Field Validation of the Arching Phenomenon of Earth Pressure Cell to Measure Vertical Stress in Flexible Pavement

Earth pressure cell (EPC) is used to measure vertical stresses at different depths of pavement due to traffic loading. Typically, it is considered that this sensor is not affected by arching phenomenon. As the sensor is made up of steel, its stiffness is greater than the surrounding soil materials. Therefore, the sensor may report greater stress for arching action compared to the actual value. This study investigated the arching effect by finite element model (FEM) and validates the results by field data from installed EPCs due to traffic and falling weight deflectometer (FWD) loads on an instrumented pavement section in New Mexico, USA. Results show that vertical stress response measured on the top of sub-base (445 mm depth) and top of subgrade (645 mm depth) increases up to 2.72 and 2.21%, respectively, for arching action. The vertical stress on top of base decreases with increase in EPC stiffness. Field measured vertical stresses under traffic and FWD loads at different depths agree with these FEM outputs.