NUMERICAL AND EXPERIMENTAL INVESTIGATION OF LOOSE SAND-SCRAP TIRES MIXTURE STIFFNESS

Abstract

Rubber-sand mixtures have many applications in geotechnical engineering. Considerable literature exists on the mechanical behavior of dense sand shredded rubber mixtures, but up to the author's knowledge, there are no such studies on sand-filled used whole car tires. The latter is ubiquitously used in developing countries to create cheap and quick backfill. The paper presents results from three-dimensional finite element models and plate load tests on layers of loose sand and whole tire mixtures in a steel tank. The finite elements program ANSYS is used to compare between a true 3D realization of the tire shape and a homogenized representation of the mixture. Numerical and laboratory results show how interpreted stiffness values depart from literature and physical laws of mixing soft and stiff components because the whole tire is used instead of shredded chips. The paper applies the equivalent thickness method to interpret the plate load test results and compute mixture stiffness for different thicknesses and shows good agreement with numerical back analysis. The application of plate load tests in the field and using the proposed approximate method is recommended to assess mixture stiffness rather than using assumed values from the literature. The paper presents an empirical correlation between the normalized layer thickness and the mixture stiffness for firstorder predictions.