Service technique de laviation civile DGAC/STAC Infrastructure research Current Research Work FAA Airport Pavement Working Group Atlantic City, NJ 24-26

Service technique de l’aviation civile

DGAC/STACInfrastructure research

Current Research Work

FAA Airport Pavement Working Group Atlantic City, NJ 24-26 April, 2011

2Current research workService technique de l’aviation civile25 april 2012

Main research topics

French rational design method for airfield pavements

Materials characterization and testing methods : material exchange FAA <-> DGAC/STAC

Dynamic F/HWD data analysisTowards a rational PCNReliability of friction measurementsWater depth modeling on runways



A new technical manual

A rational method used in France for highway design for more than 30 years

Development of the airfield rational design method from the highway one.

First restricted to new flexible airfield pavement.



2 steps :

−Mechanical design

−Freeze / thaw verification

The mechanical design in 6 steps :

1/ Gathering the data and design parameters (traffic, layers thicknesses, material types and characteristics, risk coefficient…)



2/ Stresses / Strains calculation with an isotropic linear elastic multilayered model

Discretization of the horizontal calculation planes (x,y) located at heights zk using a grid (xi, yj, zk).

x : longitudinal axis of the moving load

y : transverse direction

Calculation planes located at:

the HMA base

(horizontal extensions)

the top of the unbound layers (vertical contractions)



3/ Individual damage calculation without wandering

Deformations induced by the set of moving loads of a landing gear taken into account through the "Miner law continuous integration ":

0

0

X if Xwith X

otherwise

(x) : longitudinal deformation variation



4/ Individual damage calculation with wandering

5/ Cumulated damage calculation

6/ Iterative calculations, setting of the layers’ thickness so that:

- ddcumulated 1 (and lower than 1),

- technological limits regardings materials are satisfied.


The technical manual and its software are achieved

Next steps :− trial period by experts to get a feedback

− diffusion to all the users

and further applications : overlay design, rigid pavement design, rational ACN/PCN.



Materials characterization and testing methods

To compare US and French material properties and behaviour

To compare US and French testing methods used for materials characterization

To compare US and French rational design methods

Analysis of NAPTF data to validate/refine this rational design method. The method has been calibrated using the results of two Airbus full-scale testing programs (flexible PEP and HTPT)



Materials exchange FAA <-> DGAC/STAC :

French materials received by FAA November 2010:

– Asphalt materials from 1995 facility:

• 101x69x20 cm block (includes surface and base HMA layers).

– Asphalt materials from Bonneuil instrumented facility:

• 63x54x21 cm block (includes surface and base HMA layers).

• 6 HMA cores of varying depth.– Approximately 150 kg of bagged GNT2

(capping layer) from Bonneuil instrumented facility.

• US testing is achieved



Materials exchange FAA <-> DGAC/STAC :

U.S. material samples received by STAC April 2011:– (2) Econocrete (lean concrete)

beams, Item P-306, in steel molds.

– (3) Econocrete (lean concrete) cylinders, Item P-306.

– (2) Blocks of asphalt base material, Item P-403.

– (4) Buckets and (1) bag of crushed aggregate base material, Item P-154 (Crushed quarry screenings).

• All materials from NAPTF test items.

• French testing has just been completed



And now, in progress :

Comparison and data analysis of the results obtained by FAA and DGAC/STAC


French HWD pavement testing methodology (flexible pavements)

A new technical guide for:

1) pavement testing

2) data analysis:-Backcalculation

-Critical strains calculations

-Determination of pavement residual life, and/or bearing capacity (Single Wheel Load, PCN?)

Consistent with the new design guidance


Dynamic F/HWD data analysis

Technical guide and associated software (PREDIWARE) almost achieved

Next steps:

− validation by a user committee

− release

Next studies:

− overlay design

− rigid pavement assessment


Towards a rational PCN

Study in progress, a new work axis :

The aim is to cross the work done on the rational design method and on the HWD data analysis to develop a method to calculate a rational PCN.


Reliability of friction measurements

Aims of the study based on the IMAG device−To identify, quantify and reduce uncertainties

−To be more confident in friction results

First step : Identification of all the parameters affecting the measurements.



• The main parameters are : Calibration, Tire (wear, pressure), Water depth, Speed, Slip rate, Horizontality of sensors

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Repea

tabi

lity

Calibr

atio

n

Device

Tire w

ear

Wat

er d

epth

Device

X T

ire w

ear

Tire w

ear X

Wat

er d

epth

Speed

Slip ra

te

Slip ra

te X

Tire

wea

r

Horizo

ntali

ty

95 km/h

65 km/h

40 km/h



• The results :

– LFC = LFCread 0,10 at 95 km/h



• To compare with :


Water depth modeling on runways

Modeling of the runway characteristics with the VANI device

−Transverse and longitudinal slopes

−Evenness

−Macro-texture

−Friction (micro-texture)


Water depth modeling on runways

Modeling of water flow lines based on VANI data

Development of a software to predict the water depth on the runway during a rainy period or a thunderstorm.

Input data :

-VANI data

-rain intensity (weather data)

Output data :

Water depth

Flow model

21Current research workService technique de l’aviation civile

Thank you

BROUTIN [email protected]/IA Infrastructures Aéroportuaires


French HWD pavement testing methodology (flexible pavements)

-Use of histories instead of only peak values for backcalculation step

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-Dynamical FE modelling

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Subgrade

Loadplate

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Structure

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Documents

Service technique de laviation civile DGAC/STAC Infrastructure research Current Research Work FAA Airport Pavement Working Group Atlantic City, NJ 24-26