1366
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Figure 1. Moisture variety in soil basement of the highway “Astana-
Burabai”, road section with cement concrete pavement
(2010-2011)
Figure 2. Moisture variety in soil basement of the highway “Astana-
Burabai”, road section with cement concrete pavement
(2010-2011
)
Moisture increase in the depths of 115 cm and 150 cm
occurs in summer and autumn seasons of the year (17-22 %)
compared with spring (10-13 %). Moisture reduces to 6-9 % in
winter season.
Moisture has not been reduced evidently in the depths of
185 cm and 220 cm in winter season. It can be explained by the
fact that in the depths, mentioned above, negative temperature
has small values. Moisture value was 15-16% in the depth of
220 cm in autumn 2010, moisture increase up to 20-21%
occurred in spring 2011, which in future was practically
constant. Moisture was of similar character of variety in the
depth of 185 cm: moisture was 6-7% in autumn 2010; it was
increased to 12% in spring 2011, and was practically constant in
summer and autumn 2011. One can see from Figure 2, that the
difference in moisture values of soil in the depth of 185 cm and
220 cm (8-10 %) during overall annual cycle is practically
constant. Meanwhile, moisture in the depth of 220 cm is larger
than in the depth of 185 cm, which can be explained by close
location of the depth in 220 cm to underground waters.
Qualitative and quantitative analysis, carried out above,
for moisture variety in points, located in different depths, has
shown complicated character and non-homogeneous of moisture
distribution in soil basement of the highway. In such cases it is
convenient to use averaged moisture indices. Therefore, Figure
3 represents diagram, showing average moisture variety for soil
basement of the highway. It reflects the following important
peculiarities for moisture variety of soil basement according to
its depth and time:
- it represents average value of liquid moisture at any
reviewed time moment;
- moisture decrease occurs on winter season due to transfer
of liquid moisture into solid condition (ice) with negative
temperatures;
- initial moisture, observed in autumn 2010,with coming
spring in 2011 has gradually been increased and further (in
summer and autumn) remains practically constant.
4
6
8
10
12
14
16
18
20
22
24
01.10.2010
31.10.2010
30.11.2010
30.12.2010
29.01.2011
28.02.2011
30.03.2011
29.04.2011
29.05.2011
28.06.2011
28.07.2011
27.08.2011
26.09.2011
26.10.2011
25.11.2011
Months
Moisture, %
- 80 сm;
- 115 сm;
- 150 сm
0
2
4
6
8
10
12
14
16
18
20
01.10.2010
31.10.2010
30.11.2010
30.12.2010
29.01.2011
28.02.2011
30.03.2011
29.04.2011
29.05.2011
28.06.2011
28.07.2011
27.08.2011
26.09.2011
26.10.2011
25.11.2011
Date
Moisture,%
Figure 3. Average moisture variety in soil basement of the highway
“Astana-Burabai”, road section with cement concrete pavement
(2010-2011)
4
6
8
10
12
14
16
18
20
22
24
01.10.2010
31.10.2010
30.11.2010
30.12.2010
29.01.2011
28.02.2011
30.03.2011
29.04.2011
29.05.2011
28.06.2011
28.07.2011
27.08.2011
26.09.2011
26.10.2011
25.11.2011
Months
Moisture
- 185 сm;
- 220 сm
4. STRENGTH-DEFORMED CONDITION OF ROAD
STRUCTURE
4.1. Mechanical characteristics
Mechanical characteristics for materials of pavement layers
have been represented in the Table 2.
Table 2. Calculated values of elasticity modulus and Poisson’s
coefficient for pavement layers
Material
Thickness
h, cm
Elasticity
modulus
Е, МPa
Poisson’s
coefficient
Cement concrete
25
37500
0.2
Crushed
stone
sand mix С 6 (40)
25
200
0.3
Coarse-grained
sand
30
120
0.3
Mechanical characteristic of soil basement vary for a
year. Their calculated values (Table 3) has been determined
considering average moisture variety of soil basement (Figure
3). Meanwhile elasticity modulus value for soil in winter season
has been determined based on the results of Prof. N.A.Tsytovich
(Tsytovich 1973), and during other seasons of the year – based
on recommendations of standard provisions (SN RK 2005). Due
to the absence of reliable data, Poisson’s coefficient value for
soil has been accepted constant and equal to 0.35.
4.2. Calculated scheme and mathematical model for road
structure
Calculated scheme for road structure has been represented in the
Figure 4. This figure shows components for stress-deformed
condition of road structure, which causes its destruction
(sagging of the surface for cement concrete pavement ℓ, tensile
stress
r
and tensile deformation
r
in cement concrete
pavement, vertical compressed deformation for the surface of
soil basement
z0
).
