The pumping test in an unconfined aquifer with and without a low-permeability soil was studied experimentally to reveal the influence of the negative air pressure(NP)caused by the upper layer on the water content(w),t...The pumping test in an unconfined aquifer with and without a low-permeability soil was studied experimentally to reveal the influence of the negative air pressure(NP)caused by the upper layer on the water content(w),the water pressure()w P,as well as on the capillary pressure()c P.The study demonstrates that the NP generated in the vadose zone during pumping in the capper aquifer has a significant influence on w,w P and c P.The c P obtained from the capped aquifer is smaller than that without the upper layer.After the NP reaches a peak,the influence of the NP on c P is gradually declined as the air inflows through the upper layer which makes the NP gradually return to zero.When the air pressure returns to the atmospheric pressure,c P in the vadose zone is only correlated with w P,the same as the case with no upper layer.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.41272251)the Research Grants Council of the Hong Kong Special Administrative Region,China(Grant No.HKU 701908P)
文摘The pumping test in an unconfined aquifer with and without a low-permeability soil was studied experimentally to reveal the influence of the negative air pressure(NP)caused by the upper layer on the water content(w),the water pressure()w P,as well as on the capillary pressure()c P.The study demonstrates that the NP generated in the vadose zone during pumping in the capper aquifer has a significant influence on w,w P and c P.The c P obtained from the capped aquifer is smaller than that without the upper layer.After the NP reaches a peak,the influence of the NP on c P is gradually declined as the air inflows through the upper layer which makes the NP gradually return to zero.When the air pressure returns to the atmospheric pressure,c P in the vadose zone is only correlated with w P,the same as the case with no upper layer.