Evaluation of dewatering-induced hydraulic and ground responses of thick multi-aquifer sandy strata without aquitards

Abstract

Abstract Currently, a great number of studies have been conducted to analyze hydraulic performance of the alternated multi-aquifer aquitard system (MAAS); while, few researches on the hydraulic performance of the strata without aquitard were known in literature. Construction of subways in Nantong, a typical costal city located at the estuary area of the Yangtze River and featuring thick water-rich sandy strata, provided a rare chance for this investigation. Based on a series of pumping tests, the hydrological characteristics of the unique full-profile water-rich sandy strata were examined extensively. Both analytical and numerical methods were adopted to analyze the results further. The results indicate that due to the absence of aquitards, there existed a strong hydraulic connection between the aquifers. Apart from the hydraulic parameters, the hydraulic recharge between aquifers has impact on the hydraulic performance as well when pumping was carried out at different burial depths. On the basis of considering the hydraulic performance of aquifers and the hydraulic connection between them, the optimal pumping scheme for underground construction or domestic water use was discussed. The findings of this study provide an insight into the distinctive full-profile water-rich sandy strata and can help engineers adopt appropriate measures to deal with pumping works under similar geohydrology conditions.