Reinforcement effect of bolts on the material surrounding underground excavations
The tensile strength transferred by a linear reinforcement, systematically installed in a material subject to compressive stresses, increases its compressive strength and elastic modulus. Therefore the tensile strength transferred to the surrounding material of underground excavations by steel bolts systematically installed in radial patterns uniformly distanced, increases the compressive strength and elastic modulus of the excavated material. Raising the compressive strength and elastic modulus of the material surrounding underground excavations, reduces the ground pressures and the radial deformations to the excavations. Therefore decreasesthe need for surface support, allows larger excavation rounds and improves the excavation processes and safety. Consequently reduces its construction time and costs. The reinforcement effect of bolts on the material surrounding underground excavations, considering the bolt`s material, diameter, length, density, and geometric arrangement, is presented. The analysis is carried out for a circular excavation in a homogeneous isotropic material subject to an in-situ isostatic state of stresses, which accomplishes Griffith-Mohr-Coulomb failure criterion, which states that failure of a material subject to compressive stresses occurs when its intrinsic tensile strength is reached.