influence considerably the permeability distribution along the fill and, consequently, the behaviour of the dam. Results show that the pore pressure immediately after deposition may reach quite high values (532 kPa), but dissipates in a short period of time (1 to 10 days). Then, this effect should be taken into account in a short-term stability analysis of tailings dams. On the other hand, after pore pressure dissipation, there is a gain in the shear strength (13 %), which should also be considered, but in a long-term stability analysis of tailings dams.     

爆破作用下坝体浸润线变化对尾矿坝稳定性的影响

基于矿山采场爆破振动实测数据和实际运行尾矿库,建立爆破振动作用下浸润线对尾矿坝稳定性影响的有限元计算模型,通过设计尾矿坝体内不同浸润线高程和采场爆破振动强度,研究采场爆破振动对尾矿坝抗滑安全系数的影响。研究表明：尾矿坝体内浸润线位置对尾矿坝抗滑稳定系数影响十分显著,浸润线越高,抗滑稳定系数越低。对于浸润线水位正常的尾矿坝,爆破振动加速度在0~0333g时,尾矿坝抗滑稳定系数随着振动强度的增加而增加;当爆破振动强度大于0333g时,尾矿坝的抗滑稳定系数则呈现几乎直线下降。运用Matlab拟合函数公式得到了爆破振动加速度与尾矿坝抗滑稳定系数间关系式。对于浸润线过高造成的病库和危库,在爆破振动作用下,浸润线对尾矿坝抗滑稳定稳定系数的影响则更加显著,尾矿坝抗滑稳定系数呈近乎直线下降。     

尾矿坝渗流计算及排渗设计

渗流稳定是影响尾矿坝安全稳定的重要因素,浸润线位置的高低直接关系到尾矿坝安全稳定。以具体尾矿坝为例,根据现场钻孔实测资料,选取合适的计算参数和边界条件,建立合理的计算模型,对排渗设施正常运营和发生破坏两种情况下的尾矿坝渗流情况进行计算分析,得出初期坝的透水性与尾矿坝渗流稳定关系密切,一旦初期坝的防渗层淤堵,出口处的渗透性降低,坝体的整体浸润线升高,甚至有可能在坝坡处出渗。采用局部水平孔排渗的方案,可以有效地起到排渗的作用,降低坝体的浸润线,保证坝体的安全。     

洪水工况下某尾矿坝动力稳定性分析

对四川某高堆尾矿库地质勘查资料进行整理,合理概化了坝体主轴剖面,采用等效黏弹性模型,对处于洪水工况下的该尾矿坝用GeoStudio有限元软件进行数值模拟研究,研究了该尾矿坝在EI Centro地震波作用下的反应加速度、位移变化、液化范围、安全系数、动力稳定性的规律,研究结果显示该尾矿坝可在洪水工况下稳定运行,为其他尾矿坝的动力稳定性分析提供参考。     

尾矿坝浸润线的雷达探测技术

浸润线是影响尾矿坝安全稳定性的一个重要因素,因此有必要对其位置和分布进行探测。探地雷达作为一种物探设备与手段已经在水坝浸润线的探测工作中得到应用,本文将雷达探测技术引入到尾矿坝浸润线的探测中,从雷达探测机理、雷达正演分析和尾矿坝浸润线的物理特征上论证了该方法的适用性和可行性。文中解释了使用雷达探测浸润线的具体方法与过程,从正演和反演两方面分析了浸润线雷达探测图像的特点。在方法实证中对一具体的尾矿坝浸润线进行了探测,发现探测结果与钻孔检测的浸润线数据基本符合,这充分说明了雷达探测技术在尾矿坝浸润线探测工作中是适用和可靠的。     

Numerical Study of the Effects of Drainage Systems on Saturated/Unsaturated Seepage and Stability of Tailings Dams

The stability of tailings dams is affected by seepage characteristics such as the location of the phreatic surface inside the dam, the effects of the capillary fringe, and the unsaturated zone above the zero pore pressure level. In this study, the performance of drainage systems in tailings dams was investigated by analyzing saturated and unsaturated seepage in the dam, considering the effects of the construction method, tailings properties, and the type of drainage systems. First, general seepage characteristics in tailings dams were studied and the effects of non-homogeneity were investigated. Our results show that in a silty tailings dam with a height of 15 m, unsaturated plus capillary seepage flux can reach 13% of the total seepage. The total head vs. discharge volume curves under various conditions were compared and their practical implications are presented. Then, stability analyses were carried out using the results of seepage analyses for different construction methods, material properties, and drainage systems. Finally, a number of practical conclusions are drawn regarding dam stability and the efficiency of toe, blanket, and chimney drains in different construction methods. Using a blanket and/or a chimney drain can increase the stability safety factor by up to two times, depending on the type of material.     

土工合成材料层间摩擦试验研究

随着我国矿产资源的开发,尾矿的粒度越来越细,尾矿库的库容和尾矿坝的高度在不断的增加,尾矿库的安全与稳定日益成为广受关注的方向。近些年来,一些学者将土工织物、土工格栅等土工合成材料运用到尾矿库筑坝工程中以提高尾矿坝的稳定性,具有重大的意义。根据不同的应用形式,形成尾砂－土工合成材料、土工合成材料－土工合成材料的接触面。作者开展尾砂与土工织物、土工织物之间、土工织物与土工格栅之间界面摩擦特性直剪试验。试验结果表明土工织物与尾矿砂界面直剪剪切曲线为理想弹塑型。土工织物与尾矿砂界面强度指标粘聚力为38.3kpa,摩擦角为30.4°。土工织物之间的直剪剪切曲线为应变软化型。土工织物之间界面峰值强度指标粘聚力为0kpa,摩擦角为18.7°。土工织物与土工格栅直剪实验曲线在5mm剪切位移之前剪应力增长较快,此后剪应力上升平缓,三条应力应变曲线都在剪切位移达到35mm时产生突降。剪切位移35mm时,土工织物与土工格栅界面强度指标粘聚力为79.6kpa,摩擦角为21.6°。试验结果可以为类似坝体的稳定计算提供依据。     

强降雨洪水条件下尾矿库溃坝灾害影响研究

强降雨是导致尾矿库发生溃坝灾害的重要因素。为进一步探究强降雨洪水条件下尾矿库溃坝灾害影响,依托四川某尾矿库为研究对象,分析不同降雨频率条件下（200年、500年、1000年）的洪水暴发强度,并结合FLO-2D软件对强降雨条件下尾矿库溃坝影响进行了数值模拟。研究结果表明：溃坝量对尾矿库溃坝致灾程度有显著影响,溃坝砂流的灾害影响程度随溃坝量的增加而增大;溃坝尾砂流的最大淹没高度和峰值流速随溃坝量的增加而增大,下泄砂流的沿程淹没高度随尾砂运动距离的增加呈下降趋势;在地面高程变化幅度大的区域砂流的流速明显偏大,地面高程变化对砂流流速变化有较大影响。根据溃坝模拟结果,对强降雨条件下的溃坝尾砂流致灾影响程度进行了预估,为相关尾矿库溃坝灾害预测提供了参考。     

尾矿高坝的边坡稳定性研究

尾矿坝的安全运行是保证矿山生产正常运行的必要条件。针对江西某尾矿高坝,在现场调查的基础上,进行了现场勘察和取样工作,分析了尾矿沉积规律和坝体组成结构,开展了不同工况下的坝体稳定性研究,并探讨了坝体灾害的防治措施。研究结果表明,从坝区至库内,尾矿由粗变细的趋势非常明显;由上到下,由于采用中线法堆积,尾矿由粗变细的趋势不大明显;尾矿坝的沉积滩形态舒缓,其坡度较为平坦,且未见尾矿泥;尾矿坝处于正常运行工况和洪水运行工况时,计算的安全系数能满足规范要求,尾矿坝基本处于稳定状态;在尾矿坝处于全饱和工况和地震工况时,计算出的安全系数远低于规范规定的要求,坝体的稳定性也明显降低,使得坝体处于极不稳定状态。     

爆破振动对上游式尾矿坝安全的影响

通过实测某矿业公司采场爆破在尾矿库基础坝处的振动加速度,将实测爆破振动加速度信号进行变幅处理后加载到依据实际尾矿库建立的有限元模型中。通过改变爆破振动幅值强度,系统研究了爆破振动对尾矿坝稳定系数、尾矿坝内孔隙水压力以及剪切应力的影响。研究表明：爆破振动对尾矿库影响存在振动强度临界值,当爆破振动强度小于临界值时对尾矿坝安全是有益的,而大于临界值则是有害的。通过有限元计算,综合安全稳定系数、孔隙水压力和最大剪切应力的变化,得出尾矿坝基础坝处的爆破振动临界加速度为0.266g,对应的振动速度为13.6 cm/s。若考虑应留有3倍以上安全储备量,则安全允许振动加速度0.089g,振动速度为4.5 cm/s。这一爆破振动速度安全判据对于类似尾矿库也具有参考意义。     

某高尾矿坝考虑渗流作用下的抗震性能分析

渗流作用和地震作用是影响尾矿坝稳定的主要因素。以云南省某尾矿坝为研究背景,基于Geo-studio软件考虑初始渗流场的影响,研究尾矿坝渗流作用下的稳定性,以及地震作用下的动位移与加速度、液化区域与震时的关系、坝坡抗震稳定性、震后永久位移及地震作用下浸润线的变化。计算结果表明：尾矿坝在渗流-应力分析中处于稳定状态。在地震作用下,尾矿坝的水平位移沿着坝高向上不断增大,最大水平位移分布在堆积坝顶部。初期坝顶和堆积坝顶加速度放大倍数分别为1.67和1.87倍。液化区域主要分布于堆积坝浅层区域。尾矿坝震后永久变形量较小,不会发生整体滑塌,但震后浸润线位置较震前显著提高,考虑增设排渗措施防止发生渗流破坏。     

降雨条件下尾矿库稳定性计算分析

通过相关物理力学试验,分析了尾砂的物理力学性质,用Geo-Studio有限元软件计算和分析降雨条件下尾矿坝的浸润线。通过Slide软件,用极限平衡法中的简化Bishop法和瑞典法对降雨条件下尾矿坝的稳定性进行分析。结果表明,尾矿坝在现状高程下,其坝体在正常运行、洪水运行和饱和运行工况时计算的安全系数均能满足规范要求,计算得到的稳定性滑面大多是经过坝体最底部的深度滑弧面,且滑弧面范围较大。     

高震区某细粒尾矿坝动力时程抗震分析

为防止尾矿坝发生液化现象而危及整个尾矿坝的稳定性,以西南高地震区某细粒尾矿坝为例,从细粒尾砂的动剪切模量和阻尼比以及相关试验参数为基础、按照近似场地人工拟合地震波为动力输入荷载、以等效循环剪应力与抗液化剪力比较作为液化判别的依据、借助时程应力有限元法为手段,详细分析了高震区细粒尾矿库的液化区域以及时程动稳定性。分析结果表明:液化区域主要集中在库尾水位以下,并随着孔隙水压力的积累,液化区域逐渐向深部和堆积子坝方向发展;时程动稳定性系数与拟静力法相比,稳定性系数偏小,其中仅一条地震波作用与拟静力法计算的稳定性系数基本相当,从而亦说明动力时程法在分析高震区尾矿坝动稳定性时,较符合实际地震动力作用过程,并优于传统的拟静力法。     

基于QUAKE/W的尾矿库地震动力响应研究

为研究尾矿库地震动力响应，以我国广东某山谷型尾矿库为对象，运用GEO-studio软件中QUAKE/W模块，建立本构模型研究坝体在初始稳定状态和动力响应状态的变化情况并根据震后液化区判断坝体是否会发生液化，提出应对措施。结果表明：在库区地震设防烈度6度工况下，发生地震前后总应力、有效应力、剪应力没有明显变化；尾矿库不同位置孔隙水压力均有升高相对升高值与地震时间呈线性关系；液化出现在大坝坡脚处，应力集中，发生液化会对坝体稳定性产生很大影响。建议增强两侧坝基和坡脚的稳定性，为此尾矿坝安全运行增加保障。     

Effect of seepage control on stability of a tailings dam during its staged construction with a stepwise-coupled hydro-mechanical model

Seepage flow renders tailings dams vulnerable to failure during their staged construction. Draining is one of the most effective measures in improving dam stability. In this study, a stepwise-coupled hydro-mechanical model is employed to examine the effect of seepage control on the stability of a tailings dam during its staged construction. The settlement and deformation of the tailings under gravity load are modelled using the Duncan–Chang non-linear elastic E–B model, and the seepage flow through the tailings with drains is characterised by a variational inequality formulation of Signorini’s condition. The Kozeny–Carman equation is calibrated to illustrate the dependence of hydraulic conductivity on the porosity and volumetric deformation of the tailings. The proposed model was applied to assess the performance of the drains designed for the Luogou tailings disposal in Luanchuan County, Henan Province, China. Numerical results show that the stress-induced variation in tailings permeability could be of 1–2 orders of magnitude, and a proper design of the drainage system is of great importance in lowering the phreatic surface and protecting the tailings from seepage erosion.     

基于FLAC2D的毛细水作用下某尾矿坝静力稳定性分析*

尾矿坝的静力稳定性受到所处各方面环境因素的影响，毛细水作用也是其中一个重要因素之一，因此采用FLAC2D对该尾矿坝在考虑毛细水作用和不考虑毛细水作用两种情况进行数值模拟，分别绘制出两种情况下的X、Y方向位移云图，主应力变化云图、剪应变增量变化云图，并计算得到两种状况下的安全系数，发现在考虑毛细水作用时尾矿坝的静力稳定性会有所降低，安全系数也降低了3.5%，分析结果为指导尾矿库安全运行提供了科学依据。