Geoengineering characterization of the rock masses of northern face of Jabal Sabir, Taiz city, Yemen

This paper is aimed at thedescription and the geotechnical characterization of the Tertiary granitic rock masses of the northern face of Sabir Mountain, Taiz city, Yemen, for the first time. For accomplishing this task, direct and indirect approaches are adopted. The direct approach is represented by field and laboratory investigations. Field investigations include discontinuity (joints) measurements/evaluation, applied Rock Mass Rating (RMR) system and Geological Strength Index (GSI) system, in addition to field tests, while laboratory investigations encompass physico-mechanical tests carried out on granitic rock materials. Indirect approach for the estimation of shear strength parameters (c, Ø), compressive strength (σcm), tensile strength (σtm) and deformation modulus (Erm) of these rock masses was made by applying the generalized Hoek–Brown failure criterion using geotechnical Roc-Lab software. The laboratory results indicate that the Tertiary granitic rock masses show wide range of variations in their physico-mechanical characteristics owing to degree of weathering /alteration and microfractures. The intact samples of Sabir granitic (Tg) rocks show "Moderate"to "High"density, "Low"to "Medium"porosity, "Good"to "Marginal"water absorption capacity and "Weak"to "Very Strong"strength. Stereographically, three main sets of discontinuities (joints) are identified at each station; however, the fourth joint set occurs, in addition to random joint sets. The discontinuities (joints) trend predominately in NE-SW and NW-SE directions in conformity with the regional structures or faults. According to Jv j/m³values, the degree of jointing of these rock masses are varied from "Moderate"to "High"jointing. These rocks are categorized as "Fair"to "Excellent"quality, "Fair"to "Good/Very Good"quality and "Poor"to "Very Good"quality classes according to RQD, RMRb89and GSI respectively. Values ofthe shear strength parameters (c and Ø) and the other rock mass parameters (σtm, σc, σcmand Erm) show variations depending on the rock mass quality and properties of intact rock. However, in general the values of the rock mass parameters are found to increase with increase in the quality of rock mass and intact rock properties

Geoengineering characterization of the rock masses of northern face of Jabal Sabir, Taiz city, Yemen

This paper is aimed at thedescription and the geotechnical characterization of the Tertiary granitic rock masses of the northern face of Sabir Mountain, Taiz city, Yemen, for the first time. For accomplishing this task, direct and indirect approaches are adopted. The direct approach is represented by field and laboratory investigations. Field investigations include discontinuity (joints) measurements/evaluation, applied Rock Mass Rating (RMR) system and Geological Strength Index (GSI) system, in addition to field tests, while laboratory investigations encompass physico-mechanical tests carried out on granitic rock materials. Indirect approach for the estimation of shear strength parameters (c, Ø), compressive strength (σcm), tensile strength (σtm) and deformation modulus (Erm) of these rock masses was made by applying the generalized Hoek–Brown failure criterion using geotechnical Roc-Lab software. The laboratory results indicate that the Tertiary granitic rock masses show wide range of variations in their physico-mechanical characteristics owing to degree of weathering /alteration and microfractures. The intact samples of Sabir granitic (Tg) rocks show "Moderate"to "High"density, "Low"to "Medium"porosity, "Good"to "Marginal"water absorption capacity and "Weak"to "Very Strong"strength. Stereographically, three main sets of discontinuities (joints) are identified at each station; however, the fourth joint set occurs, in addition to random joint sets. The discontinuities (joints) trend predominately in NE-SW and NW-SE directions in conformity with the regional structures or faults. According to Jv j/m³values, the degree of jointing of these rock masses are varied from "Moderate"to "High"jointing. These rocks are categorized as "Fair"to "Excellent"quality, "Fair"to "Good/Very Good"quality and "Poor"to "Very Good"quality classes according to RQD, RMRb89and GSI respectively. Values ofthe shear strength parameters (c and Ø) and the other rock mass parameters (σtm, σc, σcmand Erm) show variations depending on the rock mass quality and properties of intact rock. However, in general the values of the rock mass parameters are found to increase with increase in the quality of rock mass and intact rock properties

Evaluation of stability of the rock slopes in Taiz city and surrounding areas of Yemen using slope mass rating (SMR) system and kinematic analysis technique

Assessment of stability of rockslopes is important to thwart the occurrence of landslides and consequent socio-economic evils. The present maiden study is carried out in and around Taiz city known for geotechnical hazards by isolating 14 of 110 field stations located along road cuts, quarries and natural exposures representing varying lithological and geotechnical conditions. The stability of rock slopes was evaluated by applying the original Slope Mass Rating (SMR) system. The parameters of SMR system were measured based on field and laboratory investigations. The failure mode at each site and its potential failure directions were determined kinematically using the stereographical projection method employing Stereonet software. The obtained results from applying SMR system at 14 rock slope stations demonstrated that there are various modes of failure and a single slope may have been affected by more than one type of failure depending on the relationship between the discontinuities and slope face, discontinuity characteristics and lithological conditions. The calculated values of SMR show variations from 1.4 to 70.4 indicating that these values plot from "Very Bad"(Vb) class to "Good"class (IIb). The results also indicate the more scope for planner, toppling and/or big wedge failures andwarrants suitable corrective measures, especially in the areas where the SMR values fall in IV and V classes. Further, slope Nos. 5 (zone-I) and 40 (zone-I) are "Stable"against wedge and toppling failures respectively and five slope locations (22, 36, 68, 76 and 86) are "Partially Stable"against toppling failures, while two rock slope locations (Nos. 77, 92 and 96) are "Unstable"against the various failures. The unstable slope locations vulnerable for planar/falling failure are 5, 30, 57, 76 and 86. Theremedial measures to control slope failures in 14 slope locations are suggested based on SMR values