Adapting of bridges at mining area to the lowered bed of rivers

This article describes technical problems concerning bridges, dangers that arise when the bottom of the river bed is lowered during the liquidation of the floodplains. These floodplains arise as a result of terrain subsidence caused by mining exploitation. In urban areas with developed building and road infrastructure, bayous can cause significant social and material damages. One of manners of the floodplain liquidation or long-lasting lowering the water table is lowering the bottom of river channel on the leakage from bayou. Lowering the river channel can concern the section of few kilometres even long. Lowering the riverbed by dredging or considerable deepening generally does not cause important problems. Significant technical problems are generated by bridge objects. In the case of bridges, it is necessary to ensure the stability of bridgeheads, protect foundations from washing away and undermining. It is necessary to design channel reinforcement so that significant horizontal forces do not occur due to removing the part of the soil-ground from the riverbed (lack of passive ground pressure). Several technical solutions of adapting existing bridges to the lowered river bed for different structures are described.