Interaction of circular holes in an infinite elastic medium

Problems of a single cavity or a series of cavities in an infinite or semi-infinite elastic medium are of considerable interest for the analysis of stress concentration factors near the boundaries of the cavities. In the mining industry, interest in problems of this type mainly derives from displacements that occur at the soil surface, which may cause considerable damage. Similar damage may occur when constructing tunnels in densely populated areas. Analytical expressions for the subsidence due to multi-tunnelling activities usually do not match very well with the measured field results. One of the possible explanations for the discrepancy between the two is the interaction of the tunnels. Simple superposition of the effects of each tunnel may give reasonable results if the distance between the tunnels is large, but not when the tunnels are constructed close together. To gain more insight into the phenomenon of interaction, an analytical solution is presented in this paper for an infinite elastic medium. Comparison of the solution with two computer packages, FLAG 20 and PLAXIS, supports the finding that the interaction of circular holes indeed causes an increase in the displacements. (C) 2001 Elsevier Science Ltd. All rights reserved.