Tunnels, pipelines, and other subterranean circular cavities are common components of modern infrastructure. In addition, seismic activities are common in many areas with pipelines, which may put these structures under unknown risk of fracture. A particular risk case of interest can be characterized as a plane strain problem with a circular cavity and crack in an infinite plane under antiplane stress. Antiplane, i.e., mode III, loading has seen less study relative to modes I and II due to the lower risk factor in structures that are especially vulnerable to fracture (e.g., in the automotive and aerospace industries), and the increase in complexity compared to modes I and II. The work here further explores this phenomenon on circular cavities, and particularly, the effect of non-radial cracks on the stress intensity factor via a parametric study. The study introduces a semi-analytical method and also uses commercial finite element software to further expand on the investigation.