GEOTECHNICAL CIRCUMSTANCES - The Westerschelde Tunnel: Approaching Limits - page 82

ZK1 Predominantly loose SAND, alternating

with moderately solid CLAY, layered
Predominantly moderately solid SAND,
moderately fine or moderately coarse,
mildly siltish, locally with shells

2-15 0.5 -1.5

?
0.6

h/o - -

Z1 5 -15 h Rubble (pieces of basalt,

maximum

B4 (5.0-5.5), B37 (19)

ϕ 50 mm)

Rubble (pieces of brick,
maximum

B4 (29), B33 (29),
B35 (18-21)
B1 (25), B18 (20-22),
B33 (41), B39 (19)
B27 (34), B34 (34), B35 (39)

60 mm)
Small stones, concretions,
gravel, (maximum ϕ 30 mm)
Highly cemented
layers (30-70 mm thick)
Light cemented
chunks ( ϕ 10-30 mm)
Very lightly cemented little
canals in the soil, created
by organisms
Pyrite concretions (

ϕ

GZ1 Solid GLAUCONITIC SAND, moderately fine

or moderately coarse, mildly siltish

30-50 1.0 -1.5 n

In most of the drillings
(on various levels)

ϕ 10 mm) B29 (46), B32 (59)

GZ2 Solid GLAUCONITE SAND, very fine to

moderately fine, clayish to mildly siltish,
layered (layer thickness approx. 0.5-2.0 m)

10-30 1.0 n Very lightly cemented little

canals in the soil, created
by organisms

In most of the drillings
(at various levels)

Hard concretions ( ϕ 10-20 mm) In most of the drillings

(at one or some levels)

q c Cone resistance
fr. factor Friction factor
p d

Dynamic pore pressure, measured during cone penetrations (h hydrostatic, o positive pore pressures,
n negative pore pressures)

Fig. 7.9

Chart showing the geotechnical layering of
cohesionless subgrade

Chart showing the geotechnical layering of
cohesive subgrade

Fig. 7.10

Layer Geotechnical description

(in conformity with NEN 5104)

Criteria of cone
penetration tests

Matter encountered Location

(level in m-NAP)

q c
(MPa)

p d

fr. factor
(%)

K1 Soft CLAY, moderately to highly siltish,

PEAT locally
Soft CLAY, alternating with loose SAND,
mildly siltish, very layered (layer thickness
approx. 0.1 m)
Very solid BOOM CLAY, mildly to
moderately siltish

0.5 2-10 o - -

KZ1 0.5-3 1-4 o - -

BK1 4-5 4-5 o/n Hard concretions, often with

pyrite crystals (no HCI
reaction,

In most of the drillings
(at one or some levels)

10-50 mm)
Partially of septaria, with
pyrite crystals (high HCI
reaction,

ϕ

B18 (38), B19 (27)

ϕ 50-100 mm)

Chunk of rockfill, basalt
(

B40 (39; layer on top)

ϕ 60-120 mm)

BK2 Very solid BOOM CLAY, moderately to

highly siltish, with very thin sand layers
and lenses (thickness 2 mm), locally
mildly to moderately siltish (like BK1),
locally with highly siltish to clayish sand
deposits (thickness 0.2 to 1.8 m, average
approx. 0.5 m), gradual transitions

4 4-5 o/n Hard concretions, often with

pyrite crystals (no HCI
reaction, ϕ 10-50 mm)

In a number of drillings
(on various levels (BK1))

Hard concretions, looks like
petrified wood (no HCI
reaction, ϕ 50-110 mm)

B19 (50)

K2 Solid CLAY, mildly siltish to sandy - -

q c

fr. factor Cone resistance Friction factor

p d Dynamic pore pressure, measured during cone penetrations (h hydrostatic, o positive pore pressures,

n negative pore pressures)

* Layer not attained with cone penetration tests