A general solution for groundwater flow in an estuarine's leaky aquifer system after considering aquifer anisotropy

This paper presents an analytical model for describing the tidal effects in a two‐dimensional leaky confined aquifer system in an estuarine delta where ocean and river meet. This system has an unconfined aquifer on top and a confined aquifer on the bottom with an aquitard in between the two. The unconfined and confined aquifers interact with each other through leakage. It was assumed that the aquitard storage was negligible and that the leakage was linearly proportional to the head difference between the unconfined and confined aquifers. This model's solution was based on the separation of variables method. Two existing solutions that deal with the head fluctuation in one‐dimensional or two‐dimensional leaky confined aquifers are shown as special cases in the present solution. Based on this new solution, the dynamic effect of the water table's fluctuations can be clearly explored, as well as the influence of leakage on the behaviour of fluctuations in groundwater levels in the leaky aquifer system. Copyright © 2015 John Wiley & Sons, Ltd.     

Timoshenko beam solution for the response of existing tunnels because of tunneling underneath

An analytical solution for the deflection and internal forces of an existing tunnel because of tunneling underneath is presented. The existing tunnel is modeled as a Timoshenko beam resting on a Winkler foundation, which takes into account the contribution of shear deformation to the total deflection of the existing tunnel. The validity of the analytical solution is verified by a centrifuge test, and the merit of this analytical method is confirmed by comparison with the conventional Euler–Bernoulli beam model. Influential factors on the behavior of the existing tunnel are investigated by consideration of the variations of subgrade modulus, ground loss induced by the new tunnel construction, vertical clearance between the new tunnel and the existing tunnel, and relative existing tunnel–soil stiffness. Results show that the proposed analytical method is a valid and effective method to evaluate shearing‐induced deformation in existing tunnels with large diameters. Results also show that the pattern and the amplitude of the response of the existing tunnel are affected largely by ground loss induced by the new tunnel construction, vertical clearance between the new tunnel and the existing tunnel, and relative existing tunnel–soil stiffness. Copyright © 2015 John Wiley & Sons, Ltd.     

多GNSS系统组合PPP定位精度评估

采用MGEX网提供的GPS、GLONASS、BDS、GALILEO四系统双频观测数据,以CODE、GBM、WUM、GRG精密产品进行了静/准动态模式下多系统组合无电离层延迟PPP浮点解与整数钟法固定解实验。结果表明多系统的组合提升了定位精度,尤其是GLONASS的加入效果最明显,CODE与GBM产品的解算精度优于WUM、GRG产品。部分模糊度固定相比全模糊度固定的效果显著,模糊度固定明显缩短了PPP收敛时间,在静态模式下相对浮点解精度提升10%以内,动态模式下E方向与U方向精度提升效果最好。     

广义Khasminskii条件下非线性混杂随机时滞微分方程的解的存在唯一性

利用广义伊藤公式证明了混杂随机时滞微分方程(SDDE)在局部Lipschitz和广义Khasminskii条件下存在唯一解,从而涵盖了一大类非线性混杂SDDE.最后给出实例说明了理论的可行性.     

非均匀地基与均匀地基一维固结解答之间的转换关系

基于一维固结理论,研究了土层物理力学性质沿深度非均匀连续变化的固结问题。首先,利用分离变量法,获得了渗透系数和压缩系数随深度按指数函数变化的非均匀地基一维固结方程的解析表达式; 然后与Terzaghi固结理论的经典解答进行了比较,获得了两种解答之间的相似转换关系。这样,非均匀地基固结问题就可以用相同荷载以及边界条件下的均匀地基固结的经典解线性表示。因此,非均匀地基固结问题的求解转化为对相似转换系数的计算。该系数集中反映土层非均匀性对地基固结的影响,从而为解决非均匀地基一维固结问题提供了便捷途径。     

华南李家沱剖面寒武纪纽芬兰世海水氧化还原性质演化及其驱动因素

大气-海洋含氧量的演化对埃迪卡拉纪-寒武纪转折期的后生动物大爆发事件具有重要影响.为探讨寒武纪纽芬兰世中国南方海洋氧化还原性质的演化及其初级生产力、海水硫酸盐浓度等演化驱动因素, 分析了李家沱剖面纽芬兰世留茶坡组和小烟溪组微量元素、有机碳含量、有机碳同位素、总硫含量、黄铁矿硫同位素等.该剖面沉积于斜坡-盆地环境且出露齐全.该剖面上V/Sc、Th/U及Mo、U、V、Ni、Cu等元素的富集系数呈现出5个变化旋回, 其中留茶坡组中上部和小烟溪组中部各存在一氧化环境段, 其余层段处于缺氧环境, 而Re/Mo则显示仅在小烟溪组中部水体出现过短暂的氧化环境和含有游离H₂S的硫化环境, 其余层段处于没有游离H₂S的缺氧非硫化环境.Ba、Ni、Cu、Zn、Cd等微量元素的富集系数及TOC表明: 留茶坡组的有机质沉降量和埋藏量都明显小于上覆小烟溪组; 而在小烟溪组中, 其中部有机质的沉降量和埋藏量最低, 下部最高, 上部次之.TOC/TS、TS以及黄铁矿硫同位素的垂向演化趋势等都显示李家沱剖面纽芬兰世大都处于低海水硫酸盐浓度环境.低海水硫酸盐浓度是造成李家沱剖面纽芬兰世缺氧水体未富集游离H₂S的主要原因.大气含氧量的升高是导致李家沱剖面小烟溪组中部出现短暂氧化环境以及近硫化环境的主要原因.      

河北省涞源县木吉村铜(钼)多金属矿田成矿物质来源探讨

木吉村铜(钼)矿田位于太行山脉中、北段阜平幔枝构造的北东倾伏端,涞源哑铃状杂岩体连接处西侧上盘拆离带的次级断陷盆地中,主要由斑岩型铜(钼)矿、矽卡岩型铁铜矿和外围热液脉型铅锌矿构成,是河北省目前探明的唯一大型铜(钼)多金属矿田,找矿远景巨大。鉴于矿床成矿物质来源在研究矿床成因和指导找矿中的重要作用,对木吉村矿田主要矿床矿石中黄铁矿、黄铜矿、方铅矿、辉钼矿、磁铁矿、石英和石膏等单矿物进行了硫、铅、碳、氢、氧、硅、铼等同位素测定、对比和分析。结果表明:矿田中硫同位素主值域δ34S=-3.5‰~3.2‰,主平均值为0.3‰;铅同位素206 Pb/204 Pb=15.566 0~17.072 0,平均为16.547 0,207Pb/204Pb=15.031 0~15.523 0,平均为15.258 0,208 Pb/204 Pb=36.292 0~37.375 0,平均为36.721 0;碳同位素δ13 C为-2.94‰~-2.18‰,平均为-2.62‰;硅同位素δ30 SiNBS-28值域为-0.3‰~0.2‰,平均0.0‰;辉钼矿w(Re)为(23.65~266.50)×10-6,平均值为142.33×10-6;δ18 OH2O值为-10.64‰~7.70‰,极差为18.34‰,平均值为-1.47‰,较标准岩浆水值稍低,δD值为-148.4‰~-89.0‰,极差为59.4‰,平均值为-113.7‰,略低于岩浆岩δD值域。从而认为,木吉村矿田成矿物质主要来源于地球深部,成矿溶液以岩浆水为主,部分来自大气降水。     

近震波形反演震源机制解方法对比研究

分别利用近震波形反演求解震源机制解的gCAP方法和全波形反演方法反演了鲁甸MS6.5地震的震源机制解,并比较两种方法的优点与特性。结果发现,数据方位角的覆盖范围会影响解的稳定性,在使用gCAP方法时尤其需要注意;两种方法获取的震源机制解结果较为一致,走向为73°~77°,倾角为72°~85°,滑动角为157°~180°。     

盐湖提锂尾液中锂回收的吸附试验研究

从高镁锂比盐湖提锂生产尾液中回收锂,可实现锂资源高效回收利用,对企业经济效益的提高具有重要意义。以东台吉乃尔盐湖提锂尾液为原料,系统性研究了铝系层状锂吸附剂JW-LAHS对提锂尾液中锂的静态、动态吸附和解吸过程。结果表明,吸附剂的静态吸附容量为7.3 mg/g,镁锂分离因子为27.98;最佳动态吸附条件为床层高度24.8 cm,进料流速3.5 mL/min,此时穿透时间为22.0 min,Li⁺ 吸附率大于95%,饱和时间为210 min,饱和吸附容量达到5.5 mg/g,表明锂吸附剂适合从高镁锂比提锂尾液中回收锂。BDST模型能够准确预测床层穿透时间,误差小于8.61%。使用去离子水进行解吸,增大解吸流速能够加速Li⁺脱出,但对Mg²⁺ 的解吸无明显影响。解吸流速为4.6 mL/min,解吸360 min时,Li⁺ 解吸率为83.25%,总解吸液的镁锂比值为0.7,仅为提锂尾液(80)的0.88%。循环20次后吸附容量仍能保持原来的82%以上,表明锂吸附剂循环稳定性良好。     

干旱胁迫下钠复合肥对霸王(Zygophyllum xanthoxylum)根系生长的促进作用

霸王(Zygophyllum xanthoxylum)是荒漠区广为分布的一种多浆旱生植物。采用盆栽育苗的方法,初步评价了干旱胁迫下Na+对霸王根系生长的贡献,探讨了一种新型钠复合肥对霸王根系形态、生理学指标的影响。结果显示,钠复合肥能显著促进霸王根系的生长并提高其抗旱性:(1)正常浇水时,钠复合肥对霸王的促进作用主要体现在株高的增加和侧根的增长上,根系活力显著增强;(2)自然干旱15d后,钠复合肥使得霸王根系活跃吸收面积显著提高24%,促进主根的加粗和伸长以吸收更多的水分和矿质养分;(3)干旱胁迫下,钠复合肥处理使霸王根部Na+浓度保持较高水平,K+浓度下降42%。因此认为,干旱前钠复合肥显著促进了霸王侧根的生长和根系活力的提高,干旱后钠复合肥通过促进根系活跃吸收面积的扩大和主根的生长以提高霸王的抗旱性,其主要原因是根和叶中积累了较多的Na+、而非K+。