Validation of a simple hypoplastic constitutive model for overconsolidated clays
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RESEARCH PAPER
Validation of a simple hypoplastic constitutive model for overconsolidated clays Shun Wang1
•
Wei Wu1
Received: 22 June 2020 / Accepted: 23 October 2020 Ó The Author(s) 2020
Abstract Hypoplastic constitutive models are able to describe history dependence using a single nonlinear tensorial function with a set of parameters. A hypoplastic model including a structure tensor for consolidation history was introduced in our previous paper (Wang and Wu in Acta Geotechnica, 2020, https://doi.org/10.1007/s11440-020-01000-z). The present paper focuses mainly on the model validation with experiments. This model is as simple as the modified Cam Clay model but with better performance. The model requires five parameters, which are easy to calibrate from standard laboratory tests. In particular, the model is capable of capturing the unloading behavior without introducing loading criteria. Numerical simulations of element tests and comparison with experiments show that the proposed model is able to reproduce the salient features of normally consolidated and overconsolidated clays. Keywords Critical state Hypoplastic model Overconsolidation ratio Structure tensor Validation
1 Introduction Overconsolidation is one of the most important factors that significantly influence the mechanical behavior of overconsolidated (OC) clays. Over the past decades, significant progress has been made in the development of constitutive models for predicting overconsolidation behavior of clays [1, 4, 8, 9, 12, 13, 20, 25, 47–49]. One of the main considerations for the evaluation of the models is that the model parameters can be easily obtained from conventional laboratory tests. For this purpose, firstly, the model parameters should possess clear physical meaning, and secondly, the model parameters should be independent of the initial states, such as the initial confining pressure and the initial overconsolidation ratio (OCR). Many elastoplastic models can properly describe the mechanical behavior of OC clays using a set of model parameters. However, model capacity is frequently gained at the sacrifice of simplicity.
& Wei Wu [email protected] 1
Institut fu¨r Geotechnik, Universita¨t fu¨r Bodenkultur Wien, Feistmantelstrasse 4, 1180 Vienna, Austria
As an alternative to the prevailing plasticity theory, the hypoplastic models have gained much attention in the recent years [5–7, 15, 26–28, 30, 34–37, 39, 45]. Benefited from the nonlinear tensorial function, hypoplastic models are able to describe the overconsolidation behavior without resource to the concept in elastoplastic theory such as yield surface, plastic potential, differentiation between elastic and plastic behaviors, and loading criterion [38, 41–44]. Therefore, compared to the elastoplastic models, hypoplastic models are usually characterized by simpler formulations and fewer model parameters. Consequently, the numerical implementation of hypoplastic models is quite straightforward. Hypoplastic models were originall
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