福建浦城中生代铀,多金属矿床形成条件及构造环境分析     

聂淦波  隆盛银 《华东地质学院学报》1994,17(2):106-116

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Evaluation of the parameters affecting the roughness coefficient of sewer pipes with rigid and loose boundary conditions via kernel based approaches     

《国际泥沙研究》2020,35(2):171-179

One of the important issues in water transport and sewer systems is determining the flow resistance and roughness coefficient.An accurate estimation of the roughness coefficient is a substantial issue in the design and operation of hydraulic structures such as sewer pipes,the calculation of water depth and flow velocity,and the accurate characterization of energy losses.The current study,applies two kernel based approaches [Support Vector Machine(SVM) and Gaussian Process Regression(GPR)] to develop roughness coefficient models for sewer pipes.In the modeling process,two types of sewer bed conditions were considered:loose bed and rigid bed.In order to develop the models,different input combinations were considered under three scenarios(Scenario 1:based on hydraulic characteristics,Scenarios2 and 3:based on hydraulic and sediment characteristics with and without considering sediment concentration as input).The results proved the capability of the kernel based approaches in prediction of the roughness coefficient and it was found that for prediction of this parameter in sewer pipes Scenario 3 performed better than Scenarios 1 and 2.Also,the sensitivity analysis results showed that Dgr(Dimensionless particle number) for a rigid bed and w_b/y(ratio of deposited bed width,w_b,to flow depth,y) for a loose bed had the most significant impact on the modeling process.  相似文献   

大牛地气田钻杆耐磨环失效原因分析          下载免费PDF全文

李建山 《探矿工程》2005,32(3):44-47

鄂尔多斯北部大牛地地区钻井施工中钻杆偏磨、耐磨环失效现象很普遍。通过对比分析研究,认为造成钻杆耐磨环失效的主要原因有:地层研磨性、钻杆的井下工况、耐磨材料选择与敷焊工艺的影响。  相似文献   

Contrasting flow pathways within tropical forest slopes of Ultisol soils     

Nick A. Chappell  Mark D. Sherlock 《地球表面变化过程与地形》2005,30(6):735-753

There are very few experimental studies identifying hydrological pathways within rain forest slopes. Such knowledge is, however, necessary to understand why forest disturbance affects rainfall–riverflow response and nutrient migration. This study examines flow pathways within lowland rain forest slopes comprising Udults of the Ultisol soil order. Experimentation was conducted on four SE Asian hillslope units (each 5 × 5 m in plan) in the Bukit Timah catchment (Singapore Island), and in the W8S5 catchment (Sabah, Borneo Island). The flow pathways were identified by artificial tracer experiments. We evaluated how well hydrometric calculations based on tensiometry and permeametry measurements predicted the tracer patterns. The tracer work indicated much faster subsurface flows at Bukit Timah than W8S5 for the storms studied. Some explanation of the greater subsurface waterflows at Bukit Timah in comparison to W8S5 is afforded by the less steep moisture release curves which maintain hydraulic conductivity as the soil dries. Vertical flow of the tracer through the upper 1 m of soil predominated (>90 per cent of percolation) in the Bukit Timah slopes. In some contrast, a major component (approximately 60 per cent) of the tracer percolation was directed laterally within the W8S5 slopes. The flow vectors calculated using the hydrometric methods did, however, grossly under‐estimate the degree of lateral deflection of waterflow generated at W8S5 and to a lesser extent over‐estimated it at Bukit Timah. In part, these errors may relate to the inability of traditional hydrometric techniques to fully characterize the effect of the large and small ‘natural soil pipes’ present within both catchments. In conclusion, the study indicates that marked variations in flow vectors exist within the Udult great group of SE Asian soils and hydrometric calculations may be poor predictors of these dominant pathways. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Change of groundwater chemistry from 1896 to present in the Mid-Levels area, Hong Kong   总被引：1，自引：0，他引：1  

Chi-man Leung  Jiu Jimmy Jiao 《Environmental Geology》2006,49(7):946-959

In this study, groundwater quality information collected in 1896 (well waters), 1980/1981 (piezometric and seepage samples) and 2002/2003 (seepage samples) in the regions centered by the Mid-Levels area, Hong Kong Island, was compared to illustrate how groundwater quality has changed over a century and the processes controlling it. As shown by saline ammonia and nitrate levels in the late nineteenth century, groundwater was severely polluted by widespread and obvious leakage from poorly designed wastewater collection systems, although groundwater was still a drinking water source for local residents. The extremely high residual chlorines in groundwater demonstrated that large doses of disinfection agents were added to wells at that time. In view of the decline in saline ammonia and nitrate levels, groundwater became less organically polluted in the 1980s probably due to significant improvement of the design of underground sewers. However, more leakage from sources such as salty flushing water and fresh water pipes emerged in the past few decades which added complexity to groundwater chemical systems. Some chemicals were used to identify possible locations of leakages. The temporal variations of the distribution of these chemicals over the area may shed light on the rate of leakage. Leakage from service pipes seems to have improved from the early 1980s to 2002/2003. However, the area is still suffering from widespread and small-scale leakage from service pipes. More efforts should be paid to control small leakages in the future. The findings will be instructive to various government organizations such as the Water Supplies Department and Drainage Services Department to identify possible locations of unobvious leakages in the area.  相似文献   

探地雷达在管线探测与工程勘察中的应用   总被引：9，自引：0，他引：9  

汤洪志  黎正根  贺小军  罗坤 《华东地质学院学报》1999,22(2):156-166

简要地介绍了探地雷达的勘探原理,工作方法、技术,及其在工程勘察中的应用,并在前人的基础上,利用ＳＩＲ－２型探地雷达,寻找地下管线和确定工程地质界面,进行了一系列的实测工作,获得了高质、清晰、直观的ＧＰＲ图像。  相似文献   

深海采矿整体联动风险分析及应急撤离策略研究     

谢梦琪  杨高胜  陈丹东  余倩  杨光  施威 《海洋科学》2021,45(9):91-98

深海采矿作为新领域资源重点开发项目,国外已开展部分试验研究,国内现阶段仅停留在重点设备部件级功能验证,还未开展过系统整体联动,距离海洋油气等正在进行的规模化商业开采还有很大距离。本文以深海采矿系统整体联动模型为基础,与海洋油气工程作业平台技术模型进行对比,对整体联动风险点进行深度分析,并根据重点风险部件开展其悬挂模式、力学模型研究,探讨深海采矿系统整体联动时应急撤离的策略。研究总结了深海采矿系统整体联动的特点,提出了管道摇摆幅度超出设计范围、平台升沉行程超出伸缩冲程范围等两大关键风险点、提升硬管受力分析方法和对应的应急撤离方案,对深海采矿工程总体设计和工程实施具有指导意义和参考价值。  相似文献   

地震资料中柱状流体运移通道形态参数及其地质意义     

张伯达  雷振宇  郑文义  李政坤  蔡达仰  张金锋  苏明  杨睿 《海洋地质与第四纪地质》2019,39(3):171-181

深部流体在向上运移的过程中,能够形成垂直-近似垂直的柱状通道,如气烟囱构造、流体逸散管道等。利用高分辨率地震资料,能够直观地对这些柱状地球物理异常进行精细的描述与刻画,从而统计其形态参数。综合不同海域的研究成果,本次研究系统总结归纳了柱状流体运移通道的8个重要参数,分别是发育层位、终止层位、平面形状、直径、高度和宽高比、反射偏移、椭圆率、拟合椭圆方位角。形态参数分别与通道群在平面上的展布方位、特殊的海底异常地貌(如海底麻坑、丘状体等)、深部构造发育与分布(如底辟、断层等)等进行耦合关联,能够进一步揭示柱状流体运移通道的地质含义。可将形态参数分为:(1)从形态学上对柱状通道进行直接分类的参数;(2)指示柱状通道形成诱发因素或形成过程的参数;(3)划分柱状通道幕式流体活动及期次的参数;(4)定义柱状通道中流体活动时间区间的参数;(5)间接反映柱状通道中流体通量相对大小的参数。实际研究过程中,单一形态参数难以准确反映出复杂地质背景下柱状通道的真实地质含义,多参数组合、相互对比验证,能够更好地对柱状流体通道的地质含义做出综合分析。  相似文献   

上海某隧道人工地层冻结工程现场实测研究          下载免费PDF全文

程知言  邓玲  周建华 《探矿工程》2007,34(8):67-69,72

针对理论研究和冻结工程的实际需要,结合上海某隧道人工地层冻结工程实践,对土体冻结过程中温度、应力、地表变形及土体分层位移进行了现场测试,并分别对测试结果进行了归纳整理和规律性研究;最后综合分析得出了几点结论和看法。  相似文献   

Effects of lithology and land use on storm run-off in east luxembourg     

Martin R. Hendriks 《水文研究》1993,7(2):213-226

For a large part of the year, the forested catchments in the Keuper formation of east Luxembourg produce more direct run-off on a storm basis than paired cultivated catchments. The occurrence of shrinkage cracks, their pronounced opening and closing, and the occurrence of natural pipes in the forested environment play a major role in explaining this phenomenon. The effect of land use on storm run-off is studied in relation to that found for lithology in the same area.  相似文献