طراحي و ساخت دستگاه آزمايش بيرون كشش سيكلي ژيوگريد

Design and Development of Cyclic Pullout Test Apparatus

This paper presents a recently developed automated pullout apparatus for soil-geogrid strength and deformation behavior investigation. The new apparatus is capable of applying load/displacement controlled monotonic/cyclic loads at different rates/frequencies, different wave shapes and loading patterns, through a computer closed-loop system. An extruded uniaxial geogrid and silica sand are used throughout the experiments. The effects of normal pressure (surcharge) and relative density are investigated on displacement distributions and pullout capacity of the geogrid in both monotonic and cyclic tests. In monotonic tests, it is observed that with increase in relative density and surcharge, pullout resistance has increased. In cyclic tests, despite some minor observations of post-cyclic strength increased, no specific comment can be made at this stage on the post-cyclic strength.