Pullout resistance of extruded geogrids embedded in a compacted granular soil

摘要

In order to study the pullout behaviour of reinforcement geogrids embedded in granular compacted soils, a new large scale pullout test apparatus has been designed. The layout of the apparatus has been studied after a careful study of similar tests performed by other researchers in order to define a device that could reproduce, as close as possible, the real situation. More than 40 pullout tests have been performed, at constant displacement rate (1.0 mm/min), on three different HDPE extruded mono-oriented geogrids embedded in a compacted granular soil varying the specimen lengths and the applied vertical effective confining pressures. The different geogrids used in the research have been tested with tensile tests performed at different speeds, and in particular at the same speed of the pullout tests, and the granular soil have been characterized through classification, Proctor and shear tests. The pullout test results showed the influence of dilatancy phenomena and of reinforcement extensibility on the peak and the residual pullout resistance.