evaluation of masw and fwd test for measuring multi-layered … · 2015-12-08 · • kenlayer...

Evaluation of MASW and FWD Test for Measuring Multi-Layered Elastic Modulus of Chemically Stabilized Unpaved Roads Cheng Li Major Professors: Drs. Jeramy Ashlock and David White Measuring the elastic modulus for each of the material layers of unpaved roads are important • Evaluate performance and predict damage susceptibility. • Conduct mechanistic design for overlay or surface upgrade. IOWA STATE UNIVERSITY Civil, Construction, and Environmental Engineering (a) (b) (c) The MASW test procedure: (a) data collection, (b) dispersion analysis, and (c) inversion Falling weight deflectometer (FWD) test • Kuab Model 150 2m FWD • Four impact loads: 6000, 9000, 12000, and 14000 lb. • Backcalculation method: combines the Boussinesq theory and Odemark’s equivalent layer thickness assumption (AASHTO 1993). (b) (a) Surface conditions of an unpaved road test section: (a) prior to freezing and (b) post thawing Multichannel analysis of surface waves (MASW) test • A geophysical test method using wave propagation theory. • A phase-velocity and intercept-time scanning method for dispersion analysis (Lin 2014). • A hybrid genetic-simulated annealing optimization algorithm for improving inversion (Lin 2014). In situ FWD measured deflection data were compared with theoretical calculated results • KENLAYER software using theory of elastic layer systems (Huang 2004). Conclusions • The FWD backcalculation method is reliable for determining elastic modulus of two-layer unpaved road systems. • The MASW is capable of measuring the near-surface material elastic modulus of unpaved roads. • The MASW measured elastic modulus values are higher than the FWD measured results due to low testing strain levels. A comparison of FWD measured and theoretical calculated surface deflections References • AASHTO (1993). AASHTO guide for design of pavement structures 1993, American Association of State Highway and Transportation Officials, Washington, D.C. • Huang, Y. H. (2004). Pavement analysis and design, Pearson Education, Inc., Upper Saddle River, New Jersey. • Lin, S. (2014). "Advancements in active surface wave methods: modeling, testing, and inversion." Doctor of Philosophy, Iowa State University, Ames, IA. Comparisons of the MASW and FWD test results As-constructed FWD and MASW backcalculated moduli for the test sections The FWD and MASW test results conducted during curing and post-thawing period A (a) photo of the FWD test device and (b) schematic of sensors setup (a) (b) Distance from the Center of the Loading Plate (in.) 0 12 24 36 48 60 Roadway Surface Deflection (in.) 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 FWD Measured (6000 lb Load) FWD Measured (9000 lb Load) FWD Measured (12000 lb Load) FWD Measured (14000 lb Load) Calculated (Theory of Elasticity) 7-Day 20-Day 30-Day 171-Day 15% Fly Ash Section E AGG (ksi) 0 100 200 300 400 500 600 MASW Test FWD Test E SG (ksi) 0 5 10 15 20 25 30 7-Day 18-Day 28-Day 169-Day 15% Fly Ash Section 6% Cement Section Note: The FWD elastic moduli are calculated under 6000 lb applied load E AGG (ksi) 0 100 200 300 400 500 FWD MASW Testing Point Locations 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 E SG (ksi) 0 5 10 15 20 Control Section 5% Bentonite15% Fly Ash 6% Cement Note: The FWD elastic moduli are calculated under 6000 lb applied load

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Page 1: Evaluation of MASW and FWD Test for Measuring Multi-Layered … · 2015-12-08 · • KENLAYER software using theory of elastic layer systems (Huang 2004). Conclusions • The FWD

www.intrans.iastate.edu

Evaluation of MASW and FWD Test for Measuring Multi-Layered Elastic Modulus of Chemically Stabilized Unpaved Roads

Cheng LiMajor Professors: Drs. Jeramy Ashlock and David White

Measuring the elastic modulus for each of the material layers of unpaved roads are important

• Evaluate performance and predict damage susceptibility.• Conduct mechanistic design for overlay or surface upgrade.

IOWA STATE UNIVERSITYCivil, Construction, and Environmental Engineering

(a)

(b)

(c)

The MASW test procedure: (a) data collection, (b) dispersion analysis, and (c) inversion

Falling weight deflectometer (FWD) test

• Kuab Model 150 2m FWD • Four impact loads: 6000, 9000, 12000, and 14000 lb.• Backcalculation method: combines the Boussinesq theory

and Odemark’s equivalent layer thickness assumption (AASHTO 1993).

(b)(a)

Surface conditions of an unpaved road test section: (a) prior to freezing and (b) post thawing

Multichannel analysis of surface waves (MASW) test

• A geophysical test method using wave propagation theory.• A phase-velocity and intercept-time scanning method for

dispersion analysis (Lin 2014).• A hybrid genetic-simulated annealing optimization

algorithm for improving inversion (Lin 2014).

In situ FWD measured deflection data were compared with theoretical calculated results

• KENLAYER software using theory of elastic layer systems (Huang 2004).

Conclusions• The FWD backcalculation method is reliable for determining

elastic modulus of two-layer unpaved road systems.• The MASW is capable of measuring the near-surface

material elastic modulus of unpaved roads. • The MASW measured elastic modulus values are higher than

the FWD measured results due to low testing strain levels.

A comparison of FWD measured and theoretical calculated surface deflections

References• AASHTO (1993). AASHTO guide for design of pavement structures 1993,

American Association of State Highway and Transportation Officials, Washington, D.C.

• Huang, Y. H. (2004). Pavement analysis and design, Pearson Education, Inc., Upper Saddle River, New Jersey.

• Lin, S. (2014). "Advancements in active surface wave methods: modeling, testing, and inversion." Doctor of Philosophy, Iowa State University, Ames, IA.

Comparisons of the MASW and FWD test results

As-constructed FWD and MASW backcalculated moduli for the test sections

The FWD and MASW test results conducted during curing and post-thawing period

A (a) photo of the FWD test device and (b) schematic of sensors setup

(a)

(b)

Distance from the Center of the Loading Plate (in.)0 12 24 36 48 60

Roa

dway

Sur

face

Def