EROSION TECHNOLOGY for SITES EROSION TECHNOLOGY for SITES
Earth Spillway Integrity AnalysisEarth Spillway Integrity Analysis Phase 2: Inputs and Equations Phase 2: Inputs and Equations
EROSION TECHNOLOGY for SITES EROSION TECHNOLOGY for SITES
Earth Spillway Integrity AnalysisEarth Spillway Integrity Analysis Phase 2: Inputs and Equations Phase 2: Inputs and Equations
EROSION MEASUREMENT TRAINING:Maricopa County, AZ October 2011
3 PHASE Spillway Erosion Model
1. SURFACE EROSION (Cover Destruction)
3. HEADCUT ADVANCE
2. CONCENTRATED FLOW EROSION
SPILLWAY EROSION PHASESSPILLWAY EROSION PHASES
1. 1. SURFACE EROSION SURFACE EROSION (Cover Destruction)
2. CONCENTRATED FLOW EROSION 2. CONCENTRATED FLOW EROSION (Headcut Formation)(Headcut Formation)
3. HEADCUT ADVANCE3. HEADCUT ADVANCE
PHASE 2CONCENTRATED FLOW EROSION
PHASE 2PHASE 2Concentrated Flow Surface DetachmentConcentrated Flow Surface Detachment.
rr = k = kdd ( (ee - - cc))
ee = = (d+(d+d)Sd)S
Stress equation applies when eroded depth (d) is less than approach critical flow depth (phase 2).
kkd d = coefficient of detachment (material property)= coefficient of detachment (material property)
cc = critical tractive stress (material property) = critical tractive stress (material property)
SURFACE DETACHMENT
te, (Pa)
0.0 0.2 0.4 0.6 0.8 1.0 1.2
e r, (g
/cm
2 )/s
0
2
4
6
8
10
tc
kd
c e
r
10-1 100 101 102 103 10410-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
10 Clopper and Chen(1988)
9 Chen and Anderson(1987)
8 Shaikh et al.(1987)
7 McWhorter et al.(1968)
6 Hanson(1990)
5 Elliot et al.(1989)
4 Grissinger et al.(1981)
3 Arulanandan et al.(1980)
2 Fuduka & Lick(1980)
1 Partheniades(1965)
e, (N/m2)
r, (g
/cm
2 /s)
1
2
109
8
76
54
3
DETACHMENT RATE COEFFICIENTDETACHMENT RATE COEFFICIENT
The detachment rate coefficient may be externally determined and entered directly in SITES or estimated by SITES from soil properties.
Kd Versus Percent Clayfor Range of dry density values
0.01
0.1
1
10
0 20 40 60 80 100
Percent 2 Microns
Kd
Com
pute
d
d = 120 pcf
d = 100 pcf
d = 110 pcf
d = 90 pcf
d = 130 pcf
Summary of Factors to compute KdSummary of Factors to compute Kd
Dry Density, Dry Density, dd
Percent finer than 2Percent finer than 2 (% clay) (% clay) Practical range is from 0.01 to 10Practical range is from 0.01 to 10 Number is inversely related to resistance to Number is inversely related to resistance to
erosion – low value is high resistance, high erosion – low value is high resistance, high value is low resistancevalue is low resistance
Note units are in ft/hr of downward erosion per Note units are in ft/hr of downward erosion per unit applied stress of lb/ftunit applied stress of lb/ft22
Jet Erosion Test (JET)Jet Erosion Test (JET)
Jet Erosion Test in NY Spillway
CRITICAL STRESS CRITICAL STRESS for for
DetachmentDetachment
Critical stress based on loose particle condition for all materials.
Parameters Impacting Phase 2 ErosionParameters Impacting Phase 2 Erosion
SPILLWAY EROSION PHASESSPILLWAY EROSION PHASES
1. 1. SURFACE EROSION SURFACE EROSION (Cover Destruction)
2. CONCENTRATED FLOW EROSION2. CONCENTRATED FLOW EROSION
3. HEADCUT ADVANCE3. HEADCUT ADVANCE
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