Geotechnical Engineering

DHARM

728 GEOTECHNICAL ENGINEERING

(a) Post-hole auger (b) Helical auger

Fig. 18.1 Soil augers

Wash Boring

Wash boring is commonly used for exploration below ground water table for which the auger
method is unsuitable. This method may be used in all kinds of soils except those mixed with
gravel and boulders. The set-up for wash boring is shown in Fig. 18.2.

Swivel

Water hose

Pulley Tripod

Rope

To motor

Winch

Settling

tank Suction pipe

Casing

Sump

Hollow drill rod

Water flow

Chopping bit

(replaced by sampling spoon during sampling operations)

Pump

Fig. 18.2 Set-up for Wash Boring