A new test device and method: |geotextile-soil interface cylindrical test (GICT)

Abstract

The use of geosynthetics in civil engineering has covered a wide range, as they are effective in solving geotechnical problems. There has been a significant increase in the research for determination of interface friction properties of soil to geosynthetic or geosynthetic to geosynthetic interaction in geotechnical engineering. For the time being, a number of test devices and methods are utilized to determine the soil-geotextile shear strength parameters by the researchers. All these interface test devices had their own advantages and disadvantages associated with the type of the device. A new interface testing device, Geotextile-soil Interface Cylindrical Test (GICT) is developed in this study. The GICT is used to perfonn interface tests between soil and geotextile. The geotextile is glued around a cylindrical block and rotated in a soil sample where the normal load is applied radially. It has many advantages over the existing interface test devices. Unlike of the other interface devices, unlimited and continuous displacement and constant shear area are achieved during the tests. Machine friction, load eccentricity and boundary effect on the sheared sample are minimized in the GICT. It has a simple loading system and suitable for cyclic loading. The GICT is useful to detennine the interface shear parameters by testing the samples in the fixed shear or partially fixed shear testing modes. By a simple modification on the device geosynthetic to geosynthetic or geogrid interface tests and pullout tests can be perfonned. Also, the advantage of possibility to change the dimensions of shear samples enables the researcher to test various sjze samples in just one device. Fixed shear interface tests were performed in the Geotextile-soil Interface Cylindrical Test device and in a conventional 10 by 10 direct shear box. Two types of sands at very loose and dense states were tested in four types of geotextile interfaces. The tested geotextiles have different engineering properties, such as, polymer type, manufacturing method, tensile strength, compressibility and thickness. The results obtained from the GICT were compared to those obtained from the fixed shear tests in the direct shear box. The GICT gave reproducible and comparable results.