Date of Award

Summer 8-31-2018

Level of Access

Open-Access Thesis

Degree Name

Master of Civil Engineering (MCE)

Department

Civil Engineering

Advisor

Dana Humphrey

Second Committee Member

Thomas Sandford

Third Committee Member

Melissa Landon

Abstract

The objective of this study was to determine the effectiveness of Tire Derived Aggregate (TDA) as embankment and retaining wall backfill material using data from two field projects supplemented by data from previously published studies. Data collected from the two projects included horizontal earth pressure, resultant forces and moments acting in the wall stem, tensile and compressive forces within the wall, moments at the base of the wall, settlement of the TDA, time dependent temperature fluctuations within TDA, pore pressure changes in underlying foundation soil, movement of the wall face, and movement of the embankment. Data Collection was completed by instrumenting two separate projects: Limestone Run Bridge, consisting of a single span, simply supported bridge over Limestone Run, and the two adjoining approach fills, on Tarrtown Road State Route 4023, in Tarrtown, Pennsylvania; and retaining Wall 119, consisting of a reinforced concrete cantilever retaining wall structure with backfill, overlaid by an additional roadway earth embankment, on Route 91, in Riverside, California.

The scope of the project covered by this thesis was limited to analysis and interpretation of data provided by Apex Companies, LLC, GeoInstruments, Inc. (the instrumentation supplier for the Tarrtown project), the Pennsylvania Department of Transportation, and by the California Integrated Waste Management Board.

Based on the analysis of data completed, horizontal stresses for TDA material can be estimated at approximately 30 to 50% vertical overburden pressure. For at-rest conditions and vertical stresses less than 40 kPa (835 lb/ft2) an earth pressure coefficient (K) value for TDA fill of 0.5 appears reasonable. For vertical stresses greater than 40 kPa (835 lb/ft2) a K value for TDA fill of 0.33 would be reasonable. Based on strain gage results at the Riverside project site, forces and moments developed in a retaining wall are less, at similar wall heights, with TDA backfill than with conventional soil backfill.

Tilt meters located on the Riverside wall faces showed enough outward wall movement (0.019H to 0.030H) with H being the wall height, to develop fully active conditions on the wall face based on previous conclusions by Tweedie, et al. (1997) that an active condition occurs with TDA backfill when wall movements exceed 0.01H.

Based on strain gage results at the Riverside project site, forces and moments developed in a retaining wall are less, at similar wall heights, with TDA backfill than with conventional soil backfill, agreeing with previous TDA resultant force and moment conclusions established by Tweedie, et al. (1997) and Humphrey, et al. (2000).

Measured compression of the TDA layers at the Tarrtown project agreed with values expected from the design chart created by Humphrey (2005). Settlements also compare well with those from previous projects in Maine and New York. Most compression of the TDA layers occurred immediately upon placement of overburden material and ranged from 3% to 18%, with the higher values corresponding to higher overburden pressures.

Additionally, during the data collection period, no self-heating, no long term wall pressure increases, and low long term compression of TDA layers occurred.

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