TURNERFAIRBANK HIGHWAY RESEARCH CENTER Development of New Guidance
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Development of New Guidance for Scour in Erodible Rock presented by Huang, C. , Xie, Z. , Lottes, S. A. , Nityanand, S. , Shan, H. , Shen, J. and Kerenyi, K. at the NHEC Friday, August 12 th, 2016 Portland, OR
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Outline • Introduction – Scour Equations in HEC-18 – New Scour Vision - Hydraulic Loading and Erosion Force • HEC-18: Pier Scour in Erodible Rock • Abutment Scour in Erodible Rock – – – Development of Abutment Scour Decay Function Full Scale CFD Modeling Preliminary Decay Function • Next Step 2
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Scour Equations in HEC-18 Scour Type Pier Scour Contraction Scour Abutment Scour Equation Bed Material Dependency CSU FDOT Coarse Bed Material Wide Pier Rock Laursen's Clear Water Laursen's Live Bed Rock Froehlich's HIRE NCHRP 24 -20 Rock No Yes Yes No ? No No Yes ? * K – Erodibility Index of Rock Limitation 0. 004’’<D 50<3. 9’’ 0. 79’’<D 50<4. 3’’ K>=0. 1 * 0. 004’’<D 50<7. 9’’ Introduction 3
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER New Scour Vision Concept of Hydraulic Loading and Erosion Force y Introduction 4
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER New Scour Vision Concept of Hydraulic Loading and Erosion Force y Introduction 5
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER New Scour Vision Concept of Hydraulic Loading and Erosion Force y Introduction 6
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER New Scour Vision Concept of Hydraulic Loading and Erosion Force Decay Function y Soil Erosion Resistance Introduction 7
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER • HEC-18 Section 7. 13, Eq. (7. 38) by Annandale (2006) *: * Annandale, G. W. , 2006, "Scour Technology, " Mc. Graw-Hill, New York. HEC-18: Pier Scour in Erodible Rock 8 8
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Hydraulic Loading: Pier Scour Decay Function • HEC-18: Pier Scour in Erodible Rock 9 9
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Amplification and Decay Function • HEC-18 Section 7. 13, Eq. (7. 40) Amplification 9 8 7 6 5 4 3 P=8. 42 Pa Pa 2 1 Erosion Force 8. 42 Pa 0 0 0. 2 0. 4 ys=2 b y y 2. 0 Pa Decay 0. 6 0. 8 1 1. 2 HEC-18: Pier Scour in Erodible Rock 10 10
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Pier Scour in Erodible Rock • HEC-18 Section 7. 13 Load Resistance Step 1: K Step 4: Pa Step 2: Pc Step 5: P Amplification & Decay Function ys HEC-18: Pier Scour in Erodible Rock 11 11
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Abutment Scour in Erodible Rock • Interim Guidance Resistance Step 1: K Step 4: Po Step 2: Pc Step 5: P New Amplification & Decay Function ys Abutment Scour in Erodible Rock 12
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Development of Abutment Scour Decay Function Stream power P 9 8 7 6 5 4 3 2 1 0 0 0. 2 0. 4 0. 6 0. 8 1 1. 2 Abutment Scour in Erodible Rock 13
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Development of Abutment Scour Decay Function Bridge Opening W 2 Abutment y 0 P 0<= Pc Pabut=Pc 1 Note: Pc 1>Pc 2>Pc 3 ys_abut 1 Abutment Scour in Erodible Rock 14
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Development of Abutment Scour Decay Function Bridge Opening W 2 Abutment y 0 P 0<= Pc Pabut=Pc 2 Note: Pc 1>Pc 2>Pc 3 ys_abut 2 Abutment Scour in Erodible Rock 15
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Development of Abutment Scour Decay Function Bridge Opening W 2 Abutment y 0 P 0<= Pc ys_abut 3 Pabut=Pc 3 Note: Pc 1>Pc 2>Pc 3 Abutment Scour in Erodible Rock 16
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Full Scale CFD Modeling 50% of channel width Flow 131 ft 62. 5 ft 66 ft 197 ft Abutment Scour in Erodible Rock 17
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Full Scale CFD Modeling – Test Matrix Case Upstream width W 1 (ft) Upstream flow depth y 1 (ft) Upstream velocity V 1 (ft/s) Critical Stream Power Pc (lb/ft. s) 1 62. 5 5. 41 1. 80 0. 20 2 62. 5 5. 41 1. 80 0. 32 3 62. 5 5. 41 1. 80 0. 59 4 62. 5 5. 41 1. 80 0. 91 5 62. 5 5. 41 1. 80 1. 26 Abutment Scour in Erodible Rock 18
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Full Scale Abutment Scour Simulation Case 1 : Critical Stream Power Pc 1 = 0. 20 lb/ft. s Maximum scour depth Abutment Scour in Erodible Rock 19
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Full Scale Abutment Scour Simulation Case 1 : Critical Stream Power Pc 1 = 0. 20 lb/ft. s Maximum scour depth ys 1 = 7. 0 ft Flow Abutment Scour in Erodible Rock 20
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Full Scale Abutment Scour Simulation Case 2 : Pc 2 = 0. 32 lb/ft. s Case 4 : Pc 4 = 0. 63 lb/ft. s Case 3 : Pc 3 = 0. 47 lb/ft. s Case 5 : Pc 5 = 0. 79 Abutment Scourlb/ft. s in Erodible Rock 21
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Full Scale Abutment Scour Simulation Case 2 : ys 2 = 6. 6 ft Case 4 : ys 4 = 4. 1 ft Case 3 : ys 3 = 5. 1 ft Case 5 : ys 5 = 3. 4 ft Abutment Scour in Erodible Rock 22
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Preliminary Abutment Scour Decay Function 8 7 6 5 CFD Results 4 Curve-Fitting 3 2 1 0 1. 5 1. 7 1. 9 2. 1 2. 3 2. 5 2. 7 2. 9 Abutment Scour in Erodible Rock 23
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Next Step • More cases will be computed to further verify and/or modify the decay function for abutment scour – Contraction ratio Case 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 W 2 (ft) 56. 25 50 50 50 43. 75 37. 5 31. 25 W 1 (ft) 62. 5 62. 5 62. 5 y 1 (ft) 5. 41 5. 41 5. 41 V 1 (ft/s) Pc (lb/ft. s) 1. 80 0. 20 1. 80 0. 32 1. 80 0. 59 1. 80 0. 91 1. 80 1. 26 Next Step 24
TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Thank you! 25
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