Subgrade Improvement by Sand Compaction Pile

Abstract

Expansive soil becomes soft on wetting and losses its strength, resulting in differential settlement. Vast areas, particularly coastal regions, are covered with thick soft clay deposits having very low shear strength posing difficulty to use as subgrade. Such soils were avoided or proper soil improving techniques need to be adopted. Ground improvement techniques are normally preferred for economy and one of which is Sand Compaction Pile (SCP) method. SCP is widely adopted to improve weak/lose ground to achieve adequate bearing capacity and reduce the settlement. In this study the load carrying capacity of soft clay with and without compaction pile by M sand is tested using CBR test. Also, the effect of variation in the pattern of installation and spacing between the piles on the load-settlement behavior was examined. The test results indicate that compaction piles decreases the subgrade settlement and the triangular pattern with 2.5D spacing is most the effective technique. The permeability results reveal an added advantage of SCP, by draining the moisture that might have clogged between the subgrade and base course.