Scrap tire stockpiles have grown in the United States leading to a significant disposal problem. The most recent survey conducted by the Scrap Tire Management Council reported that 850 million tires are stockpiled in the United States, with an additional 250 million tires still generated each year (1995). The research described herein was undertaken to develop design guidelines for shredded tire stream crossings. The shear strength properties have been investigated for tire shreds as well as tire shreds in contact with glacial till. The shredded tires range from 40 mm to 1.4 m in length. There are several documented cases where shredded tires have been used successfully as drainage structures. Most of these projects make use of tire chips or shreds ranging from 13 to 152 mm in size. Since production costs for larger-size shreds are significantly less, they offer a distinct advantage over the smaller shreds.;This study uses large scale direct shear tests to investigate the shear strength of large-size tire shreds. Like other studies conducted on tire shreds, Mohr-Coulomb failure criterion is used to interpret laboratory results. This study concludes that for pure tire shreds, no correlation appears to exist between the size of tire shreds and Mohr-Coulomb failure parameters. At higher normal stresses, this study shows that the Mohr-Coulomb failure envelope in not linear, indicating that Mohr-Coulomb failure criterion may not be not accurate over a large stress range in interpreting the shear strength of tire shreds. This study concludes that the shear strength of shredded tires can be interpreted with the relationship: [Tau]= 1.4[Sigma]0·79. A slope stability analysis is conducted with the shear strength properties of pure tire shreds and tire shreds in contact with glacial till.
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