Civil Engineering ETDs

Publication Date

Spring 3-8-2017

Abstract

The Federal Highway Administration indicates that about 85,000 bridges in the United States have no original contract documents with information about the type, depth, geometry and material of their foundations (FHWA, 2010). Furthermore, the National Bridge Inventory (NBI) provides information about 86,133 bridges nationwide that are rated as scour critical because of unknown foundation condition. In New Mexico, there are more than 281 bridges with unknown foundations, which are owned by the New Mexico Department of Transportation; 71 of these are timber bridges. These data indicate a serious problem that needs decisive action to assess the unknown bridge foundation characteristics (types and depths of foundation) in order to evaluate the scour safety risk of timber bridges in New Mexico.

The objective of this study was to investigate the effectiveness of using the Sonic Echo (SE) method to determine unknown bridge foundation depths. The SE method was observed to be suitable for determining unknown pile depths for bridges that are supported by timber pile abutments or timber pile bents. The SE test method provides reliable and reasonable results for determining all tested piles with an accuracy of ±15 percent. The SE tests were conducted on seventeen timber piles in different locations in New Mexico. The success rate of using the Sonic Echo method to determine the depth of unknown bridge piles is 94%. The range of the depths of tested timber piles was 16 feet to 38 feet.

Keywords

Sonic Echo Test Conducted on Timber Piles, Sound Wave Calculation within Timber Pile, Effectiveness of Sonic Echo Test on Timber Pile.

Sponsors

New Mexico Department of Transportation

Document Type

Thesis

Language

English

Degree Name

Civil Engineering

Level of Degree

Masters

Department Name

Civil Engineering

First Committee Member (Chair)

Dr. Arup K. Maji

Second Committee Member

Dr. Mahmoud Reda Taha

Third Committee Member

Dr. Rafiqul A. Tarefder

Comments

Knowing the depth of bridge foundations is a very important factor for the New Mexico Department of Transportation (NMDOT) to evaluate bridge safety. At present, many Non Destructive Tests (NDT) are used to evaluate bridge foundation types and depths. Some of these methods are costly because they require additional boring to perform the tests.

In this study, the Sonic Echo (SE) test was utilized to determine unknown foundation depths for three different timber bridges that are located in New Mexico. The advantages of using the SE method are that it uses low-cost equipment, the testing is inexpensive, and it does not need additional boring. In addition, it is effective for identifying the depth of exposed piles as a proven and potential NDT method for evaluating unknown bridge foundations (Olson et al. 1998).

The objectives of this research were to investigate the effectiveness of the SE method and to describe the technical procedure to evaluate unknown timber bridge pile depths and types. As part of this effort, the IR method was used to validate the results that were obtained from using the SE test. In addition, the SE test was conducted on a wooden column and three bridges located in New Mexico. The site numbers of these bridges, as listed in the NMDOT documents, are Bridge #1676, Bridge #6922, and Bridge #1190.

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