352
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Table 6. Results of the statistical tests -
s
max
I
II
III
IV
I
+
-
+
+
II
-
+
+
+
III
+
+
+
IV
+
+
+
Table 7. Results of the statistical tests
–
ratio
s
min
/
s
max
I
II
III
IV
I
+
-
-
-
II
-
+
+
+
III
-
+
+
IV
-
+
+
4 DISCUSSION, CONCLUSIONS
4.1
The statistical features of the data bases
The ratio of the minimum and the maximum dry density is
statistically constant for sands since the coefficient of the
variation is very small. The coefficient of variation of the
e
ratio is equal to 0.061 for the calibration chamber sands; 0.060,
0.082 and 0,125 for the Groups sands I and III to IV,
respectively. The coefficient of variation of the
s
ratio is equal
to 0.024 for the calibration chamber sands; 0.0116, 0.025 and
0,044 for the Groups sands I and III to IV, respectively.
This result implies linear correlations between the minimum
and the maximum dry density data. The Pearson coefficient of
correlation at the
s
min
–
s
max
and
e
min
- e
max
was equal to 0.99,
0,99 for the Danube sands I indicating that both the
s
min
–
s
max
and
e
min
- e
max
relations are linear. The Pearson coefficient of
correlation at the
s
min
–
s
max
and
e
min
- e
max
was equal to 0.84,
0.85; 0.89 and 0.88 and; 0,64, 0,65; respectively for Groups II,
III and IV
–
being smaller, still indicating linear correlation.
The smallest coefficient of variation values (and, the largest
correlation values) of Group I sand data (produced by using the
Proctor mold for maximum void ratio) can be attributed to the
facts that the quality of testing on was good and the tested soils
were homogeneous (having continuous distribution only).
4.2
The information concerning the dry density ratio
The results of the statistical tests indicate that the ratio
s
min
/
s
max
is about equal about to 0.76 for Group I where the Proctor mold
is used for the minimum dry density test and the ratio
s
min
/
s
max
is about equal about to 0.62 for the remainder Groups where a
different mold is used (i.e. the two newly tests sand databases
–
being tested with the German Standard
–
and the Calibration
Chamber sands).
The result of the statistical tests (Tables 5 to 7)
–
show that
the minimum dry density data are significantly different for
Group I and the remainder groups but the maximum dry density
results are similar.
The significant difference in the minimum dry density
testing methods can be attributed to the fact that the molds have
different sizes (Fig 1). This point needs some further (e.g.
micromechanical) research.
4.3
The dependence of the dry denisty on the diameter
In accordance to the expectations, the measured
s
min
and
s
max
values slightly increase with the maximum grain diameter
d
max
in the tested sand databases (Figs 5 to 6).
However, an increasing bias with grain diameter - possibly
due to arching
–
is found in the minimum density results. As it
can be seen on Figure 2, the density increase is not possible to
be reproduced by the DIN 18126 for fractions being larger than
0,5 mm, instead of this, even a decrease is experienced.
4.4
Conclusions
The different dimension of the mold of the various minimum
dry density tests has some impact on the test results as follows.
The smaller width and same height may cause some kind of
arching which leads to smaller minimum dry density values and,
this effect is the function of the grain diameter.
As a by-product of the research, an additional comment can
be made. The result of the statistical analysis indicates that the
equivalence of the Modified Proctor procedure and the
Vibrating Table procedure (Poulos and Hed, 1974) can be
extended to the DIN maximum dry density testing method.
Some further research is suggested, including the separation
of the continuous and gap-graded mixtures and, on the
investigation of the micromechanical features of the minimum
dry density test.
5 ACKNOWLEDGEMENTS
The suggestion Tom Lunne, the help of Tóth Ádám és Tóth
Szabina, the support of the National Research Fund Jedlik
Ányos NKFP B1 2006 08 and the Norwegian research fund
HU-0121 are greatly acknowledged.
6 REFERENCES
Imre, E; Lőrincz, J; Trang, Q.P; Fityus, S. Pusztai, J; Telekes, G;
Schanz, T. (2009) Some dry density transfer function for sands.
Invited paper. KSCE Journal of Civil Engineering 13(4):257-272.
DOI 10.1007/s12205-009-0257-7
Imre E, Fityus S, Keszeyné E, Schanz T (2011) A Comment on the
Ratio of the Maximum and Minimum Dry Density for Sands.
Geotechnical Engineering 42(4) pp. 77-82.
Imre E, Gerendai, E; Lins, Y; Schanz T (2012) A Comment on the dry
density standards. Geotechnical Testing (submitted).
Szalkai, R. (2012) The result of the minimum
–
maximum dry density
test on 182 soil samples. Student research project (manuscript).
Lőrincz, J (1986). Grading entropy of soils Doctoral Thesis, Technical
Sciences, TU of Budapest.
Kabai, I. (1968). The compactibility of sands and sandy gravels. Acta
Technica Acad. Sci. Hung., 113-124.
Kabai, I. (1972). Relationship between the grading curve and the
compactibility. University doctoral thesis TU of Budapest, Hungary
(in Hungarian).
Kabai, I. (1974). The effect of grading on the compactibility of coarse
grained soils. Periodica Polytechnica.18 (4) 255-275.
Leussink, L.H. and Kutzner, Ch (1962) Laboratoriumversuch zur
Ferstellung der dichtesten Lagerung korniger Erdstoffe. Verüöff.
Des Inst. F. Bodenmech. Techn. Hochschule Frid. In Karlsruhe.
Lunne, T; Robertson, P.K.; Powell, J.J.M. (1992). Cone Penetration
testing. Blackie Academic & Professional.
Mayne P.W. and Kulhawy F. H. (1992). Calibration Chamber database
and boundary effects corrections for CPT data. Proc. On
Calibration Chamber Testing, New York, 1991, 257-54, Elsevier.
Rétháti, L. (1988). Probabilistic solutions in geotechnics Elsevier,
Akadémiai K. Amsterdam.
Poulos, S.J., Hed, A (1973) Density Measurements in a Hydraulic Fill.
Evaluation of Relative Density and its Role in Geotechnical
Projects Involving Cohesionless Soils. ASTM STP523. p 402-424.
