Alternate Method of Pavement Assessment Using Geophones and Accelerometers for Measuring the Pavement Response

Abstract

Pavement instrumentation with embeddable in-situ sensors has been a feasible approach to determine pavement deteriorations. Determining pavement deflections during the passage of the load is a promising strategy to determine the overall performance of the pavement. There are different devices that apply loads to the pavements and measure the deflection basin, these include static, vibratory, or impulse loadings. Most commonly used are the static loading like Benkelman beam and impulse loading like the Falling Weight Deflectometer (FWD). However, these techniques are costly and the measurements are recorded infrequently, i.e., once per year or two years. This study focuses on the use of geophones and accelerometers to measure the surface deflections under traffic loading. To develop a method to measure pavement deflections, the sensors were submitted first to laboratory tests, and then tested in situ, in a full scale accelerated pavement test. In the laboratory, the sensors were submitted to different types of loading using a vibrating table. These tests were used to determine the noise and sensitivity of the sensors, and then to evaluate their response to signals simulating pavement deflections under heavy vehicles. The sensor response was compared with measurements of a reference displacement sensor. Different processing techniques were proposed to correct the measurements from geophones and accelerometers, in order to obtain reliable deflection values. Then, the sensors were evaluated in a full scale accelerated test, under real heavy axle loads. Tests were performed at different loads and speeds, and the deflection measurements were compared with a reference anchored deflection sensor. The main advantage of using accelerometers or geophones embedded in the pavement is to enable continuous pavement monitoring, under real traffic. The sensor measurements could also be used to determine the type of vehicles and their corresponding speeds. The study describes in detail the signal analysis needed to measure the pavement deflections accurately. The measurements of pavement deflection can be then used to analyze the pavement behavior in the field, and its evolution with time, and to back-calculate pavement layer properties.

Instrumentation of Field-Testing Sites for Dynamic Characterization of the Temperature-Dependent Stiffness of Pavements and Their Layers

“…Te measured acceleration histories were used as reference values for the optimization of dynamic simulations of the behavior of pavement structures [38,60]. Measured acceleration histories were also converted, by means of double time-integration, into defection histories, see [14,55,[61][62][63][64]. Te defections were then used for back-calculation of layer properties.…”

“…Installing accelerometers at multiple depths during the construction of the pavement represented a novel challenge, difering from the installation at a single depth and after construction as described in [14,38,62,64]. As for the present study, the following two requirements had to be fulflled:…”

An experimental approach for in-situ characterization of dynamic dissipative properties of road pavements

“…To this purpose, Benkelman Beam Deflectometers, lightweight deflectometers [8], and the Falling Weight Deflectometers (FWD) [9,10] were mainly used. Recording vibrations from sensors bonded to or embedded within the pavement was also exploited to derive performance parameters of road structures under different climate and traffic conditions [11,12,13]. Crack propagation and fatigue damage were monitored by means of in situ measures [14] taken through piezoelectric sensors, which are in fact typically used to detect damage in structural components [15].…”

Technical Proposal for Monitoring Thermal and Mechanical Stresses of a Runway Pavement

“…Using geophones and accelerometers, it is possible to calculate deflections by means of a single or double integration of the recorded measurements, respectively. Due to the non-realistic deflection values obtained with simple integration, [ 34 , 35 ] proposed an original signal processing procedure to obtain them, and then to assess the elastic modulus of pavement layers by means of back-calculation procedures.…”