01590065

Component

Pavement’s performance and robustness depend on the resilience behavior of the multilayer subgrade system. Often, this resilience behavior of unsaturated subgrade is sensitive to the moisture influx occurring from seasonal changes and applied stress. Accurate assessment of this behavior is cumbersome, time consuming and costly. Several models are available in the literature to predict the modulus behavior of unsaturated subgrade. The main objective of this research is to conduct experimental study on diverse subgrade materials and evaluate three prediction models: Modified universal model, Cary and Zapata (2010) model and Siekmeier (2011) model. For this study, the subgrade materials are collected from three different states, Minnesota, Mississippi, and Louisiana, after which they were named. The effect of moisture content and unit weight on the resilient modulus properties of the subgrades is investigated by preparing the soil specimens at five different moisture contents and dry unit weight conditions along their proctor curve. Soil-water characteristic curves (SWCCs) for these test specimens were determined using pressure cell method and filter paper technique. Once compacted and desired matric suction equilibrium is achieved for each test sample, conventional resilient modulus (M sub R) tests were performed as per AASHTO T-307-99 standard procedure. From the test results, it can be observed that the compaction moisture content has significant effect on the values of M sub R of the subgrade soils. Maximum resilient modulus is observed for the specimens compacted on the dry side of optimum moisture content (OMC) and with high initial matric suction. Test results were utilized to validate modulus prediction models prominently used. Initial analysis showed high variability in prediction and measured data of the M sub R values. Modification to the arbitrary coefficients in each model using regression analysis, helped in very close predictions to the subgrade material’s unsaturated resilient modulus behavior.

This paper was sponsored by TRB committee AFP60 Standing Committee on Engineering Behavior of Unsaturated Soils.

01584066

16-4214

English

20p

2016

Transportation Research Board 95th Annual Meeting

Digital/other

Figures; Photos; References; Tables

Mathematical models; Mathematical prediction; Modulus of resilience; Moisture content; Pavement design; Regression analysis; Subgrade (Pavements); Unsaturated soils

Matric suction; Soil water characteristic curve

Design; Highways; Pavements; I22: Design of Pavements, Railways and Guideways

Transportation Research Board Annual Meeting 2016 Paper #16-4214

PRP, TRIS, TRB, ATRI

Jan 12 2016 5:52PM