A study of the response of geosynthetic reinforced flexible pavement test sections to dynamic loading

Abstract

Geosynthetic reinforcement was utilized in the construction of eighteen laboratory flexible pavement test sections. The test sections were designed to simulate a low- traffic volume secondary road built over a weak subgrade. Three types of geosynthetics were used: two types of woven geotextiles; and a geogrid. The test sections were constructed, cyclically loaded, and the resulting data were collected and analyzed. The performance of reinforced test sections was compared to that of unreinforced sections to estimate any improvement due to the reinforcement. The test sections were loaded dynamically at a frequency of 0.5 Hz using a computer controlled loading system. The loading system imparted a force of 9,000 Ibs (40 kN) to the pavement surface. The load was transn1itted to the pavement surface by a 12 in (30.54 cm) diameter rigid steel plate, which approximated a dual tire load from an 18 kip (80 kN) truck axle. Both the forces applied to the steel load plate and the deflections of the pavement surface were monitored using a computer-controlled data acquisition system. The deflection of the pavement surface was measured using an array of LVDTs. An analysis and comparison of the cumulative displacement of the pavement surface due to the number of applied loads was performed for the test sections. Load induced dynamiC and cumulative vertical earth pressures within the subgrade were monitored, analyzed, and compared for a series of reinforced and unreinforced test sections. Composite section stiffness was calculated and compared among test sections with similar subgrade CBR values.