ORGANIZATIONAL AND TECHNOLOGICAL SOLUTIONS FOR THE REPAIR AND RESTORATION OF SEWAGE TUNNELS IN THE PLACES ADJACENT TO EXPLORATION MINES

Abstract

The analysis of the occurrence of typical accidents of water drainage networks indicates a number of reasons for their failure, namely: a 2-3 times decrease in the amount of sewage over the last 20 years; increase in aggressiveness of wastewater, decrease in flow rate and increase in rainfall. During operation beyond the regulatory term, the reinforced concrete vault of the tunnel is almost completely destroyed as a result of biogenic corrosion. The listed reasons for the destruction of sewage tunnels built more than 50 years ago are generally similar in nature. From the above, it follows that the specifics of the operation of sewer tunnels can be highlighted - the cross-section diameter is more than 1500 mm and the laying depth is more than 5-7 m. It should be noted that the sections of the tunnels at the points of connection with inspection shafts, as well as the structure of inspection shafts, experience the greatest corrosion. A significant role in the repair and restoration of water drainage structures is played by the selection of materials and structures capable of counteracting the aggressive effects of hydrogen sulfide and other gases. In Ukraine and abroad, considerable experience has been accumulated in the repair and restoration of drainage network structures using materials and structures with high acid and alkali resistance. Conducted research has shown that products based on basalt have a number of advantages: high strength, fairly low weight, reliability during operation in a wide temperature range, they are not prone to corrosion and have high chemical resistance. The experience of working with pneumatic formwork gives them special importance, because they ensure the following requirements:quick installation and dismantling of the formwork; the possibility of using it for curved spatial surfaces forms, even with large spans;multiple reversibility of the formwork. The technology for the construction of the vaulted part of the sewer tunnel with internal finishing with stone casting tiles involves the following stages:dismantling of emergency sections of the tunnel (vaults, walls);clearing the tray part of the tunnel;restoration of the section of the tunnel part of the tunnel (if the tunnel is destroyed);cleaning of the existing fittings to ensure the joint operation of the tray and the protective coating of the vault being erected;installation of pneumatic formwork for the construction of the tunnel vault with internal finishing with stone casting tiles;laying stone casting tiles;installation of the necessary fittings for the protective lining of the vault made of monolithic reinforced concrete;creation of inventory formwork;laying the concrete mixture of the monolithic part of the vault;dismantling of pneumatic and inventory formwork after gaining strength of concrete;backfilling of the trench with compaction. The main period of restoration of the observation shaft with the help of lining the walls with stone-cast basalt tiles: dismantling of floor slabs; cleaning of walls from corrosion products; injection of anti-corrosion concrete on a small filler of space at the junctions of the tunnel; reinforcement of the mine walls (in case of deep corrosion of the walls); facing the walls of the observation shaft with stone-cast basalt tiles; treatment of the inner surface of operational areas and stairs with anti-corrosion epoxy polyurethane compound "AQUAKHIM". To justify the feasibility of using the proposed technology, two options for restoring the destroyed tunnel were considered: the method using stone casting tiles; the method of replacing destroyed pipes with polyethylene ones (an open method of restoration with dismantling of the destroyed tunnel). The option of restoring the sewer tunnel using stone casting tiles is almost 3 times more economical and expedient in terms of the cost of materials compared to the use of SPIRO PE pipe. The advantage of restoring sewage tunnels in this way is the durability and resistance of this material to aggressive effects, a sufficient amount of natural material in the country, and low cost. Keywords: sewage tunnel, inspection shaft, basalt, pneumatic formwork, technological solutions, open method.