1367
Technical Committee 202 /
Comité technique 202
Table 3. Calculated values of elasticity modulus for soil – light
pulverescent clay loam
Calculated date
Average
moisture
W, %
Average
temperature,
0
С
Elasticity
modulus
Е, МPa
19.11.2010
13.9
7.0
90
24.01.2011
9.5
-4.6
6500
26.02.2011
9.4
-5.2
7200
14.04.2011
13.7
-0.4
500
16.06.2011
16.3
12.3
58
29.09.2011
16.9
14.7
51
Note: Only content of unfrozen moisture has been shown in
winter season
Figure 4. Calculated scheme of road structure
Mathematical model of multi-layer elastic half-space
under influence of axle-symmetric load has been used to
calculate the above components for stress-deformed condition
of road structure (Privarnikov 1973). Load q = 0.6 МPa within
circle with diameter of D = 42 cm influenced over the surface of
concrete pavement. Such load corresponds to axle load of the
truck Q = 13 tons.
4.3. Stress-deformed condition
The results of calculation of indices for stress-deformed
condition of the road structure have been represented in the
Figures 5 and 6. Analysis of the obtained dependencies has
shown that sagging of the surface for cement concrete
pavement, tensile stress and vertical deformation on the surface
of soil basement have qualitatively similar character of variety
in annual cycle. Thus, their least values have been determined in
winter months (January, February), when upper part of soil
basement is in the most frozen condition (average temperature
in January and February is -4.6
0
С and -5.2
0
С respectively), due
to this fact soil basement has the increased rigidity (ranging
from 6500 MPa to 7200 MPa). With coming of warm season
the rigidity of soil basement reduces, which results in the value
increase of the above indices for stress-deformed condition
(SDC) of pavement. Their biggest values were obtained during
the period from June to September. Their values, obtained in the
month of November, proved to be comparable with those ones
obtained during the period from June to September. Therefore,
the reviewed case shows that sagging of cement concrete
pavement and vertical deformation of the surface for soil
basement, during long period in annual cycle – from June to
November – preserves the biggest values, which are higher in
6.0-6.5 times, compared with winter season.
0
20
40
60
80
100
120
140
160
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
▲ -
r
10
-6
; ● -
z0
10
-6
Figure 5. Tensile deformation (
r
) in cement concrete pavement and
compression deformation (
z0
) on the surface of soil basement
● - ℓ, мм; ▲ -
r
, МPа
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
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
Figure 6. Sagging (ℓ) and tensile stress (
r
) in cement concrete
pavement
It should be mentioned that tensile stress value varies
little in annual cycle. Thus, tensile stress value (1.6 MPa at
average), occurring during overall summer-autumn seasons, is
bigger only for 19 % of its least value, occurring in winter
season (1.3 MPa at average). It can be explained by the fact that
with big rigidity of cement concrete slab (Е=37 500 MPa),
which is bigger than rigidity of soil basement in 735 times in
autumn season (Е=51 MPa), rigidity increase in winter in 141
times (up to 7200 MPa) has not greatly influenced over tensile
stress value.
Character of tensile deformation variety in cement
concrete pavement differs substantially from the indices
analyzed above. Tensile deformation value varies little in
annual cycle (2.9 – 3.5
10
-5
), which also can be explained by big
rigidity of cement concrete slab.
It should be mentioned that cement concrete slab has
been calculated for sagging of pavement in spring, and sagging
increase in summer and autumn seasons can be the cause of
destruction of cement concrete slabs in the form of longitudinal,
transversal and oblique cracks (Figures 7-9).
5. CONCLUSIONS
The results of experimental investigation for moisture variety of
soil basement and calculations for indices of stress-deformed
condition for road structure, obtained the work, allow making
the conclusions as follows:
1. Moisture value and its phase content in soil basement
of the highway vary substantially in annual cycle and according
to the depth of basement.
2. Qualitative character of variety for sagging, tensile
stress in cement concrete pavement and vertical compressed
deformation of the surface for soil basement in annual cycle
