A Generalized Formulation of the Adapted Terzaghi Method of Arching in Column-Supported Embankments

Design of geosynthetic-reinforced column-supported embankments requires calculation of the reduced load on the geosynthetic reinforcement due to arching within the embankment fill. The load on the geosynthetic reinforcement is then used to calculate the tension in the geosynthetic reinforcement of a given strength and stiffness. Russell and Pierpoint (1997) proposed a method for calculating the load on the geosynthetic reinforcement in column-supported embankments based on Terzaghi's (1943) theory of arching. Their expression is developed for square columns in a square arrangement with homogeneous embankment fill material. This method shows reasonable agreement with instrumented embankments and numerical results presented in the literature but is limited to specific column geometry and homogeneous fill. Other column arrangement patterns include rectangular, equilateral triangular, and isosceles triangular, and the columns themselves may also be round. Some column-supported embankment design methods also specify a select fill material at the base of the embankment prior to placing general embankment fill material in order to further promote arching. This paper presents a method for calculating the load on the geosynthetic reinforcement in column-supported embankments for generalized column and unit cell geometry and two layers of embankment fill with differing material properties and lateral earth pressure coefficients.