Abstract
The slope instability was one of the common problems along the road that connects Gutane Migiru town to Fincha sugar factory, Western Ethiopia. The effect of the problem was intense mostly; during the rainy season, that triggers different modes of rock slope failure. As a result, the road was frequently damaged and blocked by the failed rock that in turn hinders the traffic activities. Thus, this study aimed at stability analyses of the critical slope sections using kinematic and limit equilibrium methods (LEM). The estimation of the most important input parameter in LEM analyses like cohesion and friction angle along the failure plane is often intricate and cumbersome. Hence, this paper used Rocscience software to effortlessly and instantly compute cohesion and friction angle along specific failure planes and then to carry out kinematic and LEM analyses. Besides, the strength of the intact rock was determined by the Schmidt hammer in the field and point load laboratory test. According to the kinematic analysis result, the wedge mode of rock slope failure occurred at slope sections D1S2 and D1S3 though the planar mode of failure occurred at slope sections D1S4 and D4S1. The factor of safety determined under all anticipated conditions became less than and greater than one at slope sections D1S2, D1S3, D1S4, and D4S1, and this depicts an unstable and stable slope, respectively. From the analysis result, the combined effect of rainfall, steepness of the slope dip, and joint set was the main factors that caused the slope insatiability.
Highlights
Slope instabilities are among the frequent geo-environmental hazard that occurs mostly in mountainous and hilly regions of the world
Four critical rock slope failures namely slope sections D1S2, D1S3, D1S4, and D4S1 were identified based on field manifestations like the occurrence of scarp faces, crack observed on the ground, and unfavorable orientations of major rock discontinuities
Conditions of discontinuities, slope geometry, failure plane orientations, and in situ test on intact rock strength were conducted during the field survey
Summary
Slope instabilities are among the frequent geo-environmental hazard that occurs mostly in mountainous and hilly regions of the world. More attention has been paid for many years to consider and solve the slope instability problems [1]. The slope of road constructed across the mountainous regions faces slope instability mainly during construction and modification of the road [2]. Many geotechnical engineers and engineering geologists have conducted several studies on slope stability analyses. Slope instability problems repeatedly occur due to human and natural disturbance to the delicate nature of the soil and rock slope [3]. Slope design and stability analyses should be given deliberate attention by the design engineers above all during the slope cut and modification
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