Improvement of Cauchy integral method for the stresses and displacements around the deeply-buried non-circular tunnel

For a deeply-buried non-circular tunnel, abnormal stress and displacement arise in the region far away from the excavation boundary when the Cauchy integral method is applied. It is found that the calculation error is induced by a polynomial in the analytical function. An improved method is proposed by expanding the polynomial as a power series. The improved method is suitable for calculating the stress and displacement in the whole surrounding rock. The results obtained by the improved method are in good agreement with the numerical results of ANSYS, which proves the effectiveness of the proposed method.