Author: Bing XuPublisher:
ISBN:
Category : Nondestructive testing
Languages : en
Pages :
Book Description
Assessing Pavement Layer Condition Using FWD Deflection Data
Author: Bing XuPublisher:
ISBN:
Category : Nondestructive testing
Languages : en
Pages :
Book Description
Assessing pavement layer condition using deflection data
Author: Y. R. KimPublisher:
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 3
Book Description
Use of Falling Weight Deflectometer Multi-Load Level Data for Pavement Strength Estimation
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
The objective of this study is to describe a mechanistic-empirical approach to developing an analysis method for assessing pavement layer conditions and estimating the remaining life of flexible pavements using multi-load level Falling Weight Deflectometer (FWD) deflections. A dynamic finite element program, incorporating a stress-dependent soil model, was developed to generate the synthetic deflection database. Based on this synthetic database, the relationships between surface deflections and critical pavement responses, such as stresses and strains in each individual layer, have been established. A condition assessment procedure for pavement layers using multi-load level FWD deflections is presented in this study. The results indicate that the proposed procedure can estimate the base and subgrade layer conditions. However, large variations were observed in the relationships between the DBCI and desg values and the subgrade CBR values for aggregate base pavements. A FWD test with a load of 53 kN or less does not result in any apparent nonlinear behavior of the subgrade in aggregate base pavements. With regard to the condition assessment of the asphalt concrete (AC) layer, the AC layer modulus and the tensile strain at the bottom of the AC layer are found to be better indicators than the deflection basin parameter. The procedures for performance prediction of fatigue cracking and rutting are developed for flexible pavements. The drastically increasing trend in fatigue cracking with time may not be predicted accurately using the proposed procedure. Such trends may be due to the environmental effects and the inconsistent distress measurements. Predicted rut depths using both single and multi-load level deflections show good agreement with measured rut depths over a wide range of rutting potential. However, the procedure using single load level deflections consistently underpredicts the rut depths. This observation demonstrates that the rutting prediction procedure usin.
Assessing Pavement Layer Condition Using Deflection Data
Author: Transportation Research Board. National Cooperative Highway Research ProgramPublisher:
ISBN:
Category :
Languages : en
Pages : 3
Book Description
Use of Falling Weight Deflectometer Multi-load Data for Pavement Strength Estimation
Author: Y. Richard KimPublisher:
ISBN:
Category : Pavements
Languages : en
Pages : 208
Book Description
The objective of this study is to develop a mechanistic-empirical method for assessing pavement layer conditions and estimating the remaining life of flexible pavements using multi-load level Falling Weight Deflectometer (FWD) deflections. A dynamic finite element program, incorporating a stress-dependent soil model, was developed to generate the synthetic deflection database. Based on this synthetic database, the relationships between surface deflections and critical pavement responses, such as stresses and strains in each individual layer, have been established. A condition assessment procedure for asphalt pavements that uses multi-load level FWD deflections has been developed using these relationships. The verification study was conducted using field data.
Assessing Rigid Pavement Layer Condition Using Deflection Data
Author: Jeremy Davis TroxlerPublisher:
ISBN:
Category : Nondestructive testing
Languages : en
Pages : 274
Book Description
Interpretation of Fwd Data when Pavement Layers are Not Intact
Author: Y. Richard KimPublisher:
ISBN:
Category : Pavements
Languages : en
Pages : 158
Book Description
When FWD tests are performed on broken or cracked pavements (of which information is crucial in making rehabilitation and overlay decisions), the multi-layered elastic theory-based backcalulation programs assume that the effect of these discontinuities in a cracked layer on deflection basins would be accounted for by the reduction of the elastic modulus for that layer. However, it has been concluded and confirmed by researchers and practitioners that the backcalculation algorithms based on the multi-layered elastic theory produce large variation in the algorithms based on the multi-layered elastic theory produce large variation in the 'effective' moduli of the cracked layers. Studies have also shown that significant errors in the backcalculated pavement moduli can accrue from performing a static analysis of what is inherently a dynamic test. Unfortunately, dynamic analysis usually involves complex calculations and requires significant computation time, thus making it impracticable for routine applications. This study presents a methology based on deflection basin parameters.
Flexible Pavement Condition Evaluation Using Deflection Basin Parameters and Dynamic Finite Element Analysis Implemented by Artificial Neural Networks
Author: Ranjithan, SR.Publisher:
ISBN:
Category : Artificial neural network (ANN)
Languages : en
Pages : 17
Book Description
This paper presents a methodology based on deflection basin parameters and artificial neural networks (ANNs) for processing dynamic falling weight deflectometer (FWD) measurements to estimate layer moduli and condition. Two-dimensional, dynamic, finite element analysis using the ABAQUS program was employed to develop the deflection information for this study. Unlike the majority of the existing backcalculation programs that iteratively adjust all the layer moduli to match the measured deflections, the proposed method first determines the subgrade modulus by means of two deflection basin parameters, Base Damage Index and Shape Factor F2, and then applies the estimated subgrade modulus and other parameters as input variables to a trained ANN to estimate the upper layers' moduli. Procedures in predicting layer moduli for both two- and three-layer pavement systems are presented. Field FWD measurements were analyzed both by this method and by the MODULUS program, the results of which assess the capability of the proposed method. Effects of discontinuities in the asphalt layer on the resulting FWD deflections were also studied using the finite element method. It was discovered that distresses in the asphalt layer may be detected using two deflection basin parameters, Shape Factor F2 and AREA.
Condition Assessment of Flexible Pavements Using FWD Deflections
Author: Yung-Chien LeeAssessment of Support Conditions of Concrete Pavement Using FWD Deflection Basin Data
Author: Pavana K. R. VennapusaPublisher:
ISBN:
Category : Pavements
Languages : en
Pages : 13
Book Description
Results from a field forensic investigation conducted using a falling weight deflectometer (FWD) and visual observations on a jointed concrete pavement that showed premature distresses are presented in this article. At the time of testing, the pavement was six years old and was supported on a crushed limestone granular base underlain by cohesive natural or fill subgrade. The primary objective of the field investigation was to assess whether the foundation support conditions contributed to the distresses observed. FWD tests were conducted on 140 panels over an 830-m-long section of which 25 panels showed distress. The FWD deflection basin data was used to calculate several index parameters, which showed statistically significant differences between the cracked and the uncracked slabs, which suggests that the foundation layer properties were comparatively weaker under the cracked slabs. Visual observations showed that some of the distresses were related to potential lateral movement of the slopes next to the pavement.