Deformations in Soft Clays Depend on Time and Strain-rate

摘要

It is commonly understood that the stress-strain behavior of soils, especially soft clays, is time-dependent. Study of time-dependent behavior is essential for (1) understanding the mechanism and analysis of deformation, pore water pressure responses and failure of soft soils; and (2) the design and construction of geotechnical structures on soft ground. This paper addresses the elasto-viscoplastic deformation of soft clays in terms of a stress, stress-rate, strain, strain-rate constitutive model. It examines several issues associated with the time-dependent stress-strain behavior of soft clays, including definition of a fundamental creep coefficient that is independent of stress level, two-dimensional (axisymmetric) creep deformations, and some aspects of calibration of the creep model. It provides solutions for several projects that produced pore water pressure increments larger than the applied loading. The paper includes information from a number of projects where the model has been successfully applied to practical settlement problems. It considers implications of these issues for analysing the performance of geotechnical structures on soft ground.