Aberfan, Wales, United Kingdom

Table 1. Geotechnical properties of colliery waste at Aberfan (Bishop et al. 1969, Appendix 3; Bishop, 1973, table 3).

Property

Average

Range

Tailings

D50

1.8 mm

D10

0.7 mm

% < 2 μm

Liquid limit

26.5 %

Plastic limit

19 %

Plasticity index

7.5 %

Water content (% dry wt.)

24 %

23 - 25.5 %

Bulk unit weight – wet  (lb/ft³)

111.1

95 - 129

Bulk unit weight – dry  (lb/ft³)

105.6

93 - 121

Φp’       Johnson gives 39.5

32.8^o

31.5 – 33.5^o

Permeability (cm/sec)   Johnson p. 22 gives 6.6x 10^-3

1.9x10^-5

0.5 – 4.5x10^-5

Shear plane

% < 2 μm

Liquid limit

31.0 %

Plastic limit

15.0 %

Plasticity index

16.0 %

Water content

12.7 %

9 – 16 %

Bulk unit weight – wet  (lb/ft³)

119.6

110 - 128

Bulk unit weight – dry  (lb/ft³)

111

Φ’ (taken to be  Φr’ for the bulk tailings)

18.0^o

17.5 – 18.5^o

Permeability (cm/sec)

1.82x10^-9