Semester

Summer

Date of Graduation

2006

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

Hema J Siriwardane

Abstract

Applications of geosynthetics have undergone extensive growth over the past 50 years. This study was focused on developing a better understanding the soil---geosynthetic interface properties. Two pullout test devices were built as a part of this study to investigate interface properties during pullout experiments. The objective of the study was to investigate the influence of soil type, geosynthetic type, moisture content, pullout box size, and sample size on the experimentally determined properties of the geosynthetic-soil interfaces. Three types of geosynthetic materials and three types of soils, namely natural sand, silty sand, and clayey sand were used. Geosynthetic materials A and B were geogrids, while material C was a geotextile. Two different pullout boxes were used to investigate the influence of sample size. The moisture content was varied as 0%, 10%, and 15%.;Results show that interface properties were related to the geosynthetic stiffness. Geogrids experience lower pullout capacities as the pullout box size was increased while geotextile materials behave differently. Moisture content does have an effect on pullout capacities of geogrids and geotextile materials. The pullout capacity seems to be smaller for lower values of moisture content than that for the dry soil. At higher values of moisture content (15%), the pullout capacity seems to be higher. This may be due to a reduction in frictional properties as the water acts like a lubricant initially. At higher water contents, the moisture appears to help in the development of cohesion, which in turn increases the pullout capacity. The angle of friction and effective cohesion decreased as the pullout box dimensions were increased. Interface properties of geotextile materials appear to be more sensitive to pullout box size in comparison to geogrids.

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