Fracturing around a preconditioned deep level gold mine stope

The mining faces of the highly stressed tabular stopes in South Africa's deep level gold mines are prone to a type of rock burst termed a face-burst. As a means of ameliorating these face-burst conditions, a destressing technique termed preconditioning has been employed. Part of the studies into the quantification of the effects and mechanisms of preconditioning was a detailed investigation of the fracture pattern around unpreconditioned and preconditioned stopes. Techniques included mapping of the fractures exposed in the mined areas of the stope, measurement of profiles of the stope hangingwall and the use of Ground Penetrating Radar (GPR). These studies indicate that preconditioning does not produce new sets of fractures and stress redistribution ahead of the face occurs by re-activation of specific pre-existing fractures, thereby reducing the potential for face-bursting.     

废弃矿井煤层气储层描述

综合研究和展示了废弃矿井煤层气储层特征及其空间分布规律和运移机理。参考煤层气储层描述技术,研究了废弃矿井煤层气储层描述技术,提出了废弃矿井煤层气储层描述的内容。      

A small-scale field check on the Fisher–Lehmann and Bakker–Le Heux cliff degradation models

The paper considers the development of initially straight, steep rock cliffs, bounded above and below by horizontal surfaces, in which basal debris removal is zero and degradation occurs by the weathering away of fine debris from the cliff face to form a scree at its foot. Of the slope degradation models available, the two earliest and simplest, namely the Fisher–Lehmann and the Bakker–Le Heux models, are regarded as most relevant and are briefly summarized. The main purpose of the paper is to check the predictions of these models, particularly with regard to the shape of the rock surface buried beneath the scree, against field data. Such data are sparse. It is concluded that the best field case currently available, despite its small scale, is that provided by the 1·75 m deep ditch which forms part of the experimental earthwork in the chalk on Overton Down, Wiltshire. The predictions of the two models are checked against field measurements made of the stage of degradation reached on each face of the ditch by July 1968, eight years after its excavation. These stages were influenced to different degrees by the presence of a surface turf layer. For the NE face, where this influence was least, the agreement of the predictions of the Fisher–Lehmann model with the actual rock profile is excellent and that of the Bakker–Le Heux model only marginally less so. For the SW face, as expected, the agreements are somewhat less close. These results may be to some extent fortuitous because of the influence of the turves and because the scree slopes tend to be concave rather than rectilinear, as assumed. Also, the free faces decline with time in a manner intermediate between those assumed in the two models. Larger scale field checks are clearly desirable before firm general conclusions can be drawn. Rates of crest recession for the Overton Down ditch are logarithmic with time after a very rapid initial phase. Extrapolation from the early phase of this logarithmic behaviour leads to a close estimate of the time needed for the slope to develop fully. The associated ultimate crest recession is also closely predicted by equations derived from both models. © 1998 John Wiley & Sons, Ltd.     

风险评价与风险控制技术在矿山企业中的应用

为更好地适应新形势下安全生产的需要,矿山企业结合自身的特点,以现代的系统的安全管理模式替代原来传统的管理模式,应用风险评价与风险控制技术,搭建一个以“风险控制为核心”的规范化、结构化、系统化的新的安全管理平台,可以有效地控制风险,防止和遏制各类事故的发生。     

Attributes and uncertainty of dissolved zinc data from a mined catchment

This study evaluated the attributes and uncertainty of non‐point source pollution data derived from synoptic surveys in a catchment affected by inactive metal mines in order to help to identify and select appropriate methods for data analysis/reporting and information use. Dissolved zinc data from the Upper Animas River Basin, Colorado, USA, were the focus of the study. Zinc was evaluated because concentrations were highest relative to national water quality criteria for brown trout, and zinc had the greatest frequency of criteria exceedances compared with other metals. Data attributes evaluated included measurement and model error, sample size, non‐normality, seasonality and uncertainty. The average measurement errors for discharges, concentrations and loadings were 0·15, 0·1 and 0·18, respectively. The 90 and 95% coefficients of confidence intervals for mean concentrations based on a sample size of four were 0·48 and 0·65, respectively, and ranged between 0·15 and 0·23 for sample sizes greater than 40. Aggregation of data from multiple stations decreased the confidence intervals significantly, but additional aggregation of all data increased them as a result of increasing spatial variability. Unit area loading data were approximately log‐normal. Concentration data were right‐skewed but not log‐normal. Differences in median concentrations were appreciable between snowmelt and both storm flow and baseflow, but not between storm flow and baseflow. Differences in unit area loadings between all flow events were large. It was determined that the average concentration and unit area loading values should be estimated for each flow event because of significant seasonality. Time weighted values generally should be computed if annual information is required. The confidence in average concentrations and unit area loadings is dependent on the computation method used. Both concentrations and loadings can be significantly underestimated on an annual basis when using data from synoptic surveys if the first flush of contaminants during the initial snowmelt runoff period is not sampled. The ambient standard for dissolved zinc for all events was estimated as 1600 μg l⁻¹ using the 85th percentile of observed concentration data, with a 90% confidence interval width of 200 μg l⁻¹. Copyright © 1999 John Wiley & Sons, Ltd.     

Synthetic information prediction system for crisis mine based on GIS

Reserves of some kinds of the crisis mines will be lack now or from now on, because of lacking seriously reserves of mineral resources and the crisis of exploring bases in support. So that it is urgent to predict, appraise, development and utilize the replaceable resources of the crisis mines. The mineral resources prediction software system of synthetic information is intelligent GIS which is used to quantitative prediction of large-scale synthetic information mineral target. It takes the geological body and the mineral resource body as a unit. And it analyzes the ore deposit genesis and metallotect, knows the spatial distribution laws of the ore deposit and ore body, and establish the prospecting model based on the concept of establishing the three-dimensional space of a mine. This paper will primarily discuss some important problems as follows: the secondary development of various kinds of data(including geology, geophysical prospecting, geochemical prospecting and remote sensing, etc); process synthetically and establish the synthetic information interpretative map base; correspond prospecting model with synthetic information of ore deposit; divided into statistical units of metallogenic information synthetic anomalies based on the synthetic information anomalies of ore control, then research the metallogenic information variable of unit synthetically and make quantitative prediction according to choose the quantitative prediction math model which is suitable to the demands of large-scale precision; at last, finish the target area optimization of ore deposit (body).     

辐射沙脊主要水道的演变特征及其水动力机制研究

近四十年来的水下地形资料对比显示：南黄海辐射沙洲区水道普遍存在逐渐向南偏移的趋势（西洋主槽冲深、南延,南翼烂沙洋水道、小庙洪水道向南逼进）。有关辐射沙洲整体南移的原因及机理虽有诸多猜想,但至今没有统一可靠的认识,这种趋势性过程的驱动力成为辐射沙洲区海岸冲淤动态研究及港口建设过程中亟待解决的问题。在恢复黄河北归以来苏北黄河三角洲海岸不同发育阶段的岸线位置和水下地形的基础之上,通过所建立的潮波数学模型,研究了在苏北黄河三角洲不同演变阶段南黄海潮波系统的特征及水动力变化。研究表明,随着岸线后退和水下三角洲的夷平,辐射沙洲地区潮差不断增大;水动力不断加强,而且加强的区域逐渐向南偏移,这种大范围区域性水动力主轴的向南偏移就有可能是导致辐射沙洲整体南移的主导因素之一。     

盐城滨海港区防波堤建设对水下地形的影响研究

利用双频测深仪和声学多普勒流速仪对滨海港区附近海域进行了区域测深和定点全潮水文观测,通过与以往调查研究资料的对比,分析了防波堤建成前后海底冲淤变化特征。研究结果表明:近20年以来水下岸坡为侵蚀最剧烈的区域,海底平原则处于相对稳定状态;受自然侵蚀的影响,水下岸坡继续向岸内移,目前最强侵蚀区已内移至–8~–12 m水深的水下岸坡;近年来自然侵蚀明显减弱,年均侵蚀速率约为前10年的1/4;受防波堤挡流效应的影响,口门南侧已由往复流转变为旋转流;目前已出现三大淤积区域,其中以口门处淤积最严重,最大淤积厚达3.5 m,已造成口门处水深不足–10 m;防波堤对周边海域直接影响范围约13.4 km~2,最远可达废黄河口。分析认为,防波堤建设是引起港区海底冲淤格局发生变化的主因。该研究为防波堤的后续维护及滨海港区30万t级航道工程论证提供了基础资料。     

废弃井改造为地热井工艺技术研究

中原油田区域内废弃井共2090口,经筛选可利用井有355口。根据这些废弃井不同的井身结构、水层位置、水泥返高等条件,确定了针对性的选井选层方法和废弃井改造工艺方案。配套研发优选了新型套管端部密封止水工具、套管鱼顶修复专用工具、套管切割方案和热储层酸洗方案,形成了废弃井改造的完井工艺系列技术和产能测试工艺技术。开展了马古6井现场改造实验,成功实施了井口恢复、储层解堵和试水测试,验证了改造方案和工艺配套技术的可行性和可靠性。     

缅甸不同矿点翡翠的矿物学特征

通过对缅甸达木坎矿区、帕敢矿区、隆肯矿区的4个矿点翡翠样品的偏光显微镜、电子探针、X射线粉晶衍射等测试,其结果表明:各矿点翡翠均以粒状变晶结构为主,主要矿物为硬玉,次要矿物有钠长石、云母类、辉石类、闪石类矿物、沸石类矿物等。其中,哥因角矿点翡翠矿石中有较大量辉石类矿物,纳莫矿点发现较大量方沸石矿物。沸石是含水矿物,而含水矿物作为矿脉的前锋组成矿物更为合理,故纳莫翡翠矿体形成深度应相对其它矿点更深。隆肯矿点翡翠样品w(A_l2O_3)=23.187%,w(Na_2O)=17.706%,w(TiO_2)=0.349%,w(K_2O)=0.298%,高于其它矿点;哥因角矿点翡翠样品w(CaO)=1.821%,w(MgO)=2.983%,w(FeO)=1.432%,高于其它矿点;纳莫矿点样品w(SiO_2)平均61.91%,为4个矿点中最高。