Description Of Stress-strain Behavior For Overconsolidated Clays Considering Temperature Effects

The engineering properties of clays are affected a lot by temperature change.The effects of temperature on the stress-strain behavior of clays have been studied with more attention in recent years,which has important theoretical and practical significance.This paper summarizes the effects of temperature on the mechanical behavior of clays first.The influences of temperature on the mechanical behavior of saturated clays are discussed.Based on the concept of true strength and the revised calculation method of the potential failure stress ratio,the equation of the critical state stress ratio for saturated clays under different temperatures is deduced.The naturally deposited clays generally exhibit overconsolidated characteristic.Compared with normally consolidated clays,overconsolidated clays have lower void ratio,higher strength and show dilatancy and softening behavior.Temperature is introduced as a variable into the UH model.The UH model considering temperature effects,which is proposed by studying the stress-strain characteristics of overconsolidated clays and UH(Unified Hardening)model,is developed to a model for both normally consolidated clays and overconsolidated clays.By means of the transformed stress method proposed by Yao et al.,the proposed model can be applied conveniently to three-dimensional stress states to describe the deformation of clays under triaxial compression,extension and true triaxial condition.The strain-hardening,softening and dilatancy behavior of overconsolidated clays at a given temperature can be described using the proposed model,and the volume change behavior caused by heating can also be predicted.Compared with the modified Cam-clay model,the proposed model requires only one additional parameter to consider the behavior of the decrease of preconsolidation pressure with an increase of temperature.At room temperature,the proposed model can be changed into the original UH model and the modified Cam-clay model for overconsolidated clays and normally consolidated clays,respectively.The considered temperature range here is from the melting point to the boiling point of the pore water(e.g.the experimental temperatures(20?~95?)mentioned in this paper are within this range).Comparison with existing test results shows that the model can reasonably describe the basic mechanical behavior of overconsolidated clays under various temperature paths.