摘要
本试验设计3个来自Armagosa沙漠研究站的相似原状土柱在基模势为0、-2、-5、-10cm水头状态下,分别进行保守溶质置换试验,获取12条溶质穿透曲线。改进的特征半径指数用于定量分离各基模势区间,并计算有效水力传导孔隙度描述大空隙流的变化过程。同时,基于对流扩散方程(CDE)的确定性双区模型用于拟合各个状态下溶质运动的特征参数。试验结果显示,改进后的特征半径指数和大孔隙有效传导空隙度能很好定量大空隙流变化。在大空隙流发生时,溶质运移主要受到大空隙流对流作用影响,机械弥散作用变化不大。随着大空隙流的衰减,大空隙流与基质流的侧向交换过程逐渐成为溶质穿透过程的主要影响因素。大空隙流发生与基模势的关系有利于进一步分离研究土壤非均质流与溶质交互过程。
To focus on analyzing and evaluating the macro-pore flow affecting the transport of refilled contaminants in Armagosa desert soil, the quantification research between soil potential and macropore flow should be understood, and distinguish the influence of preferential flow affecting on solute transport in porous media. Three undisturbed soil columns from Armagosa Desert Research Site （ADRS） were designed for conducting Br displace experiments in laboratory at various matric heads, such as 0, -2, -5, and -10cm as 12 breakthrough curves （BTC） were obtained. A modified representative mean pore radius （MRMPR） was applied to separate the effective hydraulic porosity （EHP） among different matric potential ranges. The deterministic two-region model based on convection-dispersion equation （CDE） was utilized to simulate solute transport at different steady states. The results showed that MRMPR and EHP can be used to quantitatively analyze the change of macro-pore flow and to estimate the generation of macro-pore flow with the help of hydraulic contributions. When macro-pore flow occurred, the solute transport was mainly controlled by water convection while the mechanical dispersivity changed a little. With the decrease of macro-pore flow, the lateral exchange between matric flow and macro-pore flow became crucial factors influencing the solute transport. The relationship between macro-pore flow and matric potential was in favor of investigating mutual processes among heterogeneous flow in soil.
出处
《水利学报》
EI
CSCD
北大核心
2010年第8期927-934,共8页
Journal of Hydraulic Engineering
基金
教育部长江学者和创新团队发展计划(IRT0717)
国家自然科学基金(50979022)
四川大学国家重点实验室开放课题(SKLH-OF-0807)
