300 ----------,---,-., ----,.-----,_
me• 42.5:0:; c••SO ID/1'1 II
><
(
V
i
11te I Jllff
t"'
m c. •l2 !,S; c•ll20 lll/$CI It
--;;-.....-, � , : "-l-"
c::
,.,.
/V•11�
s,r, 0 75• cl&affi
i
100
��---+---+--f---�-..----+---1
.
r
--.....i,,..____
'
Fig. 2. Effect of rate of applicat10n
l
--+-'---,,·;----+---+--•
of torque on shaar strength,
0 ______ _.. __ __. ___ .._ ______ .....,
0
3600
lllOO
Fig. 4.
Vane
shear strengths1tomparld wlJII
triaxial shear
1tr1ngths
of undisturbed samples.
100
Soeeo or 1013hon ol iotque 11eac1 uc / •••
, ...
.
Vftdtstu,�
w,_
...
u,., ... c, ..
D
Ufldollutl>IIG
"""'"'
.......
-
un-cl•r
•
Uncllll.ned lfatQldWood
[y'
-
Lono.,.c,.,
.
Unotllldbed
Sdel1t11tt Ro.
I/
-,,.r1.
1tu c1.a,
.
lfflll41Vf0ed
H&1\tnp
I/
I•
'"'LOl!IIGIIClly
.
Und1Uwbed
fel••fOwe
/
,-londaft .c•11
.
Und>itVfl>cd
Q .. cnAnnc /
•
,,
/
1..A
•
I�•
!/
'
_�/
..
rl •
.
�
�
I�
1/'
0
0
l 000
2 OQO
3000
Shea, 11;en11n ftom 1i1anei tt'lt
�/sq
ft
Vane tartar wllh direct re.ding dial,
/
/
l600
number of tests provided evidence that
cult. The widely used constant-rale-of•
rhe vane inslrument gave much more
strain quick undrained triaxial test is
cort5isrenr results rhan the triaxial test.
dependenl on the rate of strain. Un-
Comparison of vane factors (Fig. 3)
disturbed day fails quickly at about 3
helped lo confirm rhe v11lidity of the
percent strain and remolded clay
vane calibrations.
fails slowly at IS percent strain. �ven
Testing 1he performance in undis-
when the two show identical shear
rurbed $a_mples was a little more diffi-
strength, but with the hand vane the
l.l
Q
'
'\
.,
�
'; 1.2
"'x.
�
J 1.l
............
-
!
-x-
i--x
1.0
IU 0.6
08
1.0
1.2
1.4
1.6
v,nc d14ffleler. ln(b
Fig. 3. Vena factor for ditft11nt si:ta
ofv-.
40
Ta,
iu.Jd
flexlc 11
X
I
. .
_
..
van
ihMd
IIMd ill
rltHlu
l-
30
x-
v
x
/�
lO
./-
[71
0
0
100
2DO
Vme llellecl!On: der,ees
300
times to
failure
are nearly the same. In
this investigation the vane results were
comP.ated with undrained lriaxial re
sults,
but
in
1erms
of
rate
of
strain
there is a wide difference between the
two
tests. Hence· the need to check the
validity of the calibration when testing
undisturbed samples.
A large number of vane tests on
four-in.-diam undisturbed samples
were compared with quick undrained
1riaidal tcsls and the results plotted
(Fig. 4), Up to I.OOO lb/sq ft the re•
suits were consistent with normal vari
ation in samples. Divergence above
that figure can be aun'but.cd to the fis
suring of the London Clay used in the
tests, but is of the same order as the
difference between remolded and un
dis1urbcd triaxiaJ strengths of fissured
London Clay.
Now satisfied that the instrument
was accurate and meaningful (in • =
0 clays) it remained only to provide a
direct-reading dial. Since mus-pro
duced springs are inconsistent one
with another. ea1:h dial is individually
engraved to match individual spring
calibration.
(Metric equivalents for this article:
multiply inches by 25.4 to get millime
tcrs: pounds by 0.4536 to get kilo
grams: square feet by 0.0929 to get
,quare meters.)
0
