SUBGRADE SUPPORT CHARACTERISTICS AS INDICATED BY MEASUREMENTS OF DEFLECTION AND STRAIN

THE AIM OF THIS PROJECT WAS TO RELATE PAVEMENT DEFLECTION, AS MEASURED BY DIFFERENTIAL TRANSFORMERS, TO INITIAL CONDITIONS OF THE PAVEMENT SYSTEM. THE TWO CONDITIONS CONSIDERED WERE WARPING, RELATED TO ENVIRONMENTAL FACTORS, AND SUBBASE TYPE. THE NINE DIFFERENT SUBBASE SECTIONS ALONG THE US 41 TEST SECTION IN INDIANA WERE: PAVEMENT ON NATURAL SOIL, SOIL-CEMENT IN TWO THICKNESSES, OPEN-GRADED CRUSHED STONE IN 3 THICKNESSES, AND DENSE-GRADED CRUSHED STONE IN 3 THICKNESSES. DEPTH OF INFLUENCE WAS STUDIED TO DETERMINE PROPER MEASUREMENT DEPTH AND TO EVALUATE BOUNDARY CONDITIONS FOR STATISTICAL ANALYSIS OF THE EARTH-PAVEMENT SYSTEM. DEFLECTION WAS FOUND TO DECREASE AS SUBBASE THICKNESS INCREASED; THE THICKEST OPEN-GRADED SECTION GAVE THE LEAST DEFLECTION OF ALL.