$B6-3&MWAGK!O@J8=8(B Vol.15(1998$BG/(B12$B7n(B) JASCOME
AN APPLICATION OF MULTIPOLE INTEGRAL EQUATION METHOD
TO AN IMPROVED OVER-CORING METHOD OF CONICAL-END BORE-HOLE
Toru TAKAHASHI, Shoichi KOBAYASHI and Naoshi NISHIMURA
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The present paper describes an application of a three dimensional multipole boundary integral equation method to an improved over-coring stress relief method of a conical-end bore-hole, which is used to estimate stress states in rock mass from the measured strains on the face of a funnel-end bore-hole ( a conical-end bore-hole attached at its appex with a small-diameter inspection bore-hole) induced by over-coring with the same diameter as that of the bore-hole. Since the geometry of the over-coring is complicated and moreover precise conversion matrix is required in obtaining stresses from the measured strains, the fast multipole method is most advantageously applied. In implementation, piecewise constant shape functions with collocation technique are used to discretise the boundary integral equation and the resulting equation is solved using preconditioned GMRES. The strains induced by over-coring are simulated and shown for simple states of initial stresses.
Multipole Integral Equation Method, FMM, GMRES, Conical-end Bore-hole, Funnel-end Bore-hole, Improved Over-coring Method, Initial Stresses