Effect of Geomechanical and Geometrical Factors on Soil Arching in Zoned Embankment Dams

Soil arching in zoned embankment dams is a phenomenon where stresses are transferred from the softer core soils to the stiffer shell soils due to differential movements between the core and shell materials. In these structures, excessive stress transfer due to soil arching will lead to hydraulic fracturing occurrence in the low permeability core soils; which can cause significant internal seepage and erosion problems. To prevent hydraulic fracturing from occurring, it is beneficial to minimize the stress transfer that occurs due to the effect of soil arching at the end of construction, as this type of stress transfer reduces the total stresses that are available to resist fracturing of the clay core upon first impoundment of the dam. This paper investigates the effect of different geomechanical and geometrical factors which can influence soil arching at the end of construction and, consequently, can impact the potential for hydraulic fracturing. During this study, a set of finite element analyses was performed to assess the effect of the upstream and downstream dam side slopes, the core width, the thickness of the transition zones (i.e., filter layers), the stiffness ratio between the core and shell, the core inclination, and the foundation compressibility. In the analyses that were conducted, a large zoned embankment dam was simulated and parametric studies were performed to quantify the effect of each input parameter on the soil arching that occurs at the end of construction.