Soil-reinforcement interaction properties are fundamental designparameters in the design of reinforced earth structures. Those properties can be determined either from direct shear or pullout tests. The pullout box test was used because it is more versatile than the direct shear test method in that it can be used to study wire meshes, strips, geogrids, geotextiles, and other types of reinforcements in different soils. The internal dimension of the pullout box is 30 in. Long, 28 in. Wide, and 24 in. Deep. A finite-element program called geot2d capable of solving both the planar problem and the axisymmetric solid of revolution was developed. The soil-reinforcement system in geot2d is represented by isoparametric continuum elements, two-node membrane elements, and four-node interface elements. It is shown that with the nonlinear interface shear parameters obtained from the direct shear test pullout responses can be accurately predicted.Conversely, by matching numerically predicted pullout responses with measured pullout responses, it is possible to obtain nonlinear interface parameters directly from pullout tests, which can in turn be used to study performance of various types of reinforcements in earth structures. Effects of size of the apparatus, the reinforcement stiffness or extensibility, and the gap on pullout responses are discussed. The procedure presented takes into account those variables andthus yields soil-reinforcement interface properties both accurate and consistent for all applications. This paper appears in transportation research record no. 1278, Dynamic testing of aggregates and soils and lateral stress measurements 1990.
Abstract