Mechanistic-empirical permanent deformation models: Laboratory testing, modelling and ranking

Abstract

© 2020 Elsevier Ltd Geomaterials exhibit elastoplastic behaviour during dynamic and repeated loading conditions. These loads are induced by the passage of a train or vehicle which then generates recoverable (resilient) deformation and/or permanent (plastic) deformation. Modelling this behaviour is still a challenge for geotechnical engineers as it implies the understanding of the complex deformation mechanism and application of advanced constitutive models. This paper reviews on the major causes of permanent deformation and the factors that influence the long-term performance of materials. It will also present the fundamental concepts of permanent deformation as well as the models and approaches used to characterise this behaviour, including: elastoplastic models, shakedown theory and mechanisticempirical permanent deformation models. This paper will focus on the mechanistic-empirical approach and highlight the evolution of the models, and the main similarities and differences between them. A comparison between several empirical models as well as the materials used to develop the models is also discussed. These materials are compared by considering the reference conditions on the type of material and its physical state. This approach allows for an understanding of which properties can influence the performance of railway subgrade and pavement structures, as well as the main variables used to characterise this particular behaviour. An innovative ranking of geomaterials that relate to the expected permanent deformation and classification (UIC and ASTM) of soil is also discussed because it can be used as an important tool for the design process. Disciplines Disciplines Engineering | Science and Technology Studies

Resilient Response of Cement-Treated Coarse Post-Glacial Soil to Cyclic Load

“…In future research, we plan to perform tests with a greater number of repetitions of cyclic loads in order to determine the accumulated permanent strain and to classify the tested geomaterials in terms of shakedown theory [40][41][42].…”

A geomechanics classification for the rating of railroad subgrade performance

“…To predict permanent deformation, several approaches were proposed: numerical simulations using elastoplastic models, shakedown theory or mechanistic-empirical permanent deformation models based on laboratory tests such as cyclic triaxial tests or the hollow cylinder tests [19]. Throughout the analyses presented by these authors, more emphasis is given to the mechanistic-empirical permanent deformation models from the laboratory testing until the modelling.…”

“…The comparison regarding the permanent deformation models was already presented in the work developed by [19]. As in the previous exercise, in this parametric study, the authors attempted to compare different permanent deformation models available for different types of soils considering the empirical permanent deformation model developed by [76].…”

“…In the work developed by [19], the ranking process is described. The final ranking is depicted in Fig.…”

“…This means that this analysis also includes external factors as the physical state of the soil, which is often difficult to control because it depends on other environmental aspects. A first attempt was already performed for permanent deformation models in the work developed by [19]. Consequently, this work intends to complement it with the resilient deformation models, including comparisons among some of the selected models that are based on different materials with different classifications (UIC and ASTM), properties, granulometry and physical states.…”