Abstract:
Studies were conducted in a glass-sided laboratory soil bin. Soil deformation patterns were analysed for failure
angle, soil wedges and forward rupture and surcharge profiles. They were also observed for purposes of
correlation with the corresponding soil reactions. Forward rupture profiles were determined by using two parallel
scales and a measuring scale while soil surcharge profiles were determined with the use of a three-way coordinate
measuring system. Soil reactions (horizontal and vertical) from two identical tines (glass-sided and central) were
measured by L-shaped force transducers while a ten-turn potentiometer recorded the forward speed. The data
was amplified, logged and transferred to a computer for saving and further processing. Observed cyclic variations
in the force-time curves of the soil reactions were analysed in terms of wave length, peak to trough ratio and
amplitude. The behaviour and magnitudes of forces caused by flat rigid tines (inclined at an angle of 50 deg. to the
horizontal soil surface measured in a clockwise direction) in loam soil below the liquid limit were studied using a
glass-sided soil bin. The tines were moved in the soil bin in a quasi-static condition and the deformation observed
through the glass. Three moisture content levels (5.2%, 21% and 33.5% (d.b.)) were used. The results under the
above conditions indicated that soil reactions (horizontal and vertical) were cyclic in nature and in phase as
observed from the force-time curves and matched quite well with the soil deformation characteristics. Soil force
magnitudes for 5.2% and 21% moisture contents were basically the same in all aspects while those for 33.5% were
relatively higher but with dying off cyclicity. Correlation of these observations with previous research showed that
soil moisture content has a strong effect on force deformation and force characteristics.
