Sand-Woven Geotextile Interface Shear Strengths in Different Shearing Directions

Abstract

Woven geotextiles have been commonly used to reinforce or stabilize slopes, walls, and roads. Soil-geotextile interface shear strength is an important design parameter for these applications. Under different geometrical and/or loading conditions, the geotextile may be sheared in different directions. Therefore, it is important to understand how interface shear strengths change with shearing directions. This study aimed to investigate and compare the interface strengths between sand and woven geotextile by large interface shear tests performed in three shearing directions: (1) 0° (machine), (2) 45° (diagonal), and (3) 90° (cross-machine) under three normal stresses of 12.5, 25, and 50 kPa. The large interface shear test device consisted of an upper shear box and a lower shear box in similar dimensions of 100 mm high, 300 mm wide, and 300 mm long. One type of woven geotextile consisting of polypropylene fibers was investigated. A river sand at a dry condition was used and compacted to a relative density of 75%. The interaction coefficient between the sand and the geotextile was calculated for each test. The test results show that the shearing direction had obvious effects on the peak interface shear strength and the volumetric change during shearing. The interface shear strength and the volumetric change at the 45° shearing direction had a combined effect from those in the machine and cross-machine directions.