A laboratory study of freeze-thaw effects on hydraulic conductivity of kaolin-sand mixtures

Freeze-thaw effects on subgrade soils are of relevance to geotechnical and pavement engineering given the potential for increased road construction in colder regions due to climate change. The freezing and thawing cycles can result in changes to some soil parameters, therefore, for design processes, there is a need to characterize such progressive changes.This paper gives an overview of a laboratory experimental campaign on fine-grained soil and clay-sand mixture soil samples under multiple freezing and thawing cycles. The effects of freezing and thawing conditioning processes on the hydraulic and properties of tested soil samples were investigated. The experimental observations were used to develop transformation models for fine-grained soil and soil mixtures tested

An evaluation of non-linear undrained behaviour in the moderate strain range for fine-grained soils

To select appropriate stress-strain parameters for serviceability limit state calculations, an understanding is needed of the likely variation of stress-strain behaviour within the model displacement mechanism. One approach that may be utilised to investigate variations in stress-strain behaviour is by employing a simple non-linear model (with a small number of physically significant parameters) that simulates experimental measurements of soil stress-strain with reasonable precision. By testing the sensitivity of the model parameters to changes in physical properties that can be expected to be related to them the reliability of different models can be established. Recently, empirical analysis of the published triaxial test database RFG/TXCU-278 identified a significant positive correlation between γ50 and OCR for four test modes (CIUC, CIUE, CKUC and CKUE). In this paper, a new experimental dataset from a programme of reconstituted soil tests on Kaolin and Bothkennar Clay is used to investigate the validity of a simple non-linear model

Comparison of simple stress-strain models in the moderate strain range for fine-grained soils:A review

The prediction of stress-strain behaviour in soils is a problem that can be approached in different ways depending on the design scenario. In some cases, a multi-parameter constitutive model calibrated with non-routine soil tests may be appropriate, for example, where a model has been developed for the relevant soil at a building site subject to complex loading. However, simple characteristic parameters are desirable for examining the variability of soil behaviour especially at regional scales. This paper describes a method of assessing the suitability of simple models for simulating non-linear undrained soil stress-strain behaviour in the moderate strain range. The moderate strain range is defined by a soil strength mobilisation of 20% to 80%. Three simple stress-strain models are compared. A published database of reconstituted triaxial tests is used to evaluate the three models with selected statistical tools that quantify errors associated with the simple model approximation of the relationship between stress and strain. The paper discusses the value of computing the model error and the trade off to make between introducing a greater number of parameters (and tests) for model precision and limiting the complexity of the variability characterisation