The most commonly used method for assessing the hydraulic erodibility of rock is Annandale's method.This method is based on a correlation between the erosive force of flowing water and the capacity of rock resista...The most commonly used method for assessing the hydraulic erodibility of rock is Annandale's method.This method is based on a correlation between the erosive force of flowing water and the capacity of rock resistance. This capacity is evaluated using Kirsten's index, which was initially developed to evaluate the excavatability of earth materials. For rocky material, this index is determined according to certain geomechanical factors related to intact rock and rock mass, such as compressive strength of intact rock, rock block size, discontinuity shear strength and relative block structure. To quantify the relative block structure, Kirsten(1982) developed a mathematical expression that accounts for the shape and orientation of the blocks relative to the direction of flow. Kirsten's initial concept for assessing the relative block structure considers that the geological formation is mainly fractured by two joint sets forming an orthogonally fractured system. An adjusted concept is proposed to determine the relative block structure when the fractured system is non-orthogonal where the angle between the planes of the two joint sets is greater or less than 90°. An analysis of the proposed relative block structure rating shows that considering a non-orthogonally fractured system has a significant effect on Kirsten's index and, as a consequence, on the assessment of the hydraulic erodibility of rock.展开更多
As an effective solution for protecting the underlying permafrost and preventing roadway damages, the block-rock embankment(BRE) has been widely used on the Qinghai–Tibet Railway, Qinghai–Tibet Highway, and Ching–H...As an effective solution for protecting the underlying permafrost and preventing roadway damages, the block-rock embankment(BRE) has been widely used on the Qinghai–Tibet Railway, Qinghai–Tibet Highway, and Ching–Hong Road;and it will be promoted for other roadways in the future. To evaluate the adaptability of BRE, the catastrophe-progression method was adopted for the evaluation. By analyzing the factors affecting the stability of BRE and utilizing engineering experience, we were able to establish the mathematical model and divide the adaptability of BRE into five grades. After the verifying analysis of 28 practical engineering examples, the evaluation results are broadly in line with practical application effects. Therefore, the adaptability of BRE can be evaluated and predicted more accurately with this evaluation model.展开更多
Among the methods used for evaluating the potential hydraulic erodibility of rock,the most common methods are those based on the correlation between the force of flowing water and the capacity of a rock to resist eros...Among the methods used for evaluating the potential hydraulic erodibility of rock,the most common methods are those based on the correlation between the force of flowing water and the capacity of a rock to resist erosion,such as Annandale’s and Pells’methods.The capacity of a rock to resist erosion is evaluated based on erodibility indices that are determined from specific geomechanical parameters of a rock mass.These indices include unconfined compressive strength(UCS)of rock,rock block size,joint shear strength,a block’s shape and orientation relative to the direction of flow,joint openings,and the nature of the surface to be potentially eroded.However,it is difficult to determine the relevant geomechanical parameters for evaluating the hydraulic erodibility of rock.The assessment of eroded unlined spillways of dams has shown that the capacity of a rock to resist erosion is not accurately evaluated.Using more than 100 case studies,we develop a method to determine the relevant geomechanical parameters for evaluating the hydraulic erodibility of rock in unlined spillways.The UCS of rock is found not to be a relevant parameter for evaluating the hydraulic erodibility of rock.On the other hand,we find that the use of three-dimensional(3D)block volume measurements,instead of the block size factor used in Annandale’s method,improves the rock block size estimation.Furthermore,the parameter representing the effect of a rock block’s shape and orientation relative to the direction of flow,as considered in Pells’method,is more accurate than the parameter adopted by Annandale’s method.展开更多
基金the organizations that have funded this project:the Natural Sciences and Engineering Research Council of Canada(Grant No.498020-16)Hydro-Quebec(NC-525700)Mitacs Accelerate Program(Grant Ref.IT10008)
文摘The most commonly used method for assessing the hydraulic erodibility of rock is Annandale's method.This method is based on a correlation between the erosive force of flowing water and the capacity of rock resistance. This capacity is evaluated using Kirsten's index, which was initially developed to evaluate the excavatability of earth materials. For rocky material, this index is determined according to certain geomechanical factors related to intact rock and rock mass, such as compressive strength of intact rock, rock block size, discontinuity shear strength and relative block structure. To quantify the relative block structure, Kirsten(1982) developed a mathematical expression that accounts for the shape and orientation of the blocks relative to the direction of flow. Kirsten's initial concept for assessing the relative block structure considers that the geological formation is mainly fractured by two joint sets forming an orthogonally fractured system. An adjusted concept is proposed to determine the relative block structure when the fractured system is non-orthogonal where the angle between the planes of the two joint sets is greater or less than 90°. An analysis of the proposed relative block structure rating shows that considering a non-orthogonally fractured system has a significant effect on Kirsten's index and, as a consequence, on the assessment of the hydraulic erodibility of rock.
文摘As an effective solution for protecting the underlying permafrost and preventing roadway damages, the block-rock embankment(BRE) has been widely used on the Qinghai–Tibet Railway, Qinghai–Tibet Highway, and Ching–Hong Road;and it will be promoted for other roadways in the future. To evaluate the adaptability of BRE, the catastrophe-progression method was adopted for the evaluation. By analyzing the factors affecting the stability of BRE and utilizing engineering experience, we were able to establish the mathematical model and divide the adaptability of BRE into five grades. After the verifying analysis of 28 practical engineering examples, the evaluation results are broadly in line with practical application effects. Therefore, the adaptability of BRE can be evaluated and predicted more accurately with this evaluation model.
基金the Natural Sciences and Engineering Research Council of Canada(Grant No.498020-16)Hydro-Quebec(NC525700)the Mitacs Accelerate Program(Grant Ref.IT10008)
文摘Among the methods used for evaluating the potential hydraulic erodibility of rock,the most common methods are those based on the correlation between the force of flowing water and the capacity of a rock to resist erosion,such as Annandale’s and Pells’methods.The capacity of a rock to resist erosion is evaluated based on erodibility indices that are determined from specific geomechanical parameters of a rock mass.These indices include unconfined compressive strength(UCS)of rock,rock block size,joint shear strength,a block’s shape and orientation relative to the direction of flow,joint openings,and the nature of the surface to be potentially eroded.However,it is difficult to determine the relevant geomechanical parameters for evaluating the hydraulic erodibility of rock.The assessment of eroded unlined spillways of dams has shown that the capacity of a rock to resist erosion is not accurately evaluated.Using more than 100 case studies,we develop a method to determine the relevant geomechanical parameters for evaluating the hydraulic erodibility of rock in unlined spillways.The UCS of rock is found not to be a relevant parameter for evaluating the hydraulic erodibility of rock.On the other hand,we find that the use of three-dimensional(3D)block volume measurements,instead of the block size factor used in Annandale’s method,improves the rock block size estimation.Furthermore,the parameter representing the effect of a rock block’s shape and orientation relative to the direction of flow,as considered in Pells’method,is more accurate than the parameter adopted by Annandale’s method.
