Geotechnical properties of peat and related engineering problems.

摘要

Peats are soils of large initial water content, initial permeability, compressibility and low undrained shear strength. The purpose of this study was to gain a better understanding of peat behavior, and to investigate the similarities and differences between peats and mineral soils in terms of sampling, specimen preparation, method of testing, test results, and the methods of interpretation of the measurements. This study used the general experience gained through many decades of thorough research on mineral soils at the University of Illinois at Urbana-Champaign.;An extensive laboratory testing program was conducted on undisturbed samples from two peat deposits from Middleton, Wisconsin and James Bay, Quebec, Canada for the purpose of studying the geotechnical properties of peats. Additionally, a study of the literature on the geology and geotechnical properties of peats was conducted. This research program included the study of compressibility and permeability of peats, consolidation theories for peats, applicability of the uniqueness of EOP e-log for peats, secondary compression of peat, surcharging to reduce secondary compression in peat, and shear strength of peat. Eighty seven consolidation tests and eleven shear strength tests were performed.;Data on specific gravity, initial water content and initial void ratio, preconsolidation pressure, compression index, recompression index, secondary compression index, coefficient of consolidation, coefficient of permeability, and at rest earth pressure were obtained. Additionally, data collected from literature were incorporated with the results of this research. A detailed interpretation was carried out on the uniqueness of EOP e-log s'v for peat, the applicability of consolidation theories suggested by different authors to model time-rate of primary compression and time-rate of porewater pressure dissipation for peats, the applicability of the C alpha/Cc law of compressibility concept to peat, as well as shear strength aspects of peat.;Among the results of this research, complete sets of geotechnical properties of Middleton and James Bay peats were obtained. Such results will provide an idea about the order of magnitude of geotechnical parameters as well as the behavior of these parameters under changing conditions and with time. (Abstract shortened by UMI.).