ABSTRACT
The article presents the results of studying the fracturing of clay rocks (claystone) which are the surrounding medium of underground structures located on the territory of St. Petersburg and the Leningrad Region. The presence of systems and zones of increased fracturing having various orientation, intensity and nature that complicate the structure of the clay massif was established. The influence of the fracture intensity on strength and deformation ability of such rocks has been studied experimentally. Particular attention is paid to the assessment of fissured clay permeability in connection with the possibility of upward or downward flow of groundwater which is able to contact with clay blocks and underground structures. Data on the investigation of the chemical and physico-chemical interactions of clay rocks with groundwater of different compositions are presented. The influence of the groundwater upward flow on the change in the stress-strain state of the surrounding medium and the development of tunnel displacements is shown. The role of groundwater in the corrosive destruction of constructional and hydroisolating materials is studied. It has been experimentally proved that, during the process of groundwater flow through fissured clay rocks, biofilms form on the walls of fractures, and not inside the blocks.
