Assessing the Precision of Falling Weight Deflectometer for Field Measurements

2006 ◽  
Vol 3 (3) ◽  
pp. 14205
Author(s):  
SW Dean ◽  
B Choubane ◽  
S Gokhale ◽  
N Mike Jackson ◽  
A Nazef
Keyword(s):  
Field Measurements ◽  
Falling Weight Deflectometer ◽  
Falling Weight

Correlation of Non-Destructive Pavement Test Devices

2014 ◽  
Vol 912-914 ◽  
pp. 613-616
Author(s):  
Sheng Chun Li
Keyword(s):  
Field Measurements ◽  
Falling Weight Deflectometer ◽  
Pavement Rehabilitation ◽  
Ningxia Hui Autonomous Region ◽  
Aashto 1993 ◽  
Falling Weight ◽  
Near Future ◽  
The Relationship ◽  
Non Destructive ◽  
Rehabilitation Strategy

This paper studies the correlation of non-destructive pavement test devices, the falling weight deflectometer (FWD) and Benkelman Beam (BB), in evaluation of pavement structure capacity. Field measurements were made at an expansion highwayG6 in Ningxia Hui Autonomous Region, China. Based on the deflection results measured with FWD and BB, the relationship between FWD and BB was established. The subgrade moduli of the test section were back-calculated. The results show that the ratio of E(sta) and MR(dyn) is consistent with the suggestion of AASHTO 1993. Due to the fact that the use of FWD test is convenient and the results are stable, it demonstrates that the falling weight deflectometer (FWD) is an appropriate device to evaluate the pavement structural and to select the optimal pavement rehabilitation strategy in the near future.

scholarly journals PREDICTION OF DEPTH TEMPERATURE OF ASPHALT LAYERS IN HOT CLIMATE AREA

2018 ◽  
Vol 24 (7) ◽  
pp. 516-525 ◽  
Author(s):  
Nader Solatifar ◽  
Mojtaba Abbasghorbani ◽  
Amir Kavussi ◽  
Henrikas Sivilevičius
Keyword(s):  
Linear Regression Analysis ◽  
Field Measurements ◽  
Falling Weight Deflectometer ◽  
Actual Measurement ◽  
Temperature Variations ◽  
Hot Climate ◽  
Actual Field ◽  
Pavement Temperature ◽  
Falling Weight

In determination of flexible pavement layers moduli using Falling Weight Deflectometer (FWD), the pavement depth temperature should be determined and then the moduli should be corrected into a reference temperature. As direct measurement of pavement temperature is time consuming and is difficult to be determined in trafficked roads, some models are developed to predict temperature of asphalt layers through pavement depth, including BELLS model. The objective of this research is to determine correlation between actual measurement and prediction of temperature variations through asphalt layers with applying BELLS model. Ten new and rehabilitated pavement sites were selected in hot climate regions in Khuzestan and Kerman provinces in southern part of Iran. In typical hot summer days, pavement temperatures were measured at half and at one-third of the depth of asphalt layers and FWD testing were performed. Results indicated that a linear regression analysis of BELLS predicted temperatures versus measured values, provides very good correlation with actual field measurements of temperatures through the asphalt layers. Furthermore, predictions were more precise in rehabilitated pavements rather than in newly constructed pavements. Finally, using multi parametric linear fitting analysis, a new model was developed to accurately predict the temperature of asphalt layers in new pavements.

DIPLOBACK: Neural-Network-Based Backcalculation Program for Composite Pavements

1997 ◽  
Vol 1570 (1) ◽  
pp. 143-150 ◽  
Author(s):  
Lev Khazanovich ◽  
Jeffery Roesler
Keyword(s):  
Neural Network ◽  
Winkler Foundation ◽  
Multilayer Composite ◽  
Falling Weight Deflectometer ◽  
Subgrade Reaction ◽  
Elastic Parameters ◽  
The Neural Networks ◽  
Elastic Layers ◽  
Falling Weight ◽  
Moduli Of Elasticity

A neural-network-based backcalculation procedure is developed for multilayer composite pavement systems. The constructed layers are modeled as compressible elastic layers, whereas the subgrade is modeled as a Winkler foundation. The neural networks are trained to find moduli of elasticity of the constructed layers and a coefficient of subgrade reaction to accurately match a measured deflection profile. The method was verified by theoretically generated deflection profiles and falling weight deflectometer data measurements conducted at Edmonton Municipal Airport, Canada. For the theoretical deflection basins, the results of backcalculation were compared with actual elastic parameters, and excellent agreement was observed. The results of backcalculation using field test data were compared with the results obtained using WESDEF. Similar trends were observed for elastic parameters of all the pavement layers. The backcalculation procedure is implemented in a computer program called DIPLOBACK.

scholarly journals Propagation of Surface Waves in Asphalt Pavements Generated by Different Load Impulse of Falling Weight Deflectometer

2019 ◽  
Vol 15 (1) ◽  
pp. 29-35
Author(s):  
Jozef Komačka ◽  
IIja Březina
Keyword(s):  
Surface Waves ◽  
Travel Time ◽  
Time History ◽  
Asphalt Pavements ◽  
Load Force ◽  
Falling Weight Deflectometer ◽  
Waves Propagation ◽  
Propagation Of Waves ◽  
Falling Weight ◽  
The Waves

Abstract The propagation of waves generated by load impulse of two FWD types was assessed using test outputs in the form of time history data. The calculated travel time of wave between the receiver in the centre of load and others receivers showed the contradiction with the theory as for the receivers up to 600 (900) mm from the centre of load. Therefore, data collected by the sensors positioned at the distance of 1200 and 1500 mm were used. The influence of load magnitude on the waves propagation was investigated via the different load force with approximately the same load time and vice versa. Expectations relating to the travel time of waves, depending on the differences of load impulse, were not met. The shorter travel time of waves was detected in the case of the lower frequencies. The use of load impulse magnitude as a possible explanation was not successful because opposite tendencies in travel time were noticed.

scholarly journals Measurements of the elastic modulus of pavement subgrade layers using the SASW and FWD test methods

2015 ◽  
Vol 10 (2) ◽  
pp. 174-181 ◽  
Author(s):  
Nur Izzi Md. Yusoff ◽  
Sentot Hardwiyono ◽  
Norfarah Nadia Ismail ◽  
Mohd Raihan Taha ◽  
Sri Atmaja P. Rosyidi ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Elastic Modulus ◽  
Surface Wave ◽  
Time Lag ◽  
Test Methods ◽  
Pavement Management ◽  
Falling Weight Deflectometer ◽  
Surface Wave Propagation ◽  
Evaluation And Monitoring ◽  
Falling Weight

In pavement management systems, deflection basin tests, such as the Falling Weight Deflectometer test, are common techniques that are widely used, while the surface wave test, i.e. the Spectral Analysis of Surface Wave test, is recently employed as an alternative technique in pavement evaluation and monitoring. In this paper, the performance of both dynamic non-destructive tests on pavement subgrade investigation is presented. Surface wave propagation between a set of receivers was transformed into the frequency domain using the Fast Fourier Transform technique and subsequently a phase spectrum was produced to measure the time lag between receivers. Using the phase difference method, an experimental dispersion curve was generated. Inversion analysis based on the 3-D stiffness matrix method was then performed to produce a shear wave velocity profile. The elastic modulus of pavement layers was calculated based on linear elastic theory. In the Falling Weight Deflectometer test, seven geophones were used to collect in situ deflection data. Based on a back-calculation procedure with the ELMOD software, the elastic modulus of each flexible pavement layer can be obtained. Both techniques are able to comprehensively investigate the elastic modulus of the subgrade layer in existing pavement non-destructively. The elastic modulus between the Spectral Analysis of Surface Wave method and the Falling Weight Deflectometer test on the subgrade layer is observed to be in a good agreement. A correlation of the elastic modulus of thesubgrade layer from both techniques is also presented.

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