To assess the suitability of as-dug soft chalks for use as backfills to reinforced earth structures, an experimental structure was built at Paulsgrove Quarry Portsmouth. Three locally available chalks having saturation moisture contents of up to 29 per cent and two proprietary reinforcing systems were incorporated into the structure. Piezometers and thermocouples were installed to measure the pore water pressures and temperatures within the chalk backfills respectively, and movements of the structure were determined both during and after construction. A series of pull-out tests were also undertaken and a trial heading was excavated to confirm that a few low pull-out values were associated with inadequate compaction of the chalk backfills. The results of this study showed that soft chalks can be used successfully as backfills to such structures provided that close control is exercised on their placing and compaction.
Abstract