The stability of rock slopes is considered crucial to public safety in highways passing through rock cuts, as well as to personnel and equipment safety in open pit mines. Slope instability and failures occur due to ma...The stability of rock slopes is considered crucial to public safety in highways passing through rock cuts, as well as to personnel and equipment safety in open pit mines. Slope instability and failures occur due to many factors such as adverse slope geometries, geological discontinuities, weak or weathered slope materials as well as severe weather conditions. External loads like heavy precipitation and seismicity could play a significant role in slope failure. In this paper, several rock mass classification systems developed for rock slope stability assessment are evaluated against known rock slope conditions in a region of Saudi Arabia, where slopes located in rugged terrains with complex geometry serve as highway road cuts. Selected empirical methods have been applied to 22 rock cuts that are selected based on their failure mechanisms and slope materials. The stability conditions are identified, and the results of each rock slope classification system are compared. The paper also highlights the limitations of the empirical classification methods used in the study and proposes future research directions.展开更多
Overhanging rock slopes(steeper than 90°) are typically avoided in rock engineering design, particularly where the scale of the slope exceeds the scale of fracturing present in the rock mass. This paper highlight...Overhanging rock slopes(steeper than 90°) are typically avoided in rock engineering design, particularly where the scale of the slope exceeds the scale of fracturing present in the rock mass. This paper highlights an integrated approach of designing overhanging rock slopes where the relative dimensions of the slope exceed the scale of fracturing and the rock mass failure needs to be considered rather than kinematic release of individual blocks. The key to the method is a simplified limit equilibrium(LE) tool that was used for the support design and analysis of a multi-faceted overhanging rock slope. The overhanging slopes required complex geometries with constantly changing orientations. The overhanging rock varied in height from 30 m to 66 m. Geomechanical modelling combined with discrete fracture network(DFN)representation of the rock mass was used to validate the rock mass strength assumptions and the failure mechanism assumed in the LE model. The advantage of the simplified LE method is that buttress and support design iterations(along with sensitivity analysis of design parameters) can be completed for various cross-sections along the proposed overhanging rock sections in an efficient manner, compared to the more time-intensive, sophisticated methods that were used for the initial validation. The method described presents the development of this design tool and assumptions made for a specific overhanging rock slope design. Other locations will have different geological conditions that can control the potential behaviour of rock slopes, however, the approach presented can be applied as a general guiding design principle for overhanging rock cut slope.展开更多
Slopes consisting of interbedded strata of soft and hard rock mass, such as purplish red mudstone and grey brown arkosic sandstone of Jurassic age, are very common in Sichuan basin of China. The mudstone is soft whil...Slopes consisting of interbedded strata of soft and hard rock mass, such as purplish red mudstone and grey brown arkosic sandstone of Jurassic age, are very common in Sichuan basin of China. The mudstone is soft while the sandstone is hard and contains many opening or closing joints with a high dip angle. Some are nearly parallel and the others are nearly decussated with the trend of the slopes. Many natural slopes are in deformation or sliding because of those reasons. The stability of cutting slopes and supporting method to be taken for their stability in civil engineering are important. In this paper, the stability and deformation of the slopes are studied. The methods of analysis and support design principle are analyzed also. Finally, the method put forward is applied to study Fengdian high cutting slope in Sichuan section of the express way from Chengdu to Shanghai. The results indicate that the method is effective.展开更多
The appearance of 3D laser scanning technology is one of the most important technology revolutions in surveying and mapping field. It can be widely used in many interrelated fields, such as engineering constructions a...The appearance of 3D laser scanning technology is one of the most important technology revolutions in surveying and mapping field. It can be widely used in many interrelated fields, such as engineering constructions and 3D measurements, owing to its prominent characteristics of the high efficiency and high precision. At present its application is still in the initial state, and it is quite rarely used in China, especially in geotechnical engineering and geological engineering fields. Starting with a general introduction of 3D laser scanning technology, this article studies how to apply the technology to high rock slope investigations. By way of a case study, principles and methods of quick slope documentation and occurrence measurement of discontinuities are discussed and analyzed. Analysis results show that the application of 3D laser scanning technology to geotechnical and geological engineering has a great prospect and value.展开更多
The process of evaluating rock mass strength requires that major structural features such as joints that influence rock strength are considered. In carbonate rock masses, however, the strength of the rock mass is larg...The process of evaluating rock mass strength requires that major structural features such as joints that influence rock strength are considered. In carbonate rock masses, however, the strength of the rock mass is largely dependent on intact rock strength and structural features play a secondary role. Laboratory experiments on porous rock have shown that intact rock strength reduces with increasing porosity, which has a direct effect on the rock mass strength. Rock porosity has however not been well accounted for in rock mass characterization methods currently in use. This research applies the modified GSI method for carbonate rock masses which is based on a combination of GSI and total porosity. The main aim is to quantify the GSI with respect to rock porosity which is a direct indicator of the state of karstification, as an inherent feature that affects rock mass strength. An empirical equation is proposed whereby the GSI as observed in the field is modified by a natural log of the value of porosity, giving rise to a modified GSI (GSI<sub>m</sub>). The GSI<sub>m</sub> together with laboratory properties of rock is used to determine the properties of Vipingo coral limestone from RocLab software. A deterministic parametric slope stability analysis is done using the finite element software Phase 2 with the rock mass properties as input parameters. The analysis results point to a direct dependence of the slope stability on slope angle, slope height and rock mass strength of the lithological unit. The graphs make a useful design guide for slopes engineered in this type of rock mass.展开更多
One of the critical aspects in mine design is slope stability analysis and the determination of stable slopes. In the Chador- Malu iron ore mine, one of the most important iron ore mines in central Iran, it was consid...One of the critical aspects in mine design is slope stability analysis and the determination of stable slopes. In the Chador- Malu iron ore mine, one of the most important iron ore mines in central Iran, it was considered vital to perform a comprehensive slope stability analysis. At first, we divided the existing rock hosting pit into six zones and a geotechnical map was prepared. Then, the value of MRMR (Mining Rock Mass Rating) was determined for each zone. Owing to the fact that the Chador-Malu iron ore mine is located in a highly tectonic area and the rock mass completely crushed, the Hoek–Brown failure criterion was found suitable to estimate geo-mechanical parameters. After that, the value of cohesion (c) and friction angle (φ) were calculated for different geotechnical zones and relative graphs and equations were derived as a function of slope height. The stability analyses using numerical and limit equilibrium methods showed that some instability problems might occur by increasing the slope height. Therefore, stable slopes for each geotechnical zone and prepared sections were calculated and presented as a function of slope height.展开更多
Balia Nala is the outlet of the Nainital lake, flowing towards southeast direction. Presence of Nainital habitation at its right bank has high socio-economic importance. This study presents the stability analysis of a...Balia Nala is the outlet of the Nainital lake, flowing towards southeast direction. Presence of Nainital habitation at its right bank has high socio-economic importance. This study presents the stability analysis of a ravine/valley along Balia Nala. Variegated slates(lower Krol and upper Blaini formations) are the main rock types, wherever the outcrop does exist and rest of the area is covered by slope wash and river borne materials. Three sets of joints are presented in the area, but 4 sets of joints also exist at some locations. Nainital lake fault intersected by Manora fault from southwest direction passes through eastern side of the study area, and some small faults, which are sub-branches of Nainital lake fault, are observed(with 10 m offset) and promote the landslide in the area. This study shows that different kinds of discontinuities(joints, faults and shear zones) and rapid down cutting by the stream due to neotectonic activity affect the stability of the slope. The fragile lithology and deep V-shaped valley further accelerate the mass movement in the study area. In addition, rock mass rating(RMR), factor of safety(FOS) and graphical analysis of the joints indicate the study area as landslide-prone zone. This study will be helpful in not only reducing the risk on life of people, but also in assisting the ongoing civil work in the study area.展开更多
Nainital City of Kumaun Lesser Himalaya is prone to mass wasting processes during monsoon season,which mischievously triggers the hill slope instability in this region. Slate, dolomitic limestone, silty sandstone and ...Nainital City of Kumaun Lesser Himalaya is prone to mass wasting processes during monsoon season,which mischievously triggers the hill slope instability in this region. Slate, dolomitic limestone, silty sandstone and rhythmite of the Krol Formation are the main rock types. The present study focuses on the investigation of slope stability in the region in terms of potential seismicity and landslide. Geological and geotechnical mapping indicates that the major portion of the area is characterized by slope wash materials and buildings. The combination of 3-4 joint sets with one random joint is the main structure at outcrops.The major geological structures of this area are Nainital lake fault passing from the center of the lake, Main Boundary Thrust at SW, and Khuriya Fault passing from the SE direction of Nainital City. This work finds that different types of discontinuities(e.g. joints and faults), overburden due to unplanned civil structures,and neotectonic activity in the vicinity of this ara affect the stability of the city. The slate forms the base of the city, dipping slightly towards the lake side along the NW direction, thus accelerating the instability of this area. Rock mass rating(RMR), slope mass rating, factor of safety(FOS) and graphical analysis of the discontinuity for slope kinematics indicate that the study area is a landslide-prone zone. This study can facilitate reducing the risk of human life, and contribute to the ongoing construction works in the area.展开更多
基金financially supported by the Saudi Geological Survey through a doctoral fellowship at McGill University
文摘The stability of rock slopes is considered crucial to public safety in highways passing through rock cuts, as well as to personnel and equipment safety in open pit mines. Slope instability and failures occur due to many factors such as adverse slope geometries, geological discontinuities, weak or weathered slope materials as well as severe weather conditions. External loads like heavy precipitation and seismicity could play a significant role in slope failure. In this paper, several rock mass classification systems developed for rock slope stability assessment are evaluated against known rock slope conditions in a region of Saudi Arabia, where slopes located in rugged terrains with complex geometry serve as highway road cuts. Selected empirical methods have been applied to 22 rock cuts that are selected based on their failure mechanisms and slope materials. The stability conditions are identified, and the results of each rock slope classification system are compared. The paper also highlights the limitations of the empirical classification methods used in the study and proposes future research directions.
文摘Overhanging rock slopes(steeper than 90°) are typically avoided in rock engineering design, particularly where the scale of the slope exceeds the scale of fracturing present in the rock mass. This paper highlights an integrated approach of designing overhanging rock slopes where the relative dimensions of the slope exceed the scale of fracturing and the rock mass failure needs to be considered rather than kinematic release of individual blocks. The key to the method is a simplified limit equilibrium(LE) tool that was used for the support design and analysis of a multi-faceted overhanging rock slope. The overhanging slopes required complex geometries with constantly changing orientations. The overhanging rock varied in height from 30 m to 66 m. Geomechanical modelling combined with discrete fracture network(DFN)representation of the rock mass was used to validate the rock mass strength assumptions and the failure mechanism assumed in the LE model. The advantage of the simplified LE method is that buttress and support design iterations(along with sensitivity analysis of design parameters) can be completed for various cross-sections along the proposed overhanging rock sections in an efficient manner, compared to the more time-intensive, sophisticated methods that were used for the initial validation. The method described presents the development of this design tool and assumptions made for a specific overhanging rock slope design. Other locations will have different geological conditions that can control the potential behaviour of rock slopes, however, the approach presented can be applied as a general guiding design principle for overhanging rock cut slope.
文摘Slopes consisting of interbedded strata of soft and hard rock mass, such as purplish red mudstone and grey brown arkosic sandstone of Jurassic age, are very common in Sichuan basin of China. The mudstone is soft while the sandstone is hard and contains many opening or closing joints with a high dip angle. Some are nearly parallel and the others are nearly decussated with the trend of the slopes. Many natural slopes are in deformation or sliding because of those reasons. The stability of cutting slopes and supporting method to be taken for their stability in civil engineering are important. In this paper, the stability and deformation of the slopes are studied. The methods of analysis and support design principle are analyzed also. Finally, the method put forward is applied to study Fengdian high cutting slope in Sichuan section of the express way from Chengdu to Shanghai. The results indicate that the method is effective.
基金the Key Project of Joint Funds of Yalongjiang River Development of the National Natural Science Foundation of China (No. 50539050)
文摘The appearance of 3D laser scanning technology is one of the most important technology revolutions in surveying and mapping field. It can be widely used in many interrelated fields, such as engineering constructions and 3D measurements, owing to its prominent characteristics of the high efficiency and high precision. At present its application is still in the initial state, and it is quite rarely used in China, especially in geotechnical engineering and geological engineering fields. Starting with a general introduction of 3D laser scanning technology, this article studies how to apply the technology to high rock slope investigations. By way of a case study, principles and methods of quick slope documentation and occurrence measurement of discontinuities are discussed and analyzed. Analysis results show that the application of 3D laser scanning technology to geotechnical and geological engineering has a great prospect and value.
文摘The process of evaluating rock mass strength requires that major structural features such as joints that influence rock strength are considered. In carbonate rock masses, however, the strength of the rock mass is largely dependent on intact rock strength and structural features play a secondary role. Laboratory experiments on porous rock have shown that intact rock strength reduces with increasing porosity, which has a direct effect on the rock mass strength. Rock porosity has however not been well accounted for in rock mass characterization methods currently in use. This research applies the modified GSI method for carbonate rock masses which is based on a combination of GSI and total porosity. The main aim is to quantify the GSI with respect to rock porosity which is a direct indicator of the state of karstification, as an inherent feature that affects rock mass strength. An empirical equation is proposed whereby the GSI as observed in the field is modified by a natural log of the value of porosity, giving rise to a modified GSI (GSI<sub>m</sub>). The GSI<sub>m</sub> together with laboratory properties of rock is used to determine the properties of Vipingo coral limestone from RocLab software. A deterministic parametric slope stability analysis is done using the finite element software Phase 2 with the rock mass properties as input parameters. The analysis results point to a direct dependence of the slope stability on slope angle, slope height and rock mass strength of the lithological unit. The graphs make a useful design guide for slopes engineered in this type of rock mass.
文摘One of the critical aspects in mine design is slope stability analysis and the determination of stable slopes. In the Chador- Malu iron ore mine, one of the most important iron ore mines in central Iran, it was considered vital to perform a comprehensive slope stability analysis. At first, we divided the existing rock hosting pit into six zones and a geotechnical map was prepared. Then, the value of MRMR (Mining Rock Mass Rating) was determined for each zone. Owing to the fact that the Chador-Malu iron ore mine is located in a highly tectonic area and the rock mass completely crushed, the Hoek–Brown failure criterion was found suitable to estimate geo-mechanical parameters. After that, the value of cohesion (c) and friction angle (φ) were calculated for different geotechnical zones and relative graphs and equations were derived as a function of slope height. The stability analyses using numerical and limit equilibrium methods showed that some instability problems might occur by increasing the slope height. Therefore, stable slopes for each geotechnical zone and prepared sections were calculated and presented as a function of slope height.
文摘Balia Nala is the outlet of the Nainital lake, flowing towards southeast direction. Presence of Nainital habitation at its right bank has high socio-economic importance. This study presents the stability analysis of a ravine/valley along Balia Nala. Variegated slates(lower Krol and upper Blaini formations) are the main rock types, wherever the outcrop does exist and rest of the area is covered by slope wash and river borne materials. Three sets of joints are presented in the area, but 4 sets of joints also exist at some locations. Nainital lake fault intersected by Manora fault from southwest direction passes through eastern side of the study area, and some small faults, which are sub-branches of Nainital lake fault, are observed(with 10 m offset) and promote the landslide in the area. This study shows that different kinds of discontinuities(joints, faults and shear zones) and rapid down cutting by the stream due to neotectonic activity affect the stability of the slope. The fragile lithology and deep V-shaped valley further accelerate the mass movement in the study area. In addition, rock mass rating(RMR), factor of safety(FOS) and graphical analysis of the joints indicate the study area as landslide-prone zone. This study will be helpful in not only reducing the risk on life of people, but also in assisting the ongoing civil work in the study area.
文摘Nainital City of Kumaun Lesser Himalaya is prone to mass wasting processes during monsoon season,which mischievously triggers the hill slope instability in this region. Slate, dolomitic limestone, silty sandstone and rhythmite of the Krol Formation are the main rock types. The present study focuses on the investigation of slope stability in the region in terms of potential seismicity and landslide. Geological and geotechnical mapping indicates that the major portion of the area is characterized by slope wash materials and buildings. The combination of 3-4 joint sets with one random joint is the main structure at outcrops.The major geological structures of this area are Nainital lake fault passing from the center of the lake, Main Boundary Thrust at SW, and Khuriya Fault passing from the SE direction of Nainital City. This work finds that different types of discontinuities(e.g. joints and faults), overburden due to unplanned civil structures,and neotectonic activity in the vicinity of this ara affect the stability of the city. The slate forms the base of the city, dipping slightly towards the lake side along the NW direction, thus accelerating the instability of this area. Rock mass rating(RMR), slope mass rating, factor of safety(FOS) and graphical analysis of the discontinuity for slope kinematics indicate that the study area is a landslide-prone zone. This study can facilitate reducing the risk of human life, and contribute to the ongoing construction works in the area.
