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41.
离散裂隙渗流方法与裂隙化渗透介质建模 总被引:4,自引:1,他引:4
流体渗流模拟的连续介质方法通常适用于多孔地质体,并不一定适用于裂隙岩体,由于裂隙分布及其特征与孔隙差异较大。若流体渗流主要受裂隙的控制,对于一定尺寸的裂隙岩体,多孔介质假设则较难刻划裂隙岩体的渗流特征。离散裂隙渗流方法不但可直接用于模拟裂隙岩体非均质性和各向异性等渗流特征,而且可用其确定所研究的裂隙岩体典型单元体及其水力传导(渗透)张量大小。主要讨论了以下问题:(1)饱和裂隙介质中一般的离散流体渗流模拟;(2)裂隙岩体中的REV(典型单元体)及其水力传导(渗透)张量的确定;(3)利用离散裂隙网络流体渗流模型研究裂隙方向几何参数对水力传导系数和REV的影响;(4)在二维和三维离散裂隙流体渗流模型中对区域大裂隙和局部小裂隙的处理方法。调查结果显示离散裂隙流体渗流数学模型可用来评价不同尺度上的裂隙岩体的水力特征,以及裂隙方向对裂隙化岩体的水力特征有着不可忽视的影响。同时,局部小裂隙、区域大裂隙应当区别对待,以便据其所起的作用及水力特征,建立裂隙化岩体相应的流体渗流模型。 相似文献
42.
This paper assesses the agricultural land resources of Guiyang City by means of GIS,on the basis of the pressure-state-response model in which soil heavy metal contamination is selected as a pressure indicatror.he results suggest that most of the agricultural land resources are of good quality,However,there are 17.11km^2 dry land and paddy field,which belong to the region of serious heavy metal contamination and are not fit for planting crops.At the same time,the high quality plowland,which is suitable for cultivation,has decreased nearly by 1/3 due to soil heavy metal contamination.These findings may improve our understanding that it is very important to prevent and cure heavy metal contamination of Guiyang City. 相似文献
43.
Distribution of the rare-earth elements (REE) in dacite has been studied so as to get a better understanding of the migration
behavior of REE during alteration. Both unaltered and altered samples were collected in an unpolluted area of Guangxi Zhuang
Autonomous Region, southwest China. The REE concentrations were analyzed by ICP-MS. It is concluded that the REE were enriched
during dacite alteration in varying degrees. The chondrite-normalized REE patterns of altered samples approximately maintain
the characteristics of unaltered samples. However, if we normalize the REE concentrations of altered samples with unaltered
dacite, fractionation of REE will appear. The LREE are more enriched than HREE in all altered samples with the LREE possibly
precipitated as carbonate minerals. Both positive and negative Eu anomalies exist. Enrichment, immobility and depletion are
noticed for the element Lu. Heavy mineral alteration, difference in stability constant between carbonate LREE and HREE complexes,
downward migration of weathering fluid and microenvironment change may be responsible for the fractionation of REE in the
altered dacite. 相似文献
44.
大姚地热动态特征分析 总被引:3,自引:1,他引:3
通过大姚高精度水温观测井水地质、井孔条件的分析,震例观测资料、实验观测数据的处理,以及井水水质分析结果,表明大姚水温周期性变化的突出位置是井深75m左右,根本原因是该地层石膏脉稳定释热,含水层热水与井内冷水混合过程中,在通道内形成钙盐类沉淀物(如CaSO4CaCO3),堵塞对流通道,含水层内外压差突破被阻塞通道,热水反复侵入井内,便形成水温周期性变化。地震的孕育、发生和调整过程,由于应力场作用,产生附加地热场,水温基值发生变化,周期畸变或消失,这种附加地热动态是可以恢复的。所以认为大姚地热动态是井区特殊地层地热信息的反映。 相似文献
45.
A greenhouse experiment was conducted to investigate the effects of moderate (14 cm) vs. severe (7 cm) defoliation on tiller recruitment and mortality within the interior and on the perimeter of weeping lovegrass (Eragrostis curvula) tussocks. Tiller number per marked shoot within the interior was significantly greater in plants defoliated at 14-cm stubble height than at 7-cm stubble height (2·37 vs. 0·43, p<0·05) 28 weeks after defoliation; likewise, tiller number per marked shoot was also greater on the perimeter of tussocks in the higher stubble than the lower stubble defoliation treatment (5·10 vs. 2·03, p<0·05). Tiller natality increased significantly 4 weeks after defoliation except for tillers cut to 7-cm stubble height within the interior of tussocks where tiller natality reached a peak at 4·5 weeks after defoliation. During the later stages of canopy development, tiller numbers per marked shoot gradually declined as tiller mortality increased. Tillers began senescing 13 weeks after defoliation, and the senescence rate was 52% greater in the 7-cm stubble height treatment than in the 14-cm stubble height treatment (2·33 vs. 1·53, p<0·0001). Within the interior of tussocks, number of the marked tillers more than doubled under the 14-cm stubble height treatment, whereas the plants lost 57% of the monitored tillers under the 7-cm stubble height treatment. We concluded that the central dieback process in weeping lovegrass is accelerated by severe defoliation. 相似文献
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49.
Dinosaur tracks from the Cretaceous of South Korea: Distribution, occurrences and paleobiological significance 总被引:2,自引:0,他引:2
Abstract Abundant dinosaur fossils including dinosaur footprints, eggs and nests, teeth and bones have been found from the Cretaceous non-marine deposits of Korea. Among them, dinosaur tracks are the most distinctive, and some track sites are among the most famous in the world. Until now, 27 dinosaur track localities have been discovered from the Cretaceous strata in the Gyeongsang Basin and several small basins. Ornithopod tracks are most abundant at most Korean track sites, and most of them are identified as Caririchnium ; that is, large ornithopod footprints with wide hoof impressions. Most theropod tracks are found in Neungju Basin and they consist of various types of small or medium-sized bird-like footprints, and other large footprints. Sauropod tracks are also abundant in the Gyeongsang Basin. The sauropod tracks vary in size, shape, and pattern of trackway, and suggest that diverse sauropods existed in this area. These diverse tracks in South Korea suggest that various dinosaurs flourished at the margins of lakes distributed in the southern part of the Korean Peninsula during the Cretaceous. 相似文献
50.
Energy serves as an alternative index to response quantities like force or displacement to include the duration‐related seismic damage effect. A procedure to evaluate the absorbed energy in a multistorey frame from energy spectra was developed. For low‐ to medium‐rise frames, it required a static pushover analysis of the structure to determine the modal yield force and ductility factor of an equivalent single‐degree‐of‐freedom system for the first two modes. The energy spectra were then used to determine the energy contribution of each mode. A procedure was also developed to distribute the energy along the frame height based on energy shapes. This study showed that the second‐mode response in some cases needs to be considered to reflect the energy (or damage) concentration in the upper floors. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献