Subgrade resilient modulus prediction models for coarse and fine-grained soils based on long-term pavement performance data

Abstract

Resilient modulus (M _R) of subgrade soils is the elastic modulus based on the recoverable strain under repeated loads and depends on several factors such as soil properties, soil type and stress states. This paper presents the prediction equations to estimate M _R from a set of soil physical properties for the unified soil classification system soil types namely coarse-grained and fine-grained subgrade soils. Data extracted from long-term pavement performance information management system database for 259 test specimens of reconstituted soil samples from 19 states in New England and nearby regions in the USA and two provinces in Canada were used in this study. Generalised constitutive model consisting bulk stress and octahedral shear stress was used to predict the M _R of subgrade soils by developing equations for the regression coefficients (k-coefficients) in the constitutive model that relates them to various soil properties. Prediction models were developed by conducting multiple linear regression analysis using computer software SAS^®. To verify the prediction models, a set of fresh laboratory M _R tests were conducted on representative New England subgrade soils using AASHTO standards. The laboratory test results show that the developed models predict M _R values fairly well for the soils with their properties values within the range used in developing the prediction models.

Keywords:

• subgrade
• resilient modulus
• regression
• prediction models
• coarse-grained soil
• fine-grained soil

Acknowledgements

The research work reported herein was performed under the Project NETC 02-3 sponsored by the New England Transportation Consortium. The financial support from the Consortium is gratefully acknowledged. Authors are thankful to Connecticut Department of Transportation and Vermont Agency of Transportation for their help in the collection of soil samples for laboratory tests and to Long-Term Pavement Performance (LTPP) Technical Support Services Contractor, Oak Ridge, Tennessee, for providing the LTPP IMS (Information Management System) data CDs. Sincere thanks are also due to Braun Intertec Corporation, MN, for conducting the laboratory tests. This paper, prepared in cooperation with the New England Transportation Consortium, does not constitute a standard, specification or regulation. The contents of this paper reflect the views of the authors who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the views of the New England Transportation Consortium or the Federal Highway Administration.

Notes

^1. Formerly, Graduate Research Assistant, Department of Civil and Environmental Engineering, University of Connecticut, Storrs, CT, USA. [email protected]

Additional information

Notes on contributors

Shraddha Joshi

1. 1. Formerly, Graduate Research Assistant, Department of Civil and Environmental Engineering, University of Connecticut, Storrs, CT, USA. [email protected] 1