Hydraulic Structures: Fourth Edition

Table 15.3 Values of

K

D
in Hudson’s formula (SPM): no damage and minor overtopping

Armour unit

Number of units

Structure trunk

Structure head

Slope

in cover layer

Breaking wave

Non-breaking

■

Breaking wave

Non-breaking

wave

wave

Smooth quarrystone

2

1.2

2.4

1.1

1.9

1.5–3.0

Smooth quarrystone



3

1.6

3.2

1.4

2.3

1.5–3.0

1.9

3.2

1.5

Rough angular quarrystone

2

2.0

4.0

1.6

2.8

2.0

1.3

2.3

3.0

Rough angular quarrystone



3

2.2

4.5

2.1

4.2

1.5–3.0

8.3

9.0

1.5

Tribar

2

9.0

10.0

7.8

8.5

2.0

6.0

6.5

3.0

Dolos

2

15.8

31.8

8.0

16.0

2.0

7.0

14.0

3.0

5.0

6.0

1.5

Tetrapod

2

7.0

8.0

4.5

5.5

2.0

3.5

4.0

3.0