An Empirical Approach to Estimate EPMT and PL of Silty Clays based on SPT

Akbar Cheshomi, Ehsan Bakhtiyari, Hossein Masoumi

An Empirical Approach to Estimate EPMT and PL of Silty Clays based on SPT

Číslo: 3/2020
Periodikum: Acta Montanistica Slovaca
DOI: 10.46544/AMS.v25i3.5

Klíčová slova: Pressuremeter Modulus; Limit Pressure; SPT; PMT

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Anotace: The use of in-situ soil testing has become popular in many

geotechnical projects because of its high measurement accuracy and
low disturbance of the soil sample during the testing process.
Pressuremeter Test (PMT) and standard penetration test (SPT) are
two important in-situ tests in geotechnical engineering. The former
is an expensive and time-consuming experiment that can measure
some detailed mechanical properties of soil while the latter is lowcost and can estimate some basic soil specifications. Thus,
identifying the relationship between PMT and SPT parameters can
help improve the mechanical characterization of soil samples
through a cost-saving methodology. In this research, 47 SPT and 47
PMT were performed on very stiff and hard silty clay and clay soil
samples. The variation range of EPMT and the N60 are in the range of
16.55-75.95 MPa and 16-51, respectively. Empirical equations were
proposed between EPMT-N60, PL-N60, and EPMT-PL with R
2
≥ 0.65.
Regression analysis by determining ‘R
2
’, ‘Sig.’, and ‘F’ values
demonstrated that the proposed models are highly significant and
strongly meaningful. The Mean Square Error (MSE) and Root
Mean Square Error (RMSE) values for each relation showed that
the estimation error is very small, and the relationships are
acceptable. The equations proposed in this research can be used for
very stiff and hard silty clay and clay soil types. Also, by comparing
the N60 and EPMT/PL values, silty clay and clay soil were classified in
terms of consistency according to EPMT/PL ratio. Finally, the results
from this study were grouped and compared with those reported
earlier, leading to a practical advisory methodology for the
estimation of PMT parameters from the SPT data applicable to a
wide range of soil samples.