Experimental Research on Mechanical Properties of Key Members in Composite Slab Utility Tunnels for Nuclear Power Engineering

Combined with the characteristics of nuclear power tunnels， such as large burial depths and heavy loads， and the needs for assembly and modularization， the company has optimized a series of key technologies for the structural form of composite slab utility tunnels， component processing， and on-site assembly and construction in nuclear power engineering， thereby developing a new type of reinforced concrete composite slab utility tunnel for nuclear power projects. Regarding the key load-bearing members of the designed composite slab utility tunnel structural system， a full-scale test was first conducted on a single prefabricated slab specimen. The test investigated the crack initiation and propagation， deformation development， failure mode， and ultimate bearing capacity throughout the loading process. The test results demonstrated that the failure mode of the prefabricated slab was bending failure， and its ultimate bearing capacity and crack resistance fully satisfied the requirements of both the construction and use phases. Subsequently， an experimental study was conducted on four full-scale corbel specimens. The crack propagation process， failure mode， reinforcement stress， and ultimate bearing capacity of the corbel specimens were thoroughly investigated， with a focus on the influence and underlying mechanisms of different tensile reinforcement anchorage forms and horizontal stirrup arrangements on the cracking load， crack width， and ultimate load. The test results showed that， for the same anchorage length， bent anchorages exhibited superior performance compared to horizontal anchorages. The bent anchorage enhanced the cracking load and restrained crack propagation， while the arrangement of horizontal stirrups significantly improved the ultimate load.