Analysis of steel baffle installed on footing with dowels for resisting boulder impact

Debris flow is a common geological hazard in mountainous area. The large boulders carried by debris flow can be particularly destructive to downhill facilities. Constructing steel baffle with a footing on steep slope is a cost-effective mitigation method to dissipate the impact energy of boulders. However, current design of steel baffle and its footing and structural connections is usually highly empirical which may impede the effectiveness of baffle on resisting boulder impact. In this study, full-scale pendulum impact tests were conducted to investigate 10-kJ boulder impact on baffle installed on cubic footings with side lengths of 650 mm and 1300 mm. The pendulum impact tests were used to calibrate the input parameters of a three-dimensional (3D) finite element model. Numerical parametric study was conducted to investigate the effects of footing size and application of steel dowels on baffle to resist boulder impact with an energy up to 100 kJ. The required footing size and embedded depth of steel dowels in soil are recommended to avoid the failure of a baffle and its footing subjected to dynamic boulder impact. To predict the boulder impact force on a steel baffle, a force reduction factor of 0.03 can be used for the simplified Hertzian method. The unique results presented in this study can be used by practitioners to design baffles, instead of large reinforced concrete structure, as a more sustainable alternative mitigation measure to strengthen the resilience of mountainous communities globally.