PENNSYLVANIA STATE UNIV STATE COLLEGE COLL OF EARTH AND MINERAL SCIENCES
In order to improve aspects of materials handling in the rapid excavation process, research is underway to characterize the muck from mechanical tunnel boring machines. The specific project involves the correlation of the angle of internal friction, phi, to the size consist, often termed gradation, of this mechanically-chipped material. Existing references demonstrate that this angle depends upon mineral type, and for a given mineral type upon size of particles. Particle shape is usually a function of mineralogical character and is not as important a parameter in influencing this angle. Seven samples collected from tunnels located throughout the U.S. have been analyzed for gradation.