LARGE-SCALE MODEL TESTS OF GEOCOMPOSITE MATTRESSES OVER PEAT SUBGRADES

Prefabricated flexible polymeric soil confinement systems (called geoweb or geocell mattresses in this paper) hold great promise for increasing the trafficability and load-bearing capacity of thin granular bases placed over very compressible subgrades such as peat. A large-scale model test program was undertaken to compare the load-deformation performance of gravel-infilled geoweb/geocell mattresses and unreinforced gravel bases over peat under plane-strain static loading. In this investigation the geoweb mattress reinforcement was nonperforated plastic strips ultrasonically welded together (geoweb). The geocell reinforcement was constructed from strips of polymeric mesh (geogrid) attached by metal bodkins. Tests showed that the geocomposite matresses significantly improved the load-bearing capacity of the gravel base layer in comparison with equivalent depths of unreinforced gravel bases. The stiffer geoweb construction gave a greater load-bearing capacity at a given rut depth than did the less stiff geocell constructionn . In addition, tests showed that the reinforcing effect due to the geocomposite construction of the geoweb was initiated at a lower rut depth than was that due to the geocell structure. Comparisons between geoweb-reinforced gravel bases and unreinforced bases showed that the geoweb composites were equivalent to about twice the thickness of unreinforced gravel bases. For comparison purposes, the study also presents the results of reinforced tests using single layers of geotextile and geogrid polymeric reinforcement placed at the gravel base-peat interface.