Engineering-geological and geotechnical aspects of the construction and operation of the kuznetsovsky tunnel at the far eastern railway

The object of the research is the solid rocks massif containing the Kuznetsovskiy tunnel with a length of 3890 m, the greatest depth of the deposit is 355 m, which crosses the mountain pass section of Sikhote-Alin on the Komsomolsk-Sovetskaya Gavan line of the Far Eastern Railway. The aim of the studies was a detailed analysis of the engineering and geological conditions of the facility and their impact on construction and operation. These data are obtained as a result of field research, laboratory testing of physical and mechanical properties of rocks, evaluation of water flow to drainage structures and analytical calculations. The massif is composed by terrigenous rocks - a rhythmic interlayering of heterogeneous grained sandstones, siltstones, gravelites, conglomerates, that are classified as strong. Layering has a steep drop and a sublatitudinal strike, deviating from the axis of the tunnel by 20 - 60 °. The tunnel axis is crossed by a system of faults of various capacities, their total capacity is 334 m, which is 8.5% of the length of the tunnel. The fault zones are associated with increased fracturing, reduced stability, in places abundant water inflows that have peaks in the summer, the threat of landslides, intense silicification and sulfide mineralization. The obtained monitoring materials by methods of recording natural pulses of the electromagnetic field of the earth (NPEFE) (EEMEMP) and dipole electromagnetic profiling (DEMP) allowed to draw a conclusion about the real picture of the development and forecast of the rock pressure, as well as the dynamics of the groundwater entering the mine for safe construction and operation. The state of the geodynamic conditions of the mountain massif is characterized as stable. Available data can be used as a starting point for assessing and forecasting aspects of the construction and operation of the second stage of the tunnel.