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Long Term Behavior of Drainage Geocomposites in Environmental and Geotechnical Application
The compressive creep behavior can significantly affect the long term draining performances of drainage geocomposites due to their variation of thickness under constant loads. Extensive creep tests have been conducted under high normal loads to investigate the long term compressive creep behavior of drainage geocomposites. The information reported in this paper is based on tests under normal compressive loads of 50, 100 & 200 kPa using both the Stepped Isothermal Method (SIM) of time-temperature superposition (TTS) compressive creep test and conventional isothermal compressive creep tests performed at room temperature. The flow rate of geocomposite is usually measured in short term tests hence, the long term flow rate of draining geocomposites need to be extrapolated over the whole design life by applying a set of Reduction Factors RF, which take in to account all the phenomena that may decrease the flow rate over the entire design life compared to the short term flow rate. The suggested range and default values of the different RFs for drainage geocomposites are suggested. Since the flow in draining geocomposites does not follow the Darcy's law, hence, the flow rate is not a linear function of the geocomposite thickness, the authors propose that the available long term flow rate should be obtained as follows: Conventional and accelerated creep testing is performed for obtaining the Reduction Factor for thickness due to compressive creep RFcr-th The variation of flow rate with the thickness reduction is measured by running flow rate tests at predefined thickness of the geocomposite, based on the reduced thickness resulting from the compressive creep tests The values of the Reduction Factor for long term flow rate due to compressive creep RFcr-Q are obtained by combining the values of RFcr-Q with the results of flow rate tests at predefined thicknesses. When compressive creep tests are available but flow rate tests at defined thicknesses are not available, an approximate analytical method, using the Formula proposed by Giroud, Zhao and Richardon (2000), can be used for obtaining the analytical values RFcr-Q-GZR. Since this formula contains an unpredictable approximation of the real value of RFcr-Q obtained with the previously described rigorous procedure, the authors propose that, for avoiding a potential lower estimate, the values of RFcr-Q-GZR should be amplified by a Factor of Safety FSGZR, whose value should be selected as a function of the applied pressure through a chart proposed herein.
Long Term Behavior of Drainage Geocomposites in Environmental and Geotechnical Application
The compressive creep behavior can significantly affect the long term draining performances of drainage geocomposites due to their variation of thickness under constant loads. Extensive creep tests have been conducted under high normal loads to investigate the long term compressive creep behavior of drainage geocomposites. The information reported in this paper is based on tests under normal compressive loads of 50, 100 & 200 kPa using both the Stepped Isothermal Method (SIM) of time-temperature superposition (TTS) compressive creep test and conventional isothermal compressive creep tests performed at room temperature. The flow rate of geocomposite is usually measured in short term tests hence, the long term flow rate of draining geocomposites need to be extrapolated over the whole design life by applying a set of Reduction Factors RF, which take in to account all the phenomena that may decrease the flow rate over the entire design life compared to the short term flow rate. The suggested range and default values of the different RFs for drainage geocomposites are suggested. Since the flow in draining geocomposites does not follow the Darcy's law, hence, the flow rate is not a linear function of the geocomposite thickness, the authors propose that the available long term flow rate should be obtained as follows: Conventional and accelerated creep testing is performed for obtaining the Reduction Factor for thickness due to compressive creep RFcr-th The variation of flow rate with the thickness reduction is measured by running flow rate tests at predefined thickness of the geocomposite, based on the reduced thickness resulting from the compressive creep tests The values of the Reduction Factor for long term flow rate due to compressive creep RFcr-Q are obtained by combining the values of RFcr-Q with the results of flow rate tests at predefined thicknesses. When compressive creep tests are available but flow rate tests at defined thicknesses are not available, an approximate analytical method, using the Formula proposed by Giroud, Zhao and Richardon (2000), can be used for obtaining the analytical values RFcr-Q-GZR. Since this formula contains an unpredictable approximation of the real value of RFcr-Q obtained with the previously described rigorous procedure, the authors propose that, for avoiding a potential lower estimate, the values of RFcr-Q-GZR should be amplified by a Factor of Safety FSGZR, whose value should be selected as a function of the applied pressure through a chart proposed herein.
Long Term Behavior of Drainage Geocomposites in Environmental and Geotechnical Application
Scotto, Moreno (author) / Rimoldi, Pietro (author) / Mandavkar, Sachin (author)
2015
8 Seiten, Bilder, Tabellen, Quellen
Conference paper
Storage medium
English
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