A Laboratory Apparatus to Measure Chemico-Osmotic Efficiency Coefficients for Clay Soils
A Laboratory Apparatus to Measure Chemico-Osmotic Efficiency Coefficients for Clay Soils
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DOI：
10.1520/gtj11343j
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发表时间：
2001-09
影响因子：
1.6
通讯作者：
Michael A. Malusis;C. Shackelford;H. W. Olsen
中科院分区：
文献类型：
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作者：
Michael A. Malusis;C. Shackelford;H. W. Olsen
描述了一种用于测量存在电解质溶液的粘土的化学渗透效率系数ω的实验室装置。化学渗透实验是通过在土壤样品中建立和维持恒定的电解质浓度差，同时防止溶液流过样品来进行的。化学渗透效率系数由测量的压力差推导而来，该压力差是对施加的浓度差的响应。电解质（溶质）的有效扩散系数（D*）和阻滞因子（Rd）也可以通过测量通过试样的扩散溶质质量通量来同时确定，直到达到稳态扩散。对土工合成粘土衬垫试样进行氯化钾溶液处理的实验结果表明，ω的测量可能受到土壤-溶液相互作用以及溶质扩散引起的化学渗透压差变化的影响。因此，应使用稳态时的诱导压差来计算ω。在诱导压差中实现稳态响应所需的时间与实现所有溶质的稳态扩散所需的时间有关，并且可能受到试样边界处循环速率的影响。循环速率应足够快，以尽量减少由于扩散引起的边界浓度变化，但也应足够慢，以允许在较低浓度边界测量溶质质量通量，以评估D*和Rd。
A laboratory apparatus for measuring the chemico-osmotic efficiency coefficient, ω, for clay soils in the presence of electrolyte solutions is described. A chemico-osmotic experiment is conducted by establishing and maintaining a constant difference in electrolyte concentration across a soil specimen while preventing the flow of solution through the specimen. The chemico-osmotic efficiency coefficient is derived from a measured pressure difference induced across the specimen in response to the applied concentration difference. The effective diffusion coefficient (D*) and retardation factor (Rd) of the electrolytes (solutes) also can be determined simultaneously by measuring the diffusive solute mass flux through the specimen until steady-state diffusion is achieved. Experimental results using specimens of a geosynthetic clay liner subjected to potassium chloride solutions indicate that the measurement of ω may be affected by soil-solution interactions, as well as by changes in the induced chemico-osmotic pressure difference due to solute diffusion. As a result, ω should be evaluated using the induced pressure difference at steady state. The time required to achieve a steady-state response in induced pressure difference is related to the time required to achieve steady-state diffusion of all solutes, and may be affected by the circulation rate at the specimen boundaries. The circulation rate should be sufficiently rapid to minimize changes in the boundary concentrations due to diffusion, but sufficiently slow to allow measurement of solute mass flux at the lower concentration boundary for evaluating D* and Rd.