Permanent deformation parameters of fine – grained tropical soils

2018 ◽  
Vol 20 (7) ◽  
pp. 1664-1681 ◽  
Author(s):  
Antonio Carlos Rodrigues Guimarães ◽  
Laura Maria Goretti da Motta ◽  
Carmen Dias Castro
Keyword(s):  
Permanent Deformation ◽  
Tropical Soils ◽  
Fine Grained ◽  
Deformation Parameters

Effects of Compaction Moisture Content on Permanent Deformation of Soils Subjected to Repeated Triaxial Load Tests

2019 ◽  
Vol 2673 (2) ◽  
pp. 466-476 ◽  
Author(s):  
Caroline Dias Amancio de Lima ◽  
Laura Maria Goretti da Motta ◽  
Francisco Thiago Sacramento Aragão
Keyword(s):  
Moisture Content ◽  
Permanent Deformation ◽  
Tropical Soils ◽  
Asphalt Pavements ◽  
Design Guide ◽  
Compaction Curve ◽  
Triaxial Loads ◽  
Load Tests ◽  
Deformation Tests ◽  
Elastic And Plastic Deformation

Water content is one of the key parameters that can cause variations in the elastic and plastic deformation of pavement layers. More specifically, both the compaction moisture and the post-compaction moisture should be carefully controlled. The objective of this study is to analyze the effects of compaction moisture on the accumulation of permanent deformation when unbound materials are subjected to repeated triaxial loads. The moisture contents were defined according to the compaction curve of each soil, being one above and one below the optimum moisture content which has been typically considered for the design of asphalt pavements in Brazil. The four soils evaluated in the study are commonly used in flexible pavements and have different classifications according to the Brazilian Miniature, Compacted, Tropical (MCT) methodology tailored to classify tropical soils. Specimens were subjected to permanent deformation tests and the results obtained show that the moisture content can significantly affect the mechanical behavior of soils. That effect is significant on both sides of the compaction curve, but the permanent deformation increases as the compaction moisture content increases on the wet side. This work is part of a broader and comprehensive research project in progress in Brazil to continuously update the current version of the Brazilian mechanistic-empirical pavement design guide. The proper understanding and characterization of the resistance to permanent deformation of unbound materials is a key part of that design guide.

Effect of Severe Plastic Deformation in Machining Elucidated via Rate-Strain-Microstructure Mappings

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
S. Shekhar ◽  
S. Abolghasem ◽  
S. Basu ◽  
J. Cai ◽  
M. R. Shankar
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Strain Rate ◽  
Deformation Zone ◽  
Fine Grained ◽  
Orthogonal Machining ◽  
Deformation Parameters ◽  
Strain And Strain Rate ◽  
One To One ◽  
Surface Microstructures

Machining induces severe plastic deformation (SPD) in the chip and on the surface to stimulate dramatic microstructural transformations which can often result in a manufactured component with a fine-grained surface. The aim of this paper is to study the one-to-one mappings between the thermomechanics of deformation during chip formation and an array of resulting microstructural characteristics in terms of central deformation parameters–strain, strain-rate, temperature, and the corresponding Zener–Hollomon (ZH) parameter. Here, we propose a generalizable rate-strain-microstructure (RSM) framework for relating the deformation parameters to the resulting deformed grain size and interface characteristics. We utilize Oxley’s model to calculate the strain and strain-rate for a given orthogonal machining condition which was also validated using digital imaging correlation-based deformation field characterization. Complementary infrared thermography in combination with a modified-Oxley’s analysis was utilized to characterize the temperature in the deformation zone where the SPD at high strain-rates is imposed. These characterizations were utilized to delineate a suitable RSM phase-space composed of the strain as one axis and the ZH parameter as the other. Distinctive one-to-one mappings of various microstructures corresponding to an array of grain sizes and grain boundary distributions onto unique subspaces of this RSM space are shown. Building on the realization that the microstructure on machined surfaces is closely related to the chip microstructure derived from the primary deformation zone, this elucidation is expected to offer a reliable approach for controlling surface microstructures from orthogonal machining.

Using Transverse Profile Data to Compute Plastic Deformation Parameters for Asphalt Concrete Pavements

2000 ◽  
Vol 1716 (1) ◽  
pp. 89-97 ◽  
Author(s):  
Hesham A. Ali ◽  
Shiraz D. Tayabji
Keyword(s):  
Plastic Deformation ◽  
Prediction Models ◽  
Time Series Data ◽  
Permanent Deformation ◽  
Extended Period ◽  
Series Data ◽  
Profile Data ◽  
Actual Performance ◽  
Deformation Parameters ◽  
Transverse Profile

Previous studies have shown that the performance of in-service pavements may deviate significantly from that predicted by use of laboratory-calibrated performance models. Therefore calibration of performance prediction models with data from in-service pavements is important. Calibration of mechanistic rutting models by use of transverse profile data is explored. A well-known family of mechanistic rutting prediction models uses plastic deformation parameters [slope of elastic or plastic strain (or both) and load hardening factor] for quantification of the amount of permanent deformation resulting from each load application. For the purpose of obtaining these parameters, two traditional methods have been used: repeated load testing in the laboratory and calibration by use of time-series data from in-service pavements. Although the first suffers from the lack of compatibility between laboratory-predicted and actual performance, the second requires collection of field data for an extended period of time (years of monitoring) and may be interrupted by rehabilitation activities. The transverse profile contains valuable information that can be used for determining the contribution of each pavement layer to the observed rutting and the plastic deformation parameters. Transverse profile data were used for calibration of rutting prediction models. The stability and sensitivity of the computed parameters were also investigated.

scholarly journals Evaluation of Permanent Deformation of Unmodified and Rubber-Reinforced SMA Asphalt Mixtures Using Dynamic Creep Test

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Herda Yati Katman ◽  
Mohd Rasdan Ibrahim ◽  
Mohamed Rehan Karim ◽  
Nuha Salim Mashaan ◽  
Suhana Koting
Keyword(s):  
Creep Test ◽  
Creep Behaviour ◽  
Permanent Deformation ◽  
High Stress ◽  
Crumb Rubber ◽  
Asphalt Mixtures ◽  
Creep Model ◽  
Deformation Parameters ◽  
Dynamic Creep ◽  
C 50

This paper presents the evaluation of permanent deformation of rubber-reinforced SMA asphalt mixtures by using dynamic creep test. The effect of trans-polyoctenamer as a cross-linking agent in permanent deformation of rubberized mixtures was also evaluated. Dynamic creep test was conducted at different stress levels (200 kPa, 400 kPa) and temperatures (40°C, 50°C). Permanent deformation parameters such as dynamic creep curve, ultimate strain, and creep strain slope (CSS) were used to analyse the results. Finally, the creep behaviour of the specimens was estimated by the Zhou three-stage creep model. The results show that crumb rubber and trans-polyoctenamer significantly affected the parameters especially at high stress and temperatures. Consistent findings were observed for all permanent deformation parameters. Moreover, based on Zhou model, it was concluded that resistance to permanent deformation was improved by application of crumb rubber and trans-polyoctenamer.

scholarly journals Inverse Parametric Analysis of Seismic Permanent Deformation for Earth-Rockfill Dams Using Artificial Neural Networks

2012 ◽  
Vol 2012 ◽  
pp. 1-19 ◽  
Author(s):  
Xu Wang ◽  
Fei Kang ◽  
Junjie Li ◽  
Xin Wang
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Parameter Identification ◽  
Permanent Deformation ◽  
Three Dimensional ◽  
Analysis Model ◽  
Neural Network Models ◽  
Bp Network ◽  
Deformation Parameters ◽  
Artificial Neural

This paper investigates the potential application of artificial neural networks in permanent deformation parameter identification for rockfill dams. Two kinds of neural network models, multilayer feedforward network (BP) and radial basis function (RBF) networks, are adopted to identify the parameters of seismic permanent deformation for Zipingpu Dam in China. The dynamic analysis is carried out by three-dimensional finite element method, and earthquake-induced permanent deformation is calculated by an equivalent nodal force method. Based on the sensitivity analysis of permanent deformation parameters, an objective function for network training is established by considering parameter sensitivity, which can improve the accuracy of parameter identification. By comparison, it is found that RBF outperforms the BP network in this problem. The proposed inverse analysis model for earth-rockfill dams can identify the seismic deformation parameters with just a small amount of sample designs, and much calculation time can be saved by this method.

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