Evaluation of the hydraulic conductivity of aquifers with piles

Distributed piles are often installed in the foundation pit in sandy soil before dewatering. Hydraulic conductivity should be estimated considering the block effect of piles on groundwater seepage. Research shows that the effective medium theory (EMT) could be used to calculate the equivalent hydraulic conductivity (k _eq) of a heterogeneous medium with other material inclusions. In order to verify the applicability of EMT in an aquifer with piles, an experimental investigation is conducted. In this experiment, a sandy soil is considered as an aquifer and polyvinylchloride pipes are adopted as piles. Piles are distributed in rectangular and triangular layouts. The relationship between k _eq of the aquifer and the volume replacement ratio is plotted for these two layouts. The results indicate that EMT could well predict k _eq for the cases with the rectangular layout; however, for triangular layouts, the prediction becomes poor. To provide a better prediction of k _eq of the aquifer with piles distributed in a triangular layout, a modified EMT (MEMT) is proposed, in which a correction factor is adopted considering different layouts of piles. The MEMT can provide better k _eq predictions for an aquifer with piles in the triangular layout pattern than those obtained using the EMT.