科研之友
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摘要
A characterization study was carried out in a 10-m-thick sandfill, formed by hydraulic filling with marine sand, in Singapore. Placement methods and compaction were found to influence hydrostratigraphy. The deepest part of the sandfill consists of a loose sand layer and is overlain by a medium sand layer extending to mean sea level (MSL). At certain locations, a thin silty-sand layer was found. The different layers within the saturated zone were found to have different values for hydraulic conductivity (K) and groundwater flow velocity. Estimates for K increase according to the following sequence of methods: repacked sand column, step-pumping test, grain-size analysis and slug test. Slug tests and grain-size analysis yielded comparable estimates of K. The freshwater lens in the older part of the sandfill is about 2m thicker than in a recently completed area. Comparisons of Ca2+/Cl-, Mg2+/Cl-, K+/Cl- and Cl-/(Cl-+HCO3-) ratios indicate that the chemical composition of the groundwater at shallower depths has probably been altered by mineral dissolution. Weathering of carbonate minerals was found to be a major contributor to the major ions at these depths. The molar ratios approach the value for seawater at greater depths. The groundwater is close to equilibrium with calcite.
- 出版日期2007-12
- 单位南阳理工学院
