Perimeter Trench Excavations ~ in this method a trench wide
enough for the basement walls to be constructed is excavated and
supported with timbering as required. It may be necessary for
runners or steel sheet piling to be driven ahead of the excavation
work. This method can be used where weak subsoils are
encountered so that the basement walls act as permanent
timbering whilst the mound or dumpling is excavated and the base
slab cast. Perimeter trench excavations can also be employed in
firm subsoils when the mechanical plant required for excavating the
dumpling is not available at the right time.Basement Excavations