保定平原区潜水水化学演化特征及成因初探

研究区潜水水质总体较差,主要超标指标和组分为:(NO_3)~-、总硬度、Fe~(2+)、(NO_2)~-、TDS,其次为Cl~-、(SO_4)~(2-)。(NO_3)~-超标点大多出现在城镇居民区、农业生产区及地下水开采区,总硬度的升高主要是由水中Mg~(2+)含量的增加引起的,其含量与水中阴离子组分也有明显的正相关性,矿化度的增加则与水中(SO_4)~(2-)、Na~+的增加密切相关。与本区20世纪70—80年代水质情况对比,现在水质发生了显著的变化,总硬度、TDS、pH值基本上呈上升的趋势,高阳、雄县、安新局部地区矿化度、总硬度的增加显著,而水中各组分的增长幅度依次为:(SO_4)~(2-)Na~+(HCO_3)~-Cl~-Mg~(2+)Ca~(2+),水化学类型由70年代的HCO_3- Ca·Mg(Ca、Mg·Ca)型逐渐复杂多样化,地下水有碱化的趋势。主要从地下水开采方面初步探讨了本区水化学变化的原因。     

钢管斜撑加高压旋喷桩法在处理基坑险情中的应用

苏州某地下车库深基坑工程,地基情况为苏州典型土层,最大开挖深度5．25m,原采用钻孔灌注桩加水泥土止水帷幕进行支护。本工程原计划到2011年3月份完成基坑部分施工,但施工单位为了抢进度,等周边高层住宅施工至10层时才进行地下车库的开挖。于2011年7月份在开挖地下车库基坑时,在支护桩墙外侧出现水平方向裂缝,且发展迅速,第五天就发展为10cm,后采用坑内被动区旋喷桩加固＋钢管内支撑的形式进行处理,经过处理后,险情得到了控制,避免了更大的损失。     

Do tides affect water quality in the upper phreatic zone of a small oceanic island, Sipadan Island, Malaysia?

 Sipadan Island is a small oceanic island with limited storage of fresh groundwater. A study was carried out to determine the effect of tidal change on the groundwater quality of such an island using temperature, dissolved oxygen content, conductivity, salinity, and pH values as indicators. Overall, the results indicated that the groundwater quality changes with tides, but the trends of fluctuation differs between the observed parameters. It was found that the percentages of changes during the period of study were 0.8% (temperature), 53% (dissolved oxygen), 61% (conductivity), 58% (salinity), and 1.7% (pH) at the centre of the island; and 0.9% (temperature), 33% (dissolved oxygen), 40% (conductivity), 42% (salinity), and 9% (pH) at a station 120 m from the coast, based on 2.9-m and 2.8-m tidal ranges at each station. Received: 5 July 1995 · Accepted: 6 November 1995     

The effect of the Messinian Deep Stage on karst development around the Mediterranean Sea. Examples from Southern France

It is difficult to explain the position and behaviour of the main karst springs of southern France without calling on a drop in the water table below those encountered at the lowest levels of Pleistocene glacio-eustatic fluctuations. The principal karst features around the Mediterranean are probably inherited from the Messinian period (“Salinity crisis”) when sea level dropped dramatically due to the closing of the Straight of Gibraltar and desiccation of the Mediterranean Sea. Important deep karst systems were formed because the regional ground water dropped and the main valleys were entrenched as canyons. Sea level rise during the Pliocene caused sedimentation in the Messinian canyons and water, under a low hydraulic head, entered the upper cave levels.

The powerful submarine spring of Port-Miou is located south of Marseille in a drowned canyon of the Calanques massif. The main water flow comes from a vertical shaft that extends to a depth of more than 147 m bsl. The close shelf margin comprises a submarine karst plateau cut by a deep canyon whose bottom reaches 1,000 m bsl. The canyon ends upstream in a pocket valley without relation to any important continental valley. This canyon was probably excavated by the underground paleoriver of Port-Miou during the Messinian Salinity Crisis. Currently, seawater mixes with karst water at depth. The crisis also affected inland karst aquifers. The famous spring of Fontaine de Vaucluse was explored by a ROV (remote observation vehicle) to a depth of 308 m, 224 m below current sea level. Flutes observed on the wall of the shaft indicate the spring was formerly an air-filled shaft connected to a deep underground river flowing towards a deep valley. Outcroppings and seismic data confirm the presence of deep paleo-valleys filled with Pliocene sediments in the current Rhône and Durance valleys. In the Ardèche, several vauclusian springs may also be related to the Messinian Rhône canyon, located at about 200 m below present sea level. A Pliocene base level rise resulted in horizontal dry cave levels. In the hinterland of Gulf of Lion, the Cévennes karst margin was drained toward the hydrologic window opened by the Messinian erosional surface on the continental shelf.     

甘肃永靖黑方台灌区潜水渗流场与斜坡稳定性耦合分析

渗流场与斜坡稳定性的耦合分析是揭示灌溉诱发型黄土滑坡机理的重要途径,也是后续开展基于水位的滑坡灾害风险控制的基础.在综合分析研究区地质结构和水文地质条件的基础上,以调查、钻探、测量、三维激光扫描和监测资料为依据,联合应用Visual Modflow和FLAC3D数值模拟软件,开展潜水渗流场与斜坡稳定性的耦合分析,模型计算结果与监测及野外调查结果吻合较好,潜水渗流场的演化对斜坡稳定性具有控制作用,随着潜水位的升高,台塬周边不稳定区域逐年增加,1990、2000和2010年焦家崖头附近最大位移值分别为0.85、1.19和1.80m.     

神南矿区煤炭开采水资源漏失量评价分区

针对神南矿区煤炭开采与水资源保护的矛盾问题,通过野外踏勘资料、钻孔资料及压水试验数据等,分析了研究区水资源分布特征、土层物质含量和渗透特征以及区内工程地质条件对保护砂层潜水所起的作用。把(导水)裂隙带、岩层厚度、土层厚度作为分区因子,根据煤层采动对浅层地下水的影响程度,将研究区划分为严重失水区、一般失水区、轻微失水区和无影响区4个区;结合地貌特征,进一步细分为梁峁漏失区、梁峁无影响区、严重失水区(砂层)、一般失水区(砂层)、轻微失水区(砂层)和风沙滩地无影响区6个区。该研究成果可为区域水环境和生态环境保护提供科学评价依据。      

尾矿库筑坝期三维渗流分析

尾矿库坝体的稳定性分析需充分考虑地形的复杂程度与边界的不规则程度,从而建立尾矿库的真实三维渗流场。利用SVOffice软件在不概化地形及边界的条件下构建尾矿库的真实渗流域,模拟了最后一期填筑在正常高水位（427.77 m）及汛期最高洪水位（434.50 m）两种工况下的三维瞬态渗流场。结果显示：两种工况下,尾矿最大日排水量均为6 100 m³,此时,堆积坝两侧浸润面均有溢出,远离排水井一侧的溢出范围更大,这主要是受渗流域的影响;库内初始水位对筑坝期渗流场的分布存在较大的影响,汛期洪水位筑坝初期浸润面位置最高。由模拟结果设计了5条排渗盲沟,保证了浸润面在堆积坝任何部位均未溢出。     

Effect of climate change on the trends of evaporation of phreatic water from bare soil in Huaibei Plain,China

When the soil condition and depth to water table stay constant, climate condition will then be the only determinant of evaporation intensity of phreatic water from bare soil. Based on a series of long-term quality-controlled data collected at the Wudaogou Hydrological Experiment Station in the Huaibei Plain, Anhui, China, the variation trends of the evaporation rate of phreatic water from bare soil were studied through the Mann-Kendall trend test and the linear regression trend test, followed by the study on the responses of evaporation to climate change. Results indicated that in the Huaibei Plain during 1991-2008, evaporation of phreatic water from bare soil tended to increase at a rate of 5% on monthly scale in March, June and July while in other months the increase was minor. On the seasonal basis, the evaporation saw significant increase in spring and summer. In addition, annual evaporation tended to grow evidently over time. When air temperature rises by 1 °C, the annual evaporation rate increases by 7.24–14.21%, while when the vapor pressure deficit rises by 10%, it changes from-0.09 to 5.40%. The study also provides references for further understanding of the trends and responses of regional evapotranspiration to climate change.     

内蒙古卓资县玛珥式火山群的发现和意义

玛珥式火山易被掩埋和不易识别,它们与人们常见的高出地面的锥状体火山口不同,而以负地形、圆形或椭圆形状、面积小和高度密集成群出现为特征。位于卓资县北部的玛珥式火山群无论在规模上和保存完好程度上都是世界上第一位的。进一步研究它们将填补我国地学界对负地形玛珥式火山口的认识、研究第四纪火山地质、推动当地旅游方面都具有意义。     

淮北平原小麦和大豆生长条件下潜水蒸发实验模拟

利用五道沟水文实验站62套原状土蒸渗仪1991～2015年长系列实验资料,采用非线性拟合方法,模拟了砂姜黑土和黄潮土冬小麦和夏大豆各生育期潜水蒸发随埋深变化的规律。通过多种线型拟合,砂姜黑土两种作物潜水蒸发量随埋深的增大而递减,均呈指数函数关系;黄潮土小麦在返青前和大豆出苗-分枝期,潜水蒸发量随埋深的增大而递减,呈指数函数关系,小麦返青期以后和大豆分枝期后,潜水蒸发量在0.5～0.8m埋深区间达到最大值,在0.5～0.8m区间以浅随埋深增大而增大,在0.5～0.8m区间以深随埋深增大而减小,呈复合函数关系。