Traffic-speed deflectometers (TSD) are used in several countries to evaluate the pavement structural condition at the network level. Fatigue and rutting strains are commonly used as pavement critical responses in mechanistic-empirical design procedures to predict pavement structural performance. For successful pavement management system (PMS) application, robust indices that can be readily computed from TSD measurements and best related to the pavement critical responses should be identified. In this study, a comprehensive sensitivity analysis on deflection basin indices and their correlations with fatigue and rutting strains is performed using a range of pavement structures. A commercially available program was used in the first part of the study to compute dynamic deflection basins and evaluate the effects of material properties and vehicle speed on the indices. The indices that best relate to critical responses were identified from the software analyses and subsequently evaluated with a wider r...

An investigation of the existence of predominant frequency, fp (or frequencies), and the ability to predict critical pavement responses in asphalt layers using those predominant frequencies has been presented. The study used an extensive database of computed pavement response histories of four different asphalt pavement structures (thin and thick) at two temperatures (21 and 40°C) subjected to a tandem axle load at three speeds (16, 65, and 97 km/h) using the pavement response analysis program 3D-Move Analysis. The conversion of load duration to frequency and the validity of using one response component (σzz) alone in the estimation of the pulse time (tp) were explored. Instead of focusing on only σzz, attention is given to all pavement response components (stresses and strains). In addition, verification of whether the use of a consistent set of fp value(s) can in fact adequately capture all components of pavement response has also been undertaken. The viscoelastic properties that are representa...

In 2000, the South Dakota Department of Transportation sponsored a research study to evaluate the impact of off-road vehicles on flexible pavements. This project included field pavement responses measured under a variety of loading and environmental conditions. The objective of this investigation is to validate the applicability of the three-dimensional moving load analysis (3D-MOVE) pavement response model before attempting to generate a database of important pavement responses for representative pavements in South Dakota. The validation investigation adopted here addressed both the development of appropriate contact stress distribution for bulky off-road vehicle tires and comparison of computed and measured pavement responses. The field testing consisted of one relatively thin and one relatively thick flexible pavement tested under three types of empty and loaded off-road vehicles. Each pavement section was instrumented with pressure cells, deflection gages, and strain gages at the bottom of the asphalt...

The procedures in Mechanistic-Empirical Pavement Design Guide (MEPDG) and Caltrans software program using Mechanistic-Empirical (CalME) methodologies to address wheel wander are relatively simple and based on dividing the wheel wander distribution into a number of segments (say five) of equal areas. Such approaches suffer from a major limitation that the selection of equal segments is arbitrary, and can, therefore, lead to biased results relative to realistic transverse wheel wander distribution. The proposed Monte-Carlo simulation scheme provided cumulative distribution functions for all the critical responses and they in turn were used to estimate pavement performance (or life). The investigation covered a variety of pavement factors that significantly affect pavement performance or life. The factors included are: (1) pavement layer configuration (thin and thick); (2) pavement material properties (unmodified and polymer-modified asphalt mixture); and (3) tyre configurations (dual and wide-base). In this paper, the focus has been on the description of the proposed approach and its application in two of the important modes of failure in asphalt concrete pavements: fatigue cracking (top-down and bottom-up) and rutting. The required traffic-induced pavement strain database needed in the pavement performance investigations was developed using the 3D-Move analysis software. The proposed approach is more appealing than current procedures (e.g. MEPDG and CalME) since the pavement response distributions were derived statistically. The pavement design information presented are in the form of data sets that the pavement engineers and researchers can readily use to assess the impact of wheel wander in terms of many important factors such as pavement layer configuration, non-uniform tyre contact distribution, vehicle speed, etc., that affect long-term pavement performance.

Two traffic speed deflection devices (TSDDs) that measure surface deflections at posted traffic speeds (up to 80–96 kph) were evaluated through a recent Federal Highway Administration project that included field trials at the MnROAD facility. Four geophones were embedded near the pavement surface to measure surface deflections during field trials at each of three MnROAD cells. In addition, the MnROAD facility counted with numerous other sensors such as strain gauges to measure pavement responses and thermocouple trees to collect pavement temperature at various depths. For the implementation of TSDDs in any network-level pavement management system, it is important to utilise a proper analytical model that can accommodate moving load and viscoelastic properties of pavement layers in the simulation of TSDD measurements. The 3D-Move software was chosen for this purpose. The viscoelastic properties used for the asphalt concrete (AC) layer include dynamic modulus and damping coefficient as a function of frequency relevant to the temperature at the time of the MnROAD field trials. The field trials and available data represented realistic field case scenarios to validate once more 3D-Move specifically for TSDD measurements. The proposed dynamic analytical model provided a good match with a variety of independent pavement responses that included surface deflection bowls (measured using embedded geophone sensors) as well as horizontal strains at the bottom of the AC layers (measured using MnROAD sensors).

Altogether six mechanically stabilized earth walls were subjected to many base excitations on the National Geotechnical Centrifuge at the Univ. of California, Davis. The walls supported dry cohesionless soils deposited at the start of the test at a relative density of 65%. In general, walls behaved as expected, i.e., walls with longer reinforcement deformed less, than the walls with shorter reinforcement. There was no catastrophic failure observed in any of the six walls. The wall face displacement was not uniform across the wall face, and typically the middle of the wall displayed the largest displacement. The acceleration response near the top of the wall showed “clipping,” and during this time the lateral wall movement occurred away from the backfill. Such behavior was not observed either near the bottom of the wall or in locations away from wall, i.e., free field. Measurements show a lack of rotation near the top of the wall, while the bottom of the wall moved laterally and rotated. The acceleration f...