Browsing by Author "Toro-Escobar, Carlos"
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Item Countermeasures to Protect Bridge Piers from Scour(St. Anthony Falls Laboratory, 1998-12) Parker, Gary; Toro-Escobar, Carlos; Voigt, Richard L. Jr.This report is in fulfillment of NCHRP Project 24-7, Countermeasures to Protect Bridge Piers from Scour. The focus of the report concerns alternatives to standard riprap. installations as pier scour ,countermeasures. Two kinds of countermeasures were examined: flow altering countermeasures such as sacrificial piles and annoring countermeasures such as mattresses of cable tied blocks. None of the flow altering countermeasures were found to be overly effective. Under flood conditions in sand bed streams, riprap placed in the absence of a geotextile or granular filter layer was found to gradually settle and lose effectiveness over time even under conditions for which the riprap is never directly mobilized by the flow. This settling is due to deformation and leaching of sand associated with the passage of bedforms. Riprap performance can be considerably improved with the use of a geotextile, especially if the geotextile is sealed to the pier. Another countermeasure that provides excellent protection is a mattress of cable tied blocks underlain by a geotextile tied to the pier. Design recommendations are provided for a number of armoring countermeasures.Item Countermeasures to Protect Bridge Piers from Scour(St. Anthony Falls Laboratory, 1998-12) Parker, Gary; Toro-Escobar, Carlos; Voigt, Richard L. Jr.This report is in fulfillment of NCHRP Project 24-7, Countermeasures to Protect Bridge Piers from Scour. The focus of the report concerns alternatives to standard riprap installations as pier scour countermeasures. Two kinds of countermeasures were examined: flow altering countermeasures such as sacrificial piles and armoring countenneasures such as mattresses of cable tied blocks. None of the flow altering countenneasures were found to be overly effective. Under flood conditions in sand bed streams, riprap placed in the absence of a geotextile or granular filter layer was found to gradually settle and lose effectiveness over time even under conditions for which the riprap is never directly mobilized by the flow. This settling is due to defonnation and leaching of sand associated with the passage of bedforms. Riprap performance can be considerably improved with the use of a geotextile, especially if the geotextile is sealed to the pier. Another countenneasure that provides excellent protection is a mattress of cable tied blocks underlain by a geotextile tied to the pier. Design suggestions are provided for a number of annoring countermeasures.Item Countermeasures to Protect Bridge Piers from Scour(St. Anthony Falls Laboratory, 1998-12) Parker, Gary; Toro-Escobar, Carlos; Voigt, Richard L. Jr.This report is in fulfillment of NCHRP Project 24-7, Countermeasures to Protect Bridge Piers from Scour. The focus of the report concerns alternatives to standard riprap installations as pier scour countermeasures. Two kinds of countermeasures were examined: flow altering countermeasures such as sacrificial piles and armoring countermeasures such as mattresses of cable tied blocks. None of the flow altering countermeasures were found to be overly effective. Under flood conditions in sand bed streams, riprap placed in the absence of a geotextile or granular filter layer was found to gradually settle and lose effectiveness over time even under conditions for which the riprap is never directly mobilized by the flow. This settling is due to deformation and leaching of sand associated with the passage of bedforms. Riprap performance can be considerably improved with the use of a geotextile, especially if the geotextile is sealed to the pier. Another countermeasure that provides excellent protection is a mattress of cable tied blocks underlain by a geotextile tied to the pier. Design recommendations are provided for a number of armoring countermeasures.Item The Effect of Floodwater Extraction on the Morphology of Mountain Streams in Idaho(1999-08) Parker, Gary; Toro-Escobar, CarlosItem Hydraulic Stability of Channel LockTM Concrete Block Revetment System during Overtopping Flow(1996-09) Morgan, Scott; Toro-Escobar, Carlos; Voigt, Richard L. Jr.Item Hydraulic Stability of Conlock and Conlock II Concrete Block Revetment System During Overtopping Flow(St. Anthony Falls Laboratory, 1998-04) Voigt, Richard L. Jr.; Toro-Escobar, Carlos; Morgan, ScottThe St. Anthony Falls Hydraulic Laboratory (SAFHL) was contracted by Hydro-Turf & Associates to perform hydraulic testing of their Conlock and Conlock II concrete revetment systems. The testing was performed during February 1995 in SAFHL's largest flume, measuring 6 ft high x 9 ft wide x 253 ft long, with a maximum discharge capacity of 300 ft^3/s. The tests were undertaken to evaluate block performance to provide information regarding failure thresholds under controlled laboratory conditions. The testing was conducted in a manner to replicate as close as practical, the testing performed by Simon's, Li and Associates, Inc., for the Federal Highway Administration's overtopping embankment studies. A detailed description of the test setup is included later in this report. The embankment was constructed at the downstream end of the channel, extending into the tailgate pit. This allowed construction of an embankment 5.5 ft high and a maximum overtopping depth of 3.5 ft. The 3:1 downslope followed a 20 ft level section; both the embankment and level section were installed to the full 9 ft width of the channel. The full width was chosen to minimize sidewall effects.Item Movable Bed Physical Model of Howard Creek(St. Anthony Falls Hydraulic Laboratory, 1993-01) Voigt, Richard L.; Parker, Gary; Bauers, Curt; Toro-Escobar, CarlosSt. Anthony Falls Hydraulic Laboratory was contracted by the West Virginia office of the U. S. Soil Conservation Service to construct and evaluate a physical scale hydraulic model of Howard Creek as it flows through White Sulphur Springs, West Virginia. The reach in question extends from the Garden Street bridge on the upstream end to just past the Greenbrier Avenue bridge on the downstream end. This reach is subject to periodic flooding and has several complicating features. The complications include the confluence of Dry Creek just upstream of Big Draft Road near midreach, a substantial change in slope from approximately 0.00405 to 0.00151 near this confluence, and a corresponding change in sediment size distribution progressing downstream. In addition, the entire reach is closely surrounded by private residences as well as some commercial and public buildings. The Soil Conservation Service is proposing channel modifications designed to reduce flooding in this reach. This study primarily evaluates performance of the proposed design with regard to sediment scour and deposition, and bank protection performance under conditions of both sediment deficient and sediment surplus, for each of 2-year, 10-year, and 100-year floods. (Please note that throughout the report the words starved or deficient are used interchangeably.) This report covers the model design, model construction, the choice and sizing of suitable model sediment and riprap, calibration of the model, testing, modifications, and conclusions.