## 3 Full-Scale Accelerated Loading Test  
The full-scale accelerated loading test was conducted using the full-scale NE-ALT system (National Center for Materials Service Safety, University of Science and Technology Beijing, Beijing, China, 2022) to measure the dynamic responses of asphalt pavement in dry and saturated conditions. The full-scale NE-ALT system is mainly composed of a loop testing track and a vehicle simulator, as shown in Figure 4. The former includes two 40 m linear segments and two 60 m curve segments, while the field test site was set at the middle position of a linear segment. The latter simulates vehicle loading using a standard tandem-axle eight-wheel frame, and relevant sensors, which included stress, strain (in vertical, transverse, and longitudinal directions), and pore water pressure were buried in the middle of the outer wheel path nearest to the control building, as shown in Figure 5. The strain sensor's dimension is 30 mm in diameter and 110 mm in length, the stress sensor's dimension is 35 mm in diameter and 25 mm in height, and the dimension of the pore water pressure sensor is 20 mm in diameter and 10 mm in height, as shown in Figure 6. The measuring ranges of stress, strain, and pore water pressure are 0-1.5 MPa, \(-\)1500-1500 \(\mu\)\(\varepsilon\), and \(-\)0.1-1.0 MPa, respectively. The measuring frequency was controlled at 1 kHz. The buried depths of these sensors were all controlled at 0.05 m, which made the sensors' effective testing surfaces located at the bottom of the upper layer of asphalt pavement. The vehicle simulator drives along the guide track located on two sides of asphalt pavement, which makes it possible to strictly control the relative positions between sensors and wheel paths.  
The vehicle speed and load are controlled by adjusting the motor's revolutions per minute (RPM) and the servohydraulic system's applied vertical load, respectively, while relevant adjustable ranges are 0-30 km/h and 8-28 tons, respectively. Signals generated by rear axle wheels were measured and analyzed in this study, which mainly reflected the characteristics of internal structural dynamic responses, especially for asphalt pavement in saturated conditions [1]. A series of vehicle loading parameter combinations are proposed to evaluate variation trends of dynamic responses of asphalt pavement in dry and saturated conditions, as shown in Table 3. In particular, the vehicle load in field tests was represented as single-wheel grounding pressure. Field tests were conducted in the weather with the air temperature around 28 \({}^{\circ}\)C, while tests in dry conditions were first conducted and followed by those in saturated conditions. To saturate the asphalt pavement, a huge with its tap kept open was placed on the road surface to continually water the asphalt pavement through the entire night, then the asphalt layers were thoroughly saturated from the road surface to its bottom layer. As surface runoff was unavoidably taken away by the moving vehicle tires during the field tests in saturated conditions, the method of continuously watering was taken to supply enough surface runoff with a certain depth on the asphalt pavement. More details concerning field tests can be found in Reference [22]. In particular, the parameter combination of single-wheel grounding pressure of 0.7 MPa and vehicle speed of 20 km/h  
Figure 4: Full-scale accelerated loading test system.  
in the field measurements was set the same as that in the numerical simulation. Signal magnitudes were obtained by MATLAB programming and further analyzed to validate the numerical simulation.  
Figure 5: Layout of the buried sensors: (**a**) Horizontal layout; (**b**) Relative position between vehicle tires and buried sensors.  
Figure 6: Buried sensors: (**a**) Longitudinal sensor; (**b**) Transverse sensor; (**c**) Vertical sensor; (**d**) Pore water pressure sensor; (**e**) Stress sensor.