Acta Scientiarum Polonorum

Abstract: The influence of cut-off wall depth on dewatering process of deep pit excavation, pored to the high discharged aquifer, located in urbanized metropolitan area, is presented in the paper. The simulation was performed for designed “Rondo Daszyńskiego” Station of the second line of Warsaw Subway. The most unfavorable hydrogeological conditions were found nearby this Station. The considered project of the station construction assumes dewatering with depression wells inside area protected by cut-off walls to the depth of 10 m below bottom of pit excavation. Cut-off walls will create also vertical barrier surrounding the pit excavation. FEMWATER numerical program was used for simulation of the excavation dewatering and underground waters flow. In spite of the fact that different variants of cut-off walls depth were taken into account, flow prediction results in large discharge capacity and high depression of groundwater level. That can be danger for underground water volume and finally it causes buildings subsoil settlement. The disadvantage influence of excavation dewatering on trees plant growing on surrounding area can be also analyzed. Predicted results can make consider the decision of the station construction with the use of horizontal injection barrier in the zone surrounded with cut-off walls.