Purpose. The paper addresses the rock mass state estimation while excavating a cross-heading through the area of regional fault “Bohdanivskyi” based on probabilistic approach to assessing the rock strength. Methods. The boundaries and fault zone extension are specified based on geological service database. This hazardous fault area has been confirmed, and the expected water inflow and methane emission have been identified based on the probe holes drilled ahead of the advancing face. To assess the strength of rocks, the statistical strength theory is used. Numerical simulation is performed using finite element method that is well-tested in geomechanical problems. Findings. The technique of rock mass strength estimation using structural factor based on statistical strength theory has been implemented to improve the adequacy of mathematical modeling. Numerical simulation of geomechanical processes based on finite element method and Hoek-Brown failure criterion is carried out. The changes of rock stress-strain state while excavating the cross-heading through various sites of the fault zone are determined depending on the level of rock disintegration. Originality. New regularities of rock mass behavior within the fault area are determined based on developed technique of rock strength assessment considering the rock mass disintegration and watering. Practical implications. Estimation of rock failure has resulted in designing the combination of support systems comprising metal sets, rockbolts and shotcrete.