AN APPLICATION OF THE FINITE ELEMENT METHOD FOR SIMULATION OF UNDERGROUND EXCAVATIONS AND SUPPORT SYSTEMS

Numerical methods in geomechanics have become popular tools for studying, evaluating and predicting deformations and stress distributions around underground excavations. However, attention to nonlinear constitutive behavior of materials, simulations of discontinuities (between two dissimilar media), and support systems have not been considered in great detail. The work presented in this thesis is aimed at exploring and evaluating some of the problems associated with discontinuities and support systems by the finite element analysis. The research can be divided into two areas, a civil engineering problem depicting the excavation of underground tunnels at Atlanta, Georgia, and a mining engineering problem represented by a longwall panel extraction at the York Canyon Mine, New Mexico.; Prior to the finite element computer simulation of the underground tunnels, a laboratory experimental study was conducted for determinations of the material properties based on rock samples obtained from the tunnel's site. It included the unconfined compressive, indirect tensile and confined compressive strength tests on rock cylinders. Moreover, three stress dependent path tests, conventional triaxial compression (CTC), hydrostatic compression (HC), and simple shear (SS), were conducted on 4.00 inch (10.16 cm) cubical samples.; The material properties determined from these tests were then used in the computer simulations of the underground tunnel problem. For the longwall panel extraction simulation, the materials properties used were adopted from available material properties test results conducted on rock samples obtained from the mine site.; Comparisons between the observed and calculated displacements resulted in good agreement, but the correlation between the observed and calculated stress changes was not fully satisfactory.; The results of the simulation of installation of support with and without an interface are considered encouraging. This analysis indicated the importance of including support systems as a part of the simulation sequences as well as the influence of the interface on the stress and displacement distributions around underground excavations.; In summary, the results obtained show the important role of the finite element method can play for the prediction and evaluation of stress distributions and displacement fields associated with underground excavations involving many complex factors.