Abstract

An experimental study was undertaken to study the principles of soil compaction and establish a relation between the undrained shear strength of compacted clay and its moisture content. Compaction of soil is an important prerequisite for the construction of man-made structures like bridges, roads, dams, embankments etc. In the present study fine grained saturated clay finer than 2 × 10^-6 m were used for all purposes. An important property of cohesive soils is that compaction increases their shear strength and compressibility. The shear strength of clay is the maximum shear stress it can sustain. It is helpful as the common soil failures are due to shear failures (Iannacchione et al., 1994). Undrained condition of clayey soil occurs when pore water pressure of soil changes due to external loading. If the soil is sheared without changing the water content its strength remains the same. During the study the optimum moisture content was analyzed from the compaction curve. Finally, the shear strength curve was drawn for different compaction efforts which clearly showed an exponential decrease in the shear strength of clayey soil with gradual increase in the water content. Factors other than the change in water content and compaction energy were not considered.

Key words: Undrained shear strength, optimum moisture content, dry density, compaction curve.