Estimation of Pre-consolidation Stress of Compacted Fine-Grained Soils—By User-Friendly Methods

Abstract

Over consolidated natural soils exhibit characteristic stress, known as pre-consolidation stress (σ_p¹) which represents the maximum stress to which the soil has been subjected in the past. The soil used in various geotechnical mass applications like earthen embankments, dam, etc., will be subjected to some specified compactive effort which is akin to over consolidation. Hence, compacted soils are also expected to possess a characteristic stress similar to preconsolidation stress of over-consolidated natural soils. Compacted fine-grained soil application for civil engineering applications is becoming more vital role to non-availability of coarse-grained soils at large. The engineering behaviour of fine-grained soils becomes more complex because of the presence of different clay minerals in various proportions. The present experimental study aims to study the variation of pre consolidation stress of compacted fine-grained soils having same liquid limit, different plasticity characteristics and clay mineralogy subjected to light and heavy compaction energy levels. An attempt has been made for the detailed study of the variation of preconsolidation stress by five user-friendly methods documented in the literature with placement conditions, clay minerology and compaction energy levels. Very interesting observations were made with respect to variation of preconsolidation stress with clay mineralogy, compaction energy levels and placement conditions. Useful correlations were also developed for the estimation of preconsolidation stress with particular reference to the method of determination of σ_p¹ and engineering behaviour like compaction characteristics. The study also highlights the role of clay minerology on pre-consolidation stress and placement condition.