Reasons of transition tunnel construction to the pre-emergency state and the nature of landslide displacements trimmed slope, which can be traced in the context of the Lower Cambrian blue clay are defined. Influence of microbial activity as a negative factor fracture of structural materials, as well as strength reducing of blue clay. Regularities of changes in the state and the strength of blue clay at the depth, taking into account their degree of disintegration – layering and fracturing. The quantitative evaluation of stability of the construction of the transport tunnel, taking into account changes in the strength of blue clay as an fissered medium at different positions of the landslide surface. The strategy of measures to ensure the reliability of the facilities.