Mechanistic Modeling of Unbound Granular Materials

Mechanistic Modeling of Unbound Granular Materials
Author: Bereket Yohannes
Publisher:
Total Pages: 109
Release: 2009
Genre: Granular materials
ISBN:

Several tests are used for characterizing unbound granular materials for pavement applications. The California Bearing Ratio (CBR), resilient modulus (MR), Dynamic Cone Penetrometer (DCP) tests are three of the most common tests used for this purpose. The objective of this research is twofold. The first is to develop numerical models for these three tests. The second is to investigate relationship between basic material properties, boundary conditions, and test results, ultimately, to develop a physics-based correlation between these tests. A 3-D discrete element method (DEM) based model is adapted to simulate these tests. Good agreement is observed between the results of the simulations and sample numerical and experimental studies on granular materials. The DEM code is used to determine effects of aggregate shape, coefficient of friction, gradation, stiffness and other details on test results. The model is also used to investigate statistics of inter-particle interaction between the granular particles.

A Structural Material Model for Granular Bases

A Structural Material Model for Granular Bases
Author:
Publisher:
Total Pages:
Release: 1997
Genre:
ISBN:

Techniques typically used in mechanistic analyses to characterize the behavior of unbound granular materials in a flexible pavement often predict stress conditions exceeding the material's static strength. Some pavement analysis tools such as ILLI-PAVE attempt to adjust predicted stresses in unbound layers so that they do not violate the Mohr-Coulomb failure envelope. However, the adjusted stresses are used only to calculate the resilient modulus to be used in the next iteration of the model, resulting in final stresses that are questionable and that frequently exceed the material's strength. Laboratory resilient modulus tests were conducted on granular at stress states exceeding the material's static shear strengths. Based on the data obtained, a material model for unbound granular material was developed that is a modification of the commonly used k-theta-n model for unbound granular materials. In addition, an advantage of the modified model is the ability to analyze the structural effects of granular materials having different shear strength characteristics. For the covering abstract of this conference see IRRD number 872978.

Mathematical Modeling in Mechanics of Granular Materials

Mathematical Modeling in Mechanics of Granular Materials
Author: Oxana Sadovskaya
Publisher: Springer Science & Business Media
Total Pages: 396
Release: 2012-06-08
Genre: Technology & Engineering
ISBN: 3642290531

This monograph contains original results in the field of mathematical and numerical modeling of mechanical behavior of granular materials and materials with different strengths. It proposes new models helping to define zones of the strain localization. The book shows how to analyze processes of the propagation of elastic and elastic-plastic waves in loosened materials, and constructs models of mixed type, describing the flow of granular materials in the presence of quasi-static deformation zones. In a last part, the book studies a numerical realization of the models on multiprocessor computer systems. The book is intended for scientific researchers, lecturers of universities, post-graduates and senior students, who specialize in the field of the deformable materials mechanics, mathematical modeling and adjacent fields of applied and calculus mathematics.

Advances in Transportation Geotechnics

Advances in Transportation Geotechnics
Author: Ed Ellis
Publisher: CRC Press
Total Pages: 786
Release: 2008-08-01
Genre: Technology & Engineering
ISBN: 0203885945

Highways provide the arteries of modern society. The interaction of road, rail and other transport infrastructure with the ground is unusually intimate, and thus needs to be well-understood to provide economic and reliable infrastructure for society. Challenges include not only the design of new infrastructure (often on problematic ground), but inc

Pavements Unbound

Pavements Unbound
Author: Andrew Dawson
Publisher: CRC Press
Total Pages: 388
Release: 2014-09-01
Genre: Technology & Engineering
ISBN: 9781439833803

Nearly all highway, airport, dock and industrial pavements contain large quantities of untreated aggregate in the form of unbound pavement layers. In many pavements, which are lightly or moderately trafficked, crushed rock or gravel derived aggregates comprise the majority of the construction or, in the case of unsealed pavements, all of the structure. This book provides studies of the performance and description of this material that will help the reader to better understand its characteristics and behaviour both alone and as part of the pavement structure it forms. This work will be useful to practitioners, policy makers, researchers and students. It forms a sequel to the earlier book "Unbound Aggregates in Road Construction" also published by Balkema

Modelling of the Resilient and Permanent Deformation Behaviour of Subgrade Soils and Unbound Granular Materials

Modelling of the Resilient and Permanent Deformation Behaviour of Subgrade Soils and Unbound Granular Materials
Author: Haithem Soliman
Publisher:
Total Pages: 0
Release: 2015
Genre:
ISBN:

Laboratory characterization of subgrade soils and unbound granular materials is an essential component of the Mechanistic-Empirical Pavement Design Guide (Pavement ME). The design thickness and performance of a pavement structure are highly dependent on the deformation behaviour of subgrade and granular material. Specifications for granular materials vary among transportation agencies based on the availability of materials, climatic conditions, and function. Specifications aim to provide durable materials that meet design requirements and achieve the target design life with cost effective materials. The objectives of the research are to: • evaluate resilient modulus of typical fine-grained soils under traffic loading. • evaluate resilient modulus, permanent deformation, and permeability of typical unbound granular materials. • evaluate the effect of moisture and fines fraction on the performance of unbound granular materials and subgrade soil. • develop prediction models for resilient modulus to improve reliability of Level 2 inputs in the Pavement ME. • provide test data in support of updating Manitoba Infrastructure and Transportation specifications for unbound granular materials to improve the performance of pavement structures. Resilient modulus tests were conducted on three types of subgrade soil (high plastic clay, sandy clay, and silty sand/sandy silt) at four levels of moisture content. Resilient modulus, permanent deformation and permeability tests were conducted on six gradations representing two types of granular material (100% crushed limestone and gravel) at two levels of moisture content. Prediction models were developed for resilient modulus and compared to the models developed under the Long Term Pavement Performance program. The proposed models provided more reliable predictions with lower root mean square error. The deformation behaviour of the granular materials was classified according to the shakedown and dissipated energy approaches. Among the tested fines contents, limestone and gravel materials with optimum fines contents of 4.5% and 9%, respectively, had better resistance to plastic deformation and higher resilient modulus. The dissipated energy approach can be used to determine the stress ratio for the boundary between post compaction and stable zones from multistage triaxial testing. Result of permeability tests showed that the hydraulic conductivity of unbound granular material increased as the fines content decreased.

Geotechnics for Transportation Infrastructure

Geotechnics for Transportation Infrastructure
Author: Ravi Sundaram
Publisher: Springer
Total Pages: 702
Release: 2019-05-30
Genre: Science
ISBN: 9811367019

This book presents selected papers from the International Symposium on Geotechnics for Transportation Infrastructure (ISGTI 2018). The research papers cover geotechnical interventions for the diverse fields of policy formulation, design, implementation, operation and management of the different modes of travel, namely road, air, rail and waterways. This book will be of interest to academic and industry researchers working in transportation geotechnics, as also to practicing engineers, policy makers, and civil agencies.