In-situ Frictional Tests for Geomembrane/Soil and Geomembrane/Geotextile Interface

Geomembranes and geotextiles, recently, are becoming to be widely used as a component of liner system in waste landfill. The frictional characteristics on interface between geomembrane/soil and geomembrane/geotextile are very important factor to design liner's structure such as its anchorage or side slope angle. In this paper, convenient in-situ equipment to measure a frictional resistance between geomembrane/soil and geomembrane/geotextile was developed. The in-situ tests were conducted on two loam ground and on drain sand at construction site. The ground condition was prepared as natural moisture condition and submerged condition. The geosynthetics used included six geomembranes such as smooth HDPE, HDPE with spike, EPDM, TPO, PVC and reinforced CPE and two geotextiles such as continuous nonwoven and stapled nonwoven. As the results, it is found that the ratio of frictional coefficient estimated at submerged condition to one at natural condition is about 70-80% for loam ground while it is 90% for drain sand. The frictional coefficients between smooth surfaced geomembrane and stapled nonwoven geotextile estimated at in-situ tests is good agreement with the relationship between normal stress and shear stress obtained by direct shear tests in laboratory.