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161.
在地理信息系统(GIS)中,为了使地图线状要素数据的可视化有较高的质量,就需要对线状要素进行光滑处理。如何使得折线光滑后,让原始点更多地保留下来,是衡量该类地图数据精度的重要依据。本文提出了一种折线光滑处理的三点算法,该方法拟合精度高且算法简单,具有较强的实用性,可用于自动化制图、GIS等地图线状要素的绘制中。 相似文献
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163.
由于煤矿再生岩体围岩结构和成分进行了重组,其力学特性将发生本质变化。根据再生岩体压实成岩过程中破碎岩体多次受压的实际情况,采用广西州景煤矿再生顶板破碎围岩进行有侧限条件的分次压实试验。结果表明:分次压缩过程可分为压实破碎、压实应力记忆和压密固结3个阶段。在第1次压缩时,压实特性曲线呈线性变化,后续压实特性曲线逐渐向指数形式转变,而"压实应力记忆"阶段表现为多项式变化。在侧限压缩条件下,提出以最小势能原理作为判定不规则岩样挤压破碎判据。破碎岩样压缩特性受压实次数和装岩高度的影响,破碎岩样分次压实次数越多,累积压缩应变越大,后续压缩时的应力增量越大。装岩高度越大,压缩至相同压应力时,累积总应变越大。压实应力达到一定程度,不同粗粒径破碎岩样的粒径分布规律趋于一致,据此建立了破碎岩样粒径分布与工程中破碎岩体压实程度之间的相关关系。 相似文献
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165.
YAMDROK MELANGE,SOUTH TIBET 相似文献
166.
Bottom sediments near shipyards are often susceptible to receiving accidental spills of TBT and metals or their degradation products from hull scraping of antifouling system paints applied prior to 2008, when the AFS Convention 2001 was not in force. We investigated TBT and metal contamination of sediments near the shipyards of a small marina located in Busan, Korea and found that they were highly contaminated with TBT, Cu, and Zn. To better understand the environmental impacts and to make an optimal remediation plan, we characterized individual antifouling fragments in terms of metal and TBT contents, magnetic properties, and grain-size. Coarse-sized individual antifouling fragments exhibited simultaneously high levels of TBT, metals and high magnetic susceptibility, and appeared to be a major source of pollution in the sediment. Therefore, magnetic separation in combination with size-separation appears to be a cost-effective remediation method to remove the TBT and metals from contaminated shipyard sediments. 相似文献
167.
Rock fragment distributions and regolith evolution in the Ouachita Mountains,Arkansas, USA 总被引:2,自引:0,他引:2
Rock fragments in the regolith are a persistent property that reflects the combined influences of geologic controls, erosion, deposition, bioturbation, and weathering. The distribution of rock fragments in regoliths of the Ouachita Mountains, Arkansas, shows that sandstone fragments are common in all layers, even if sandstone is absent in parent material. Shale and sandstone fragments are produced at the bedrock weathering front, but the shale weathers rapidly and intact fragments are rare in the solum. Sandstone is weathered from ridgetop outcrops and transported downslope. Some of these fragments are moved downward, by faunalturbation and by transport into pits associated with rotting tree stumps. Upward movement by treethrow is common, resulting in a net concentration of rocks near the surface. However, the highest fragment concentrations are in the lower regolith, indicating active production at the weathering front. The regolith is a dynamic feature, reflecting the influences of vertical and horizontal processes, of active weathering at the bedrock interface, and of surficial sediment movements. The role of trees in redistributing rock fragments suggests that significant regolith mixing occurs over time scales associated with forest vegetation communities, and that forest soils have likely been extensively mixed within Holocene and historic time. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
168.
腾冲火山地热构造带空气钻探试验研究 总被引:5,自引:0,他引:5
腾冲火山地热构造带地层破碎、漏失、缺水严重,传统的钻井液循环体系建立需要大量工程用水。为此,钻探成本和效率将是突出问题。针对项目区地层和环境条件,结合"云南腾冲火山地热构造带科学钻探工程"项目,在上部由气孔状玄武岩、火山灰、致密玄武安山岩交替互层的复杂地层中进行了空气钻探试验。当无法建立循环体系时,采用"空气顶漏"钻进工艺,可以实现空气正循环取心钻探和大口径空气潜孔锤扩孔钻进,并且岩心采取率和质量得以保证。与其它方法相比可以解决无水地区的钻探问题,同时,具有效率高、成本低、钻孔质量好等特点。 相似文献
169.
凉亭金矿产于信阳群龟山组上部以绢云石英片岩、碳质绢云石英片岩为主的第四岩性段内,严格受东西向构造破碎带控制。破碎带蚀变强烈、种类繁多,与矿化关系密切的有硅化、绢云母化、褐铁矿化,深部有黄铁矿化等。矿化带原生晕表现为高背景值、强异常的特征。Ag、As、Pb、Mo、Bi标型元素与Au密切相关。本文着重讨论最佳指示元素在不同地层中分布规律、蚀变与矿化富集、原生异常与矿化(体)的关系等,同时建立指示元素的垂直和水平侧向分带序列。 相似文献
170.
In the Inner Western Alps, three different types of block-in-matrix structures (BIMs) formed sequentially through time at a convergent plate margin. These show the superposition of progressive deformation from (i) subduction to eclogite-facies depths, (ii) collision, accretion, and exhumation of oceanic crust, represented by the Monviso Meta-ophiolite Complex, to (iii) collision, accretion, and exhumation of the continental Dora Maira units. The Type 1 occurs in the metasedimentary cover of the Dora Maira Unit and consists of a map-scale broken formation with boudinaged ‘native’ blocks of marble (Early Jurassic) in a calcschist matrix. It results from the tectonic overprinting of exhumation-related folding (D2-stage) on an earlier subduction-related dismembered succession (D1-stage). Type 1 also includes ‘non-mappable’ BIMs with ‘exotic’ blocks, resulting from the gravitational collapse of the Triassic carbonate platform of European Continental Margin, triggered by the Early Jurassic rifting. In the Monviso Meta-ophiolite Complex, Types 2 and 3 represent tectonically induced broken and dismembered formations, respectively. They differ from each other in the degree of stratal disruption of primary interbedded horizons of mafic metabreccia (Type 3) and mafic metasandstone (Types 2 and 3) sourced by the Late Jurassic–Early Cretaceous denudation of an oceanic core complex. Dismembered interbeds (Type 2) and isolated blocks were mixed together (Type 3) by the overlap of D2 tectonics and late- to post-exhumation extensional shearing (D3-stage). Development of these types of BIMs may be common in many exhumed convergent plate margins, where severe tectonics and metamorphic recrystallization under high-pressure conditions normally prevent the reconstruction of BIMs or mélange-forming processes. Our findings show that documenting the mode and time of the processes forming BIMs is highly relevant in order to reconstruct the oceanic seafloor morphology and composition of associated stratigraphic successions, and their control in the evolution of those convergent plate margins. 相似文献