A NEW RESEARCH TOOL FOR MEASURING PAVEMENT DEFLECTION

Abstract

THE LANE-WELLS MEASUREMENT SYSTEM FOR PAVEMENT DEFLECTION WAS INVESTIGATED AND RESULTS AND DATA ARE PRESENTED ILLUSTRATING HOW THE DEFLECTION BASIN IS AFFECTED BY VARIATIONS IN THE STRUCTURAL DESIGN OF FLEXIBLE PAVEMENTS. THE LANE-WELLS DYNAFLECT CONSISTS OF A SMALL TWO-WHEEL TRAILER CONTAINING A DYNAMIC FORCE GENERATOR AND EQUIPPED WITH A SET OF MOTION-SENSING DEVICES. DEFLECTIONS OF THE ROADWAY, OR OTHER MATERIAL BENEATH THE TRAILER, CAUSED BY A CYCLIC DOWNWARD FORCE, ARE MEASURED WHILE THE TRAILER IS HALTED BRIEFLY AT EACH TEST LOCATION. DEFLECTIONS ARE READ DIRECTLY ON THE FREQUENCY AND DEFLECTION METERS. THE CYCLIC FORCE IS PRODUCED BY A PAIR OF COUNTER-ROTATING UNBALANCED FLYWHEELS. TWO ECCENTRIC ROTATING MASSES PRODUCE A VERTICAL REACTION FORCE WHICH IS TRANSMITTED TO THE GROUND. THE HORIZONTAL REACTIONS CANCEL BY VIRTUE OF THE OPPOSING ROTATIONS. THE INSTANTANEOUS FORCE IS PROPORTIONAL TO THE UNBALANCED MASS AND TO ITS VERTICAL ACCELERATION. EXPERIMENT TO DATE WITH THIS SYSTEM WARRANTS THE CONCLUSION THAT IT IS RUGGED, RELIABLE, SIMPLE AND ECONOMICAL IN OPERATIONS, AND CAPABLE OF BECOMING A USEFUL TOOL IN THE MEASUREMENT OF THE RELATIVE STIFFNESS OF PAVEMENT STRUCTURES.