CONSOLIDATION SETTLEMENT OF RESIDUALLY-DERIVED LATERITIC SOILS FROM PART OF SW NIGERIA

Abstract

Consolidation of lateritic soils and related properties had been the subject of few investigations. Previous studies have evaluated the coefficients of compressibility and consolidation of lateritic soils. Initial results indicated that the soils have considerable strength despite the appreciable clay content. Another report revealed probable differential settlement of small magnitude if employed as foundation materials. As a result, there has been a growing interest to investigate settlement effects of lateritic soils. The present investigation focuses on the how total settlement is influenced by complexity and heterogeneity of lateritic soils. The studied soils were developed over the Precambrian, migmatised gneisses of the Basement Complex of Southwestern Nigeria.

 Physical model tests out on 12 disturbed and 12 undisturbed soil samples were carried out following the BS Part 2 and Part 8, 1337, IS: 2720 Part 15 and ASTM Designation 4767-11. Results show that the soils contain a variety of particle sizes, with clay and sand being the dominant fractions. They also exhibit very low permeability, low to medium plasticity and cohesive strength range of 20 - 95 kN/m². The total settlement values are not in any definite order with depth, but increases with increase in confining pressure. They range between 0.31 and 1.125mm at 800kN/m². It is apparent that the tolerable settlements of different structures on the soils vary considerably, which may result to misalignment from foundation settlements causing structural damage to a building frame nuisance.