The hydrogeological conditions for the construction of the subway in St. Petersburg are complex. To avoid water flow in the tunnel, it is necessary to calculate the height of water conducting fractures zone for massif. The article considers the geological structure of the soil in St. Petersburg, the value of the boundary curvature for the massif is calculated. The thickness of the sediments with disturbed water resistance was determined, and the dangerous sections of the tunnel under construction in the Nevsko- Vasileostrovskaya line are indicated.

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International Journal of Civil Engineering and Technology (IJCIET)
Volume 10, Issue 02, February 2019, pp. 635-643, Article ID: IJCIET_10_02_061
Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=10&IType=02
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication Scopus Indexed
ASSESSMENT OF DEVELOPMENT OF WATER
CONDUCTING FRACTURES ZONE IN THE
MASSIF OVER CROWN OF ARCH OF
TUNNELING (CONSTRUCTION)
Gusev V. N., Maliukhina E.M. & Volokhov E.M.
Saint Petersburg Mining University, Saint Petersburg (ex Leningrad), Russian Federation
Tyulenev M. A.
T.F Gorbachev kuzbass state technical university, kemerova,Russian federation
Gubin M. Y.
Open Joint Stock Company Scientific, Research, Design And Surveying Institute
«Lenmetrogiprotrans» Saint Petersburg (ex Leningrad), Russian Federation
ABSTRACT
The hydrogeological conditions for the construction of the subway in St. Petersburg
are complex. To avoid water flow in the tunnel, it is necessary to calculate the height
of water conducting fractures zone for massif. The article considers the geological
structure of the soil in St. Petersburg, the value of the boundary curvature for the massif
is calculated. The thickness of the sediments with disturbed water resistance was
determined, and the dangerous sections of the tunnel under construction in the Nevsko-
Vasileostrovskaya line are indicated.
KEY WORDS: water conducting fractures zone, boundary curvature, metro
tunneling
Cite this Article: Gusev V. N, Maliukhina E.M, Volokhov E.M, Tyulenev M. A and
Gubin M. Y, Assessment of Development of Water Conducting Fractures Zone in the
Massif Over Crown of Arch of Tunneling (Construction), International Journal of Civil
Engineering and Technology, 10(02), 2019, pp. 635–643
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=02
1. INTRODUCTION
The construction of the subway tunnels in St. Petersburg is provided with heavy mining and
geological conditions: deposit inundationut, natural water objects (rivers and canals). For
example, a double-tracked tunnel under construction of the Nevsko-Vasileostrovskaya line

2. Gusev V. N, Maliukhina E.M, Volokhov E.M, Tyulenev M. A and Gubin M. Y
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passes beneath the bottom of the Neva River connecting the Primorskaya and
Novoskresovskaya metro stations. The opening of Novokrestovskaya metro station confined
to Football World Cup in 2018.
When tunneling, due to shifts and deformations in the massif above the tunnel sheath, a
zone of water conducting fractures zone (WCFZ) of technogenic origin is formed.
Investigations of the mechanism of formation of WCFZ show that the height of the propagation
of this zone over the mine workings, in this case above the tunnel, depends on the level of
deformations achieved in the layers of the massif, the content of rocks of the clayey
composition in the thickness under processing and the thickness of the deposits [1, 2]. Since
the tunnel passed through the sediments, in analyzing the geological situation, attention was
paid to the thickness of the sediments and the presence of rocks of clayey composition (sandy
loams, loams) and the level of deformations achieved by the reference points of the profile
lines of the surface observation station that were beyond located along and across the axis of
the tunnel.
2. GEOLOGICAL STRUCTURE OF THE SOILS OF ST. PETERSBURG
The tunnel was carried out in sediments, the lithology of which is typical for the conditions of
St. Petersburg. Along the route of the tunnel in the area where the observation station was laid,
the structure of sediments, in the direction from the surface to the tunnel, according to
geological data, is composed of the following lithological types of rocks (Fig. 1).
The soils are soapy (sand, sandy loam, loam) and bulk, there is no data on the angle of
internal friction.
Medium sand, brown and grayish-brown, medium-density, with interlayers of sandy loam,
saturated with water, angle of internal friction φ = 37º.
Silty sands, gray, medium-dense, with interlayers of sandy loam, with an admixture of
organic substances, saturated with water, φ = 26º.
Medium sand e, brownish-gray, medium-density, with interlayers of sandy loam, with a
rare gravel, saturated with water, φ = 37º.
Sandy loams are silty, gray, layered, with an admixture of organic substances, with sand
interlayers, loam, plastic and fluid, φ = 21º.
Sandy loamy are silty and sandy, gray, layered, with nests of sand, with rare gravel, pebbles,
plastic and flowing, φ = 19º.
Light loams, silty, gray, layered, with an admixture of organic substances, with interlayers
of sandy loam and sand, fluid and fluid-plastic, φ = 13º.
Loams are heavy silty and clays are lightly silty, grayish-brown and brown, banded, with
interbeds of sands, fluid and fluid-plastic φ = 10º.
Loams are heavy and light silty, gray, layered, with interlayers of sand, sandy loam, soft-
plastic and turgid, φ = 19º.
Light loams, sandy and silty, gray, with gravel and pebbles up to 20-25%, boulders, soft-
plastics (those that are sandy) and tu-hopplastic (those that are silty) φ = 22º.
Sandy loams sandy and silty, gray, less brownish-gray, with gravel and pebbles up to 20-
25%, boulders, plastic, φ = 24º.
Clay greenish-gray, dislocated, solid, φ = 21 º.
For the analysis, 5 sites were chosen along the tunnel route, characterizing the variability
of sediment thickness and tunneling conditions relative to the water body of the river. Neva
River (Figure 1):

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1) the section below the well No. 5396, where the profile line is located (perpendicular to
the axis of the tunnel);
2) area under well No. 5394 - the beginning of the passage of the tunnel under the river.
Neva;
3) area under well No. 5091 - tunneling under the river. The Neva;
4) area under well No. 5366 - tunneling under the river. The Neva;
5) area under well No. 5367 - tunneling under the river. The Neva;
The distribution of the thickness of sediments and clays in the composition of sediments on
the specified sections of the tunnel route above its shelf is presented in Table 1.
In sections 1 and 2 of clay-bearing rocks, sandy loam and loam occur, approximately equal
in thickness, in loam No. 3, No. 4, No. 5, mainly loam occurs. According to the geological
data, sandy loam with an internal friction angle of φ = 21 ° and a suglinka with an internal
friction angle φ = 13 ° are widely spread on these sections, the description of which is presented
in the legend of lithotypes to the geological section (Fig. 1) and is presented in the text .
3. DETERMINATION OF HEIGHT OF THE WCFZ
The height of the WCFZ is the vertical distance from the roof of the tunnel (the shell of the
tunnel) to the layer with a bend equal to the value of the boundary curvature KГ. The boundary
curvature (KГ) for the conditions under consideration is defined as follows.
The boundary curvature of which the deposits can lose their waterproof properties, is
calculated as follows (1).
KГ = KГо + ΔKГ, (1)
where Kг - the boundary curvature for the conditions, 1 / m; Kгo - the boundary curvature
of the worked-in massif, taking into account the presence of a clayey composition in the
stratum, 1 / m; ΔKГ - increment of the boundary curvature, taking into account the effect of
sediment, 1 / m. In the formula (1), Kг - defined as follows [1, 2]:
KГo = 0.8eA • 10-3
, (2)
Where A - content of clay composition, fractions. For the conditions under consideration,
the content of clay rocks varies within 95-98%; therefore, it was assumed that A = 1, i.e. the
content of clay rocks is 100%.
KГo = 2.175 • 10-3
1 / m. The increment ΔKГ in the formula (1) is determined from
ΔKГ = 0.4H • 10-3
, (3)
Where H - thickness of the sediment above the tunnel sheath. The results of calculating the
boundary curvature for sections 1-5, made according to the expression (1), are given in Table.
2.

4. Gusev V. N, Maliukhina E.M, Volokhov E.M, Tyulenev M. A and Gubin M. Y
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Table 1.The thickness of sediments and clay rocks over the tunnel at various sections of the route
№
site
№ boreholes
where the
thickness of the
sediment above
the tunnel
sheath was
determined
Thickness
of
overburden
(H), m
Clay
thickness of
overburden
(hг), m
Comments
1 2 3 4 5
1. 5396 20.2 18.4
Before the tunnel under the Neva
River
2. 5394 19.0 15.4
The entrance of the tunnel entrance
to the Neva River
3. 5091 14.0 13.2 The tunnel under the Neva River
4. 5366 11.6 10.0
The tunnel under the Neva River (
the minimum of clay thickness of
overburden )
5. 5367 11.0 10.5
The tunnel under the Neva River (
the minimum thickness of
overburden )
Fig. 1. Geological section along the tunnel route

5. Assessment of Development of Water Conducting Fractures Zone in the Massif Over Crown of
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In site 1, the maximum curvature of the surface was obtained from the observations on the
profile line and amounted to K1 = 1.5 • 10-3
1 / m. In other sections, the curvature (its maximum
value) is obtained using the actual curvature K1 and the dependence of vertical shifts and
deformations on the vertical distance from the mine workings or tunnel, which is set forth in
[3]. According to this dependence for area 2, we can write
2
1
2
2
2
1
H
H
K
K
= , (4)

6. Gusev V. N, Maliukhina E.M, Volokhov E.M, Tyulenev M. A and Gubin M. Y
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Where from
2
2
2
11
2
H
HK
K
⋅
= , (5)
Where K1 - the maximum curvature, actually obtained from the profile line (Table 2); H1,
H2 - sediment thickness between the shell of the tunnel and the surface, respectively, in sections
1, 2 (Table 2); K2 is the calculated curvature in section 2 (Table 2). By analogy, for sections 3,
4, 5
2
3
2
11
3
H
HK
K
⋅
=
; (6)
2
4
2
11
4
H
HK
K
⋅
=
; (7)
2
5
2
11
5
H
HK
K
⋅
=
, (8)
where K3, K4, K5 are the calculated curvature, respectively, in sections 3, 4, 5 (Table 2);
H3, H4, H5 - sediment thickness between the shell of the tunnel and the bottom of the Neva
river, respectively, at sites 3, 4, 5 (Table 2); The actual curvature (K1) and the calculated values
of the curvature of the surface and bottom of Neva river, according to formulas (5) - (8) for
sections 2-5 are given in Table 2. It can be seen from the calculations that the lower the
thickness of the sediments, the greater the deformation of curvature. The calculated curvature
values (K2, K3, K4, K5) are obtained through the actual maximum curvature obtained from
observations along the profile line (K1).
Table 2 The results of the calculation of the boundary curvature and the height of propagation of the
WFCZ over the tunnel for different sections of the route
№
site
Thickne
ss of
overbur
den (H),
м
Boundar
y
curvatur
e (KГ),
1/m
curvature
of the
surface
and
bottom of
Neva river
(K), 1/m
Height
of
WFCZ
(НТ),
м
The remaining waterproof
part of the sediment thickness
(Δ=H-HТ),
м
Comments
absolute
value,
м
% clay
thickness of
overburden (H)
at the site
1 2 3 4 5 6 7 8
1. 20.2 10·10-3 1.5·10-3 7.7 12.5 62%
Before the tunnel
under the Neva River
2. 19.0
9.775·1
0-3 1.695·10-3
7.9 11.1 58%
The entrance of the
tunnel entrance to the
Neva River
3. 14.0
7.775·1
0-3 3.123·10-3 8.9 5.1 36%
The tunnel under the
Neva River
4. 11.6
6.815·1
0-3 4.549·10-3 9.5 2.1 18%
The tunnel under the
Neva River
5. 11.0
6.575·1
0-3 5.058·10-3
9.6 1.4 13%
The tunnel under the
Neva River

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The thickness of the sediment with the water impermeability (or the height of the WFCZ)
for site 1 is determined on the basis of the actual curvature of the profile line K1 = 1.5 • 10-3
1
/ m, the boundary curvature in this section KГ1 and the dependence of vertical shifts and
deformations on the vertical distance from the mine or a tunnel similar to (4) [3]. As a result,
you can write
2
1
2
1
1
1
H
H
K
K Т
Г
= , (9)
1
1
11
Г
Т
K
K
HH = , (10)
where - HT1 - the thickness of the sediments with the disturbed water resistance (or the
height of the WFCZ) for section 1 (Table 2); H1 - sediment thickness between the shell of the
tunnel and the surface in site 1; K1 - the maximum curvature actually obtained along the profile
line; KГ1 is the boundary curvature for the thickness of the H1 sediment (Table 2). By analogy
with (10), the predicted values of the thicknesses of the sediments with the disturbed water
impermeability (or the propagation height of the WFCZ) for sections 2, 3, 4, 5
2
2
22
Г
Т
K
K
HH = ; (11)
3
3
33
Г
Т
K
K
HH = ; (12)
4
4
44
Г
Т
K
K
HH = ; (13)
5
5
25
Г
Т
K
K
HH = ; (14)
where HT2, HT3, HT4, HT5 are the thicknesses of the sediments with the water impermeability
(or the propagation height of the WFCZ), respectively, for sections 2, 3, 4, 5 (Table 2); H2, H3,
H4, H5 - sediment thickness between the shell of the tunnel and the bottom of the Neva river,
respectively, in sections 2, 3, 4, 5; K2, K3, K4, K5 - the calculated curvature respectively on
sites 2, 3, 4, 5; KГ2, KГ3, KГ4, KГ5 - the predicted values of the boundary curvature, respectively,
in sites 2, 3, 4, 5 (Table 2).
To assess the degree of disturbance of the watertightness of the sediment thickness above
the tunnel, the value of the remainder of this power over the upper boundary of the WCFZ in
absolute (Δi) and relative (δi in%) values was determined:
Δi = Hi - HТi; (15)
δi = (Δi / Hi)·100%, (16)
where i -the number of the site according to Table. 1 (i = 1, 2, ..., 5); Hi - thickness of
sediment between the shell of the tunnel and the bottom of Neva river in the corresponding
areas (Tables 1 and 2); HTi - the thickness of the sediments with the disturbed water resistance
(or the height of the propagation of the WFCZ) at the respective sites (Table 2).
As a result of the assessment, the minimum amount of sediment thickness not disturbed by
water-conducting fractures was found in section 5, which was Δ5 = 1.4 m (δi = 13%) with the

8. Gusev V. N, Maliukhina E.M, Volokhov E.M, Tyulenev M. A and Gubin M. Y
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total sediment thickness H5 = 11.0 m (Table 2). The maximum thickness of the sediments
undisturbed by the water-conducting cracks, due to the large total thickness of the sediments
above the tunnel sheath (H1 = 20.2 m), was found in site 1, which amounted to Δ5 = 12.5 m (δi
= 62%).
Since the sediments do not practically expand under the shift, the relative maximum settling
(q0) can be assumed to be close to unity. In this case, it was assumed that q0 = 0.95. Hence the
subsidence of the tunnel in the vicinity of the shelter (ηarch) will be
ηarch = η1/ q0 = 0.192м / 0.95 = 0.202 м, (17)
where η1 - maximum actual settling in site1, obtained from observations along the profile
line.
The resulting subsidence at the level of the sheath (ηarch) of the tunnel corresponds to the
concept of effective power (mе), i.е. technogenic void space near the tunnel, causing the surface
to settle in area 1 η1 = 0.192 m. Thus, the effective power for this mode of tunnel penetration
is me = 0.202 m.
As calculations showed, when tunneling a potentially hazardous area for water
breakthroughs is site 5. Here, the tunnel will pass at a minimum depth below the river bottom,
accordingly the sediment thickness will also be minimal, and the zone of water-conducting
fractures is maximum ( Table 2). If the upper limit of the WCFZ reaches the bottom of the
river, the bottom will experience a bend equal to the boundary curvature for this section of KГ5
(Table 2). The calculated curvature K5, obtained from the normal operation of the tunnel board,
is shown in Table. 2. To what extent should the curvature (Δk) increase so that the upper
boundary of the WCFZ reaches the bottom, which can lead to the breakthrough of water into
the tunnel, is determined as follows:
Δk = [(KГ5 − K5) / K5]·100% ≈ 30%. (18)
Calculations based on subsidence also showed an increase of 30%. Hence, the settling at
the level of the shallow of the tunnel (ηarch) or the effective power (mе) should not exceed 0.202
m • 1.3 = 0.263 m. From here the main recomendation: when passing the tunnel under the Neva
River, strictly observe the mode of penetration, which was before the entrance of the tunnel
under Neva river.
4. CONCLUSIONS
[1] The calculations showed that in all the sites considered (sites 1, 2, ..., 5), the height of the
propagation of the WFCZ does not exceed the depth of the tunneling.
[2] The most potentially dangerous area, from the point of view of the great penetration of
water, up to its breakthrough, is site 5. Here, above the tunnel, the smallest sediment
thickness (11.0 m), the highest propagation height of the WFCZ (9.6 m) and the minimum
sediment thickness , undisturbed by water-conducting fractures (1.4 m) and retained its
waterproof properties.
[3] The value of effective thickness me = 0.202 m is obtained. It is shown that when tunneling
under the river Neva it should not exceed the value of 0.263 m. Otherwise, a water
breakthrough may occur in section 5. To prevent this, it is necessary to preserve the
technological schedule and the operating mode of the shield that were before the entrance
of the tunnel under the river Neva.
LITERATURE
[4] B.Ya. Gvirtsman.1977. Safe excavation of coal under water objects , N.N. Katsnelson, E.V.
Boshenyatov, G.A.Nesterov, V.P.Samarin. Moscow: Nedra

9. Assessment of Development of Water Conducting Fractures Zone in the Massif Over Crown of
Arch of Tunneling (Construction)
http://www.iaeme.com/IJCIET/index.asp 643 editor@iaeme.com
[5] Gusev V.N. 1999.Geomechanics of technogenic water-supplying tracks / St. Petersburg.
Mining Institute. SPb
[6] Avershin C.G. 1954. Mining works under structures and reservoirs. Moscow:
Ugletekhizdat
[7] Elena Maliukhina , Vladimir Gusev.2016. “Prediction of water conducting fracture zone”
International Journal of Applied Engineering Research ISSN 0973-4562 Volume 11,
Number 11
[8] Gusev V.N., 2016 , Forecasting safe conditions for developing coal bed suites under
aquifers on the basis of geomechanics of technogenic water conducting fractures, Journal
of Mining Institute, Vol.221, p. 638-643