Use of Shredded Waste Tires in Rockfall Protection Structures

Project Summary: Rockfall is a significant problem that affects certain parts of the United States and large parts of Japan. Rockfall may be considered as a subcategory of landslides. The velocity of falling rocks may reach 30 m/s or higher, which is the fastest among various types of landslides. Large amounts of waste tires are generated in both the U.S. and Japan on an annual basis. The USEPA reported that 290 million waste tires were generated in 2003 with the continued generation at a rate of 1 tire per person on an annual basis. In Japan, approximately 1 million tons of waste tires are generated per year. Even though approximately 80% and 90% of tires are recycled in some manner in the U.S. and Japan, respectively, significant amounts remain in the waste stream due to the large rates of generation. A new beneficial reuse application is investigated in this study as an alternative to further divert tires from the waste stream. Preliminary laboratory tests and numerical modeling were conducted to assess the feasibility of using shredded rubber tires in the construction of rockfall protection structures. In particular, use of tire chips and tire-soil mixtures was evaluated as a supplementary or main energy attenuation layer against impact loads of falling rocks. The laboratory tests and numerical analyses indicated that design of rockfall mitigation structures with reduced structural requirements may be possible with the inclusion of tire chips in energy attenuation layers.

Principal Investigators: Jim Hanson, Senro Kuraoka (Nippon Koei Co., Ltd., Japan), and Nazli Yesiller

Funding Agency: In-kind support from Nippon Koei Co., Ltd., Japan

Publications:
Hanson, J. L., Kuraoka, S., and Yesiller, N., (2011), “Assessment of Use of Shredded Waste Tires in Rockfall Protection Structures,” Proceedings of the Ninth Japanese Geotechnical Society National Symposium on Environmental Geotechnics, Japanese Geotechnical Society, Tokyo, p. 391-396.