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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 3
W. R. L. da Silva | L. R. Prudencio Jr
|
A. L. de Oliveira
Figure 10 – Characteristic compressive strength of the concrete lining in different sections of the tunnel
Table 5 – Characteristic compressive strength of the shotcrete lining in different stretches of the tunnel
Tunnel Stretch
Section: right
f ,
ck
[MPa]
Section: left
f ,
ck
[MPa]
Section: top
f ,
ck
[MPa]
f ,
cj
[MPa]
s ,
d
[MPa]
f ,
cj
[MPa]
s ,
d
[MPa]
f ,
cj
[MPa]
s ,
d
[MPa]
1
0.0 – 100.0m
25.8
2.6
21.6
23.5
3.0
18.6
24.9
3.1
19.8
2
100.0 – 150.0m
25.9
3.6
20.0
22.0
3.6
16.1
26.3
3.4
20.6
3
150.0 – 200.0m
19.7
4.1
13.0
22.2
3.9
15.8
26.0
3.6
20.1
4
200.0 – 250.0m
18.7
2.0
15.4
23.2
3.7
17.2
23.8
1.9
20.8
5
300.0 – 350.0m
19.4
3.7
13.3
23.2
3.7
17.1
27.7
3.2
22.4
6
350.0 – 400.0m
23.4
3.7
17.3
11.8
4.9
3.7
24.7
5.1
16.3
7 400.0 – 450.0m 19.2 4.9 11.2 17.8 6.3 7.5
26.4
3.8 20.2
strength were determined in different parts of the tunnel, with the
highest values observed in the first 150.0 m of the tunnel, which is
older than the final stretch of the tunnel.
In the study of the probe penetration test variability, a coefficient of
variation of ~8.0% was obtained. Nevertheless, the variability ob-
served in loco appears to be relatively higher than this value. This
fact is mainly due to, but not limited to, factors such as a discon-
tinuity of the shotcrete thickness and the lack of homogeneity of
the shotcrete due to the lack of control of the projection technique.
Finally, it is possible to conclude that the proposed methodology
is suitable for estimating the compressive strength of the shotcrete
structures. However, when possible, a greater number of repeti-
tions of the test should be performed to account for variability and
thus achieve a better correlation of the results.
6 Acknowledgements
The authors wish to express their appreciation to the Erasmus Mundus
External Cooperation Window EMECW – EU-Brazil Startup for funding
the first author’s PhD studies at Czech Technical University in Prague.
7. References
[01] MALHOTRA, V.M., CARINO, N.J. Penetration
Resistance Methods. In: Handbook of non-destructive
testing of concrete. 2nd Ed. CRC Press (2004) 33-50.
[02] NAWY, E.G., Concrete Construction Engineering
Handbook. Nondestructive test methods. 2ndEd. CRC
Press (2008) 902-975.
[03] HOBBS, B., KEBIR, M.T. Non-destructive testing
techniques for the forensic engineering investigation
of reinforced concrete building. Forensic Science
International 167 (2007) 167-172.
[04] ZHU, W., GIBBS, J.C., BARTOS, P.J.M. Uniformity
of in-situ properties of self-compacting concrete in
full-scale structural elements. Cement and Concrete
Composites 23 (2001) 57-64.
[05] BILGIN, N., DINCER, T., COPUR, H. The performance
prediction of impact hammers from Schmidt hammer
rebound values in Istanbul metro tunnel drivages.
Tunnelling and Undergraound Space Technology 17
(2002) 237-247.