Finite-difference model of land subsidence caused by cluster loads in Zhengzhou,China          下载免费PDF全文

ZHAO Yue-wen  WANG Xiu-yan  LIU Chang-li  LI Bing-yan 《地下水科学与工程》2020,8(1):43-56

Groundwater exploitation has been regarded as the main reason for land subsidence in China and thus receives considerable attention from the government and the academic community.Recently,building loads have been identified as another important factor of land subsidence,but researches in this sector have lagged.The effect of a single building load on land subsidence was neglected in many cases owing to the narrow scope and the limited depth of the additional stress in stratum.However,due to the superposition of stresses between buildings,the additional stress of cluster loads is greater than that of a single building load under the same condition,so that the land subsidence caused by cluster loads cannot be neglected.Taking Shamen village in the north of Zhengzhou,China,as an example,a finite-difference model based on the Biot consolidation theory to calculate the land subsidence caused by cluster loads was established in this paper.Cluster loads present the characteristics of large-area loads,and the land subsidence caused by cluster loads can have multiple primary consolidation processes due to the stress superposition of different buildings was shown by the simulation results.Pore water migration distances are longer when the cluster loads with high plot ratio are imposed,so that consolidation takes longer time.The higher the plot ratio is,the deeper the effective deformation is,and thus the greater the land subsidence is.A higher plot ratio also increases the contribution that the deeper stratigraphic layers make to land subsidence.Contrary to the calculated results of land subsidence caused by cluster loads and groundwater recession,the percentage of settlement caused by cluster loads in the total settlement was 49.43%and 55.06%at two simulated monitoring points,respectively.These data suggest that the cluster loads can be one of the main causes of land subsidence.  相似文献   

利用稳定同位素(15N)示踪技术研究浮游藻类氮素吸收速率特征     

韩菲尔  赵中华  李大鹏  张路 《海洋与湖沼》2019,50(4):811-821

浮游藻类对溶解态氮的吸收同化是湖泊氮生物循环和水体富营养化发生机制探讨的关键环节。本文通过~(15)N稳定同位素添加实验以铜绿微囊藻(Microcystis aeruginosa)、海链藻(Thalassiosira sp.)、卡德藻(Tetraselmis sp.)、剧毒卡尔藻(Karlodinium veneficum)以及盐水隐藻(Rhodomonas salina)为研究对象,从浮游藻类氮素吸收时间、营养盐基质以及藻种差异三个方面研究五种藻类对铵氮(NH_4~+-N)、硝氮(NO_3~--N)、尿素氮(Urea-N)三种形态氮的吸收特征。研究发现:(1)浮游藻类对三种形态氮的吸收均在1h时吸收速率最高,其氮素吸收过程为快速吸收。(2)浮游藻类优先吸收还原态氮,其中NH_4~+-N吸收速率最高,当培养周期为1d和4d时浮游藻类对NH_4~+-N吸收速率的均值分别为4.05和4.15μmol/(L·h);浮游藻类对Urea-N吸收相对偏好系数为25.18—713.42,表现出对小分子溶解态有机氮的特定偏好性。(3)不同藻种对氮素吸收具有不同特征,其中,剧毒卡尔藻对三种形态氮的吸收速率均为最高,而铜绿微囊藻的吸收速率均为最低;不同藻种不同培养时间氮素吸收速率差异与浮游藻类生长周期等特性有关。不同浮游藻类对不同形态氮素表现出吸收特异性,对水体氮负荷和浮游藻类水华优势种形成将产生重要影响。  相似文献   

Genesis of S-type Granites in the Pengshan Sn-polymetallic Ore Field, Northern Jiangxi Province and its Implications     

YIN Qingqing  XIANG Xinkui  YU Zhendong  YANG Xiufeng  WANG Tianchen  ZHONG Bo  TAN Rong  LIAO Jianhai  ZHU Yuansong 《《地质学报》英文版》2020,94(6):1860-1873

The Pengshan Sn-polymetallic ore field is located in the southeastern part of the Yangtze block, spanning the southeast edge of the MLYDZ and the northern edge of the mid-segment of the Jiangnan Uplift, and on one side of the MLYDZ. The studies of LA–ICP–MS zircon U–Pb chronology and petrogeochemistry for Early Cretaceous acid granites from the Pengshan ore field were carried out in this paper. We report zircon U–Pb geochronology and whole-rock geochemistry for acid granites in the Pengshan ore field. The zircon U–Pb ages of the muscovite-granite, biotite adamellite and granite-porphyry are 127.6 ± 1.7 Ma, 126.9 ± 1.6 Ma and 126.6 ± 2.0 Ma, respectively. The granites in Pengshan are characterized by a high silicon content and are rich in alkali. They belong to high-potassium, calc-alkaline, peraluminous granite. The rocks have a relatively high Rb/Ba ratio, and the data points for muscovite-granite and biotite adamellite all fall within the clay-rich sources region, near the pelite-derived end-member, showing that the Pengshan muscovite-granite and biotite adamellite mainly originated from the partial melting of metapelites with high maturity. The transformation of the compressional and extensional tectonics in this region approximately 128 Ma obviously lags behind that in the mid-segment of the Jiangnan Uplift (135 Ma), but occurred earlier than the MLYDZ (126 Ma). The Pengshan ore field extends from the mid-segment of the Jiangnan Uplift to the MLYDZ. Although the tectonic stress field is constrained by the combination of the two secondary tectonic units, the time of tectonic system transformation is closer to the MLYDZ because the spatial orientation of the area is enclosed in the MLYDZ. Relevant geophysical and drilling data confirm the rationality of Pengshan–Ao’xia as a multi-center vertical zoning ore field, and show the scientificity of the prospecting idea of abutting joint between the north-west of Pengshan area and the south-east of Ao’xia area.  相似文献   

The cumulative characteristics of PAEs in PM2.5 in Changji,Northwest China     

Yuyan Liu  Caiye Ji  Bo Fu  Yongxin Yu  Haofeng Liu  Yaxing Shen 《自然地理学》2020,41(4):332-342

ABSTRACT

This paper discusses characteristics of the seasonal variation in phthalate acid esters (PAEs) in the PM_2.5 in the city of Changji, which is located an arid area of Xinjiang Province, northwest China. Samples were collected using a Laoying 2030 median discharge intelligent total suspended particulate (TSP) sampler and analyzed by a Shimadzu GC-2010 gas chromatograph. The results showed that PAEs in PM_2.5 were mainly composed of phthalic acid dibutyl phthalate (DBP) and phthalic acid (2-)ethyl hexyl ester (DEHP). DBP and DEHP are the most commonly used plasticizers, accounting for the majority of plasticizers used, and have large environmental emissions. Compared with the proportions of TSPs, proportions of DBP and DEHP in the PM_2.5 were lower, while the proportions of DMP and DEP were higher. A correlation exists between the distribution of PAEs and the particle size and concentration of atmospheric particulates. Seasonal variations in DBP and DEHP were the same, with lowest concentrations in the summer. Although seasonal variation in DMP was not the same as those of DBP and DEHP, the general trend was similar. Seasonal variation in DEP was different from those of other PAEs. This pattern is related to PAE characteristics and seasonal variations in their sources.  相似文献   

资源环境承载协调理论与评价方法     

李瑞敏  殷志强  李小磊  刘琼  孟晖  黄道袤  王轶  王龙平  王欣宝  刘建奎  孙超  赵德刚 《地质通报》2020,(1):80-87

资源环境承载能力评价是进行国土空间规划和用途管控的基础性工作,越来越受到国家重视。在资源环境承载能力研究实践中,以自然资源环境系统及其与社会经济系统的关系为主要研究对象,创新性提出了"资源环境承载协调理论",并基于此理论初步建立了不同空间尺度的地质资源环境承载能力评价技术方法,构建了地质环境、地下水资源、矿产资源等不同资源环境要素的承载能力评价指标体系,包括承载本底评价指标和承载状态评价指标。规范了不同尺度的资源与环境承载能力评价流程,为有序推动全国、区域及市县尺度的自然单元和行政单元的地质资源环境承载能力评价工作提供了强有力的。  相似文献   

遥感技术在“6·17”丹巴堵江泥石流灾害链灾区应急救援抢险决策中的应用     

唐尧  王立娟  赵娟  张成信 《中国地质调查》2020,7(5):114-122

2020年6月17日,四川丹巴县半扇门镇梅龙沟发生泥石流,阻断小金川河,形成堰塞湖,造成重大财产损失与人员伤亡。为掌握第一手灾情,辅助开展应急救援,以国产高分二号卫星数据为主要数据源,结合无人机航空摄影数据和灾后现场调查等资料,开展了“6·17”丹巴堵江泥石流灾害链灾区应急调查与分析。研究认为: 灾区影响人口约6.5万人; 国网丹巴县供电公司应急救援队与小金县联通通信应急抢险救援队距离最近,半扇门中学等5所学校可作为临时安置避难场所备选; 受影响矿山企业6家、重要水库1座、水电站1座; 泥石流沟总体呈NW—SE向展布,掩没面积约14.27万m²; 堰塞湖湖面面积约1.03 km²,淹没区约49.8万m²,路基路面全毁路段约2.1 km,下游疑似灾害隐患点9处,因灾受损民居25处、桥梁5处; 优选了2条灾后通达性较好的通往泥石流重灾区的救援生命线。借助遥感技术深入分析泥石流灾害链影响人口等灾情先期研判、灾情灾损应急调查及应急救援生命通道优选,对我国西南山区类似条件地质灾害隐患点的应急抢险救援、防灾减灾工作具有重要的指导意义。  相似文献   

Does geographic distance have a significant impact on enterprise financing costs?     

Sun  Wei  Li  Qihang  Li  Bo 《地理学报(英文版)》2019,29(12):1965-1980

Journal of Geographical Sciences - As information technology has been applied more broadly and transportation infrastructure has improved, persistent debate has existed as to the question of...  相似文献   

Base cation concentrations in forest litter and topsoil have different responses to climate and tree species along elevational gradients   总被引：1，自引：0，他引：1  

XUE Feng  ZHAO Ming-fei  WANG Yu-hang  KANG Mu-yi  XING Kai-xiong  WANG Guo-yi  SHI Jing-jing  CHEN Chen  JIANG Yuan 《山地科学学报》2019,(1)

The forest litter is an essential reservoir of nutrients in forests, supplying a large part of absorbable base cations(BC) to topsoil, and facilitating plant growth within litter-soil system. To characterize elevational patterns of base cation concentrations in the forest litter and topsoil, and explore the effects of climate and tree species, we measured microclimate and collected the forest litter and topsoil(0-10 cm) samples across an elevational range of more than 2000 m(1243 ～ 3316 m a.s.l.),and analyzed the concentrations of BC in laboratory. Results showed that: 1) litter Ca concentration displayed a hump-shaped pattern along the elevational gradients, but litter K and Mg showed saddle-shaped patterns. Soil Ca concentration increased with elevation, while soil K and Mg had no significant changes. 2) Ca concentration in the forest litter under aspen(Populus davidiana) was significantly higher than that in all other species, but in topsoil, Ca concentration was higher under coniferous larch and fir(Larix chinensis and Abies fargesii). Litter K and Mg concentrations was higher under coniferous larch and fir, whereas there were nosignificant differences among tree species in the concentrations of K and Mg in topsoil. 3) Climatic factors including mean annual temperature(MAT), growing season precipitation(GSP) and non-growing season precipitation(NGSP) determined BC concentrations in the forest litter and topsoil. Soil C/N and C/P also influenced BC cycling between litter and soil. Observation along elevations within different tree species implies that above-ground tree species can redistribute below-ground cations, and this process is profoundly impacted by climate. Litter and soil Ca, K and Mg with different responses to environmental variables depend on their soluble capacity and mobile ability.  相似文献   

1960-2015年青海三江源地区降水时空特征   总被引：5，自引：0，他引：5  

刘晓琼  吴泽洲  刘彦随  赵新正  芮旸  张健 《地理学报》2019,74(9):1803-1820

青海三江源地区是中国生态系统最为敏感和脆弱的地区,其降水特别是生长季降水的波动,是影响本区及江河中下游水资源安全、生态系统可持续发展的关键因素。综合线性趋势、Mann-Kendall检验、BG分割算法、R/S、EEMD等多方法细致辨识了1960-2015年研究区降水量序列的时空特征。结果显示：① 三江源降水量总体呈现弱增趋势,21世纪以来降水量显著增加,各子源区气候倾向率不尽相同;② 年、季降水量自东南向西北递减,澜沧江源区夏季降水和黄河源区秋季降水呈弱减趋势,雨量弱减区在空间上呈斑块状分布;③ 年、季降水量年代际变化和增湿率的空间差异较明显,春夏季降水气候倾向率与经纬度、海拔的复相关性显著高于冬季;④ 20世纪90年代中后期,各子源区降水总体显现增强信号,并于2002年前后发生突变;⑤ 年际和低值年代际显著周期是造成降水量变动的主要因素;⑥ 除澜沧江源区夏季降水趋于减少外,其他年、季降水量变化呈现增幅不一的转湿趋势;⑦ 横向比较各子源区可见,长江源区降水变化更能表征高原气候变化。研究结果显示,研究区降水时空序列变化具有明显的区域和季节差异性特征,与以往类似研究存在些许差异,可见为有效提高气候序列演变过程及突变诊断的准确性,仍需进一步融合多方法实施集成分析。  相似文献   

南海北部陆坡西部海域“海马”冷泉甲烷渗漏及其海底表征     

赵静  梁前勇  尉建功  陶军  杨胜雄  梁金强  陆敬安  王建军  方允鑫  龚跃华  何雪宝 《地球化学》2020,(1):108-118

2015年3月"海马"号遥控无人潜水器(ROV)在南海北部陆坡西部海域首次发现活动冷泉,并命名为"海马"冷泉,此后中国地质调查局广州海洋地质调查局先后组织了3个航次,对"海马"冷泉开展进一步勘查和研究。本次研究在综合分析4个航次调查数据的基础上,初步阐述"海马"冷泉的分布范围、地形地貌、生物群落、自生碳酸盐岩和流体活动等特征。总体而言,"海马"冷泉区地势平缓,气体渗漏现象非常发育,是以CH4为主要气体渗漏形成的活动冷泉区,且气体渗漏活动具有时空迁移性。气体碳同位素组成表明,海马冷泉区的CH4为混合成因气,且以微生物成因为主;"海马"冷泉区发育有多种类型的化能自养冷泉生物群落,冷泉区种类丰富,目前已报道了多个冷泉生物新种。这些发现为研究南海北部陆坡西部海域天然气水合物分解及其环境效应、冷泉生物生命起源与演化和南海与印度洋及太平洋物种迁移贯通等科学问题提供重要依据。  相似文献