地下水含水介质的弥散度测定

以水动力弥散理论为基础,根据改进的水动力弥散装置,以氯化钠作为示踪剂,用电导仪间接地测定溶质的突破曲线,最后用解析法确定地下水多孔介质中溶质迁移的弥散度。     

Laplace变换边界积分方程与Schapery数值反演法模拟溶质运移问题

本文将对流－弥散方程化为纯尔散方程，采用Ｌａｐｌａｃｅ变换，Ｓｃｈａｐｅｒｙ数值反演法求解，通过裕列计算对选取不同的Ｌａｐｌａｃｅ变换参数的计算结果进行比较，分析Ｌａｐｌａｃｅ变换参数对计算精度的影响，给出Ｐ值的选取方法式。     

粘性土壤溶质运移新模型的应用

将Moldrup等提出的模拟水流和溶质运移的运动平均斜率模型和运动浓度斜率模型联合,模拟了重粘土在入渗和蒸发条件下的水盐动态并与特征-有限差分数值模型的计算结果进行了比较。在模拟过程中新模型显示出更加高效的优点,这对粘性土壤地区盐渍化趋势的长期预报具有重要的实际意义。     

裂隙岩体溶质运移模型综述

本文综述了裂隙岩体系统中溶质运移的概念模型和数学模型。分析了目前各种裂隙岩体系统中溶质运移的数学模型的适用性和优缺点，为选取合理的数学模型求解具体的问题提供了参考依据。最后提出了有待进一步研究的问题。     

Reach-Scale Cation Exchange Controls on Major Ion Chemistry of an Antarctic Glacial Meltwater Stream

McMurdo dry valleys of Antarctica represent the largest of the ice-free areas on the Antarctic continent, containing glaciers, meltwater streams, and closed basin lakes. Previous geochemical studies of dry valley streams and lakes have addressed chemical weathering reactions of hyporheic substrate and geochemical evolution of dry valley surface waters. We examine cation transport and exchange reactions during a stream tracer experiment in a dry valley glacial meltwater stream. The injection solution was composed of dissolved Li⁺, Na⁺, K⁺, and Cl^-. Chloride behaved conservatively in this stream, but Li⁺, Na⁺, and K⁺ were reactive to varying degrees. Mass balance analysis indicates that relative to Cl^-, Li⁺ and K⁺ were taken up in downstream transport and Na⁺ was released. Simulations of conservative and reactive (first-order uptake or generation) solute transport were made with the OTIS (one-dimensional solute transport with inflow and storage) model. Among the four experimental reaches of Green Creek, solute transport simulations reveal that Li⁺ was removed from stream water in all four reaches, K⁺ was released in two reaches, taken up in one reach, and Na⁺ was released in all four reaches. Hyporheic sediments appear to be variable with uptake of Li⁺ in two reaches, uptake of K⁺ in one reach, release of K⁺ in two reaches, and uptake of Na⁺ in one reach. Mass balances of the conservative and reactive simulations show that from 1.05 to 2.19 moles of Li⁺ was adsorbed per reach, but less than 0.3 moles of K⁺ and less than 0.9 moles of Na⁺ were released per reach. This suggests that either (1) exchange of another ion which was not analyzed in this experiment or (2) that both ion exchange and sorption control inorganic solute transport. The elevated cation concentrations introduced during the experiment are typical of initial flows in each flow season, which flush accumulated dry salts from the streambed. We propose that the bed sediments (which compose the hyporheic zone) modulate the flushing of these salts during initial flows each season, due to ion exchange and sorption reactions.     

土石混合介质中非反应性阴离子运移试验研究

为探讨化学物质在土石混合介质中的运移过程和机理,采用饱和稳态流下的Cl-1混合置换试验,测定水流和溶质运移过程,分析土石混合介质的溶质穿透曲线特征及碎石组成和含量对运移过程的影响。选用CXTFIT2.1的平衡和物理非平衡对流弥散模型,对参数弥散系数D和滞留因子R进行反求。结果显示:不同土石比的D变异较大:0.258~22.31 cm2/h。R的波动范围为0.6~1.54;碎石含量影响土石介质的溶质运移过程表现为平均孔隙流速、弥散系数、弥散度均与土石比成负指数的幂函数关系。对碎石粒径与溶质运移参数进行相关分析发现,小粒径的碎石含量增加,则孔隙流速和弥散系数有减少的趋势,而大于10 mm的碎石有利于溶质的运移。通过土石介质的非反应性阴离子的混合置换试验研究,可以为非均一介质中化学物质运移提供参考。     

深基坑底板地层压力注浆设计与施工实践

结合常德市第一人民医院门急医技大楼的工程实际，介绍了深基坑底板地层压力注浆的机理，探讨了设计过程中几个主要参数的取值，指出了压力注浆的施工方法。     

土壤水分与溶质运移机制的分形理论研究进展

土壤中水分和溶质运移一直是土壤-水环境系统中的研究热点,也是目前仍未得到很好解决的问题.将分形理论应用于土壤水分溶质运移机制的研究,探讨其领域中的众多复杂问题,是一种全新的思路和方法.在对土壤结构定量化的分形表征进行简要阐述的基础上,重点介绍了分形理论在水分特征曲线和水力传导度等土壤水分运动基本参数的分形模型、土壤水分运移过程模拟、土壤溶质运移的非费克现象、弥散度的尺度效应以及溶质运移机制研究方面所取得的一系列成果,并就分形理论今后在土壤水分、溶质运移研究中的应用作了展望.     

内陆单斜构造内咸水入侵淡水含水层三维数值模拟：——以山西柳林？…

本文建立了内陆单斜构造内咸水入侵淡水含水层的三维可混溶溶质运移模型。同时,为了尽可能提高模拟精度,还建立了区域二维水流模型和水质模型,为三维模型提供边界条件。模型应用于描述柳林电厂水源地咸－淡水界面运移特征,模拟效果良好,还据此预报了咸水入侵的可能性并探讨了淡水流的强弱对咸－淡水界面运移的影响。     

非饱和土中溶质迁移参数反演的HISR方法

以非饱和土中溶质迁移参数反演问题为背景, 依据正则化方法的思路, 以Itakura Saito距离作为同伦函数中的平凡问题, 将同伦方法引入非线性参数反演问题的求解, 进而提出一种求解非线性参数反演问题的大范围收敛(HomotoyItakura SaitoRegularization, HISR) 方法.为保证迭代稳定性, 并同时削弱观测噪声的影响, 同伦参数的修正采用了连续化修正方法.本文将HISR方法应用于求解带有平衡及非平衡吸附效应的一维非饱和土中溶质迁移参数反演问题, 计算结果表明HISR方法具有大范围收敛性及计算稳健性, 同时有较强的抵抗观测噪声的能力.