A.N. Galybin

A measuring scheme for determining in situ stresses and moduli at large scale

This paper proposes and analyses a new measuring arrangement for the cylindrical jack method of determining in situ stresses and elastic moduli. The new methods measuring scheme is free of the shortcomings associated with Dean and Beattys variant, and its proposed system will facilitate in situ stress and moduli determination over a large scale. Its main innovations are its proposed arrangement of measuring points, and the adoption of modern displacement measurement transducers with a sufficient resolution level. The paper presents mathematical analyses of the Dean-Beatty measuring scheme for the cylindrical jack method and of the proposed new measuring scheme. An algorithm is described, which uses the least squares method to solve the system using the proposed scheme, and reconstruct the shear modulus, the stresses, and Poissons ratio. A numerical example is given of the reconstruction of the stresses and moduli. The proposed measuring scheme allows the simultaneous reconstruction of the stress components and elastic moduli of a rock mass, at a scale considerably larger than with conventional methods such as overcoring, although it can only be applied near the surface of an excavation.

Non singular terms in stresses near the tip of an arbitrarily loaded edge crack

Distribution of stresses along the line of continuation of the edge crack in the half plane is obtained by solving the Riemann boundary value problem. The leading asymptotic terms in stresses near the tip of the arbitrarily loaded edge crack are presented in a convenient form as the convolution of the solution for concentrated forces with the applied load