Electrical analogue studies of the influence of soil compaction and smear in the vicinity of a pipe drain on drain performance

Abstract

An electrical analogue has been constructed to examine the influence on water-table behaviour of local impermeabilities caused during installation, near a pipe drain, under steady state discharge conditions. Compaction beneath the pipe and smear alongside the drain are shown to increase the water-table height. Smear beside the drain is found to have greater effect than compaction beneath the drain which causes minimal rise in water table when limited to less than two drain diameters in width. Any smear beside the pipe combined with base compaction causes a rapid and unacceptable rise in the water table. The use of the analogue has been extended to study the relative benefits afforded by smear alleviation both above and beside the pipe. Removal of vertical smear above the pipe soffit reduces water-table height considerably but unacceptable levels still persist. To obtain acceptable water level reduction, smear must be removed immediately adjacent to the pipe.