THE IMPACT OF DISCONTINUITY ON THE STABILITY OF TUNNEL EXCAVATION IN KARST

The position of primary and secondary (stratification surfaces and fractures) discontinuities in relation to the tunnel route significantly affects the stability of the tunnel excavation. Primary discontinuities represent interlayer surfaces or stratification surfaces that formed during the period of rock formation itself, while secondary discontinuities represent fractures, i.e., discontinuities that formed after the sedimentation process was completed and are associated with tectonic activities. In addition to existing discontinuities, groundwater can also affect the stability of the tunnel excavation.