Purpose <p>Border roads in hilly terrains are often vulnerable to blast attacks, particularly from surface blasts caused by explosive-laden vehicles. Such blasts can not only damage the pavement infrastructure but also destabilize adjacent slopes. Despite the critical nature of these locations, the impact of blast-induced loading on their stability remains insufficiently explored in existing literature, highlighting the need for further investigation.</p> Methods <p>This study examines the impact of surface blast loads on hill roads bordered by slopes, with a focus on the responses of both the uphill and downhill slopes. Numerical simulations are carried out using two-dimensional finite element analysis in PLAXIS 2D. The slope behavior is assessed based on the soil state, considering the influence of slope geometry. The blast wave is characterized using Friedlander’s equation, representing a spherical charge detonated in free air. To confine the computational domain to the area of interest, free-field boundaries are implemented, with free-field elements applying the corresponding motions at the model edges. The soil is modeled using a linear elastic–perfectly plastic Mohr-Coulomb constitutive model.</p> Results <p>Heave at critical locations increases with blast pressure but decreases with higher relative density. Lateral stresses rise with ground slope and reduce with density. Blasts on the right lane (near the upper slope) induce slightly higher lateral stress than those on the left. A semi-circular failure surface emerges, expanding with slope angle and TNT charge weight.</p> Conclusions <p>This study holds strong potential for evaluating blast-induced instability of hilly roads, aiding in the protection of defense transportation routes in critical border regions. It highlights the influence of relative density and blast pressure on the terrain’s response.</p>