疏浚淤泥流动固化土的压汞试验研究

采用压汞法对疏浚淤泥流动固化土进行了微观孔隙结构的研究,分析了固化土的孔隙体积及入口孔径分布特征与固化材料掺量及固化土龄期的关系,并将微观试验结果与固化土的物理指标和强度特性进行了比较。结果表明,采用压汞法研究疏浚淤泥流动固化土的微观孔隙空间分布是成功的,压汞试验得到的微观孔隙特征与众多学者通过宏观力学试验得出的强度规律是一致的,微观结构试验能够很好地解释宏观物理力学性状。随着固化材料掺量的增加和龄期的增长,淤泥固化土的孔隙体积和D50孔径明显减小,入口孔径分布特征亦发生了相应变化。所得流动固化土的入口孔径主要分布在0.01～10 ?m之间,最大分布孔径在0.5～2 ?m之间。     

Sensors,empowerment, and accountability: a Digital Earth view from East Africa

Abstract

Several innovative ‘participatory sensing’ initiatives are under way in East Africa. They can be seen as local manifestations of the global notion of Digital Earth. The initiatives aim to amplify the voice of ordinary citizens, improve citizens' capacity to directly influence public service delivery and hold local government accountable. The popularity of these innovations is, among other things, a local reaction to the partial failure of the millennium development goals (MDGs) to deliver accurate statistics on public services in Africa. Empowered citizens, with access to standard mobile phones, can ‘sense’ via text messages and report failures in the delivery of local government services. The public disclosure of these reports on the web and other mass media may pressure local authorities to take remedial action. In this paper, we outline the potential and research challenges of a ‘participatory sensing’ platform, which we call a ‘human sensor web.’ Digital Africa's first priority could be to harness continent-wide and national data as well as local information resources, collected by citizens, in order to monitor, measure and forecast MDGs.     

O2-O2云反演算法及其在TROPOMI上的应用

利用遥感技术对大气环境污染进行监测时,云是影响痕量气体反演精度的重要因素,因此在痕量气体反演中需要对云的影响进行校正,通常使用的云参数主要是有效云量和云压。本文基于O₂-O₂ 477 nm吸收波段构建了O₂-O₂云反演算法：首先,根据有效云量和云高与连续反射率和O₂-O₂斜柱浓度之间的对应关系,结合假定的云模型利用VLIDORT辐射传输模型建立关于有效云量和云压的查找表;然后,通过差分吸收光谱技术拟合卫星载荷观测的大气层顶辐射,获得O₂-O₂斜柱浓度并计算连续反射率;最后,结合辅助数据,根据查找表进行插值反演获得有效云量和云压。通过将算法应用到OMI观测数据,将反演结果与OMCLDO2产品进行对比验证,有效云量和云压空间分布一致,相关系数R均超过0.97;并还将该算法应用于下一代大气成分监测仪器TROPOMI,与FRESCO+产品对比,有效云量和云压空间分布基本一致,当地表类型为海洋时,有效云量相关系数R大于0.97,云压相关系数R大于0.94,云压反演结果存在一定的区别;通过将O₂-O₂云反演算法和FRESCO+云压反演结果与CALIOP Cloud Layer产品进行对比,结果表明,在低云情况下,O₂-O₂云反演算法线性回归方程斜率为0.782,截距为198.0 hPa,相关系数R为0.850,算法表现优于FRESCO+。而在高云情况下,FRESCO+反演结果更接近CALIOP云压结果。在OMI和TROPOMI上的应用表明O₂-O₂云反演算法在大气云反演中具有较高的准确性和可行性,可以为大气痕量气体反演的校正提供云参数,并为中国同类型卫星载荷的云反演算法提供算法参考。     

Environmental hydrogeology of the southern sector of the Samborombon Bay wetland,Argentina

The Samborombon Bay wetland is located on the west margin of the Rio de la Plata estuary, in the Province of Buenos Aires, Argentina. This paper analyses the geological, geomorphologic, soil and vegetation characteristics of the southernmost sector of this wetland and their influence on surface water and groundwater. The study area presents three hydrologic units: coastal dunes, sand sheets and coastal plain. Coastal dunes and sand sheets are recharge zones of high permeability with well-drained, non-saline soils, and a few surface water flows. Changes in the water table are related to rainfall. Groundwater in coastal dunes is Ca–Mg–HCO₃ to Na–HCO₃, and of low salinity (590 mg/l). Groundwater in sand sheets is mainly Na–HCO₃ with a salinity of about 1,020 mg/l. The coastal plain exhibits medium to low permeability sediments, with submerged saline soils poorly drained. Groundwater is Na–Cl with a mean salinity of 16,502 mg/l. A surface hydrological network develops in the coastal plain. Surface water levels near the shoreline are affected by tidal fluctuations; far from the shoreline water accumulates because of poor drainage. Both sectors have Na–Cl water, but the former is more saline. Human intervention and sea level rise may affect the wetland severely.     

黄土台缘滑坡地表水入渗问题分析

黄土塬区提灌工程保证了农业生产,却造成了地下水位大幅抬升,使得近年来黄土台缘滑坡不断发生。黄土滑坡一个普遍特征就是后缘发育地裂缝以及落水洞,使地表水（灌溉水以及降雨）直接灌入坡体,诱发了大量黄土滑坡。因此,地表水入渗对于黄土滑坡机理研究以及滑坡防治具有重要意义。文章基于对陕西泾阳南塬黄土滑坡的现场调查,对黄土台缘滑坡地表水入渗工程地质问题进行了初步分析,包括：①地表水入渗与落水洞形成机制;②地表水入渗途径及其与黄土滑坡发育过程的关系;③降雨因素对于黄土滑坡的影响程度。     

Variation in DOC and trace metal concentration along the heavily urbanized basin in Kathmandu Valley,Nepal

Water samples were analyzed for DOC and trace metals from Bagmati River within Kathmandu valley, Nepal, to understand the variation trends of DOC and trace metals and their relationship along the drainage network. The variability in organic matter and wastewater input within the Bagmati drainage basin appeared to control DOC and most of the trace metal concentration. The large input of organic matter and wastewater creates anoxic condition by consuming dissolved oxygen and releasing higher concentrations of DOC, trace elements such as nickel, arsenic, barium, cadmium, and copper with downstream distance. Concentrations of DOC and trace metals like barium and zinc showed strong relationships with human population density and suggest that human activities have strong control on these parameters along the drainage network. The DOC and most of the trace metal concentration increased with downstream distance and appeared to be directly associated with human activities. The variation trends of most of the trace metals appeared to be the same; however, concentration varied widely. Inputs of organic matter and wastewater due to human activities appeared directly to be associated for the variation of DOC and trace metals along the Bagmati drainage network within Kathmandu valley.     

关于吉林地区挖孔桩设计问题的探讨

探讨了在吉林地区高层建筑中有关桩基规范执行及设计施工过程中常见的问题。通过对不同直径的桩端进入持力层深度的对比 ,明确 2d与 4d的对比要求 ,即持力层厚度的保证比进入持力层深度更重要。针对通长配筋“一通到底”的设计给施工带来的不便及浪费提出了新的建议。通过实践给出“α”角的建议值 ,既能减小扩大桩头斜面上受到卸荷后侧土压力 ,又可减少施工时的坍方。最后对降水及护壁提出了结合实际地质情况的 4种方法。     

红三角地区农产品虚拟水的计算分析

农业是世界上最大的水资源利用部门,各种农产品中“寄存”了大量的水资源,蕴涵在产品生产和各种服务中的水资源就是产品或服务中的虚拟水.以红三角地区为例,分析了郴州市、韶关市、赣州市主要农产品的演变特征,计算了主要农产品的虚拟水含量及消费情况,在此基础上探讨了红三角地区农产品的战略性调整和水资源有效配置的政策意义.计算表明,不同区域生产同类型农产品所耗费的水资源不同,加上消费数量的差异,使居民人均农产品虚拟水消费也存在明显差异.红三角地区水资源富足的地区可通过农产品贸易方式更好地发挥区域水资源优势,主动开发和生产高效益的水资源密集型农产品;对局地水资源缺乏的山区,需要通过农产品生产的战略性调整,通过购入水资源密集型农产品,大力发展高效益的特色农业,实现生态-经济-水的良性循环.     

不等长工作面台阶区域覆岩运动诱冲机制及防治

针对阳城煤矿不等长工作面台阶区域发生冲击地压灾害问题,基于工作面特殊布置方式及覆岩赋存特征,采用理论分析、数值模拟和现场实测等方法,分析了台阶区域覆岩结构运动特征和围岩应力演化规律,研究了台阶区域冲击地压诱发机制。研究结果表明：1304工作面台阶区域覆岩经历了“OX-S-C”型较为复杂的结构演变,覆岩空间结构由OX向S型转换时,顶板岩层大面积破断下沉,在台阶区域形成多个悬臂梁结构,越往高位,悬臂梁长度越大;受覆岩运动和采动应力场叠加影响,煤岩体形成高应力集中区,在顶板岩层动载冲击作用下,煤岩体弹性应变能突然释放,诱发冲击地压。采用COMSOL软件对不同卸压钻孔参数下煤体应变能分布特征进行模拟研究,优化了台阶区域卸压钻孔参数。根据模拟结果,随着钻孔孔径、孔深增大及间距减小钻孔卸压效果越明显,考虑工程实际,确定孔径为150 mm、孔深为30 m、间距为1 m为合理有效的卸压钻孔参数,并应用于1302工作面台阶区域的冲击地压防治,取得了较好的防冲效果。     

晋东南辛安泉域地下水水质污染现状及污染成因分析

辛安泉是北方第二大泉，泉域面积１３０００ｋｍ＾２。根据环境水文地质条件，将拉域划分为四个子系统。采用饮用水卫生标准和污染起始值对系统内地下水水质进行评价，并对其污染成因进行了分析。