Actes du colloque - Volume 2 - page 841

1724
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
(where
D
is the diameter of the tunnel). The effective counter
pressure that can be developed over the height of the face may
therefore be insufficient at the bottom of the face, and excessive
at the top. This is confirmed by a discharge of foam onto the
surface at two points along the route of the tunnel on the
Gruzinskii Street line.
Table 1. Shallow service tunnels in Moscow, settlements due to its
construction were used for method of surface settlements predictions.
Project
Geologic-
engineeringconditions
V
L
,
%
H
,
m
D
,
m
χ
=
H
/
D
Storm drain
collector
for
Gruzinskii
Street line.
Station No.
1
0.5 m of fill sands; up to
12 m sands ranging from
silty to coarse, loose
sands of medium
density, and saturated
sands; groundwater table
at 2-4 m
2.6 4.0
4
1
Storm-drain
collector on
Gruzinskii
Street line.
Station No.
4
0.5 m of fill sands; up to
12 m sands ranging from
silty to coarse, loose
sands of medium
fineness, and saturated
sands; groundwater table
at 2 m
4.3 4.5
4
1.13
Collector at
Il'inskaya
substation.
Section 1
2 m of medium-fine sand
with construction debris;
1 m of sand of medium
fineness; up to 8 m of
silty, semi-hard, medium
density, moist and
saturated clay;
groundwater table at 3 m
5
5.4 3.2 1.69
Novobratts
evo-
Voikovskay
a collector.
Section
between
chamber
Nos. 5-7
3 m of fill sands; 2 m of
highly plastic clays; then
fine sands; groundwater
table at 1.5-4 m
1.1 6.0 3.5 1.71
Collector
from
Ugresha
substation.
Section No.
4
0.5 m of fill, and sand to
lowest bed of formation
in region analyzed; up to
12 m of alluvial and
fluvioglacial sands of
medium fineness, coarse
and gravelly sands,
moist and saturated
sands, silty and fine
sands, and moist sands
of medium density;
groundwater table at 3 m
5
5.5 3.2 1.72
Collector
from
Ugresha
substation.
Section No.
3
1.30 m of fill, and sand
to lowest bed of
formation of region ana-
lyzed; up to 10 m
alluvial and fluvioglacial
sands of medium
fineness, coarse and
gravelly sands, moist
and saturated sands, silty
and fine sands, and moist
sands of medium
fineness; groundwater
table at 3 m
5
5.8 3.2 1.80
Collector
from
Ugresha
substation.
Section No.
2
2.5 m of fill, and sand to
lowest bed of region
analyzed; up to 10 m of
modern alluvial, fine
clayey and silty,
saturated sands of
medium density;
groundwater table at 3 m
5
6.1 3.2 1.90
Project
Geologic-
engineeringconditions
V
L
,
%
H
,
m
D
,
m
χ
=
H
/
D
Collector at
Il'inskaya
substation.
Section 3
2 m of sand of medium
fineness with
construction debris; 3.8
m of silty, semi-hard
clay; up to 8 m of moist
and saturated sand of
medium fineness and
medium density;
groundwater table at 2.5
m
5
7.4 3.2 2.31
Collector
from
Ugresha
substation.
Section No.
5
4.60 m of fill, 0.7 m of
peat, and sand to lowest
bed of formation in
region analyzed; up to
10 m of alluvial and
fluvioglacial sands,
coarse and gravelly
sands, moist and
saturated sands, silty and
fine sands, and moist
sands of medium
fineness; groundwater
table at 3 m
5
7.4 3.2 2.31
Novobratse
vo-
Voikovskay
a collector.
Section
between
chambers
No. 10-13
1.5-2 m of fill sands; 3-4
m of sands of medium
fineness; water table at
4-5 m
2.2
7
3
2.33
Collector
from
Zolotarev-
skaya
substation.
Section 5
6.3 m of fill layer
composed of sandy-
loam/clayey-loam soils;
1.4 m of silty, highly
plastic clayey loam; up
to 4.6 m fine sand of
medium density;
groundwater table at 3 m
3
8.1 3.2 2.53
Collector
from
Zolotarev-
skaya
substation.
Section 1
1.5 m of fill layer
composed of sandy-
loam/clayey-loam soils;
1.5 m of silty, slightly
plastic clayey loam; 4 m
of sandy, highly plastic
clayey loam;
groundwater table at 3-4
m
2
5.4 3.2 1.68
According to experimental data acquired during construction
of the utility tunnels, the coefficients
V
L
decrease with
increasing
H
/
D
. If the sheet piling passes close to the fill layer,
or proceeds into it,
V
L
increases. For the hydrogeologic
conditions, the lower the groundwater table (GWT), the lower
V
L
.
In developing a method for settlement prediction,
approximations were obtained for ground-surface settlements on
five projects. The confidence coefficient of the approximation
R
2
= 0.92-0.99. The coefficients before the parameters in the
formulas were established for each section [1]. Based on the
correction factors of the approximations, their dependencies on
the relative depth of embedment in the form of a second-degree
polynomial are obtained by the method of least squares:
2
1
353 0
147 1 525 1


 
,
,
,
) (C
;
2
2
212 0
871 0 231


 
,
,
,
) (C
(1)
Using the correction factors, we developed a method for
prediction of surface deformations during the construction of
shallow utility tunnels, which is represented by the following
formula for ground-surface settlements
2
2
2
2
1
x
l
x) (C
max v
v
e
S) (C)x(S

  
(2)
1...,831,832,833,834,835,836,837,838,839,840 842,843,844,845,846,847,848,849,850,851,...913