scholarly journals Relationship between deformation moduli obtained using light falling weight deflectometer and static plate test on various types of soil

2014 ◽  
Vol 9 (4) ◽  
pp. 251-259 ◽  
Author(s):  
Karel Pospisil ◽  
Petr Zednik ◽  
Josef Stryk
Keyword(s):  
Test Methods ◽  
Falling Weight Deflectometer ◽  
Loading Test ◽  
Plate Test ◽  
Plate Loading Test ◽  
Static Modulus ◽  
Different Types ◽  
Falling Weight ◽  
The Relationship ◽  
Plate Loading

There is increasing effort to optimize test methods for evaluation of subgrade. It takes effect in aspiration in replacement of static plate loading test by other faster test methods. One of them is the use of Light Falling Weight Deflectometer. In many countries in Europe both static and dynamic plate tests are standardized. The presented paper introduces results of the research project dealing with the sensitivity of the relationship between static modulus and modulus obtained from the Light Falling Weight Deflectometer on specific types of soil. It is shown that there are significant differences in relationship between moduli values obtained using both methods on different types of soil.

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.

Pavement displacement sensitivity to layer moduli

2002 ◽  
Vol 39 (6) ◽  
pp. 1395-1398
Author(s):  
Dieter Stolle
Keyword(s):  
Finite Element ◽  
Surface Displacement ◽  
Falling Weight Deflectometer ◽  
Contribution Ratio ◽  
Displacement Sensitivity ◽  
Stiffness Characteristics ◽  
Element Technique ◽  
Falling Weight ◽  
The Relationship ◽  
Displacement Measurements

The backcalculation of layer moduli using falling weight deflectometer data has proven to be challenging owing to the insensitivity of displacement measurements to the stiffness characteristics of some layers. This note describes a rigorous, yet simple, finite element technique for identifying the relationship between surface displacement and the elastic modulus of each layer. An example is given to demonstrate the application of the procedure.Key words: pavements, subgrade, backcalculation, contribution ratio.

Comparison of Plasticity Values as Determined by the Williams Parallel-Plate and Mooney Plastometers

1945 ◽  
Vol 18 (4) ◽  
pp. 877-881
Keyword(s):  
Parallel Plate ◽  
Compressive Force ◽  
Flow Equation ◽  
High Rate ◽  
Plate Test ◽  
Shear Rates ◽  
High Shear Rates ◽  
Different Types ◽  
Close Relationship ◽  
The Relationship

Abstract A preliminary comparison of plasticity readings by the Mooney and Williams parallel-plate plastometers shows that, for stocks of similar type, the two readings are closely related, but the relationship is different for different types of stocks, being dependent on the value of the exponent n in the plastic flow equation. Following up a previous conclusion (Reports No. 205 and 216) that the lack of a close relationship between plasticity figures obtained by the Mooney and parallel-plate instruments is due to the former giving a much higher rate of shear, it is now found that parallel-plate values obtained under conditions that give high shear-rates agree much better with Mooney values than do those obtained under the usual (low rate of shear) conditions. In the parallel-plate test a high rate of shear can be obtained by taking readings after a short compression period, by increasing the compressive force, or by reducing the volume of the specimen. These results thus suggest that the parallel-plate test, operated under appropriate conditions, might be made a satisfactory alternative to the Mooney test.

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