The stress relief correction method considering irregular borehole shapes

In situ stress is an essential parameter that directly affects all engineering construction and scientific research in deep rock masses. The shapes of deep borehole are often highly irregular, so that the traditional in situ stress measurement methods based on the assumption of circular or cylindrical boreholes are no longer applicable. We propose a stress relief correction method considering irregular borehole shape using the complex function method of elasticity. The conformal mapping function is introduced to project the irregular shape into a unit circle and the relationship between the strains at the borehole wall and the far-field in situ stress components are solved by the Cauchy integral methods. The results show the following: (1) The stress results from the stress relief correction method are consistent with the theoretical solutions and numerical simulation results for circular and square boreholes. (2) The irregular borehole shape significantly changes the distribution of stress magnitude and the direction of strain measurement on the borehole wall. The stress relief correction method considering irregular borehole shapes provides an essential theoretical basis for deep rock mass engineering construction and deep oil and gas field exploration.