PROBLEMS OF FRICTION POSED BY THE USE OF GEOMEMBRANES ON DAM SLOPES - EXAMPLES AND MEASUREMENTS

Two examples are presented of the use of geomembranes for the water-proofing of earth fill dams approximately 15 m high. These are, firstly, a PVC geomembrane used as an upstream facing on the Aubrac dam and, secondly, a bitumen membrane used as an internal core in the Valence d'Albi dam. A partial slip of the facing during the construction of the Aubrac dam illustrates the difficulties involved in laying a geomembrane on a dam slope, and led to measurement of the friction at the geotextile-geomembrane interface on a 1·00 m × 1·00 m inclined plane. The advantage of this method is that it recreates test conditions that are close to real conditions, particularly where normal stresses are very low. This method gave much lower frictional angles than those determined by the shear test apparatus. As a result of these tests, friction on the smooth face of the bituminous geomembrane was increased for the second dam by burning the polyester film in situ. © 1990.