Assessing Hydraulic Fracturing in Earthen-Rockfill Dam Core based on Extended Finite Element (XFEM) Framework

Hydraulic fracturing in clay core of earth-rock fill dams appear when fluid pressure becomes higher than the total stress at a point, developing tensile effective stress conditions within the soil. In this paper, hydraulic fracture in an earth-rockfill dam is modelled using eXtended Finite Element Method (XFEM). The finite element simulation of Hyttejuvet dam is carried out to exhibit the pore pressure developments at various locations of the dam, which are compared with measured in-situ measurement and monitoring data. A prominent arching at the mid-depth of the upstream core face could be noticed at the location of crack appearance in the dam. The fracture occurs in a nearly vertical direction, orthogonal to the maximum effective tensile stress direction within the core. The influence of various characteristic properties of core material on initiation of hydraulic fracture is investigated. It is concluded that increasing the permeability of the core delays the fracture initiation while inducing a smaller crack in the core. Adopting a core material with higher modulus of elasticity can reduce arching phenomenon in the dam to ensure a less severe crack formation. Additionally, increase in the maximum reservoir level is found to induce larger crack in the dam core.