TY - CONF A1 - Retzlaff, J. A1 - Müller-Rochholz, J. A1 - Klapperich, H. A1 - Böhning, Martin T1 - The behaviour of geosynthetics under cyclic load T2 - EuroGeo4, 4th European Geosynthetics Conference, September 7-10, 2008, Edinburgh, UK N2 - Whenever geosynthetics are used to reinforce or stabilise infrastructural elements such as road- and railways, bridge abutments, run- and taxiways on airports or to protect coastlines of canals and other steep slopes they may be exposed to cyclic loads. Therefore, a reduction factor for dynamic effects on the geosynthetic tensile strength has been included into the calculation of the Long Term Design Strength (LTDS). An approach to assess the behaviour of geosynthetics is to adopt Woehler- or Smith graphs and Haigh-diagrams for polymers. This is because an endurance limit for polymers, which defines an infinite life under a defined cyclic load, has not been seen so far. A huge amount of mechanical testing is needed to predict the behaviour of geosynthetics against this particular background. To reduce these efforts while getting an indication of the cyclic effect on geosynthetics, a combined method of mechanical and chemical analysis has been developed. The pure tensile strength tests to determine the residual strength after cyclic stress has been amended by IR-spectroscopy and Differential Scanning Calorimetry (DSC). In this context the chain change model of PET has been proven as valid for cyclic loads as well, which helps to define the endurance limit of materials made out of PET. For polyolefins such as PP and PE, a limit for the maximum alternating load has been identified at the point of the stress strain graph where the actual and the numerical stress of a material diverge from each other. Cyclic tensile strength tests have been carried out in a hydraulic test frame. The test parameters have been set to simulate the service life of a railway bed trafficked by high speed trains (ICE). T2 - EuroGeo4, 4th European Geosynthetics Conference CY - Edinburgh, UK DA - 2008-09-07 KW - Cyclic load KW - Dynamic loads KW - Laboratory test KW - Reduction factor KW - Reinforcement KW - Stiffness PY - 2008 IS - Paper 179 SP - 1 EP - 7 AN - OPUS4-18425 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -