Impact Response Analysis of Buried Gas Pipelines under Continuous Excavation by Hydraulic Backhoe Excavators

In recent years, damage to buried pipelines caused by hydraulic engineering machinery such as backhoe excavators has become increasingly frequent. For unintentional excavation activities near deep-buried pipelines, there exists a continuous excavation process by the excavator that gradually reduces the overlying soil. To analyze the dynamic response characteristics of buried pipelines under multiple excavations by the excavator, a bucket-soil-pipeline model was established using the discrete element-continuous difference coupling method. The excavation process is completed through multiple excavations, progressively reducing the soil cover over the pipeline with each shovel. The research results indicate that during multiple excavation, as the soil cover decreases, both the excavation force and resistance acting on the pipeline increase with each shovel. The excavation force of the third shovel increases by approximately 2–3 times compared to the first two shovels. The stress on the pipeline exhibits an elliptical diffusion pattern that decreases outward, and the radial strain of the pipeline is symmetrically distributed along the horizontal plane of the axis, with strain increasing further from the axis. The pipeline’s vibration acceleration fluctuates as the bucket approaches the pipeline, with a peak value of 4.23 m/s2 before contact and 17.26 m/s2 after impact. For a specific excavation condition, the study investigated the damage zoning of the pipeline by combining the analysis of pipeline vibrations and excavation loads. These results provide a reference for studying the noncontact damage mechanism of pipelines and offer insights for the prevention and control of third-party damage to pipelines.