The excavation of large underground caverns easily induces brittle cracking failure of high sidewall under high ground stress and other complex condition. Based on Mohr-Coulomb criterion and tensile strain criterion

a new composite tensile-shear yield criterion of high sidewall for large underground powerhouse was proposed. At first

according to the elastoplastic theory

associated and non-associated plastic flow rule were adopted independently for tension and shear yield. The calculation formula of this rule is deduced in detail in the finite difference method; and the dividing boundary of tensile and shear yield surface in stress space is determined. Then dynamic link library of the software is programmed adopting the C language; and the criterion can be used in the general software. Finally

taking the Lashiwa hydropower station located in the high geostress region for example

compared to FLAC3D own tensile-shear yield criterion

the results show that the tensile failure of high sidewall is obvious; and plastic zone and stress relaxation area is smaller by considering the tensile strain yield criterion; the proposed criterion can describe brittle cracking failure features of hard rock for high sidewall. Calculation of large hard rock underground caverns proves that the proposed criterion is reasonable.