The document summarizes an engineering geological study of support requirements for a diversion tunnel at the Boztepe dam site in eastern Turkey. Empirical, theoretical, and numerical methods were used to characterize the rock mass and determine support needs. Field studies found the site contained basalt and tuffite units. Laboratory testing provided mechanical properties of intact rock samples. Rock mass quality was evaluated using RMR, Q, and GSI classification systems. Support requirements were proposed and numerically analyzed using the finite element method. A combination of approaches was found to provide a more reliable design.
Geoengineering Characterization of the Rock Masses of Northern Face of Jabal ...IJERA Editor
This paper is aimed at the description 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, φ), 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/m³ values, 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, RMR89 and GSI respectively. Values of the shear strength parameters (c and φ) and the other rock mass parameters (σtm, σc , σcm and 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.
Integrated ERT and Magnetic Surveys in a Mineralization Zone in Erkowit - Red...IJERA Editor
The present study focus on integrated geophysical surveys carried out in the mineralization zone in Erkowit region, Eastern Sudan to determine the extensions of the potential ore deposits on the topographically high hilly area and under the cover of alluvium along the nearby wadi and to locate other occurrences if any. The magnetic method (MAG) and the electrical resistivity tomography (ERT) were employed for the survey. Eleven traverses were aligned approximately at right angles to the general strike of the rock formations. The disseminated sulfides are located on the alteration shear zone which is composed of granitic and dioritic highly ferruginated rock occupying the southwestern and central parts of the area, this was confirmed using thin and polished sections mineralogical analysis. The magnetic data indicates low magnetic values for wadi sedimentary deposits in its southern part of the area, and high anomalies which are suspected as gossans due to magnetite formed during wall rock alteration consequent to mineralization. The significant ERT imagesdefinelow resistivity zone as traced as sheared zones which may associated with the main loci of ore deposition. The study designates that correlation of magnetic and ERT anomalies with lithology are extremely useful in mineral exploration due to variations in some specific physical properties of rocks.
Evaluation on coal resource estimation and drillhole spacing optimizationrudyhendrawan
Evaluation on Coal Resource Estimation and Drillhole Spacing Optimization Based on Geostatistical Approach, with a Case Study on Coal Deposit at South Kalimantan, Indonesia. Mohamad Nur HERIAWAN, Rudy Hendrawan NOOR, SYAFRIZAL, and Sudarto NOTOSISWOYO
Performance of square footing resting on laterally confined sandeSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Geoengineering Characterization of the Rock Masses of Northern Face of Jabal ...IJERA Editor
This paper is aimed at the description 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, φ), 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/m³ values, 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, RMR89 and GSI respectively. Values of the shear strength parameters (c and φ) and the other rock mass parameters (σtm, σc , σcm and 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.
Integrated ERT and Magnetic Surveys in a Mineralization Zone in Erkowit - Red...IJERA Editor
The present study focus on integrated geophysical surveys carried out in the mineralization zone in Erkowit region, Eastern Sudan to determine the extensions of the potential ore deposits on the topographically high hilly area and under the cover of alluvium along the nearby wadi and to locate other occurrences if any. The magnetic method (MAG) and the electrical resistivity tomography (ERT) were employed for the survey. Eleven traverses were aligned approximately at right angles to the general strike of the rock formations. The disseminated sulfides are located on the alteration shear zone which is composed of granitic and dioritic highly ferruginated rock occupying the southwestern and central parts of the area, this was confirmed using thin and polished sections mineralogical analysis. The magnetic data indicates low magnetic values for wadi sedimentary deposits in its southern part of the area, and high anomalies which are suspected as gossans due to magnetite formed during wall rock alteration consequent to mineralization. The significant ERT imagesdefinelow resistivity zone as traced as sheared zones which may associated with the main loci of ore deposition. The study designates that correlation of magnetic and ERT anomalies with lithology are extremely useful in mineral exploration due to variations in some specific physical properties of rocks.
Evaluation on coal resource estimation and drillhole spacing optimizationrudyhendrawan
Evaluation on Coal Resource Estimation and Drillhole Spacing Optimization Based on Geostatistical Approach, with a Case Study on Coal Deposit at South Kalimantan, Indonesia. Mohamad Nur HERIAWAN, Rudy Hendrawan NOOR, SYAFRIZAL, and Sudarto NOTOSISWOYO
Performance of square footing resting on laterally confined sandeSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Evaluation of Structural Geology of Jabal OmarIJERD Editor
The proposed Jabal Omar Development project includes several multi-storey buildings, roads, bridges and below ground structures. Dykes and joints are the most common geological features in the area; they vary in thickness and orientation. The spacing between adjacent discontinuities largely control the size of individual blocks of rock masses which govern the stability of rock structures. The shearing and faulting system normally associated with tectonic movement making the area very weak, highly weathered and unstable. All Structural geological units analyzed using stereographic projection
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
THE EFFECT OF GEOTECHNICAL PROPERTIES ON THE BEARING CAPACITY OF SELECTED SOI...IAEME Publication
Study of the characteristics of the physical, chemical and engineering of the soil is considered as an important matter in the processes of engineering projects (such as highways, dams, bridges, etc..). Study was done at selected locations in the governorate of Al-Najaf by drilling three boreholes with 10m depth, for disturbed (DS) and undisturbed (US) samples, to determine soil characteristics, and the level of groundwater depth in the study area because of their effect on the design of foundations. The laboratory and field tests showed that the soil is clayey high plasticity (CH) in most of the study area, while the chemical analysis of the water in the boreholes has a high concentration of SO4 (1031-1037) mg/l and PH values range from (7.7-8.0). The number of blows in the standard penetration (SPT) test was between (58-86) blows. The depth of groundwater was (0.5-0.9) m in the boreholes. The bearing capacity using the dynamic method was (21.45–31.35) T /m² for all boreholes, while the bearing capacity using the static method for depths from (1-3) m ranged from (9.82-14.20) T /m². The study concluded that this soil needs some engineering treatments before establishing the engineering structures.
Engineering Characterisation of Aggregates from Some Selected Areas in Kumasi...IJAEMSJORNAL
The increase in engineering projects translates to an increase in demand for construction materials, for example, aggregates which are a major component in concrete works. There are many quarries in the Kumasi area which produce aggregates for use in construction works. However, there is no readily available information on the geological and geotechnical properties of these aggregates for use by engineers during the planning, design and construction of projects. This project therefore sought to characterise the aggregate from selected areas (close to some major quarries) in Kumasi based on their geological and engineering properties for construction purposes. Results of the study indicate that Aggregates from sampling locations KP and CS passed the FI test with those from CS being the only ones to pass for EI, making them the best aggregates in terms of Flakiness and Elongation Indices. The aggregates from all the sampling locations passed for the Specific Gravity and Water Absorption tests with CS aggregates giving the best results indicating high strength and good rate of water absorption. Aggregate from sampling location NM gave the best result for the Aggregate Impact Value test indicating high resistance to sudden impacts and shocks. With the Ten Percent Fines Value and the Aggregate Crushing Value Tests, CS yet again produced the aggregates with the best results. The aggregate gave a very high result even under the wet/soaked condition when all the others were giving very low results. Aggregates from this sampling locations can withstand loading gradual compression better than the rest. Finally, the KP aggregates gave the best results for the Los Angeles Abrasion Value which suggests such materials to be the hardest and toughest to resist crushing, degradation and disintegration. Aggregates from the CS, however gave the second best results. From the study, it was concluded that the most suitable location to obtain good quality aggregates is around CS as its aggregates gave the best results in almost all the tests.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Prediction Models for Estimation of California Bearing Ratio for Cohesive Soilijtsrd
Cohesive soils are well known for their low strength properties. Thus, they are inappropriate for geotechnical works. Soils may be stabilized to increase strength and durability. Stabilization with cement is a common treatment technology. The present study examines the strength of cement stabilized soil. The laboratory tests were carried out in order to study the strength of california bearing ratio (CBR). Nine clayey soils with different properties were mixed with various amounts of cement content (3, 6, 9 and 12%) and compacted at the optimum moisture content and maximum dry density. Soaked or unsoaked condition of soil affects the CBR value. The test results show that unsoaked CBR before stabilization ranges between 2.78% and 10.22% which that of its corresponding soaked samples range between 1.01% and 9.5%. After stabilization, the values of unsoaked CBR range between 3.08% and 47%. The maximum values of unsoaked CBR are within 10.8% to 47%. So it can be used as sub-base condition. The conventional CBR testing method is expensive and time consuming. The laboratory test results were used for the development of regression based model to predict unsoaked and soaked CBR values for natural and cement stabilized soil. Aye Aye Myat | Nyan Myint Kyaw | Htay Win"Prediction Models for Estimation of California Bearing Ratio for Cohesive Soil" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-3 , April 2018, URL: http://www.ijtsrd.com/papers/ijtsrd12819.pdf http://www.ijtsrd.com/engineering/civil-engineering/12819/prediction-models-for-estimation-of-california-bearing-ratio-for-cohesive-soil/aye-aye-myat
Geophysical Investigations of a Pavement Failure Along Akure-Ijare Road, Sout...iosrjce
Geophysical investigations were carried out along two failed segments of Akure-Ijare road, named
locality 1 and locality 2, with the aim of establishing the cause(s) of the incessant pavement failure along the
road. The geophysical investigations involved the Very Low Frequency Electromagnetic (VLF-EM) and
Electrical Resistivity Methods. The VLF-EM measurements were taken at intervals of 10 m along traverses
parallel to road pavements. Two techniques were adopted for the electrical resistivity method namely: the
vertical electrical sounding (VES) and a combination of horizontal profiling and sounding using dipole-dipole
configuration with inter stations separation (a) of 5 m and an expansion factor (n) that varies from 1 to 5. The
Schlumberger configuration was used for the VES with AB/2 varying from 1 to 65 m. Nine (9) and twelve (12)
VES were carried out at localities 1 and 2 respectively. The VLF-EM method revealed that the road pavement is
founded on a weakly conductive material devoid of major geological structure. The Vertical electrical sounding
curves range from A, H to KH. The geoelectric sections generally identified three to four geologic sequences
that comprise topsoil, weathered layer, partly weathered/fracture basement and fresh basement. At locality 1,
the topsoil/subsoil on which the road is founded are of low resistivity generally less than 100 Ω-m composed of
clayey materials, while the road pavement along locality 2 is within the resistive topsoil or directly on bedrock.
The bedrock along this locality is generally shallow (< 2 m) with an uneven interface. Therefore, from the
results of the investigation the causes of road failure in the studied roadway are heterogeneity and clayey nature
of the topsoil/sub-grade material, lack of proper drainage at the road embankment and poor construction
material.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
This study was carried out to determine the subsurface lithology and possible depths for structural foundations in Ignatius Ajuru University of Education, Port Harcourt in southern Nigeria using electrical resistivity techniques of VES and borehole logging. Model ABEM SAS 300B Terrameter aided by SAS 200 log meter were used for the data collection while version IPWIN2 software was used for the processing of the VES data. Six profiles of different locations, using maximum current electrode spread of 200 m and maximum potential electrode spread of 30 m, were used to obtain resistivity range of 1.2 to 4335 Ωm for three to four geoelectric sections covering depth interval of 19.8 m in the area. The borehole data covered a depth range of 0 to 20 m. The results show lithostratigraphy sequence of silty sands, laterite, grain and coarse sands with resistivity values of 721 to 4000 Ωm. These soils can support structures with foundations as close as 0.5 m to 3 m or more below the earth surface because laterite and sandy soils have the ability of a firm grasp of structural foundations as they do not retain moisture that will cause foundational deformation and shifting that may eventually lead to collapse of the structures.
The effect of disturbance factor on the stability of tunnels (Case study: Tun...IJRES Journal
Disturbance factor (D) is related to excavation method and cause damage and stress relief in the rock masses. The convergence and plastic zone around tunnels depends on the disturbance factor of rocks.This study has been in the tunnel No.2 of Kurdistan in NW of Iran which is composed of shale rocks. In tunnel modeling, different disturbance factors(0 to 1) areanalyzed using phase2 software and the amount of displacement and extent of plastic zone in around the tunnelis determined. The obtain results show that by increasing of disturbance factor, the displacement and plastic zone around the tunnel has increased and the most increase has occurred in disturbance factors 0.8 to 1. Therefore, for excavation of this tunnel, the blasting method should not be used and instead of it, the mechanical methods must be used.
Evaluation of Structural Geology of Jabal OmarIJERD Editor
The proposed Jabal Omar Development project includes several multi-storey buildings, roads, bridges and below ground structures. Dykes and joints are the most common geological features in the area; they vary in thickness and orientation. The spacing between adjacent discontinuities largely control the size of individual blocks of rock masses which govern the stability of rock structures. The shearing and faulting system normally associated with tectonic movement making the area very weak, highly weathered and unstable. All Structural geological units analyzed using stereographic projection
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
THE EFFECT OF GEOTECHNICAL PROPERTIES ON THE BEARING CAPACITY OF SELECTED SOI...IAEME Publication
Study of the characteristics of the physical, chemical and engineering of the soil is considered as an important matter in the processes of engineering projects (such as highways, dams, bridges, etc..). Study was done at selected locations in the governorate of Al-Najaf by drilling three boreholes with 10m depth, for disturbed (DS) and undisturbed (US) samples, to determine soil characteristics, and the level of groundwater depth in the study area because of their effect on the design of foundations. The laboratory and field tests showed that the soil is clayey high plasticity (CH) in most of the study area, while the chemical analysis of the water in the boreholes has a high concentration of SO4 (1031-1037) mg/l and PH values range from (7.7-8.0). The number of blows in the standard penetration (SPT) test was between (58-86) blows. The depth of groundwater was (0.5-0.9) m in the boreholes. The bearing capacity using the dynamic method was (21.45–31.35) T /m² for all boreholes, while the bearing capacity using the static method for depths from (1-3) m ranged from (9.82-14.20) T /m². The study concluded that this soil needs some engineering treatments before establishing the engineering structures.
Engineering Characterisation of Aggregates from Some Selected Areas in Kumasi...IJAEMSJORNAL
The increase in engineering projects translates to an increase in demand for construction materials, for example, aggregates which are a major component in concrete works. There are many quarries in the Kumasi area which produce aggregates for use in construction works. However, there is no readily available information on the geological and geotechnical properties of these aggregates for use by engineers during the planning, design and construction of projects. This project therefore sought to characterise the aggregate from selected areas (close to some major quarries) in Kumasi based on their geological and engineering properties for construction purposes. Results of the study indicate that Aggregates from sampling locations KP and CS passed the FI test with those from CS being the only ones to pass for EI, making them the best aggregates in terms of Flakiness and Elongation Indices. The aggregates from all the sampling locations passed for the Specific Gravity and Water Absorption tests with CS aggregates giving the best results indicating high strength and good rate of water absorption. Aggregate from sampling location NM gave the best result for the Aggregate Impact Value test indicating high resistance to sudden impacts and shocks. With the Ten Percent Fines Value and the Aggregate Crushing Value Tests, CS yet again produced the aggregates with the best results. The aggregate gave a very high result even under the wet/soaked condition when all the others were giving very low results. Aggregates from this sampling locations can withstand loading gradual compression better than the rest. Finally, the KP aggregates gave the best results for the Los Angeles Abrasion Value which suggests such materials to be the hardest and toughest to resist crushing, degradation and disintegration. Aggregates from the CS, however gave the second best results. From the study, it was concluded that the most suitable location to obtain good quality aggregates is around CS as its aggregates gave the best results in almost all the tests.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Prediction Models for Estimation of California Bearing Ratio for Cohesive Soilijtsrd
Cohesive soils are well known for their low strength properties. Thus, they are inappropriate for geotechnical works. Soils may be stabilized to increase strength and durability. Stabilization with cement is a common treatment technology. The present study examines the strength of cement stabilized soil. The laboratory tests were carried out in order to study the strength of california bearing ratio (CBR). Nine clayey soils with different properties were mixed with various amounts of cement content (3, 6, 9 and 12%) and compacted at the optimum moisture content and maximum dry density. Soaked or unsoaked condition of soil affects the CBR value. The test results show that unsoaked CBR before stabilization ranges between 2.78% and 10.22% which that of its corresponding soaked samples range between 1.01% and 9.5%. After stabilization, the values of unsoaked CBR range between 3.08% and 47%. The maximum values of unsoaked CBR are within 10.8% to 47%. So it can be used as sub-base condition. The conventional CBR testing method is expensive and time consuming. The laboratory test results were used for the development of regression based model to predict unsoaked and soaked CBR values for natural and cement stabilized soil. Aye Aye Myat | Nyan Myint Kyaw | Htay Win"Prediction Models for Estimation of California Bearing Ratio for Cohesive Soil" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-3 , April 2018, URL: http://www.ijtsrd.com/papers/ijtsrd12819.pdf http://www.ijtsrd.com/engineering/civil-engineering/12819/prediction-models-for-estimation-of-california-bearing-ratio-for-cohesive-soil/aye-aye-myat
Geophysical Investigations of a Pavement Failure Along Akure-Ijare Road, Sout...iosrjce
Geophysical investigations were carried out along two failed segments of Akure-Ijare road, named
locality 1 and locality 2, with the aim of establishing the cause(s) of the incessant pavement failure along the
road. The geophysical investigations involved the Very Low Frequency Electromagnetic (VLF-EM) and
Electrical Resistivity Methods. The VLF-EM measurements were taken at intervals of 10 m along traverses
parallel to road pavements. Two techniques were adopted for the electrical resistivity method namely: the
vertical electrical sounding (VES) and a combination of horizontal profiling and sounding using dipole-dipole
configuration with inter stations separation (a) of 5 m and an expansion factor (n) that varies from 1 to 5. The
Schlumberger configuration was used for the VES with AB/2 varying from 1 to 65 m. Nine (9) and twelve (12)
VES were carried out at localities 1 and 2 respectively. The VLF-EM method revealed that the road pavement is
founded on a weakly conductive material devoid of major geological structure. The Vertical electrical sounding
curves range from A, H to KH. The geoelectric sections generally identified three to four geologic sequences
that comprise topsoil, weathered layer, partly weathered/fracture basement and fresh basement. At locality 1,
the topsoil/subsoil on which the road is founded are of low resistivity generally less than 100 Ω-m composed of
clayey materials, while the road pavement along locality 2 is within the resistive topsoil or directly on bedrock.
The bedrock along this locality is generally shallow (< 2 m) with an uneven interface. Therefore, from the
results of the investigation the causes of road failure in the studied roadway are heterogeneity and clayey nature
of the topsoil/sub-grade material, lack of proper drainage at the road embankment and poor construction
material.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
This study was carried out to determine the subsurface lithology and possible depths for structural foundations in Ignatius Ajuru University of Education, Port Harcourt in southern Nigeria using electrical resistivity techniques of VES and borehole logging. Model ABEM SAS 300B Terrameter aided by SAS 200 log meter were used for the data collection while version IPWIN2 software was used for the processing of the VES data. Six profiles of different locations, using maximum current electrode spread of 200 m and maximum potential electrode spread of 30 m, were used to obtain resistivity range of 1.2 to 4335 Ωm for three to four geoelectric sections covering depth interval of 19.8 m in the area. The borehole data covered a depth range of 0 to 20 m. The results show lithostratigraphy sequence of silty sands, laterite, grain and coarse sands with resistivity values of 721 to 4000 Ωm. These soils can support structures with foundations as close as 0.5 m to 3 m or more below the earth surface because laterite and sandy soils have the ability of a firm grasp of structural foundations as they do not retain moisture that will cause foundational deformation and shifting that may eventually lead to collapse of the structures.
The effect of disturbance factor on the stability of tunnels (Case study: Tun...IJRES Journal
Disturbance factor (D) is related to excavation method and cause damage and stress relief in the rock masses. The convergence and plastic zone around tunnels depends on the disturbance factor of rocks.This study has been in the tunnel No.2 of Kurdistan in NW of Iran which is composed of shale rocks. In tunnel modeling, different disturbance factors(0 to 1) areanalyzed using phase2 software and the amount of displacement and extent of plastic zone in around the tunnelis determined. The obtain results show that by increasing of disturbance factor, the displacement and plastic zone around the tunnel has increased and the most increase has occurred in disturbance factors 0.8 to 1. Therefore, for excavation of this tunnel, the blasting method should not be used and instead of it, the mechanical methods must be used.
Determination of Thickness of Overburden in Basement Area Using Schlumberger ...iosrjce
The overburden thickness of Abuja (Lat. 70
12´N – 9
0 30´ N and Long. 50
24´E- 7
0
19´E)
has been estimated. The geophysical method used was the electrical resistivity and the electrodes
array was Schlumberger type. The equipment utilized were four electrodes, hammer, four reels of
wires, crocodile clips, measuring tape, global positioning systems(GPS) and a terrameter. The survey
was carried out in two locations and the average resistivity values of the first four geoelectrical layers
were from the surface, 590 Ωm, 1800 Ωm, 1900 Ωm and 760 Ωm. These layers were interpreted as
probably top soil, laterite, weathered basement rock and fairly weathered basement rock. The
average thickness of the overburden was found to be 5.43m
Topographic influence on stability for gas wells penetrating longwall mining ...legend314
Gas wells that penetrate mineable coal seams may be subject to distress caused by ground movements due to longwall mining. Especially important are the lateral shear offsets and axial distortion, which are most damaging for wellbores. To replicate typical conditions in the Appalachian basin, a geological model that considers the combined effects of topography, weak interfaces between monolithic beds and various mining depths is presented in the foregoing. These conditions adequately represent the principal features of the anticipated response of gas wells that are near-undermined by longwall panels. We examine the magnitudes of longitudinal distortions, lateral shear offsets, delaminations, and vertical and lateral strains along vertical wells drilled to intersect the seam at various locations within the longwall pillar. We analyze the distribution of these deformations and predict areas where the most severe deformation would occur.
Experimental Study of Bearing Capacity in Single and Group Stone Columns With...Samirsinh Parmar
Soil improvement,
Experimental Study,
Stone Column,
Stone Column in Clay,
Encased Stone column,
Uncased stone column,
Group of stone column,
Moisture content of clay,
Granular pile,
Bearing Capacity,
Single stone column,
group of stone column,
water content vs depth,
Load vs settlement,
Geo Environmental Investigation of Abuad Dumpsite, Southwestern NigeriaIJERA Editor
Geoenvironmental study of ABUAD female dumpsite was conducted to investigate the suitability of its location
and potential impact on groundwater in the environment. Profiling and Vertical electrical sounding methods
were employed using Dipole - Dipole and Schlumberger configuration respectively. Five points were sounded
and one profile was occupied. Three heterogeneous subsurface lithologic units were established namely; lateritic
topsoil, clayey-sand, and, fresh basement. The curve types are simple H and HA. The topsoil and clayey-sand
materials are characterized with relatively low resistivity values while the fresh basement materials are
characterized with high resistivity values. The average resistivity and thickness values for the topsoil are
280.0Ωm and.2.3m respectively. Clayey-sand was encountered in all the locations with average resistivity and
thickness values of 32.0Ωm and 7.3m respectively. Basement is relatively shallow in the study area, it was
encountered in all the locations with an average resistivity and depth values to the top of basement of 674Ωm,
and 9.6m respectively. Overburden materials are relatively thin within the area with an average resistivity and
thickness values of 156Ωm, and 9.6m respectively. The overburden materials constituting the aquiferous units
within the study area are porous, vulnerable, and good paths for leachate migration. The relatively low
resistivity values within the clayey-sand layers (14 - 61Ωm) are suggestive of leachate intrusion, while relatively
high resistivity values of the impervious basement are due to their crystalline nature. The proximity of the
dumpsite to both the cafeteria and residential halls is a cause for concern.
Geophysical Investigations of a Pavement Failure Along Akure-Ijare Road, Sout...iosrjce
IOSR Journal of Applied Geology and Geophysics (IOSR-JAGG) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of Applied Geology and Geophysics. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Applied Geology and Geophysics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
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He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
2. Z. Gurocak et al. / Engineering Geology 91 (2007) 194–208
Fig. 1. The location map of study area.
observations. Likewise, analytical and numerical
approaches are dependent upon the strength parameters
of associated rock masses that are used as input
195
parameters when using an analytical and numerical
approach. Therefore, the stability analysis of a tunnel is
likely to suggest a safer design if a combination of
empirical, theoretical, and numerical approaches is used.
The field site used in this study is located 10 km
northwest of Yazihan, in the north of the city of Malatya,
in eastern Turkey (Fig. 1). The Boztepe dam which is
under construction on the Yagca stream is located at this
site. The dam project is designed to regulate water
drainage and irrigate the agricultural areas of the
Yazihan plain. The design of the Boztepe dam project
is under the supervision of General Directorate of State
Hydraulic Works (DSI, 1997), of Ministry of Energy
and Natural Resources in Turkey. The diversion tunnel
of the Boztepe dam has a length of 565 m, having
circular geometry with 5 m in diameter. It cuts across
basalts and tuffites. The tunnel will have a maximum
overburden of about 38 m for basalts and about 27 m for
Fig. 2. Geological map and cross-section of Boztepe dam site.
3. 196
Z. Gurocak et al. / Engineering Geology 91 (2007) 194–208
bedded, with bed thicknesses ranging from 300 to 600 mm
in the lower levels and 50 to 200 mm in the upper levels.
Joints within the tuffite are commonly altered and filled
with clay or calcite having 20 to 30 mm thickness.
The basalts overlying the tuffites are dark grey in
color. In the lower levels, they are mainly pillar lavas
while near the top they commonly occur as columnar
structures (Gurocak, 1999). Vesicles are rare and the
basalts are generally well-jointed. The agglomerate
member overlying the basalts is generally dark in color
and massive in structure. The individual boulders are
weakly rounded, having a maximum size of 0.7 m. This
unit also contains interlayer of tuff and basalt flows.
Overlying the agglomerate are mainly Quaternary
deposits, namely talus and alluvial materials.
During the field surveys, engineering geological map
of the Boztepe dam site and the geological cross section
along the diversion tunnel was constructed. The field
studies also included the orientation, persistence,
spacing, opening, roughness, the degree of weathering
and filling of discontinuities in the basalts and tuffites.
Fig. 3. The histograms for RQD of basalts (A) and tuffites (B).
tuffites. The dam site is located within the Yamadag
Volcanics, which is composed of basalt, tuffite and
agglomerate. Geological mapping and geotechnical
descriptions were conducted in the field.
The physical, mechanical and elastic properties of the
rocks under consideration were determined from laboratory testing on intact rock samples. These tests include
an evaluation of uniaxial compressive strength (σc),
Young's modulus (E), Poisson's ratio (ν), unit weight
(γ), internal friction angle (ϕ), and cohesion (c). The
rock mass properties of the dam site were determined by
using different rock mass classification systems.
Table 1
Engineering properties of joints and bedding surfaces and their
percentage distribution
Properties
Spacing
Percentage
Basalt Tuffite
Spacing (mm)
a
Persistence (m)a
Aperture (mm)a
2. Geology, field and laboratory studies
The Boztepe dam site consists of various age units
ranging from the Upper Miocene to the Quaternary.
Middle–Upper Miocene volcano-sedimentary rocks that
are known as Yamadag Volcanics, are exposed in the
region. These rocks are a part of the extensive Miocene
volcanism in the Eastern Anatolian Region. The Yamadag
volcanites are represented in the study area by four
different rock units extending upwards from a sandstone–
claystone through tuffite, basalt and agglomerate members. As seen in Fig. 2, at the dam site, the main valley is in
tuffite with basalt forming the plateau to the east. The
tuffites are dirty white or light grey colored and well-
Description
Roughnessa
Weathering (Wc) b
a
b
b20
Extremely close
spacing
20–60
Very close spacing
60–200
Close spacing
200–600 Moderate spacing
600–2000 Wide spacing
b1
Very low persistence
1–3
Low persistence
3–10
Medium persistence
10–20
High persistence
N20
Very high persistence
b0.1
Very tight
0.1–0.25 Tight
0.25–0.50 Partly open
0.50–2.50 Open
2.5–10
Moderately wide
N10
Wide
IV
Rough undulating
V
Smooth undulating
VI
Slickensided
undulating
VII
Rough planar
VIII
Smooth planar
IX
Slickensided planar
≤1.2
Fresh/Unweathered
1.2–2
Moderately weathered
N2.0
Weathered
According to ISRM (1981).
According to Singh and Gahrooee (1989).
5
2
33
42
20
–
33
56
11
–
–
8
14
10
16
48
4
11
3
10
16
69
10
3
8
9
34
31
14
12
–
2
20
51
15
5
7
–
61
6
9
22
67
11
88
–
–
–
2
98
4. Z. Gurocak et al. / Engineering Geology 91 (2007) 194–208
197
Fig. 4. Stereographic projection of bedding surface (A) and joint sets (B) in tuffites and joint sets (C) in basalts.
In addition, an examination was made of 1195 m of the
core, from 20 boreholes drilled by the General Directorate
of State Hydraulic Works (DSI, 1997). The RQD values
of the basalts and tuffites were determined. The
histograms shown in Fig. 3 were prepared using the
RQD divisions proposed by Deere (1964). From this
figure, the rock quantities of the basalts have the following
distribution: 6% excellent, 14% good, 32% fair, 23%
poor, and 25% very poor. Similarly, the tuffites have the
following distribution of rock quality: 4% excellent, 11%
good, 28% fair, 21% poor, and 36% very poor.
As the study area is located in a seismically active
region, the basalts exposed around the Boztepe dam site
contain systematic joint sets. However, tuffites are
sedimentary rocks and contain bedding surfaces. Table 1
shows the main orientation, spacing, persistence, aperture
and roughness of discontinuities. These were described
using the scan-line survey method following the ISRM
(1981) description criteria. The degree of weathering of
the discontinuous surfaces was assessed using the Schmidt
hammer and the weathering index was calculated from the
equation proposed by Singh and Gahrooee (1989):
Wc ¼
rc
;
JCS
ð1Þ
where
σc
JCS
Uniaxial compressive strength of fresh rock
(MPa), and
Strength of discontinuity surface (MPa).
JCS was calculated from the following equation:
LogJCS ¼ 0:00088gR þ 1:01;
ð2Þ
where
γ
R
Bulk volume weight (kN/m3), and
Hardness value from rebounding of Schmidt
hammer.
5. 198
Z. Gurocak et al. / Engineering Geology 91 (2007) 194–208
Table 2
Laboratory tests results of basalts and tuffites
Properties
Min
Max Mean Std. err.
Basalt
Uniaxial compressive strength (σc, MPa)
Young's modulus (E, GPa)
Poisson's ratio (ν)
Unit weight (γ, kN/m3)
Cohesion (c, MPa)
Internal friction angle (ϕ, deg)
8.72
1.6
0.241
23.10
12 a
42a
76.46
96.7
0.286
28.10
40.64
30.91
0.27
25.55
19.67
47.17
0.02316
1.48
Tuffite
Uniaxial compressive strength (σc, MPa)
Young's modulus (E, GPa)
Poisson's ratio (ν)
Unit weight (γ, kN/m3)
Cohesion (c, MPa)
Internal friction angle (ϕ, deg)
1.97
0.6
0.17
12.00
1.80a
33a
21.20
10.5
0.22
22.10
8.21
2.23
0.20
16.50
5.72
2.615
0.02517
0.04
Std. err.: standard error.
a
Values obtained by using triaxial test.
In the study area, a total of 388 bedding surfaces and
520 joint measurements were taken from tuffites and
basalts. Discontinuity orientations were processed
utilizing a commercially available software DIPS 3.01
(Diederichs and Hoek, 1989), based on equal-area
stereographic projection, and major joint sets were
distinguished for basalts and tuffites (Fig. 4).
The following major orientations of the bedding
surface for tuffites were observed:
Bedding surface:
Joint set 1:
Joint set 2:
Joint set 3:
14/100
80/220
87/259
77/305
The major orientations of the joint sets for basalts are
listed below:
Joint
Joint
Joint
Joint
set
set
set
set
1:
2:
3:
4:
78/192
71/3
67/287
72/99
According to ISRM (1981), the joint sets in the
basalts have close to very close spacing, low persistence, moderate width, rough-planar and moderately
weathered character. The discontinuities in tuffites
have close spacing, medium to high persistence,
moderate width, and rough-planar and weathered
character.
Uniaxial compressive strength, deformability, unit
weight and triaxial compressive strength tests were
conducted in accordance with the ISRM suggested
methods (ISRM, 1981). Pertinent results are summarized in Table 2. The average uniaxial compressive
strength of basalts is 40.64 MPa, Young's modulus is
30.91 GPa, Poisson's ratio is 0.27, unit weight is
25.55 kN/m3, cohesion is 12 MPa and friction angle is
42°. The average uniaxial compressive strength of
tuffites is 8.21 MPa, Young's modulus is 2.23 GPa,
Poisson's ratio is 0.20, unit weight is 16.50 kN/m3,
cohesion is 1.80 MPa and friction angle is 33°.
3. Rock mass classification systems
Rock mass classification systems are important for
quantitative descriptions of the rock mass quality. This
in turn led to the development of many empirical design
systems involving rock masses. Many researchers
developed rock mass classification systems. Some of
the most widely used rock mass classification systems
include RMR and Q. These two classification systems
are utilized in this research.
3.1. RMR system
Bieniawski (1974) initially developed the rock mass
rating (RMR) system based on experience in tunnel
projects in South Africa. Since then, this classification
system has undergone significant changes. These
changes are mostly due to the ratings added for ground
Table 3
RMR89 rating for basalts and tuffites
Classification
parameters
Basalt
Value of
parameters
Rating Value of
parameters
Rating
Uniaxial
compressive
strength (MPa)
RQD (%)
Discontinuity
spacing (cm)
Discontinuity
condition
Persistence (m)
Aperture (mm)
Roughness
Filling
Weathering
Groundwater
condition
Basic RMR value
Rating adjustment
for joint
orientation
RMR
Rock mass quality
40.64
5
8.21
2
62
160
12
7.3
25
90
6
6
1–3
2.50–3.00
Rough-planar
Calcite b 5 mm
Moderately
Dry
4
1
5
4
3
15
3–10
2.5–10
Rough-planar
calcite N 5 mm
Highly
Dry
2
0
5
2
1
15
56.3
0/−5
Fair
39
−5
Very
favorable/Fair
56.3/51.3
Fair rock
Tuffite
34
Poor rock
6. Z. Gurocak et al. / Engineering Geology 91 (2007) 194–208
199
Table 4
Q rating for basalts and tuffites
Classification parameters
Basalt
Tuffite
Value of parameters
RQD (%)
Joint set number (Jn)
Joint alteration number (Jr)
Joint alteration number ( ja)
Joint water reduction factor ( jw)
Stress reduction factor (SRF)
Q
Rock mass quality
Rating Value of parameters
62%
62
Four joint sets plus random joints 15
Rough planar
1.5
Moderately altered
6
Dry excavation or minor inflow
1
Medium stress
1
1.03
Poor rock
water, joint condition and joint spacing. In order to use
this system, the uniaxial compressive strength of the
intact rock, RQD, joint spacing, joint condition, joint
orientation and ground water conditions have to be
known. In this study, the RMR classification system
(Bieniawski, 1989) is used and the results are summarized in Table 3. This rating classifies basalt as a fair
rock mass, while tuffite as a poor rock mass.z
3.2. Q system
Barton et al. (1974) developed the Q rock mass
classification system. This system is also known as the
NGI (Norwegian Geotechnical Institute) rock mass
classification system. It is defined in terms of RQD, the
function of joint sets (Jn), discontinuity roughness (Jr),
joint alteration (Ja), water pressure (Jw) and stress
reduction factor (SRF). Barton (2002) compiled the
system again and made some changes on the support
recommendations. He also included the strength factor
of the rock material in the system.
Q¼
RQD Jr Jw
:
Jn Ja SRF
ð3Þ
Recently, Barton (2002) defined a new parameter, Qc,
to improve correlation among the engineering parameters:
Qc ¼ Q
rc
;
100
ð4Þ
Rating
25%
25
Three joint sets and a bedding surface plus random joints 12
Rough-planar
1.5
Highly altered
8
Dry excavation or minor inflow
1
Low stress, near surface
2.5
0.156
Very poor rock
and very poor rock mass, respectively (Table 4). The Qc
values for basalt and tuffite are 0.42 and 0.013, respectively.
4. Estimation of rock mass properties
The rock mass properties such as Hoek–Brown
constants, deformation modulus (Emass) and uniaxial
compressive strength of rock mass (σcmass) were
calculated by means of empirical equations in accordance with the RMR89, Q, Qc and GSI.
4.1. Geological strength index (GSI) and Hoek–Brown
parameters
The geological strength index (GSI) was developed by
Hoek et al. (1995). The GSI is based on the appearance of
a rock mass and its structure. Marinos and Hoek (2001)
used additional geological properties in the Hoek–Brown
failure criterion and introduced a new GSI chart for
heterogeneous weak rock masses. The value of GSI was
obtained from the last form of the quantitative GSI chart,
which was proposed by Marinos and Hoek (2000).
The Hoek and Brown (1997) failure criterion was used
for determining the rock mass properties of basalt at the
dam site. Hoek et al. (2002) suggested the following equations for calculating rock mass constants (i.e., mb, s and a):
GSI−100
mb ¼ mi exp
;
ð5Þ
28−14D
Table 5
GSI and calculated Hoek–Brown parameters values
Unit
GSI
mi constant
mb constant
s constant
48
32
25
13
3.903
1.146
0.0031
0.0005
0.507
0.520
ð6Þ
ð7Þ
a constant
Basalt
Tuffite
GSI−100
;
s ¼ exp
9−3D
1 1
a ¼ þ e−GSI=15 −e−20=3 ;
2 6
where σc is uniaxial comprehensive strength of intact rock.
According to the Q classification system, basalt and
tuffite at the dam site can be considered as poor rock mass
where D is a factor that depends upon the degree of
disturbance to which the rock mass is subjected to by blast
7. 200
Z. Gurocak et al. / Engineering Geology 91 (2007) 194–208
damage and stress relaxation tests. In this study, the value of
D is considered zero. The calculated GSI is and the Hoek–
Brown constants are listed in Table 5.
Table 6
Selected equations for estimating deformation modulus of rock mass
Emass
Author
Equations
Equation
number
Bieniawski
(1978)
For RMR N 50,
(9)
Serafim and
Pereira
(1983)
For RMR b 50,
4.2. Strength and deformation modulus of rock masses
Several empirical equations have been suggested by
different researchers for estimating the strength and
modulus of rock masses based on the RMR, Q and GSI
values. In this study, the strength of rock masses was
calculated from the following equation suggested by
Hoek et al. (2002):
rcmass
ðmb þ 4s−aðmb −8sÞÞðmb =4 þ sÞa−1
;
¼ rci
2ð1 þ aÞð2 þ aÞ
ð8Þ
where σci is uniaxial compressive strength of the intact
rock, mb, s and a are rock mass constants. The strength
of rock masses for basalt and tuffite were determined as
10.6 and 1.08 MPa, respectively.
The deformation modulus of rock masses was
calculated suggested by different researchers based on
RMR, Q and GSI values. In this study, the equations in
Table 6 were used for determining deformation modulus
of rock masses. The calculated values of rock mass
deformation modulus are summarized in Table 7.
A reliable stability analysis and prediction of the
support capacity are some of the most difficult tasks in
rock engineering. Therefore, in the current study several
methods are used to conduct stability analysis and determine the support capacity. For the tunnel support design
of the diversion tunnel at the Boztepe dam site, empirical,
theoretical and numerical approaches were employed.
The vertical stress was assumed to increase linearly
with depth due to its overburden weight, as follows:
rv ¼ gH;
ð20Þ
where γ is unit weight of the intact rock in MN/m , and
H is the depth of overburden in m.
The horizontal stress was determined from the
following equation suggested by Sheorey et al. (2001):
3
m
bEmass G
rv þ
ðH þ 100Þ;
1−m
1−m
Emass ¼ 10
(10)
RMR−10
40
rffiffiffiffiffiffiffiffi
rci GSI−10
10 40
100
Hoek and
Brown
(1997)
Emass ¼
Read et al.
(1999)
RMR 3
Emass ¼ 0:1
10
Ramamurthy
(2001)
Emass ¼ Ei exp½ðRMR−100ÞŠ=17:4
(13)
Ramamurthy
(2001)
Emass ¼ Ei expð0:8625 logQ−2:875Þ
(14)
Barton (2002)
1=3
Emass ¼ 10Qc
(15)
(11)
(12)
rffiffiffiffiffiffiffiffi
rci GSI−10
10 40
100
(16)
Hoek et al.
(2002)
5. Tunnel stability and support analysis
rh ¼
Emass ¼ 2RMR−100
ð21Þ
where β = 8 × 10− 6/°C (coefficient of linear thermal
expansion), G = 0.024 °C/m (geothermal gradient), ν is
the Poisson's ratio, Emass is deformation modulus of
rock mass, MPa.
Emass ¼
Ramamurthy
(2004)
Emass ¼ Ei exp−0:0035½5ð100−RMRÞŠ
(17)
Ramamurthy
(2004)
Emass ¼ Ei exp−0:0035½250ð1−0:3logQÞŠ
(18)
Emass ¼ Ei 0:02 þ
(19)
Hoek and
Diederichs
(2006)
1−
D
2
1
1þ
eð60þ15D−GSIÞ=11
RMR = rock mass rating.
Q = rock mass quality.
Qc = rock mass quality rating or normalized Q.
GSI = geological strength index.
σci = uniaxial comprehensive strength of intact rock.
Ei = Young's modulus.
D = disturbance factor.
The far-field stress σ0 was calculated using the
following equation:
r0 ¼
rv þ rh1 þ rh2
;
3
where σhl and σh2 are horizontal stresses.
ð22Þ
8. Z. Gurocak et al. / Engineering Geology 91 (2007) 194–208
201
Table 7
Calculated values of deformation modulus of rock masses Emass
Modulus of rock mass (Emass, GPa)
Eq. (9)
Eq. (10)
Eq. (11)
Eq. (12)
Eq. (13)
Eq. (14)
Eq. (15)
Eq. (16)
Eq. (17)
Eq. (18)
Eq. (19)
Avrg
St. dev.
7.6
–
Basalt
Tuffite
–
3.98
5.68
1.02
15.57
3.93
2.16
0.05
1.77
0.06
7.49
2.35
5.68
1.02
13.77
0.70
12.92
0.75
6.91
0.17
7.96
1.40
4.72
1.51
Avrg: average. St. dev.: standard deviation. Eq.: equation.
The 5-m-diameter tunnel was excavated at a
maximum depth of 38 m in basalt and 27 m in tuffite
below the ground surface. The far-field stresses for
basalt and tuffite were determined as 0.53 MPa and
0.22 MPa, respectively.
Proof (kN/m2), was calculated by using the following
equation:
5.1. Empirical approach
The support pressure was calculated as 0.135 MPa
according to the Barton et al. (1974) approach and
0.059 MPa according to the Bieniawski (1974) approach
for the basalts. However, for tuffite the corresponding
values were found to be 0.072 MPa and 0.055 MPa,
respectively. As one can see that from these results, the
support pressure obtained from the Q criterion is greater
than obtained by the RMR criterion and is considered
more realistic.
The tunnel supports were defined in accordance with
the recommendations of the RMR and Q systems.
Bieniawski (1989) suggested supports for different rock
mass classes in the RMR89 system. As noted earlier,
according to the RMR89 system on the one hand, basalts
and tuffites are fair and poor rock masses, respectively.
Correspondingly according to the Q system on the other
hand, basalts and tuffites are poor and very poor rock
masses, respectively. A summary of the estimated supports
using the RMR89 and Q systems are presented in Table 8.
Bieniawski (1974) used RMR, width of opening W
(m), and unit weight of overburden γ (kN/m3) to
determine the support pressure. From the formula
below, the support pressure Proof, is found in kN/m2:
Proof ¼
100−RMR
W g:
100
ð23Þ
Another approach was proposed by Barton et al.
(1974) that depends on rock mass quality, Q, and
discontinuity roughness, Jr . The roof support pressure,
Table 8
Estimated support categories of basalts and tuffites
Unit
Basalt
RMR
RMR 56.3/51.3
classification
Fair rock
system
Support Systematic bolts
4 m long, spaced
1.5–2 m in crown
and walls with
wire mesh in crown.
50–100 mm in crown
and 30 mm in sides.
Tuffite
34
Poor rock
Systematic bolts
4–5 m long,
spaced 1–1.5 m
in crown and walls
with wire mesh.
100–150 mm in
crown and 100 mm
in sides.
Q classification Q
1.03
0.156
system
Poor rock
Very poor rock
ESR
1.6
1.6
De
3.125
3.125
Support Systematic bolting,
4 m long bolting,
4 m long, spaced
spaced 1.3–1.5 m
1.7 m with 40–50 mm and 90–120 mm
unreinforced shotcrete fibre reinforced
shotcrete
De ¼
Excavation span; diameter or height ðmÞ
Excavation support ratio ðESRÞ
Proof ¼
200 1=3
Q :
Jr
ð24Þ
5.2. Theoretical approach
In this study, a theoretical approach, called the
convergence–confinement technique, was used for
stability analysis. This methodology has been described
by Carranza-Torres and Fairhurst (1999) for rock masses
that satisfy the Hoek–Brown criterion. A cylindrical
tunnel of radius R, subjected to a uniform far-field stress
Table 9
Far-field stress, shear modulus of rock mass, actual critical internal
pressure, radius of plastic zone, maximum deformation and strain
values obtained from the convergence–confinement method
Unit
σ0
Gmass Pi
(MPa) (GPa) (MPa)
Basalt 0.53
Tuffite 0.22
3.13
0.58
Pi cr
Rpl uel
upl
Strain
r
r
(MPa) (m) (mm) (mm) (%)
0.000049 0.000 0.00 0.211 0.000 0.0084
0.00191 0.0143 3.47 0.000 0.441 0.0176
9. 202
Z. Gurocak et al. / Engineering Geology 91 (2007) 194–208
Table 10
Material properties of basalts and tuffites for numerical model
Property
Basalt
Material type
Young's modulus (GPa)
Poisson's ratio
Compressive strength (MPa)
m parameter
s parameter
Material type
Dilation parameter
m residual
s residual
Isotropic
7.96
0.27
10.61
3.903
0.0031
Plastic
0°
1.9515
0.00155
Tuffite
Value
Isotropic
1.40
0.20
1.08
1.146
0.0005
Plastic
0°
0.573
0.00025
σ0, and internal pressure Pi was considered. The rock
mass, in which the tunnel is excavated, is assumed to
satisfy the Hoek–Brown failure criterion.
The actual critical internal pressure Picr is defined as
(Carranza-Torres and Fairhurst, 2000):
Picr ¼
⁎ s
Pi − 2 mb rci ;
mb
ð25Þ
The scaled critical internal pressure is evaluated from
the following equation:
1 pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi2
⁎
1− 1 þ 16S0 ;
ð26Þ
Pi ¼
16
in which S0 is the scaled far-field stress given by:
S0 ¼
r0
s
þ
;
mb rci m2
b
ð27Þ
where σ0 is far-field stress, and Pi is the scaled internal
pressure defined by:
Pi ¼
pi
s
þ
;
mb rci m2
b
ð28Þ
where pi is uniform internal pressure.
If the internal pressure Pi is greater than the actual
critical internal pressure Picr, no failure will occur, and
the behavior of the surrounding rock mass is elastic, and
el
the inward elastic displacement ur of the tunnel wall is
given by:
uel ¼
r
r0 −Pi
R;
2Gmass
ð29Þ
where σ0 is far-field stress, Pi is scaled internal pressure,
R is the tunnel radius and Gmass is the shear modulus of
the rock mass.
If the internal pressure Pi, on the other hand, is less
than the actual critical internal pressure Picr, failure is
where
s and mb Hoek–Brown constants,
σci
uniaxial compressive strength, and
scaled critical internal pressure.
Pi⁎
Table 11
Stresses and displacements before and after support for basalts and tuffites
Location
Parameter
Basalt
Before support
After support
Before support
After support
Right wall
σ1 (MPa)
σ3 (MPa)
x-displacement (m)
y-displacement (m)
Total displacement (m)
σ1 (MPa)
σ3 (MPa)
x-displacement (m)
y-displacement (m)
Total displacement (m)
σ1 (MPa)
σ3 (MPa)
x-displacement (m)
y-displacement (m)
Total displacement (m)
σ1 (MPa)
σ3 (MPa)
x-displacement (m)
y-displacement (m)
Total displacement (m)
0.964
0.052
0.205
1.32e − 003
0.205e − 004
0.953
0.057
1.60e − 006
0.204e − 004
0.204e − 004
0.960
0.054
0.204e − 004
6.35e − 007
0.204e − 004
0.964
0.082
1.06e − 006
0.204e − 004
0.204e − 004
0.920
0.136
1.79e − 004
2.37e − 007
1.79e − 004
0.939
0.128
1.84e − 007
1.80e − 004
1.80e − 004
0.938
0.127
1.79e − 004
3.91e − 007
1.79e − 004
0.943
0.130
1.74e − 007
1.81e − 004
1.81e − 004
0.072
9.80e − 003
1.20e − 003
1.76e − 005
1.20e − 003
0.080
0.011
1.07e − 005
1.18e − 003
1.18e − 003
0.068
8.74e − 003
1.20e − 003
4.64e − 006
1.20e − 003
0.083
0.011
8.03e − 006
1.19e − 003
1.19e − 003
0.315
0.129
2.22e − 004
1.09e − 006
2.22e − 004
0.313
0.131
2.20e − 004
1.03e − 006
4.37e − 004
0.310
0.131
2.20e − 004
1.03e − 006
2.20e − 004
0.313
0.130
9.32e − 007
2.21e − 004
2.21e − 004
Roof
Left Wall
Floor
Tuffite
10. Z. Gurocak et al. / Engineering Geology 91 (2007) 194–208
203
Fig. 5. Stresses around tunnel before and after support for basalts.
expected to occur. Then the radius of the broken zone
Rpl is defined by:
Àpffiffiffiffiffiffi pffiffiffiffiffiÁ
Rpl ¼ R exp2 Picr − Pi :
ð30Þ
Hoek and Brown (1997) suggested the following
pl
equation to evaluate the total plastic deformation ur
for rock masses:
qffiffiffiffiffiffi
2
3
⁎
2
Rpl
upl 2Gmass 41−2m Pi
1−2m
r
¼
þ 15
þ
⁎
R r0 −Picr
R
2 S0 −P⁎
4 S0 −Pi
i
qffiffiffiffiffiffi
⁎
!2
!
Rpl
Rpl
1−2m Pi
þ1
 ln
−
2 ln
2 S0 −P⁎
R
R
i
ð31Þ
where R is the tunnel radius, ν is the Poisson's ratio, and
Gmass is the shear modulus of rock mass. Carranza-
Torres and Fairhurst (2000) suggested the following
equation for calculating rock mass shear modulus:
Gmass ¼
Emass
;
2ð1 þ mÞ
ð32Þ
where Emass is the deformation modulus of the rock
mass.
Internal pressure Pi was assumed to be zero in this
study for unsupported tunnel cases in basalt and tuffite.
el
The calculated parameters of σ0, Gmass, Pi, Picr, Rpl, ur ,
pl
ur and strain for basalt and tuffite are summarized in
Table 9.
The actual critical internal pressure (Picr = 0.0 MPa) is
less than the internal pressure (Pi = 0.000049 MPa) for
basalt. In this case, basalts will behave elastically and
failure will not occur. The inward elastic displacement
of tunnel walls and strain were calculated as 0.211 mm
and 0.0084%, respectively. For tuffites, the actual
11. 204
Z. Gurocak et al. / Engineering Geology 91 (2007) 194–208
Fig. 6. Stresses around tunnel before and after support for tuffites.
internal pressure (Picr = 0.0143 MPa) is higher than the
internal pressure (Pi = 0.00191 MPa). Tuffites will
behave plastically and failure is expected to occur. The
radius of plastic zone and the strain for tuffite were
calculated as 3.47 m and 0.0176%, respectively.
Hoek and Marinos (2000) suggested that for
formations with strain values less than one, few
stability problems are expected. Simple tunnel support
design methods are suggested to be used for such
cases.
5.3. Numerical approach
In order to verify the results of the empirical
analyses, a two-dimensional hybrid element model,
called Phase2 Finite Element Program (Rocscience,
1999), was used in the numerical analysis conducted
here in. The rock mass properties assumed in this analysis were obtained from the estimated values presented
in Section 4. The Hoek–Brown failure criterion was
used to identify elements undergoing yielding and the
plastic zones of rock masses in the vicinity of tunnel
perimeter. Plastic post-failure strength parameters were
used in this analysis and residual parameters were
assumed as half of the peak strength parameters.
The far-field stresses for basalt and tuffite were used
as 0.53 MPa and 0.22 MPa, respectively, as determined
in Section 5.2. To simulate the excavation of the
diversion tunnel in basalt and tuffite, two different finite
element models were generated using the same mesh
and tunnel geometry, but different material properties.
The outer model boundary was set at a distance of 6
12. Z. Gurocak et al. / Engineering Geology 91 (2007) 194–208
205
Fig. 7. The displacement behavior and extent of plastic zone before and after support for basalts.
times the tunnel radius. A total of 3048 three-noddedtriangular elements were used in the finite element
mesh. The following sections were used:
Section I tunnel running through basalt
Section II tunnel running through tuffite
The required parameters and their numerical values
for basalts and tuffites are given in Table 10. For
unsupported and supported cases, total displacements
and stresses at the walls, roof and floor of the tunnel for
the two different rock types are presented in Table 11 and
Figs. 5 and 6. The total displacement behavior and extent
of plastic zone before and after support for basalt and
tuffite are given in Figs. 7 and 8, respectively.
It can be seen from Figs. 7 and 8 that the extent of
failure zone for basalts is less than the corresponding zone
for tuffites. The maximum total displacement values for
13. 206
Z. Gurocak et al. / Engineering Geology 91 (2007) 194–208
Fig. 8. The displacement behavior and extent of plastic zone before and after support for tuffites.
unsupported tunnel in basalts and tuffites are 2.05e − 004
and 1.20e − 003 m, respectively. The displacement values
for basalt and tuffites are very small. However, the extent
of plastic zone and elements undergoing yielding suggest
that there would be stability problems for the tunnel
driven in basalts and tuffites. In basalts, only some yielded
elements were observed and the thickness of plastic zone
was limited, as shown in Fig. 7.
The support elements used consist of rock bolts and
shotcrete, as proposed by the empirical methods. The
properties of support elements, such as length, bolt
patterns and thickness of shotcrete are similar to those
proposed by the empirical methods. For tunnel in
basalts, 4-m-long rock bolts with 2-m spacing and 100mm-thick shotcrete are proposed. For tuffites, 5-m-long
rock bolts with 1-m spacing and 150-mm-thick shotcrete
14. Z. Gurocak et al. / Engineering Geology 91 (2007) 194–208
207
Table 12
Radius of plastic zone and maximum total displacements obtained from Phase2
Unit
Radius of plastic zone, Rpl (m)
Maximum total displacement (m)
Unsupported
Supported
Unsupported
Supported
Basalt
Tuffite
2.68
4.21
2.50
2.50
2.05e − 004
1.20e − 003
1.79e − 004
2.20e − 004
are proposed as support elements. After considering
support measures in the numerical model, not only the
number of yielded elements but also the extent of plastic
zone decreased substantially, as shown in Figs. 7 and 8.
The maximum total displacement values for basalt and
tuffites decreased to 1.79e − 004 and 2.20e − 004 mm,
respectively, as shown in Table 11. For basalts and
tuffites, the radius of plastic zone and the maximum total
displacements obtained from Phase2 FEM analysis for
unsupported and supported cases are presented in
Table 12.
number of yielded elements and the size of plastic zone
around the tunnel.
The results obtained from the empirical, theoretical
and numerical approaches were fairly comparable.
However, the validity of the proposed support systems
should be checked by comparing the results obtained by
a combination of empirical, theoretical and numerical
methods with the measurements that will be carried out
during construction.
6. Conclusions
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and its application in tunneling. Proceedings of the Third
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Bieniawski, Z.T., 1978. Determining rock mass deformability:
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Bieniawski, Z.T., 1989. Engineering Rock Mass Classifications.
Wiley, New York. 251 pp.
Carranza-Torres, C., Fairhurst, C., 1999. The elasto-plastic response of
underground excavations in rock masses that satisfy the Hoek–
Brown failure criterion. Int. J. Rock Mech. Min. Sci. 36 (6), 777–809.
Carranza-Torres, C., Fairhurst, C., 2000. Application of the convergence–confinement method of tunnel design to rock masses that
satisfy the Hoek–Brown failure criterion. Tunn. Undergr. Space
Technol. 15 (2), 187–213.
Deere, D.U., 1964. Technical description of rock cores for engineering
purposes. Rock Mech. Rock Eng. 1, 17–22.
Diederichs, M.S., Hoek, E., 1989. DIPS 3.01, Advanced Version
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the State Hydraulic Works. Elazig, Turkey.
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In this study, empirical methods were used to
estimate the rock mass quality and support elements
for basalts and tuffites in the diversion tunnel at the
Boztepe dam site. Based on the information collected in
the field and laboratory, the RMR and Q classification
systems were used to characterize the rock masses.
These classification systems were also employed to
estimate the support requirements for the diversion
tunnel. The Hoek–Brown parameters and support
measure recommendations from the empirical results
were used as input in the numerical analyses.
According to the results obtained from the empirical,
theoretical and numerical analysis, there were some
stability problems for basalts. The empirical methods
recommend the utilization of rock bolts and shotcrete as
support elements for basalts. The results of theoretical
and numerical method show that basalts are expected to
have some deformations. Numerical modeling was used
to evaluate the performance of the recommended
support system. However, the results from the finite
element methods are similar to the results from the
empirical methods. When the recommended support
systems were considered, the displacements were
reduced significantly in the numerical analysis.
The empirical approach indicated that substantial
support was necessary for tuffites, and both theoretical
and numerical approaches agreed concerning the
important stability problems. However, after considering the support elements, the numerical analysis showed
that there was a considerable decrease in both the
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