Abstract

Construction of mountain roads at western Saudi Arabia is a challenge, where the rock masses are high-rising, steep slopes. Al-Hada mountain road of almost 22 km long shows many incidents of rockfalls. A studied 100 m long portion of mountain road lie along a man-made and natural sharp slope cut suffers from slope failures, rockfalls incidents, mainly in rainy seasons. The igneous rock masses are medium quality. The 40 m-height rock slope-cut along the road has no benches. The steep man-made rock slope cut is very close to the road, forming a potentially source for rockfalls. The Swedge, Roctopple, and RocFall computer program utilized to perform modeling and mitigation of the rock slope. No remedial measures taken to prevent the debris flows to take place. Input parameters such as block size, seeder point’s locations of blocks falls, slope angle, restitution coefficients, and slope roughness used to model the rock mass characteristics such as strength, bounce height, kinetic energies, and translational and rotational velocities. Modeling of the input parameters indicates the increase of the hit energy and end-point of rockfalls as the block size and slope angle increases.

1. INTRODUCTION

The slope failures, landslides and rockfalls frequently occur along mountain roads in rugged terrains. One of the most difficult terrains in western Saudi Arabia is the Al-Hada descent (Fig. 1). The famous Al-Hada descent lies at the upstream high elevation region of Wadi Na’man in the western part of the Kingdom of Saudi Arabia (KSA), which known as Arabian Shield. The elevations at the top of the Al-Hada road reach almost 2,000 m a.m.s.l. and its alignment lies within the sharp cliff edges of the Sarawat Mountains at the highest elevations. Before ascend the road starts from about 500 m elevation and reaches to more than 2,000 m, in a number of road twists.

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