Dilatancy Behavior of Soil-Structure Interfaces for Farm Roads and Embankments

The dilatancy behavior is one of the major factors that control the performance of agricultural earth structures during the pullout of geosynthetic and geogrid subject to reinforced slopes, earth embankments or dams. In this article, a new apparatus according to the JIS standard for pullout test is built to evaluate the dilatancy behavior of two types of soils reinforced with geosynthetic/geogrid. A series of pullout tests are carried out to study the effect of type of reinforcements and soils on dilatancy behavior at soil-reinforcement interfaces. Two types of geosynthetic and geogrid, such as, stabilanka and fortrac those are widely used in Japan and globally, are demonstrated. All the pullout tests are performed under six normal stress conditions in order to obtain more precise results of the dilatancy behavior. The parameters of dilatancy behavior of pullout tests are quantified in terms of vertical displacements. The analyses of the data and information reveal that fortrac has higher dilatancy in clayey soil whereas stabilanka has higher dilatancy in sandy soil. Among the four cases investigated in this article, the highest dilatancy is occurred for fortrac in clayey soil. It is concluded that the fluctuating nature of dilatancy which is usually observed in the soil-soil interface without any reinforcement is significantly improved due to the use of reinforcement in soil and almost constant dilatancy is obtained at soil-structure interfaces even until the end of horizontal displacement.