DEFORMATION AND FORCE CHARACTERISTICS CAUSED BY INCLINED TINES IN LOAM SOIL BELOW LIQUID LIMIT

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.