Large-Scale Experimental Study of the Response of Steel Buried Pipe Subjected to Rockfall Impacts

Protecting pipelines from impact load due to rockfall in mountainous regions is a challenging problem. Many researchers have studied rockfall characteristics and impact loading, however, there is still a lack of large-scale studies about the impact of rockfall on steel buried pipes. In this study, three large-scale tests were carried out to investigate the response of steel buried pipe, including rock penetration, impact force during penetration, circumferential strain, and vertical deformation of the pipe under different falling heights of a large spherical mass. In order to establish a well-based connection between prototype and large-scale models, a comprehensive scaling rule was applied in a way that the response of the prototype and large-scale models approached the same values. The results showed that increasing drop height causes an incremental rate of peak deceleration of the falling mass, and therefore larger impact forces were measured on the trench surface. The equivalent stiffness of the soil-buried pipe system during the impact load proved that the response of the system was mostly governed by the soil rather than the pipe. For this study, the through-wall bending stress of the pipe at drop heights of 3.5 and 4.5 m exceeded the recommended permissible range, and so failing to satisfy this design criterion.