Evaluating Influence Depth of Light Weight Deflectometer through Finite Element Modeling

Tirado, Cesar; Mazari, Mehran; Carrasco, Cesar; Nazarian, Soheil

doi:10.1061/9780784479216.070

Cited by 10 publications

(7 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, a Zorn ZFG 2000 LWD was modeled with steel considered as a linear elastic material rather than a rigid material. Other LWD devices may yield different magnitudes of load but with similar trends (4).…”

Section: Fe Model Of Lightweight Deflectometermentioning

confidence: 99%

See 1 more Smart Citation

Simulation of Lightweight Deflectometer Measurements Considering Nonlinear Behavior of Geomaterials

Tirado¹,

Gamez-Rios²,

Fathi³

et al. 2017

Transportation Research Record

Self Cite

View full text Add to dashboard Cite

Lightweight deflectometers (LWDs) are being used more often for modulus-based quality control of earthwork. One of the practical concerns about implementation of LWDs is that the equation used to estimate the LWD modulus is based on elastic half-space theory and does not account for the nonlinear behavior of soil and soil–impact plate interaction. The finite element method can be used to study the effects of nonlinear behaviors of geomaterials and the soil–plate interaction on the measured deflections. This study provides a means for accounting for the impact of these parameters on the measured responses and the depths of influence. A dynamic finite element model that considers the nonlinear behavior of geomaterials was developed to simulate the LWD on a pavement structure. A comprehensive range of single-layer and two-layer systems with a wide range of properties and thicknesses was considered. Transfer functions were developed to adjust the surface deformations and moduli from the responses obtained from a simple layered elastic static model. The study provides practical relationships that minimize the additional effort in implementing time-consuming dynamic finite element methods. The relationships proposed in this study can be used to estimate more representative target LWD modulus values.

show abstract

Section: Fe Model Of Lightweight Deflectometermentioning

confidence: 99%

“…In multilayer soil systems, the layer thicknesses also affect the surface modulus estimation (3). The state of the practice has shown that different makes of LWDs yield different surface moduli (4).…”

mentioning

confidence: 99%

Simulation of Lightweight Deflectometer Measurements Considering Nonlinear Behavior of Geomaterials

Tirado¹,

Gamez-Rios²,

Fathi³

et al. 2017

Transportation Research Record

Self Cite

View full text Add to dashboard Cite

show abstract

“…One notable advancement in assessing layer properties is the lightweight deflectometer (LWD), gaining popularity due to the success of its predecessor, the falling weight deflectometer [1]. LWD offers a rapid, cost-effective, and nondestructive method for evaluating the structural adequacy of compacted road materials, setting it apart from other devices [4][5][6].…”

Section: Repeated Lightweight Deflectometer (Rlwd) Testmentioning

confidence: 99%

“…It is widely recognized that accurate characterization of unbound granular materials (UGMs) and subgrade soils is essential for effective pavement design and rehabilitation. The implementation of the modern Mechanistic-Empirical Pavement Design Guide (MEPDG) requires accurate modulus parameters for each unbound pavement layer [1]. Resilient modulus (Mr), derived from the repeated load triaxial (RLT) test, is a fundamental engineering property used to define the stress-strain relationships of UGMs and subgrade under cyclic loading.…”

Section: Introductionmentioning

confidence: 99%

Using Repeated Light-Weight Deflectometer Test Data to Predict Flexible Pavement Responses Based on the Mechanistic–Empirical Design Method

Kuttah

2024

Construction Materials

View full text Add to dashboard Cite

This study investigated the potential of lightweight deflectometer (LWD) data in predicting layer moduli and response measurements within the Mechanistic–Empirical Pavement Design Guide. To achieve this goal, field repeated LWD tests and laboratory repeated load triaxial tests were carried out on granular base material compacted at 3% and 6% water content, sandy subgrade soil compacted at 3%, 4% and 9% water content and silty sand subgrade soil compacted at 8% and 10% water content. The results revealed that substituting traditional repeated load triaxial (RLT) data with LWD data for predicting these parameters was notably effective for cohesionless materials, especially for unbound granular materials (UGMs) compacted at optimum water content. The accuracy and reliability of predictions were remarkably high, showcasing the potential of LWD to enhance efficiency and precision in pavement design within this context. Conversely, for cohesive road materials, the study emphasized the importance of considering specific material properties and water content when integrating LWD into the Mechanistic–Empirical Pavement Design Guide. The distinctive characteristics and behaviors of cohesive materials necessitate a nuanced approach. This understanding is critical to ensuring the accuracy and reliability of pavement design and assessment across diverse conditions. In summary, the study presents a promising avenue for utilizing LWD data in cohesionless road materials, offering potential cost and time-saving advantages. Additionally, it underscores the necessity of tailored approaches when considering material properties and moisture content for cohesive materials, thereby advancing the field of pavement engineering by providing insights for improved practices and adaptable frameworks.

show abstract

“…One final topic of concern with regard to the LWD and what characteristics it may be measuring on these winter surfaces is the depth of influence, or measurement, of the LWD. The depth of measurement for the LWD is a matter of significant research (Tirado et al 2015). Both (1) how deep into the soil or other material the LWD load is penetrating and ( 2) how the center geophone and the configuration of the outer radial geophones, which measure vertical surface deflections caused almost entirely by strains deeper in the material (Senseney and Mooney 2010), are capturing that response are topics of ongoing discussion.…”

Section: Lwd Depth Of Influencementioning

confidence: 99%

Using the light weight deflectometer to assess groomed snow and ice surfaces

Wieder¹,

Shoop²,

Barna³

2019

View full text Add to dashboard Cite

The Light Weight Deflectometer (LWD) was designed to test the compaction or bearing capacity of in-place aggregate base-course materials. This study evaluated the potential of the LWD to also characterize groomed snow and ice surfaces as the ability to characterize the strength, or bearing capacity, of winter surfaces is crucial for evaluation of vehicle mobility in cold climates.LWD tests were run on a variety of groomed snow and ice surfaces over asphalt pavement, gravel, and soil in the winter of 2018 in both Montana and Michigan. The LWD measures load and deflection, enabling calculation and backcalculation of stiffness parameters for the test surface layers. The initial results were reasonable for the snow layers analyzed. The Impulse Stiffness Modulus, calculated as the impact load divided by the deflection response, presents as a reasonable property for analysis, requiring no assumptions about other snow layer properties. However, the LWD components, specifically the rubber load buffers, may have issues with the effects of low temperature testing. These effects need to be considered when testing snow and ice surfaces. Additionally, the stress and compaction levels that most represent the conditions of interest for mobility purposes need to be determined. Specific and consistent LWD equipment configuration and test procedures need to be determined and implemented in further testing of winter surfaces.

show abstract

Evaluating Influence Depth of Light Weight Deflectometer through Finite Element Modeling

Cited by 10 publications

References 8 publications

Simulation of Lightweight Deflectometer Measurements Considering Nonlinear Behavior of Geomaterials

Simulation of Lightweight Deflectometer Measurements Considering Nonlinear Behavior of Geomaterials

Using Repeated Light-Weight Deflectometer Test Data to Predict Flexible Pavement Responses Based on the Mechanistic–Empirical Design Method

Using the light weight deflectometer to assess groomed snow and ice surfaces

Contact Info

Product

Resources

About