The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Anton Schleiss - One of the best experts on this subject based on the ideXlab platform.
-
design of riverbank Riprap using large individually placed blocks
Journal of Hydraulic Engineering, 2019Co-Authors: Mona Jafarnejad, Mário J. Franca, Michael Pfister, Anton SchleissAbstract:AbstractThe protection of river banks in mountain rivers by Riprap requires large blocks with weights typically exceeding 1 t. Thus, the blocks have to be placed individually. Such packed Riprap ha...
-
probabilistic failure analysis of Riprap as riverbank protection under flood uncertainties
Stochastic Environmental Research and Risk Assessment, 2017Co-Authors: Mona Jafarnejad, Michael Pfister, Eugen Bruhwiler, Anton SchleissAbstract:Existing riverbank Riprap could face the risk of failure if the flood regime changes in future. Additionally, changed sediment transport in rivers, as a possible result of climate change, impacts the failure risk of flood protection measures. Evaluation of this potential failure is the primary issue of Riprap stability and safety assessment. The consequences of the bank failure are probably uncontrolled erosion and flooding with disastrous consequences in residential areas or damage to infrastructures. Thus, a probabilistic analysis of Riprap failure considering different mechanisms due to the flood and sediment transport uncertainties is required to assess embankment stability. In this article, the concept of a probabilistic assessment model based on Monte Carlo simulation method, moment analysis methods, and Rosenblueth point estimation method are presented to define the failure risk of Riprap as the river bank protection. The probability of failure in different modes, namely direct block erosion, toe scouring and overtopping, has been defined by taking into account the river bed level variation based on bedload transport described with a probabilistic function of the peak discharge. The result of three models comparison revealed a good agreement (the average deviation of less than 2%) in estimation of Riprap failure probability. This model is a strategical tool to search the critical river reaches and helps to evaluate the risk maps. So that, the model could cover the engineering aspect of environmental stability in the rivers with Riprap as the bank protections.
-
Time-based failure analysis of compressed riverbank Riprap
Journal of Hydraulic Research, 2016Co-Authors: Mona Jafarnejad, Mário J. Franca, Michael Pfister, Anton SchleissAbstract:ABSTRACTMethods to design Riprap-lined channels usually refer to dumped material. Large blocks placed individually by machinery are used when more stability is required. They offer additional resistance against flow erosion since space between blocks is minimized and interlocking increased. The behaviour of this protection has rarely been studied. An experimental investigation was carried out on the stability of compressed Riprap as riverbank protection. Riprap was reproduced by uniform crushed limestones with three block sizes. Tests were conducted for three channel slopes under supercritical flow conditions and for constant bank slope. A time-based analysis allowed establishing relations among time to failure, friction velocity, and dimensionless bed shear stress. The results of 45 tests confirm that the rate of block erosion is significantly reduced with increase in the Riprap diameter. The time to failure of the Riprap protection depends strongly on the longitudinal slope and on the block sizes. An em...
-
Sizing of Riprap for spill-through abutments
Proceedings of the Institution of Civil Engineers - Water Management, 2010Co-Authors: António H. Cardoso, Gonzalo Simarro, O. Le Doucen, Anton SchleissAbstract:An experimental investigation of Riprap stability at spill-through abutments has been carried out in two similar horizontal-bed flumes, avoiding Riprap failure modes other than shear failure and erosion failure. Tests were conducted for two common abutment side slopes, sub-critical flow regime, short to intermediate abutment lengths and high bed roughness. The aim of the experiments was to determine the size of stone Riprap necessary to resist (a) shear failure in aprons placed at the base of spill-through abutments, and (b) erosion failure over their side slopes. Results are compared with predictions of stone Riprap size given by expressions found in the literature. The predictor of Pagan–Ortiz is confirmed as being appropriate for shear failure at abutment aprons and can be adapted to account for erosion failure over abutment side slopes. Alternatively, two new expressions, written in terms of the (critical) approach flow intensity required to make the Riprap stones move, are suggested.
Michael Pfister - One of the best experts on this subject based on the ideXlab platform.
-
design of riverbank Riprap using large individually placed blocks
Journal of Hydraulic Engineering, 2019Co-Authors: Mona Jafarnejad, Mário J. Franca, Michael Pfister, Anton SchleissAbstract:AbstractThe protection of river banks in mountain rivers by Riprap requires large blocks with weights typically exceeding 1 t. Thus, the blocks have to be placed individually. Such packed Riprap ha...
-
probabilistic failure analysis of Riprap as riverbank protection under flood uncertainties
Stochastic Environmental Research and Risk Assessment, 2017Co-Authors: Mona Jafarnejad, Michael Pfister, Eugen Bruhwiler, Anton SchleissAbstract:Existing riverbank Riprap could face the risk of failure if the flood regime changes in future. Additionally, changed sediment transport in rivers, as a possible result of climate change, impacts the failure risk of flood protection measures. Evaluation of this potential failure is the primary issue of Riprap stability and safety assessment. The consequences of the bank failure are probably uncontrolled erosion and flooding with disastrous consequences in residential areas or damage to infrastructures. Thus, a probabilistic analysis of Riprap failure considering different mechanisms due to the flood and sediment transport uncertainties is required to assess embankment stability. In this article, the concept of a probabilistic assessment model based on Monte Carlo simulation method, moment analysis methods, and Rosenblueth point estimation method are presented to define the failure risk of Riprap as the river bank protection. The probability of failure in different modes, namely direct block erosion, toe scouring and overtopping, has been defined by taking into account the river bed level variation based on bedload transport described with a probabilistic function of the peak discharge. The result of three models comparison revealed a good agreement (the average deviation of less than 2%) in estimation of Riprap failure probability. This model is a strategical tool to search the critical river reaches and helps to evaluate the risk maps. So that, the model could cover the engineering aspect of environmental stability in the rivers with Riprap as the bank protections.
-
Time-based failure analysis of compressed riverbank Riprap
Journal of Hydraulic Research, 2016Co-Authors: Mona Jafarnejad, Mário J. Franca, Michael Pfister, Anton SchleissAbstract:ABSTRACTMethods to design Riprap-lined channels usually refer to dumped material. Large blocks placed individually by machinery are used when more stability is required. They offer additional resistance against flow erosion since space between blocks is minimized and interlocking increased. The behaviour of this protection has rarely been studied. An experimental investigation was carried out on the stability of compressed Riprap as riverbank protection. Riprap was reproduced by uniform crushed limestones with three block sizes. Tests were conducted for three channel slopes under supercritical flow conditions and for constant bank slope. A time-based analysis allowed establishing relations among time to failure, friction velocity, and dimensionless bed shear stress. The results of 45 tests confirm that the rate of block erosion is significantly reduced with increase in the Riprap diameter. The time to failure of the Riprap protection depends strongly on the longitudinal slope and on the block sizes. An em...
Kem C Kadavy - One of the best experts on this subject based on the ideXlab platform.
-
protection against scour at saf stilling basins
Journal of Hydraulic Engineering, 1993Co-Authors: C E Rice, Kem C KadavyAbstract:Severe scour may occur downstream of SAF stilling basins and some type of protection may be required to ensure the integrity of the structure. Tests were conductred using physical models to determine the minimum size and length of Riprap required for stability when the Riprap was placed at the elevation of the end sill and the elevation of the basin floor. For both placements, the size of Riprap required for stability increases exponentially with the Froude number. Larger Riprap is required for stability when the Riprap is placed at the end sill elevation compared to when it is placed at the basin floor elevation. Relationships are presented to determine the size and length of Riprap required to ensure basin integrity.
-
Riprap design for saf stilling basins
Transactions of the ASABE, 1992Co-Authors: C E Rice, Kem C KadavyAbstract:Physical model tests were conducted to determine criteria for the size and placement of Riprap downstream of SAF stilling basins to ensure basin integrity. Relationships are presented to determine the depth, width, and length for preformed scour holes as a function of the Froude number and Riprap size. Results show that the Riprap size required for stability increases exponentially with Froude number. Smaller Riprap is required for stability if the Riprap is recessed below the elevation of the basin floor. For level Riprap placement, larger Riprap is required for stability when the Riprap is placed at the end sill elevation compared to placement at the basin floor elevation.
Phil G Combs - One of the best experts on this subject based on the ideXlab platform.
-
Riprap sizing for ars type low drop stilling basins
Journal of Hydraulic Engineering, 1993Co-Authors: Derek D Johns, Chester C. Watson, Phil G CombsAbstract:The Agricultural Research Service (ARS)‐type low‐drop structure was developed and utilized to stabilize incising channels in northern Mississippi. The structure consists of a sheet pile stabilizer weir and stilling basin protected by Riprap. Field inspections and laboratory tests have indicated that the current sizing criteria for Riprap protection in the impingement area of the stilling basin may be inadequate during flood events. A 1:12 Froude scale model study was conducted with prototype median Riprap sizes ranging from 0.61 m (23.9 in.) to 0.JHEND8 119 m (36.5 in.), prototype discharges ranging from JHEND8 119.7 m3/s (3,308 cfs) to 221.1 m3/s7,801 cfs), and submergences ranging from 0.41 to 1033. The ratio of the approach unit discharge and median rock size was related to the submergence for calculating the stable Riprap size. The unit discharge at the weir and the submergence appear to be indicators of Riprap stability in the stilling basin..
-
Riprap Sizing for ARS‐Type Low‐Drop Stilling Basins
Journal of Hydraulic Engineering, 1993Co-Authors: Derek D Johns, Chester C. Watson, Phil G CombsAbstract:The Agricultural Research Service (ARS)‐type low‐drop structure was developed and utilized to stabilize incising channels in northern Mississippi. The structure consists of a sheet pile stabilizer weir and stilling basin protected by Riprap. Field inspections and laboratory tests have indicated that the current sizing criteria for Riprap protection in the impingement area of the stilling basin may be inadequate during flood events. A 1:12 Froude scale model study was conducted with prototype median Riprap sizes ranging from 0.61 m (23.9 in.) to 0.JHEND8 119 m (36.5 in.), prototype discharges ranging from JHEND8 119.7 m3/s (3,308 cfs) to 221.1 m3/s7,801 cfs), and submergences ranging from 0.41 to 1033. The ratio of the approach unit discharge and median rock size was related to the submergence for calculating the stable Riprap size. The unit discharge at the weir and the submergence appear to be indicators of Riprap stability in the stilling basin..
Mona Jafarnejad - One of the best experts on this subject based on the ideXlab platform.
-
design of riverbank Riprap using large individually placed blocks
Journal of Hydraulic Engineering, 2019Co-Authors: Mona Jafarnejad, Mário J. Franca, Michael Pfister, Anton SchleissAbstract:AbstractThe protection of river banks in mountain rivers by Riprap requires large blocks with weights typically exceeding 1 t. Thus, the blocks have to be placed individually. Such packed Riprap ha...
-
probabilistic failure analysis of Riprap as riverbank protection under flood uncertainties
Stochastic Environmental Research and Risk Assessment, 2017Co-Authors: Mona Jafarnejad, Michael Pfister, Eugen Bruhwiler, Anton SchleissAbstract:Existing riverbank Riprap could face the risk of failure if the flood regime changes in future. Additionally, changed sediment transport in rivers, as a possible result of climate change, impacts the failure risk of flood protection measures. Evaluation of this potential failure is the primary issue of Riprap stability and safety assessment. The consequences of the bank failure are probably uncontrolled erosion and flooding with disastrous consequences in residential areas or damage to infrastructures. Thus, a probabilistic analysis of Riprap failure considering different mechanisms due to the flood and sediment transport uncertainties is required to assess embankment stability. In this article, the concept of a probabilistic assessment model based on Monte Carlo simulation method, moment analysis methods, and Rosenblueth point estimation method are presented to define the failure risk of Riprap as the river bank protection. The probability of failure in different modes, namely direct block erosion, toe scouring and overtopping, has been defined by taking into account the river bed level variation based on bedload transport described with a probabilistic function of the peak discharge. The result of three models comparison revealed a good agreement (the average deviation of less than 2%) in estimation of Riprap failure probability. This model is a strategical tool to search the critical river reaches and helps to evaluate the risk maps. So that, the model could cover the engineering aspect of environmental stability in the rivers with Riprap as the bank protections.
-
Time-based failure analysis of compressed riverbank Riprap
Journal of Hydraulic Research, 2016Co-Authors: Mona Jafarnejad, Mário J. Franca, Michael Pfister, Anton SchleissAbstract:ABSTRACTMethods to design Riprap-lined channels usually refer to dumped material. Large blocks placed individually by machinery are used when more stability is required. They offer additional resistance against flow erosion since space between blocks is minimized and interlocking increased. The behaviour of this protection has rarely been studied. An experimental investigation was carried out on the stability of compressed Riprap as riverbank protection. Riprap was reproduced by uniform crushed limestones with three block sizes. Tests were conducted for three channel slopes under supercritical flow conditions and for constant bank slope. A time-based analysis allowed establishing relations among time to failure, friction velocity, and dimensionless bed shear stress. The results of 45 tests confirm that the rate of block erosion is significantly reduced with increase in the Riprap diameter. The time to failure of the Riprap protection depends strongly on the longitudinal slope and on the block sizes. An em...
