Determining Depth to Apparent Stiff Layer from FWD Data

Rohde, G. T.; Smith, R. E.

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Determining Depth to Apparent Stiff Layer from FWD Data

1991-10-01
By Rohde, G. T. ; Smith, R. E.

File Language:

English

Details

Creators:

Rohde, G. T. ; Smith, R. E.
Corporate Creators:

Texas Transportation Institute. Texas A&M University
Corporate Contributors:

Texas Department of Transportation. Division of Transportation Planning ; United States. Department of Transportation. Federal Highway Administration
Subject/TRT Terms:

Data Analysis Deflection Tests Falling Weight Deflectometers Field Tests Nondestructive Tests Pavement Performance Sediments Stiffness
Publication/ Report Number:

FHWA/TX-SI-1159-1
Resource Type:

Tech Report
Geographical Coverage:

Texas ; United States
Corporate Publisher:

Texas Transportation Institute. Texas A&M University
Abstract:

Nondestructive deflection testing (NOT) has become an integral part of the structural evaluation of pavements. Interpretation of the measured deflection data is extremely complex, and the analyzed pavement is often modelled as a multilayered elastic system. In this model the subgrade is usually defined as uniformly stiff and infinitely thick, or a rigid layer is placed at an arbitrary depth. The actual subgrade on which the tested pavement structure is founded, varies considerably from this model. It is not infinitely thick, and whether the subgrade is sedimentary or residual in nature, its stiffness normally changes with depth. This change in stiffness can be due to shallow bedrock, material differences, the stress history, or an apparent increase in stiffness due to the stress dependent behavior of most soils. In this study a method to determine the depth to an apparent rigid layer from surface deflections is developed. This method is based on Bousinesq's equation and is related to a three-layer linear elastic system through an extensive regression analysis. The procedure is validated using field data. The inclusion of an apparent rigid layer into the pavement model led to considerable improvements in the back calculated layer moduli.
Format:

PDF
Funding:

2-8-87-1159
Collection(s):

US Transportation Collection
Main Document Checksum:

urn:sha-512:80e0dab9fe45d9b11e71defe47e206d2d18ef5ac4f37185beefc38469f25fcca1374eef5d556f2f6f777ae31e92ca36a9de35a3bfc09c091c0c6bf89a29d4a01
Download URL:

https://rosap.ntl.bts.gov/view/dot/86125/dot_86125_DS1.pdf
File Type:

[PDF - 5.95 MB ]

File Language:

English

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