A Study on Secondary Compression of Compacted Fine-Grained Soils

Abstract

A manifestation of the effects of structural mechanics is the relationship linking the structure of soil and mechanical behavior. Compaction is a mechanical process modification of soil structure by the expulsion of pore air from the voids, whereas consolidation is a process of expulsion of pore water pressure in which settlement takes place. Secondary compression generally happens after the end of primary consolidation may demonstrate a steady decrease or increase over a substantial period. In order to calculate long-term foundation deformation, understanding the impact of secondary compression is fundamental. Foundation failures can happen by either shear failure or settlement failure, whereas shear failure is instantaneous and settlement failure occurs over a while. Depending on the magnitude and demographic location of the structure, the permissible settlement of the structure should not settle more than 25 and 40 mm allowable as per IS guideline to minimize distress to the foundation. The present experimental study is made on five field soils, and two soils having a liquid limit of 55% and another three soils of 68% of a liquid limit have been also considered. These soils were subjected to IS light and heavy compaction energy levels and static compaction to attend the desired compaction characteristics and achieve the required OMC and MDD; additionally, soils were subjected to a one-dimensional consolidation test from a seating load of 6.25–1600 kPa through a load increment ratio of 1 for different placement conditions. The variation of void ratio with pressure for the soil having a different clay mineralogy for different placement conditions was analyzed. Correlations were developed between pressure and the magnitude of secondary compression, for soils having different clay mineralogy.