COMPRESSIBILITY AND SHEAR STRENGTH CHARACTERISTICS OF IMPACT COMPACTED LACUSTRINE CLAY
Abstract
In this study, the effects of the primary compaction variables on the compressibility and shear strength characteristics of laboratory impact compacted lacustrine clay, both for the short and long term periods, were investigated. The end of construction shear strength and compressibility characteristics were determined from unconsolidated undrained shear strength and consolidation tests on as-compacted samples. The undrained compressive strength can be defined as either a function of the "overconsolidation ratio" (defined in total stress terms) or as a function of dry density, initial degree of saturation, compaction water content and confining pressure. A procedure for the prediction of as-compacted prestress based on the precompaction soil conditions, relevant compaction variables and general soil behavior during compaction is presented. The as-compacted prestress decreases with compaction water content, and increases with compaction energy particularly for dry-of-optimum water content samples. The long term shear strength and compressibility characteristics were investigated by consolidated undrained and drained shear strength tests, and consolidation tests on compacted samples saturated by a back pressure process. The percent volumetric strains are dependent on compaction water content, as-compacted void ratio, as-compacted prestress and confining pressure. Skempton's pore pressure parameter at failure is dependent on the "overconsolidation ratio", compaction water content and as-compacted void ratio. The effective stress strength parameters for the shearing conditions investigated are dependent on the as-compacted void ratio and compaction water content. Using statistical techniques, prediction models were developed for the shear strength and compressibility characteristics investigated. A systematic approach to the prediction of settlement and shearing strength characteristics within an embankment is also presented and illustrated with an example.
Degree
Ph.D.
Subject Area
Civil engineering
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