scholarly journals Study of the Permanent Deformation of Soil Used in Flexible Pavement Design

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Wendel S. Cabral ◽  
Suelly H. A. Barroso ◽  
Samuel A. Torquato
Keyword(s):  
Prediction Models ◽  
Permanent Deformation ◽  
Test Procedure ◽  
Flexible Pavement ◽  
Empirical Methods ◽  
Geotechnical Parameters ◽  
Repeated Load ◽  
Pavement Layers ◽  
Pavement Structures ◽  
Repeated Load Triaxial

The decreasing supply of soils with geotechnical parameters suitable for pavement designs is a visible problem in our environment. In order to establish more efficient designs and adequate construction criteria, it is essential to understand the performance of materials. This is a study of the permanent deformation (PD) of soil used in pavement layers, obtaining prediction models through the technique of artificial neural networks, in addition to the design of pavement structures using mechanistic-empirical and empirical methods. The multistage repeated load triaxial (RLT) test, as well as numerical analyses of stresses and displacements using the CAP3D program, was used. The results showed that both the test procedure and the prediction models performed satisfactorily in obtaining PD behavior. Moreover, designs using the methods adopted resulted in distinct structures, that is, thickness different from the granular pavement layers. It was concluded that the model and test procedure exhibit significant potential for characterizing and modeling the PD of granular materials.

Using Repeated-Load Triaxial Tests to Evaluate Plastic Strain Potentials in Subgrade Soils

2005 ◽  
Vol 1913 (1) ◽  
pp. 86-98 ◽  
Author(s):  
Anand J. Puppala ◽  
Suppakit Chomtid ◽  
Venkat Bhadriraju
Keyword(s):  
Plastic Strain ◽  
Test Procedure ◽  
Soil Layer ◽  
Silty Sand ◽  
Triaxial Tests ◽  
Plastic Strains ◽  
Plastic Deformations ◽  
Subgrade Soils ◽  
Repeated Load ◽  
Repeated Load Triaxial

The design and the analysis of flexible pavement systems depend on soil layer characterization, traffic loads, and number of passes. The current AASHTO design method for flexible pavements uses resilient characteristics of subsoils to characterize and determine the structural support of each layer and to design the thickness of the layers. This moduli property, however, does not fully account for the plastic strain or rutting potentials of subsoils, as in the cases in which silt and mixed soils undergo high plastic deformations but possess high resilient properties. A study was initiated to establish a test procedure to use a repeated load triaxial device to measure plastic strain potentials of subgrade soils. Laboratory-compacted soil specimens were subjected to a repeated deviatoric load, determined as a percentage of static deviatoric load at failure under un-consolidated undrained conditions. The plastic strains were monitored during 10,000 repeated load cycles, and the accumulated plastic deformations were determined. The test procedure and test results conducted on two types of soils, a coarse sand and silty sand, are presented. Effects of soil type, compaction moisture content, dry unit weight, confining pressure, and deviatoric stresses on the plastic strains were addressed.

scholarly journals INTERFACE CONDITION INFLUENCE ON PREDICTION OF FLEXIBLE PAVEMENT LIFE

2007 ◽  
Vol 13 (1) ◽  
pp. 71-76 ◽  
Author(s):  
Hassan Ziari ◽  
Mohammad Mahdi Khabiri
Keyword(s):  
Transfer Functions ◽  
Fatigue Cracking ◽  
Flexible Pavement ◽  
Interface Condition ◽  
Premature Failure ◽  
Design Procedures ◽  
The Road ◽  
Critical Stresses ◽  
Pavement Layers ◽  
Pavement Structures

The effects of interface condition on the life of flexible pavements have been determined. The methodology consists of implementing a previously derived interface constitutive model into the Kenlayer programme to compute the stresses and strains in typical flexible road structures. The shell transfer functions for fatigue cracking and terminal serviceability were used to estimate the pavement life. The behaviour of in‐service pavements indicates that the condition of the bonding between pavement layers plays an important role in the road structures performance. Premature failure of road sections due to layer separation, leading to redistribution of stresses and strains in the pavement structure, is often encountered, especially in areas where the vehicles are more likely to apply horizontal forces. In computing the critical stresses and strains, most of the mechanistic design procedures of flexible pavement structures consider that pavement layers are completely bonded or completely unbounded.

scholarly journals Structural Evaluation of Full-Depth Flexible Pavement Using APT

2021 ◽  
Author(s):  
Tommy E. Nantung ◽  
Jusang Lee ◽  
John E. Haddock ◽  
M. Reza Pouranian ◽  
Dario Batioja Alvarez ◽  
...  
Keyword(s):  
Asphalt Concrete ◽  
Prediction Models ◽  
Design Method ◽  
Permanent Deformation ◽  
Pavement Design ◽  
Asphalt Pavements ◽  
Statistical Parameters ◽  
Significant Difference ◽  
Pavement Structures ◽  
Rutting Behavior

The fundamentals of rutting behavior for thin full-depth flexible pavements (i.e., asphalt thickness less than 12 inches) are investigated in this study. The scope incorporates an experimental study using full-scale Accelerated Pavement Tests (APTs) to monitor the evolution of each pavement structural layer's transverse profiles. The findings were then employed to verify the local rutting model coefficients used in the current pavement design method, the Mechanistic-Empirical Pavement Design Guide (MEPDG). Four APT sections were constructed using two thin typical pavement structures (seven-and ten-inches thick) and two types of surface course material (dense-graded and SMA). A mid-depth rut monitoring and automated laser profile systems were designed to reconstruct the transverse profiles at each pavement layer interface throughout the process of accelerated pavement deterioration that is produced during the APT. The contributions of each pavement structural layer to rutting and the evolution of layer deformation were derived. This study found that the permanent deformation within full-depth asphalt concrete significantly depends upon the pavement thickness. However, once the pavement reaches sufficient thickness (more than 12.5 inches), increasing the thickness does not significantly affect the permanent deformation. Additionally, for thin full-depth asphalt pavements with a dense-graded Hot Mix Asphalt (HMA) surface course, most pavement rutting is caused by the deformation of the asphalt concrete, with about half the rutting amount observed within the top four inches of the pavement layers. However, for thin full-depth asphalt pavements with an SMA surface course, most pavement rutting comes from the closet sublayer to the surface, i.e., the intermediate layer. The accuracy of the MEPDG’s prediction models for thin full-depth asphalt pavement was evaluated using some statistical parameters, including bias, the sum of squared error, and the standard error of estimates between the predicted and actual measurements. Based on the statistical analysis (at the 95% confidence level), no significant difference was found between the version 2.3-predicted and measured rutting of total asphalt concrete layer and subgrade for thick and thin pavements.

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