Rockfall Analysis, Modeling and Mitigation Along Al-Hada Descent Road, Saudi Arabia

Abstract

In western Saudi Arabia, constructing mountain roads in harsh terrains is a challenge, where the rock masses are characterized by high-rising and steep slopes, and full of terrain problems. Al-Hada mountain road of almost 22 km long shows many examples of rockfall’s incidents. A 100 m long a man-made and natural sharp slope cut suffers from rockfall’s incidents on the road, mainly in rainy seasons. The rock masses are mainly medium quality igneous rocks. The dip of the man- made rock slope cut is 65–85° is close to the road, and height reaches up to 50 m on natural slopes behind, which are potentially source areas of rockfalls. The dominant geotechnical properties of the rock masses were studied in order to identify the active parameters on rockfalls. The DIPS and RocFall computer program was utilized to perform the risk analysis on this steep rock slope. Input parameters such as: (1) block size, (2) seeder point’s locations of falling blocks, (3) slope angle, (4) restitution coefficients, and (5) slope roughness was studied to model the potential of fallen rock blocks in terms of: (1) bounce height, (2) kinetic energies and (3) translational and rotational velocities. The seeder points vary along the topography profile, also the block size varies according to the joints sets distribution. The program modeled the proposed location, height and energy of the rockfall barriers. The results of such a study provide a solution to prevent the falling rock blocks from reaching the road at such critical rock slope cuts.