Numerical analysis of the impact of drill-and-blast tunneling on an overlying landfill

The Jigongshan Mountain Tunnel in Shenzhen, China was excavated under the Xiaping landfill using the drill-and-blast tunneling method. Existing literature has not yet proposed any approaches for evaluating the impact of tunneling blasting load on landfills. In this study, field measurements on vibration acceleration induced by blast were firstly conduct under the landfill. Then, 3D dynamic numerical models were established to simulate the rock damage and vibration under the blasting load. A new elastoplastic damage model considering tensile-shear stress was employed to describe rock damage propagation. Next, the thresholds of rock damage and vibration were proposed under tunneling blasting. The impact of drill-and-blast tunneling on the overlying landfill was evaluated from two perspectives of rock damage and vibration based on critical numerical analyses. Finally, the evaluation results were proved by field tests of electrical resistivity tomography (ERT) and water sample analysis. Results indicate that under the blasting load, the maximum rock damage depth is 8.5 m, and the blast-induced vibration attenuates within 5 m, both posing a negligible threat to the landfill liner integrity. This study presents a new numerical approach for evaluating the landfill integrity under the tunnel excavation blasting and provides valuable references for similar projects worldwide.