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101.
Acta Geotechnica - The critical state of anisotropically consolidated clay is not well captured by the classical anisotropic bounding surface plasticity model without considering the real... 相似文献
102.
Li Huang Jia-le Kang Xiao-dong Shen Jian-ye Sun Qing-guo Meng Qiang Chen Gao-wei Hu Chang-ling Liu Neng-you Wu 《China Geology》2022,5(2):310-321
Blockage in water-dominated flow pipelines due to hydrate reformation has been suggested as a potential safety issue during the hydrate production. In this work, flow velocity-dependent hydrate formation features are investigated in a fluid circulation system with a total length of 39 m. A 9-m section pipe is transparent consisted of two complete rectangular loops. By means of pressurization with gas-saturated water, the system can gradually reach the equilibrium conditions. The result shows that the hydrates are delayed to appear as floccules or thin films covering the methane bubbles. When the circulation velocity is below 750 rpm, hydrate is finally deposited as a “hydrate bed” at upmost of inner wall, narrowing the flow channel of the pipeline. Nevertheless, no plugging is observed during all the experimental runs. The five stages of hydrate deposition are proposed based on the experimental results. It is also revealed that a higher driving pressure is needed at a lower flow rate. The driving force of hydrate formation from gas and water obtained by melting hydrate is higher than that from fresh water with no previous hydrate history. The authors hope that this work will be beneficial for the flow assurance of the following oceanic field hydrate recovery trials.©2022 China Geology Editorial Office. 相似文献
103.
针对塔西南西昆仑山前基底寒武系膏盐层的分布情况, 采用物理模拟研究方法,设计了研究基底滑脱层的分布对褶皱
冲断带影响的两组实验。实验结果表明:基底滑脱层的分布对构造变形样式的发育及变形前锋的传播有重要的控制作用。
具体表现为在基底寒武系膏盐层分布靠近山前的苏盖特地区变形整体表现为滑脱式的宽缓箱状褶皱的发育;寒武系膏盐层
分布较远离山前的柯东地区在缺失寒武系膏盐层的山前地区,表现为叠瓦状逆冲断层的发育,形成断层相关的紧闭褶皱,
往北有寒武系膏盐层发育的固满地区才发育较大型的箱状背斜。实验过程中苏盖特地区的变形前锋往前陆方向传播得更快
更远,而柯东地区变形前锋往前陆方向传播得较慢较近,从而在变形过程中二者的变形前锋容易出现一个“Z”字形转折。 相似文献
冲断带影响的两组实验。实验结果表明:基底滑脱层的分布对构造变形样式的发育及变形前锋的传播有重要的控制作用。
具体表现为在基底寒武系膏盐层分布靠近山前的苏盖特地区变形整体表现为滑脱式的宽缓箱状褶皱的发育;寒武系膏盐层
分布较远离山前的柯东地区在缺失寒武系膏盐层的山前地区,表现为叠瓦状逆冲断层的发育,形成断层相关的紧闭褶皱,
往北有寒武系膏盐层发育的固满地区才发育较大型的箱状背斜。实验过程中苏盖特地区的变形前锋往前陆方向传播得更快
更远,而柯东地区变形前锋往前陆方向传播得较慢较近,从而在变形过程中二者的变形前锋容易出现一个“Z”字形转折。 相似文献
104.
The active region model (ARM) has been developed as a practical and effective approach for characterizing and representing
preferential flow patterns in unsaturated soils. However, studies on methods to determine the ARM parameter (γ) are very limited. The major objective of this work was to refine the methods for determining the ARM parameter (γ) using the data from field-scale dye staining experiments. For this purpose, 13 field-scale dye staining experiments were
conducted in silty clay, loam and sand with various initial and boundary conditions. The distributions of soil water content
and fraction of stained region were measured to determine the ARM parameter (γ). Three determination methods of ARM parameter (γ) were presented according to the different distribution patterns of the soil water content of stained region. The efficiency
of these approaches was demonstrated with the results from 13 field-scale dye staining tests that were directly related to
preferential flow patterns. Impacts of soil texture on soil water redistribution, and effects of initial soil water content
and infiltration amount on the preferential flow heterogeneity were also discussed in this research. 相似文献
105.
Sequential extraction and leaching characteristics of heavy metals in abandoned tungsten mine tailings sediments 总被引:1,自引:0,他引:1
Pyeong-Koo Lee Min-Ju Kang Ho Young Jo Sang-Hoon Choi 《Environmental Earth Sciences》2012,66(7):1909-1923
The chemical speciation of potentially toxic elements (As, Cd, Cu, Pb, and Zn) in the contaminated soils and sulfides-rich tailings sediments of an abandoned tungsten mine in Korea was evaluated by conducting modified BCR sequential extraction tests. Kinetic and static batch leaching tests were also conducted to evaluate the potential release of As and other heavy metals by acidic rain water and the leaching behaviors of these heavy metals. The major sources of the elements were As-, Zn- and Pb-bearing sulfides, Pb carbonates (i.e., cerussite), and Pb sulfates (i.e., anglesite). The biggest pollutant fraction in these soil and tailing samples consists of metals bound to the oxidizable host phase, which can be released into the environment if conditions become oxidative, and/or to residual fractions. No significant difference in total element concentrations was observed between the tailings sediments and contaminated soils. For both sample types, almost no changes occurred in the mobility of As and the other heavy metals at 7 days, but the mobility increased afterwards until the end of the tests at 30 days, regardless of the initial pH. However, the mobility was approximately 5–10 times higher at initial pH 1.0 than at initial pHs of 3.0 and 5.0. The leached amounts of all the heavy metal contents were higher from tailings sediments than from contaminated soils at pH > 3.0, but were lower at pH < 3.0 except for As. Results of this study suggest that further dissolution of heavy metals from soil and tailing samples may occur during extended rainfall, resulting in a serious threat to surface and groundwater in the mine area. 相似文献
106.
On the basis of the data of glacier mass balance during 1946?C2005 over Svalbard, Northern Scandinavia, and Southern Norway, the characteristics of glacier mass-balance are analyzed, and its sensitivity to climate change is calculated using a simple degree-day model. The mass balance of glaciers in these three regions reached maximum or comparatively high values in the late 1980s or the early 1990s. After that there was an accelerating negative tendency. A glacier with more positive mass balance has a higher sensitivity to equilibrium-line altitude (or climate) change and vice versa. On average, the mass loss during the entire period in these three regions was equivalent to the result of an air temperature rise of 0.32°C relative to zero net balance state. The highest temperature increase is found in Svalbard, and is 0.55°C; however, a rise of only 0.12°C is found in Southern Norway. The net balance sensitivity to a hypothetical air temperature increase of +1°C ranges from ?0.31 to ?1.03?m?w.e.?a?1, and the net balance sensitivity to an assumed increase in snow precipitation of +10% varies from +0.05 to +0.37?m?w.e.?a?1; thus, a 31% increase in snow precipitation is needed to compensate for the net mass loss induced by an air temperature increase of +1°C. The summer balance sensitivity to a hypothetical air temperature increase of +1°C varies from ?0.39 to ?0.95?m?w.e.?a?1, and the winter balance sensitivity to an assumed increase in snow precipitation of +10% ranges from +0.02 to +0.38?m?w.e.?a?1. This study confirms early findings that maritime glaciers have comparatively higher mass balance sensitivity than continental glaciers. 相似文献
107.
108.
Information about seasonal crop water consumption is useful to develop the appropriate irrigation scheme. Measurements of energy balance components using the Bowen ratio method were made for a complete growing season at a vineyard in the arid region of northwest China. Vine in the experiment was furrow‐irrigated using a trellis system. The measured evapotranspiration was compared with estimates using the soil water balance method. It is shown that the Bowen ratio method provided accurate estimates of evapotranspiration from the vineyard and this requires that the Bowen ratio system is appropriately installed. The energy balance components showed typical diurnal pattern with peaks that occurred around the midday, except for the ground heat flux which delayed its peak by 2–3 h. The sensible heat flux was greater than the latent heat flux and followed the net radiation closely. The ratio of the latent heat flux to net radiation was low in the early growing season and increased over time. Under the limited irrigation experienced in the vineyard, the latent heat flux was controlled by available soil moisture and the total evapotranspiration in the growing season was 253 mm. The seasonal progression of the crop coefficient is similar to that reported in the literature, with the maximum occurring during the month of September. The crop coefficient can be estimated as a non‐linear function of day of year (DOY) and used to estimate evapotranspiration from vineyards in the region. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
109.
长江经济带城市群要素集聚能力差异的比较研究 总被引:1,自引:2,他引:1
城市群作为当前区域发展的主要空间载体,在区域发展竞争中扮演着越来越重要的角色。论文结合互联网大数据抓取等手段,以长江经济带5个城市群为研究对象,对城市群间要素集聚能力差异进行比较研究,发现:① 长江经济带城市群间要素集聚能力差异与长江经济带社会经济发展的区域差异相吻合,城市群要素集聚格局呈现出由东向西梯度衰减的分布特征;② 城际层面要素集聚能力差异的两极分化现象显著,以城市群首位城市为中心的要素集聚“核心—边缘”空间结构特征较为鲜明;③ 长江经济带城市群内科技创新、对外开放、金融等要素的集聚格局具有明显的差异分化和集聚分布指向特征;④ 长江经济带城市(群)要素集聚能力等级规模结构分布总体符合位序-规模法则,可分为“均衡型”和“离散型”2种类型,首位城市要素集聚首位度随城市群要素集聚能力高低呈现出“两端高、中间低”的特征。 相似文献
110.
1INTRODUCTIONIrrigated ricefieldsarecharacterizedbylargespatialandtemporalvariationsin CH4 emissiontotheatmo-sphere.Accordingly,thereisagreatuncertaintyintheestimate ofCH4 emissionsfromricefields.GreateffortshavebeenmadetoestimatetheCH4 emissionsfromricefieldsandseveralapproacheshavebeendeveloped.TherepresentativemethodsincludetheIPCC(Inter-governmentPanelofClimateChange)region-specificemissionfactormethodandthemodelcalculationmethod.Toimprovethecalculationaccuracy,theIPCCmethodreq… 相似文献