Some additional parameters for breach flow (HMBreach) has to be specified, when using this model
3.5 Parameters for the advanced check on breaching (HMBreach)
3.5.1 Initial conditions of upper layer
Name in English | Name in Dutch | Description | Symbol | Unit | Default decimals + (range) |
---|---|---|---|---|---|
Froude number | Froude getal |
|
| – | 2 Fixed value |
Concentration | Concentratie |
|
| % | 12 Fixed value |
Minimal initialization height | Minimale initiele hoogte |
|
| m | 0.1 (0.1-5.0) |
Maximal initialization height | Maximale initiele hoogte |
|
| m | 2.5 (0.1-5.0) |
Interval | Interval |
|
| m | 0.01 (0.1-1.0) |
3.5.2 Layer discretization
Name in English | Name in Dutch | Description | Symbol | Unit | Default decimals + (range) |
---|---|---|---|---|---|
Maximum thickness highest layer | Maximale dikte bovenste laag | For the calculation, the soil profile is divided into sub-layers. This is the maximum thickness of the highest layer of the soil profile. |
| m | 0.05 (0.01-1) |
Maximum thickness lowest layer | Maximale dikte onderste lag | For the calculation, the soil profile is divided into sub-layers. This is the maximum thickness of the lowest layer of the soil profile. |
| m | 0.5 (0.01-1)
|
3.5.3 Approval criterion
Name in English | Name in Dutch | Description | Symbol | Unit | Default + decimals + (range) |
---|---|---|---|---|---|
Ratio sand transport | Verhouding Zandtransport | Ratio between the sand transport at the toe and the sand transport at the top of a sand cluster, indicating if the considered initialization height is sufficient to produce a breach flow slide, characterized by a strongly increasing sand transport rate along the slope. The minimal initialization height for which this is the case is defined as the critical height. | RatioZV | - | 10 (2-100) |
Allowable critical height | Toelaatbare kritische beginhoogte | If the critical initialization height is higher than the allowable critical height, the slope is safe. If not, it means that the probability that a breach flow slide will occur is high. | hallowable | m | 1.0 |
3.5.4 Physical constants
Symbol | Description | Unit | Default + decimals + (range) |
---|---|---|---|
a_1_n0 | Constant erosion formula | – | 1.0 Fixed value |
Aeros | Constant erosion formula | – | 0.012 Fixed value |
Beros | Constant in erosion formula | – | 1.3 Fixed value |
dn | Porosity increase during dilatancy. | – | 0.04 Fixed value |
f0 | Darcy-Weisbach bed friction coefficient. | – | 0.1 Fixed value |
fki | Ratio of bed to internal friction. | – | 0.333 Fixed value |
i | Hydraulic gradient. Default is 0. | – | 0 Fixed value |
rk3 | Constant in entrainment model. | – | 0.0015 Fixed value |
temp | Water temperature. Defines viscosity, fall velocity and permeability | ºC | 15.0 (0.0-30.0) |