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Journal of Geography and Geology; Vol. 4, No. 2; 2012
ISSN 1916-9779
E-ISSN 1916-9787
Published by Canadian Center of Science and Education

Stability of Rock Slopes along Raidah Escarpment Road, Asir Area,
Kingdom of Saudi Arabia
Ahmed M. Youssef 1,3, Norbert H. Maerz2 & Abdulla A. Al-Otaibi3
1

Geology Deprtment, Faculty of Science, Sohag University, Egypt

2

Program Head,Geological Engineering, Missouri University of Science and Technology, Rolla, MO, USA

3

Geological Hazards Department, Applied Geology Sector, Saudi Geological Survey, Jeddah, KSA

Correspondence: Ahmed M. Youssef, Geology Deprtment, Faculty of Science, Sohag University, Egypt;
Geological Hazards Department, Applied Geology Sector, Saudi Geological Survey, P.O. Box 54141, Jeddah
21514, KSA.Tel: 966-568-448-782. E-mail: amyoussef70@yahoo.com
Received: April 1, 2012
doi:10.5539/jgg.v4n2p48

Accepted: April 19, 2012

Online Published: May 18, 2012

URL: http://dx.doi.org/10.5539/jgg.v4n2p48

Abstract
The Raidah Escarpment road is located north west of Abha city, Asir region, Kingdom of Saudi Arabia. This
escarpment road represents an important corridor in the area whichconnects different villages and tourist resorts
with each other. The total length of this road section is about 9 km which passes through a highly mountainous
area. The road also passes through areas of different geological hazards (rock, debris flow, soil, and weathered
zones). The different environmental factors (e.g. intensive rainy summer), variable geological and structural
elements (weakrocks, slide debris weak soils, shear zones, and faults) difficult road characteristics (narrow
roads with tight horizontal andvertical curvature) and various human activities in the area make the road
susceptible to frequent slope failures (rockfalls, rock sliding, debris flow, soil slides, and raveling) from time to
time. This paper deals with the evaluation of the stability of the rock cutsalong the Raidah escarpment road
using two methods including a structural controlled method and a raveling type method.
Raidah escarpment rock cuts have been classified into sixty nine stations which were investigated and
subsequently rated. Results of this study indicated that: (1) Based on the structiural control mode of failures, it
was found that 12 stations are potentially unstable due toplanar, wedge, and toppling failures, and out of them
five stations have a major impact on the road in the event of failure, including stations 11, 17, 20, 31, and 40. (2)
According to the Modified Colorado Rockfall hazard rating system, it was found that 13, 12, 13, 17, and 49
stations are of high, high to moderate, moderate, moderate to low, and low hazard. On the other hand, it was
found that13, 11, 11, and 69 stations have a high, high to moderate, moderate, and low impact on the road in the
case of failure. (3) According to the field simulation tests it was found that 6 stations potentially show highly
problems from rolling and bouncing rocks. However, out of these sites it was found that only 4 stations have a
high impact on the road due to rolling and bouncing. (4) the areasthat are impacted by the debris flows have
been mapped and determined. Finally, different recommendations and remediation methods have been discussed
to minimise the impact of problimatic sites.
Keywords: slope stability, raidah escarpment, rating systems, structural controlled sliding, KSA
1. General Background of the Raidah Area
The Raidah area is a mountainous terrain and it is located inthe Asir region on the western side of the Kingdom
of Saudi Arabia (KSA) (Figure 1). Many highways have been constructed in the Asir reigon, and these roads and
highways traverse through topographically challenging terrain which in many cases requires the construction of
significant rock cuts. Many of these rock cuts were constructed using uncontrolled blasting techniques and/or
mechanical...