Models of underground openings
In the following simulations, three simple shapes of underground openings, with circular, elliptical and inverted U cross-sections, are considered. The specific geometries and loading conditions for these three geometries are shown in Figure 2.7. Applied boundary stresses in the vertical and horizontal directions are denoted as p and kp, respectively, where j is usually called lateral pressure coefficient. These models have a common dimension of 240 mm 240 mm. The diameter of the circular opening,the transverse axis of the elliptical opening and the width of the inverted U-shaped opening are all 1/4 of the length of the whole model. These cases of simple excavation geometries and an assumed homogeneous rock mass with known elastic properties are examined as reference or base cases for the subsequent analyses with RFPA2D, which take account of heterogeneity of the medium and damage associated with fracture formation.