594
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
6 CONCLUSIONS
Geotechnical study by CPT or CPTu can determine continuous
vertical profile of cone tip resistance (q
c
), sleeve friction (f
s
) and
pore water pressure (u) in every inch of the subsoil depth.
Hence, the shear strength parameters can be well determined
which have major role in geotechnical design.
In this study two main theories have been implemented for
the estimation of shear strength parameters by using CPT i. e.,
bearing capacity in cone tip and direct mode of shear failure in
along penetrometer jacket. So far, different researchers have
studied on determination of shear strength parameters from CPT
and CPTu data which solely have presented S
u
in fine grained or
ϕ
angle in granular soils. The entire of CPTu data, q
c
, f
s
and u
are used to calculate C and
ϕ
, via bearing capacity theory and
shear stress relation at failure condition. By combining these
relations and applying the proposed analytical Eslami and
Fellenius, (1997) model based on CPTu results and direct shear
failure along cone sleeve, the drained shear strength parameters
values include cohesion and internal friction angle can be
derived simultaneously.
In proposed procedure the error creation reaches to minimum
value through inaccurate records, because of the simultaneous
use of each three output quantities. The existence methods for
determining the internal friction angle are rely on only one of
the test outputs (depending only to q
c
) while the inaccurate
records creates more error in shear strength parameters. But,
three parameters q
c
, f
s
and u are dependent on friction angle in
presented procedure and lead to prorate the error cases. The
current procedures do not contain any recommendation for soil
cohesion and it is one of the advantages in the proposed
procedure. The presented procedure differs from common
procedure results by increasing fine grains in soil. Comparison
with 25 data sets of C and
ϕ
from laboratory tests and predicted
by the proposed method indicate good agreement and
consistency.
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