弃渣场边坡稳定性特征分析

针对弃渣场边坡容易发生细沟侵蚀的问题,采集弃渣场坡面不同坡位的弃渣样品,对弃渣容重、含水量、饱和导水率、饱和含水量、砂粒含量、碎石含量等物理指标进行测定;与此同时,还对各点的样品进行直剪试验,并以此对弃渣场边坡稳定性特征进行分析。结果表明:新形成弃渣场坡面由上而下,其土体内摩擦角ψ逐渐增大,而土体粘滞系数C的变化与弃渣场坡面形成过程关系密切,一般而言,坡面的上部和下部粘滞系数C较小,说明弃渣场坡面上部土体的稳定性较中下部弱;对土体其他物理性质指标与土体的内摩擦角ψ、粘滞系数C进行相关性分析,结果显示内摩擦角ψ与>0.075 mm细粒含量的相关系数为-0.427*,粘滞系数C与饱和导水率的相关系数为0.514**,表明饱和导水率和细粒物质含量对于弃渣场坡面土体稳定性具有重要影响。     

生产建设项目水土保持方案弃渣场截水沟设计探讨

生产建设项目水土保持方案编制弃渣场是重点,弃渣场水土保持措施体系中截水沟设计是不可忽略的一项重要措施。弃渣场截水沟布设,主要是防止上游坡面或沟道来水冲刷、损毁弃渣场渣面、渣坡,保证弃渣场稳定。截水沟设计需要更规范、更准确,在此基础上,以坡地型(含平地型)和沟道型两种典型弃渣场为对象,对截水沟设计等内容进行研究探讨。     

水电站建设项目弃渣场岩土侵蚀研究

弃渣场是水电站建设项目水土流失最敏感的部位之一,弃渣堆积过程破环了原有岩土结构、地形和植被,且堆积坡度大,稳定性差,岩土侵蚀程度剧烈,岩土侵蚀类型多样。以金沙江上游金安桥大型水电站工程弃渣场为例,通过定位观测和调查,对其土壤侵蚀形式及成因进行了分析,测算了弃渣场不同部位的土壤侵蚀模数。结果显示,弃渣场不同部位存在溅蚀、面蚀、沟蚀、沉陷、陷穴、岩土泻溜、滑塌、滑坡等侵蚀形式;弃渣场不同部位无截排水措施的开挖边坡细沟侵蚀带、弃渣堆积平台和运渣道路不均匀面蚀带、有截排水措施和无截排水措施的弃渣堆积边坡水力-重力侵蚀带,其岩土侵蚀模数是原地貌平均侵蚀模数的73、124、186和887倍,而修建截排水措施后弃渣堆积坡面的侵蚀模数是无措施的弃渣堆积坡面的1/7.2倍。     

不同植被恢复年限弃渣场边坡土壤物理性质特征

研究不同植被恢复年限弃渣场土壤侵蚀物理性质特征,可为生产建设项目弃渣场水土流失防治及植被恢复提供理论基础。本文以重庆市典型弃渣场为研究对象,采用野外调查及室内综合分析等方法研究不同恢复年限弃渣场的边坡不同部位土壤物理性质特征。结果表明:不同恢复年限弃渣的细小颗粒(0.25mm)含量差异较大,其随着时间的增加呈先减小后增加的趋势;随着恢复年限增加,弃渣容重呈减小的趋势,2月弃渣容重在1.48~1.64 g/cm3,4年弃渣容重可达1.20~1.40 g/cm3,而弃渣场不同坡位的总孔隙度均与土壤容重呈反比;土壤水分含量明显增大,4年弃渣边坡的自然含水率为2月和2年弃渣的2倍左右,田间持水量也以4年弃渣最大,其平台及边坡的平均持水量为22.26%;在植物根系及其枯落物作用下,弃渣边坡土壤物理性质得到改善,其增强了边坡稳定性。     

开发建设项目借土场、弃渣场的分类、选择及防治措施布局

根据我们编制水土保持方案的工作实践，对借土场和弃渣场分别进行了分类：借土场可分为沿等高线借土、不跨山脊坡面借土和跨山脊坡面借土三大类；弃渣可分为填洼(塘)弃渣、沟道弃渣、坡面弃渣和平地弃渣四大类。提出了借土场和弃渣场的优先选择方法：借土方式应优先选择沿等高线借土，跨山脊坡面借土次之，最后考虑不跨山脊坡面借土；弃渣方式应优先选择填洼(塘)弃渣，平地弃渣次之，最后选择沟道弃渣或坡面弃渣。根据借土场、弃渣场类型的不同，合理布设了综合防护措施。     

水电站弃渣场岩土侵蚀人工模拟降雨试验研究

在金安桥水电站选定渣场弃渣颗粒径级分析基础上,用人工模拟降雨方法,对弃渣堆积平台和边坡的岩土侵蚀特征进行了研究,结果显示:(1)堆积弃渣颗粒在剔除>2 cm石块后,粒径>4 mm弃渣颗粒占48.42%,比原地貌表层土壤大13.64%,而原地貌表层土壤中粒径<0.25 mm颗粒占15.81%,弃渣中相同径级的颗粒占8.56%。(2)一次降雨过程中,弃渣堆积平台径流量最大,是原地貌荒草地的2.27倍,弃渣堆积坡面径流量最小,仅为原地貌荒草地的45.5%。(3)一次降雨过程中,弃渣堆积平台和坡面的初始含沙率均低于植被条件较差的原地貌荒草地的含沙率,达到稳定含沙率时,弃渣坡面的含沙率与原地貌荒草地接近,而渣场堆积平台的含沙率远低于原地貌荒草地。(4)一次降雨过程中,相同时段内的产沙总量原地貌荒草地最大,弃渣堆积平台次之,弃渣堆积坡面最小。(5)弃渣场岩土侵蚀过程中,产流量与产沙量之间呈显著的幂函数关系。     

吉沙水电站工程施工区渣土抗剪强度试验研究

在分析施工区渣土容重的基础上,用微型剪力仪对其抗剪强度进行了测定分析,结果显示:①弃渣堆积平台和运渣道路的渣土容重开挖边坡弃渣堆积边坡,其均值分别为1.85g/cm3、1.45g/cm3和1.05g/cm3,说明运渣道路经不断碾压,渣土密实,弃渣边坡的自然堆积渣土,疏松多孔。②随着堆积年限的不同,弃渣边坡抗剪强度的大小有显著差异,堆积3年的弃渣其抗剪强度2年弃渣1年弃渣;同一坡面不同堆积部位的弃渣,其渣土抗剪强度呈坡上坡中坡下的趋势。③渣土堆放时间越长,植被恢复程度越好,渣土抗剪强度就越大。④施工区不同类型植被覆盖下原生土壤的抗剪强度大小依次为:高山松林灌木丛和草地乔灌木混交林,分别为当年堆渣坡面的9.25、8.75、8.75和6.50倍,也是弃渣平均抗剪强度的1.68倍。     

重庆市生产建设项目弃渣场水土保持型生态修复模式

随着社会经济的快速发展重庆市生产建设项目类型和数量大幅度增加,各种生产建设项目的弃土弃渣是人为水土流失的重要地貌单元,本文对重庆市各种生产建设项目弃渣场的水土保持生态修复条件、修复原理和典型修复模式设计进行了研究。认为:1重庆市良好的光热和降雨条件为弃渣场生态修复提供了基本自然环境条件,较快的母岩风化速率和丰富的植物资源为弃渣场生态修复提供了丰富的土壤、养分和种质资源。2弃渣场水土保持型生态修复应坚持以近自然修复为目标,以乡土植被为主要建群物种,以渣顶和坡面为主要地貌单元,以堆放完成期为重点修复时期的基本原理。3设计了土质沟道弃渣场、石质坡面弃渣场和土石质河滩地弃渣场三种不同的水土保持生态修复模式,可为重庆市弃渣场水土保持型生态修复提供技术支持和部分参数。     

水电站施工期的水土流失特点及防治措施

由于水电开发在我国能源发展中的优势地位,近年西南地区和云南省水电站建设步伐明显加快,但水电开发对生态环境的影响也日益突出.针对水电站建设施工特点和人为水土流失特点,指出"三通一平"阶段和大坝浇筑前是水土流失的重要时段,弃渣场和施工道路是水土流失的关键部位.提出了弃渣场合理选址、基础处理、径流排导、弃渣拦挡、弃渣平台及边坡治理,以及施工道路合理截排水,稳定开挖边坡,保护路基,下边坡挡护,适当绿化的具体防治方案.     

水电站工程弃渣场土壤侵蚀规律研究

采用现场调查和定位观测等方法,对金安桥水电站工程弃渣场弃渣容重、粒径组成,原地貌和渣场绿化边坡、弃渣场松散堆积物边坡以及堆积平台和运渣道路的土壤侵蚀量进行了研究.结果显示:①弃渣场不同部位的渣土容重均值分别为1.70 g/cm3、1.30g/cm3和0.96g/cm3;②弃渣颗粒在剔除＞ 2cm石块后,粒径＞4mm的弃...     

铁路工程建设弃渣流失试验研究

铁路工程建设施工期长 ,工程建设产生的弃渣量大且分散 ,极易造成严重的弃渣流失。以胶州—新沂铁路工程窑峪子沟的弃渣为研究对象 ,通过雨后对弃渣流失的观测 ,分析了弃渣流失的主要影响因素 ,提出了积极的防护建议。     

Comparison of ammonium bicarbonate‐DTPA,ammonium carbonate,and ammonium oxalate to assess the availability of molybdenum in mine spoils and soils

Abstract

A variety of extractants has been used to assess the availability of molybdenum (Mo) in soils. Most of the extractants have been studied from a deficiency aspect rather than for soils with Mo toxicity, and none of them have been used to extract available Mo from mine spoils. The purpose of this study was to examine the potential of different chemical extractants for assessing the availability of Mo in mine spoils and soils. One mine spoil and three soils were treated with sodium molybdate and then subjected to wetting and drying cycles for two months. These spoil/soils were extracted with ammonium bicarbonate DTPA (AB‐DTPA), ammonium carbonate, and ammonium oxalate solution for available Mo. Crested wheatgrass (Agropyron cristatum) and alfalfa (Medicago sativa) were grown in the spoil/soils in a greenhouse to determine plant uptake of Mo. Additionally, four mine spoils and six soils were extracted and analyzed for available Mo as mentioned above. The results obtained by these three extractants were highly correlated. It was found that ammonium oxalate extracts the greatest amount of Mo among the three extractants from spoil/soils since it dissolves some adsorbed Mo from Fe‐oxide and Al‐oxide. The changes in pH of spoil/soils did not have a significant effect on the amount of Mo extracted by any of these methods. The relationships between Mo uptake and Mo extracted by each method were all significant at 1% level. None of the extractants were clearly better or worse than the others. All three methods can be used to assess Mo availability, and potential toxicity from plant uptake of Mo from reclaimed spoils.     

Nutrient availability in the initial stages of surface mine spoil reclamation — Impact on plant growth

The aim of this study was to characterise nutrient availability in the initial stages of reclamation and its impact on the growth of Secale multicaule L., the typical cover crop in newly established Pinus silvestris L. stands. A field experiment testing different levels of nutrient supply (N, P, K) was conducted on a carboniferous and a non-carboniferous sandy mine spoil representing typical mine spoils in the open-cast lignite mining district of Lower Lusatia. On both types of mine spoils, primarily N and P limited plant growth. On non-carboniferous mine spoil, low P availability to plants was alleviated by mineral fertiliser application while on carboniferous mine spoil, due to P immobilisation, P availability was still limiting plant growth after similar levels of P fertilisation. The elevated N_min content in carboniferous mine spoil compared to non-carboniferous mine spoil is probably the result of less N leaching as the dominant N form in carboniferous mine spoil is NH₄⁺ while the highly mobile NO₃^— is prevailing in the non-carboniferous mine spoil. N release from geogenic organic matter in carboniferous mine spoil as suggested by comparable N_t contents in pedogenetically formed soil organic matter is less likely.     

Earthworm response to 10 weeks of incubation in a pot with acid mine spoil,sewage sludge,and lime

Applications of sewage sludge and lime have been used to restore some of the nearly 1.0 million ha of unreclaimed acid mine spoils in the United States. Earthworms might also aid in the reconstruction of mine spoils, but the earthworm response to mine spoils and sludge has not been widely studied. The objective of the present study was to examine growth of the earthworm Lumbricus terrestris in pots containing acidmine spoils, sewage sludge, and lime, and the growth of two common reclamation grasses, timothy (Phleum pratense L.) and tall fescue (Festuca arundinacea Schreb.), to the addition of earthworms. After 10 weeks, earthworms growing in the mine spoil treated with sewage sludge showed an increase in mean specific mass of 26.9% and in projected specific area of 24.5%. In contrast, earthworms growing on mine spoils without sludge decreased in mass by an average of 39.6% and in area by 21.0%. Soil pH influenced earthworm area, but not mass: earthworms growing on mine spoils (with or without sludge) showed an increase in mean surface area of 2.9% at pH 5.3 and a decrease of 11.2% at pH 6.5. The presence of earthworms significantly increased the belowground production of plant roots, but had no effect on either soil bulk density or above-ground production of plant biomass. The addition of earthworms to acid mine spoils treated with sewage sludge and lime might aid in the redevelopment of soil quality and biological diversity.     

Soil and vegetation inter-relationships on reclaimed coal mine sites

Abstract. A spoil and vegetation survey was conducted of five fields reclaimed from coal mine spoils seeded in different years at the Whitewood mines of south-central Alberta, Canada. It aimed to understand the causes of visibly wide variations in ground cover of the seeded species which was mainly alfalfa. Sites were initially stratified into productivity classes: A (high), B (medium), and C (low) based on the seeded species, and then sampled. Cover and dry weight declined linearly with age of reclaimed field. The spoil at class-A sites contained more clay than that of class-C sites. It also contained more moisture and a better cover. Electrical conductivity (EC) and the concentrations of soluble B, Mg, Na, and K in the spoil were significantly greater at class-C sites. Cover and dry weight of the seeded species were negatively correlated with EC, B, Mg, and Na in the spoil, thus implicating these factors in poor vegetative productivity, particularly in the dry conditions that typify this part of Alberta.     

Using rainfall simulation to guide planning and management of rehabilitated areas: Part I. Experimental methods and results from a study at the Northparkes Mine,Australia

An Erratum for this article has been published in Land Degradation & Development 11(4) 2000, 399. A study using simulated rain and overland flows was carried out on a 6‐km‐long bund constructed at the NorthParkes Mine, New South Wales, Australia. The bund has been progressively constructed using 5‐m lifts to achieve final heights of 10–20 m. The slope profile consisted of alternate benches and batters of approximately 30 per cent gradient. For the topsoil placed on the bund, properties assessed included infiltration, erodibility, effects of plant cover on infiltration and erosion, and of slope length on erosion. Studies also considered permeability of the underlying spoil material, and compared susceptibility to erosion by overland flows of the two spoil materials available for bund construction. For sites that had been revegetated for one and two years, infiltration increased and soil erodibility decreased with time under vegetation. There were large increases in infiltration with increasing vegetative cover, and high infiltration rates at 100 per cent cover. The soil loss ratio curve fitted to erosion data showed larger effects of cover on erosion than predicted by the universal soil loss equation (USLE). Overland flow studies indicated no effect of slope length on erosion rates, and indicated ‘target’ levels of vegetative cover necessary to prevent rill development. Permeability of spoil underlying topsoil at one site was shown to be high, and unlikely to impede water entry and drainage. Overland flow studies showed marked differences between the two spoils studied in both critical shear for rill initiation and in rill erodibilities. Implications of the results obtained on rehabilitation planning and management are discussed. Copyright © 2000 John Wiley & Sons, Ltd.     

Environmental impacts of abandoned dredged soils and sediments Available options for their handling, restoration and rehabilitation

Aim and background  

In the process of creating safe navigable waterways for oil exploitation, the companies operating in the Niger Delta generate tons of sulfidic spoils. These are often deposited over bank, mostly upon fringing mangroves, and abandoned. This leads to a myriad of environmental problems. The extent of these impacts is not exactly known, but was inferred from the activities of oil companies operating in the area. This paper describes the impacts following the disturbance of sulfidic sediment through dredging and by subsequent poor spoil management practices. Environmental impacts of exposed and abandoned sulfidic sediments. The practice of dumping and abandoning sulfidic dredged spoils along canal banks triggers a series of environmental problems leading to extreme acidification, heavy metal pollution, and general habitat degradation which prevent the re-colonization of the sites by native species. The resultant spoil dumps remain bare for several years and they become colonized by invasive species later. Later still they may become attractive to the local population as sites for houses, fishing camps and home gardens, which is nevertheless regarded as a positive impact.     

浙江山地丘陵区公路工程弃渣处理探讨

 在山地丘陵区公路工程建设过程中,受地形等条件影响,往往开挖弃渣点多、量大,若弃渣防护不当,极易产生水土流失危害。根据工程区实际情况,提出浙江山地丘陵区公路工程项目弃渣处理的基本原则,并以浙江省龙庆公路庆元段(545、5省道)改善工程为例,论述山地丘陵区公路工程弃渣处理的具体方法及针对不同类型弃渣场的防护措施。     

青海省公路弃土场土壤侵蚀规律天然降雨试验研究

以青海省平阿高速公路弃土场作为研究对象,在雨季进行了天然降雨试验研究,分析了弃土场土壤侵蚀特征及影响因素.结果表明,该区弃土场土壤侵蚀与降雨量和降雨强度有密切的相关关系,大部分土壤侵蚀均发生在降雨较大的7-9这3个月.在40°左右的坡度条件下,坡度变化对土壤侵蚀量的影响很大,坡度稍有增加,水土流失就会大幅增加;在植被建植初期,耕作土比红弃土更易发生水土流失.     

工程堆积体流速及产沙特征对坡长及砾石作用响应

随着经济社会的高速发展以及工程建设项目的快速递增,大量生产建设项目扰动地表并破坏原地貌植被,大范围且不平衡的挖填活动使得多余的土石混合堆积,尤其在山区工程建设形成的多余土石混合介质,堆积在沟道和河道上游及边坡,在强降雨条件下易发生严重水土流失,甚至造成滑坡、泥石流等灾害。以人为重塑工程堆积体为研究对象(坡度25°),通过模拟降雨试验,开展极端降雨条件下(降雨强度为2.5 mm/min)不同坡长(3,5,6.5,12 m)及砾石质量分数(0,10%,20%,30%)共同作用对堆积体流速空间分布特征及产沙特性影响的研究。结果表明：(1)坡长12 m时流速在降雨全过程始终处于波动状态,随砾石质量分数增大,波动幅度减小,而坡长3,5,6.5 m下的流速随产流历时呈先递增后趋于稳定的变化趋势。中下坡位平均流速是中上坡位的1.12～1.54倍,随着坡长增大,平均流速递增17.81%～335.94%,含砾石堆积体平均流速较纯土堆积体降低22.88%～54.67%,砾石质量分数比坡长对流速影响更显著。(2)纯土堆积体平均侵蚀速率随坡长显著增大,递增幅度达7.88%～87.67%,而含砾石堆积体随坡长增...