地铁盾构施工对临近隧道底板沉降影响分析

随着城市地下交通现代化建设的进程,多条地下铁路在地下立交的情况已越来越多.盾构施工难免会引起已建隧道底板的沉降变化.本文结合一实例,介绍了施工期间的沉降观测方法,对可能引起底板变形的原因进行了分析,对指导类似盾构施工起了实际的指导意义.     

Study on the isotherms of the interaction between suspended particles and Cu (II) in the Huanghe River

The isotherms of the interaction between the suspended particles and Cu²⁺, and the effects of lysine and asparaginic acid on the isotherms in the Huanghe (Yellow) River were studied by applying the theory and method of interfacial stepwise ion/coordination particle exchange. We obtained a new stepped river isotherm, formed by two curves joined together with a “plateau” in the middle. The adsorption equilibrium constantsK ₁ andK ₂ were calculated by using the isothermal equation of surface stepwise ion exchange. Amino acid in small amount promotes exchange adsorption of the suspended particles with Cu²⁺. The degree of promotive action relates to the isoelectric point of amino acid. The promotive effect of lysine is bigger than that of asparaginic acid. Project 29361001 supported by NSFC.     

不同食物与放养水层对九孔鲍生长的影响

采用室内池子多层笼养殖方式 ,以加工海带、鲜江艹离 与 A,B2种片状饲料为饵料 ,试验了不同食物与不同放养水层对九孔鲍生长影响 ,结果表明 :( 1)从壳长增长上 ,海带与饲料 B近似 ,各为 11.3与 11.2 mm;其次为饲料 A,10 .2 mm;而江 艹离 最差 ,仅 7.7mm;( 2 )在体重增长上 ,以饲料 B最高 ,平均每只为 3.3g,其次为饲料 A与海带 ,平均每只 2 .9g,而江艹离 仅 1.8g;( 3)从试验期间所获体重增长比壳长增长看 ,两种饲料 ( B为 2 95,A为 2 84 mg/mm)均比两种海藻高 (海带为 2 57,江艹离 为 2 34mg/mm) ;( 4 )从垂直 11层笼子九孔鲍生长的比较 ,下层的好于上层 ,越是下层越好 ,投喂两种饲料在体重上差别更明显。     

Spatiotemporal characteristics of Qinghai Lake ice phenology between 2000 and 2016

Journal of Geographical Sciences - Lake ice phenology is considered a sensitive indicator of regional climate change. We utilized time series information of this kind extracted from a series of...     

The spatial local accuracy of land cover datasets over the Qiangtang Plateau,High Asia

We analyzed the spatial local accuracy of land cover (LC) datasets for the Qiangtang Plateau, High Asia, incorporating 923 field sampling points and seven LC compilations including the International Geosphere Biosphere Programme Data and Information System (IGBPDIS), Global Land cover mapping at 30 m resolution (GlobeLand30), MODIS Land Cover Type product (MCD12Q1), Climate Change Initiative Land Cover (CCI-LC), Global Land Cover 2000 (GLC2000), University of Maryland (UMD), and GlobCover 2009 (Glob-Cover). We initially compared resultant similarities and differences in both area and spatial patterns and analyzed inherent relationships with data sources. We then applied a geographically weighted regression (GWR) approach to predict local accuracy variation. The results of this study reveal that distinct differences, even inverse time series trends, in LC data between CCI-LC and MCD12Q1 were present between 2001 and 2015, with the exception of category areal discordance between the seven datasets. We also show a series of evident discrepancies amongst the LC datasets sampled here in terms of spatial patterns, that is, high spatial congruence is mainly seen in the homogeneous southeastern region of the study area while a low degree of spatial congruence is widely distributed across heterogeneous northwestern and northeastern regions. The overall combined spatial accuracy of the seven LC datasets considered here is less than 70%, and the GlobeLand30 and CCI-LC datasets exhibit higher local accuracy than their counterparts, yielding maximum overall accuracy (OA) values of 77.39% and 61.43%, respectively. Finally, 5.63% of this area is characterized by both high assessment and accuracy (HH) values, mainly located in central and eastern regions of the Qiangtang Plateau, while most low accuracy regions are found in northern, northeastern, and western regions.

     

Trends and risk evolution of drought disasters in Tibet Region,China

Journal of Geographical Sciences - The risk posed by natural disasters can be largely reflected by hazard and vulnerability. The analysis of long-term hazard series can reveal the mechanisms by...     

How forest gaps shaped plant diversity along an elevational gradient in Wolong National Nature Reserve?

Journal of Geographical Sciences - Understanding the underlying ecological processes that control plant diversity within (α-diversity) and among (β-diversity) forest gaps is important for...     

基于水利益共享的跨境流域水资源多目标分配研究——以澜沧江-湄公河为例

以水利益共享代替分水的理念有利于充分发挥水资源效益和减少区域矛盾冲突,但由于缺乏具体可实施的分配模式一直停留在设想阶段。基于水利益共享理念,建立跨境流域水资源多目标分配指标体系,并结合澜沧江-湄公河流域跨境水资源利用现状及需求,提出澜沧江-湄公河流域跨境水资源多目标分配模型。为基于水利益共享的跨境水资源多目标分配提供了具有充分可操作性的指标体系和分配模型,有助于推进跨境流域水利益共享的实施,实现区域双边或多边在水资源利用上的共赢和发展目标。     

环境管制对佛山市污染密集型企业空间格局变化的影响——基于2004年、2008年、2013年经济普查数据的实证

以佛山市2004年、2008年和2013年3次经济普查数据库中的污染密集型企业为研究对象,采用格数据空间回归模型,研究了佛山市污染密集型企业空间格局变化特征,并探究了环境管制对污染密集型企业及不同行业的企业空间格局变化的影响。研究发现:① 环境管制严格程度的变化使其从影响企业区位变动次要因素逐渐成为推动企业空间格局变化的重要因素,说明了环境管制变化会引起其对污染密集型企业区位变动作用程度的变化。② 在城市内部尺度,地方政府权衡污染行业整治利弊后,针对不同区域不同行业制定的差异化环境管制力度和模式,形成了不同行业空间格局响应的差异。研究结果对理解环境管制影响污染行业空间格局变化提供更微观的视角,对环境管制政策实现企业更替和产业升级具有一定启示,也对政府产业和环境政策制定具有借鉴意义。     

1990～2010年中国人口收缩区分布的时空格局演变——基于不同测度指标的分析

在人口收缩内涵界定的基础上,采用总人口和劳动力等直接指标结合出生率、老龄化率等间接指标进行综合测度,在地级尺度和县市尺度上分析了1990~2010年中国人口收缩区的数量变化、空间分布及演化特征（由于获取限制,未包含港澳台地区数据）,并对比了不同测度指标和方法之间的差异。主要的研究发现如下：①人口收缩区在数量上有明显的增长,收缩程度呈现出明显加剧趋势;②人口收缩区在中部和西部偏东地区快速扩张,川黔渝地区、长江中游地区、东北地区最为严重;③单一指标在识别人口绝对收缩方面效果较好,而且总人口指标往往比劳动力指标更早的反映一个区域的人口状况;④综合指标测度的方法能够更加全面的判断一个区域的人口发展状况,进而识别出人口处于相对收缩状态的区域;⑤人口收缩在县市尺度上比在地级尺度上表现更为明显,但两者的差异呈缩小趋势。基于以上研究发现,建议政府更加重视区域人口收缩问题及其对社会经济发展的影响。