Risk assessment in Bursa Keles road parting Orhaneli provincial road tunnel works

This study addresses the identification of all potential hazards and carrying out risk assessment studies in the Bursa-Keles Junction Orhaneli Provincial Road Doğancı variant tunnel, which is under construction in Bursa, in order to prevent accidents, increase efficiency in routine manufacturing stages and ensure safer working conditions. In the light of all this information, the 5x5 L type matrix method, one of the risk analysis methods, was used and the correct risk assessment method was tried to be determined. With the risk assessment studies carried out, hazardous situations were determined in areas where tunneling methods were used and potential risks were evaluated. Progress is being made on the Doğancı variant tunnel using the Austrian Tunneling Method (NATM) construction technology. In the NATM method, progress is made by drilling/blasting method in hard rock conditions where the ground is medium-hard and hydraulic breakers are ineffective. The excavation material released by excavation work and/or drilling/blasting in the last excavation area of the tunnel is discharged to a special area (waste area) separated outside the tunnel with the help of work machines. At this stage, the ventilation system of the equipment is carried out through a fan tube in order to minimize the dust and gases released and to provide safe working conditions for the employees by cleaning the dirty air inside. During the production, support is provided in the final excavation area of the tunnel, especially in weak ground conditions, there are no dents, slips, etc. It continues with the application of pre-sprayed concrete (Shotcret) applied on open ground in order to avoid such situations and not to risk employee health. Subsequently, shoring made of steel mesh and profile iron designed in accordance with the project is installed. After the steel mesh and shoring surfaces are covered with sprayed concrete to prevent their contact with the ground/rock environment, the bolts with statically calculated lengths and spacing are drilled and placed in their places by a work machine called Jumbo, and the next stage, bolt injection, is started. The section that forms the bottom section of the tunnel (invert) ensures the assembly of the entire system and is also the first preparation for the arch concrete application. At this stage, the pre-designed concrete is tested in the invert area where excavation and fortifications are made, and thus the first stage of the final coating, which consists of two stages, is completed. In the second stage, geotextile and membrane production is carried out to ensure the drainage of the water coming into the tunnel. Finally, at the final concrete coating stage, a steel mold is installed and the steel mold is filled with high-strength concrete and the manufacturing is completed. In summary, the risk factors encountered during this manufacturing are; They are grouped under headings such as Blasting, PPE Use, Ventilation, Lighting, Electrical Works, Working at Height and Work Machine Use. Possible risks that may arise in all manufacturing stages were meticulously examined and 25 separate activity areas were determined. Within a total of 25 activity areas; A total of 215 hazards were identified, including 3 absolutely intolerable risks, 51 risks requiring urgent action, 122 risks requiring precautions and 39 tolerable risks. In line with this data, the Risk Analysis table is constantly updated, from implementation to monitoring, of the precautions to be taken for major and job-specific hazards that may be encountered at each manufacturing stage. Keywords: 5x5 Matrix Method, Natm, Occupational Health and Safety in Tunnels Risk Assessment, Tunnel Industry