01.11
product manual
H-4227
Vane Inspection Kit
Introduction
The inspection vane is used to measure in-situ undrained shear strength in clays.
It is primarily intended for use in trenches and excavations at depths up to 3m.
This can be extended with additional optional extensions.
The range of the instrument is from 0 to 260kPa when three different size vanes are
used. Accuracy should be within 10% of the reading.
Description
The measuring part of the instrument is a spiral-spring, (max. torque transmitted 30
kgcm). When the handle is turned, the spring deforms and the upper part and the
lower part of the instrument get a mutual angular displacement. The size of this
displacement depends on the torque required to tum the vane. By means of a
graduated scale shear strength of the clay is obtained.
The lower and upper halves of the instrument are connected by means of threads.
The scale is also supplied with threads, and follows the upper part of the instrument
by means of two lugs. The O-point is indicated by a line on the upper part. When
torque is applied, the scale-ring follows the upper part of the instrument, and when
failure in the clay is obtained, the scale-ring will remain in its position due to the
friction in the threads.
Four sizes of four-bladed vanes are supplied:
20 x 40mm (standard): Reading is direct-Range is 0 to 130kPa (1.3 TSF)
16 x 32mm (extra vane): Multiply reading by 2-Range is 0 to 260kPa (2.6 TSF)
25.4 x 50.8 (extra vane): Multiply reading by 0.5-Range is 0 to 65kPa (0.65 TSF)
50.8 x 101.6mm (extra vane):, Multiply reading by 0.0625-Range is 0 to 8.125kPa
(0.08TSF).
• Note that each mark on graduated scale equals 1kPa. Therefore, the mark 1
actually represents 10kPa when using the standard (20 x 40mm) vane. The
maximum possible reading is 130kPa using the standard vane and 260kPa when
using the smallest (16 x 32mm) vane.
The “area ratio” of the vanes are 14, 16.5 and 24% (ratio of cross sectional area of
vane to the area to be sheared).
The vane blades are soldered to a vane-shaft, which can be extended by one or
more 0.5m long rods. The connection between the shaft-rods and the instrument is
made by threads. To make the connection as straight as possible, the rods have to
be screwed tight together and with threads free from dirt.
The maximum shear strength that can be measured with the inspection vane is
260kPa. In clays with this shear strength, a force of about 40 to 50 kilos is required to
press the vane down into the clay. The vane-shaft is designed to take this -force, but
if extension rods are used, precautions against buckling are suggested.
nnmm
Working Instructions
General Procedure
1. Connect required vane and extension rods to the inspection vane instrumen
WHILE SCREWING VANE OR RODS TO INSTRUMENT, HOLD ONTO LOWER PART
of the instrument.
2. Push vane into the ground to the required position.
MAKE NO TWISTING MOTION TO VANE DURING PENETRATION.
3. Make sure that the graduated scale is set to 0 position.
4. Tum handle clockwise.
TURN AS SLOWLY AS POSSIBLE WITH CONSTANT SPEED.
5. When the lower part moves at same rate as upper part (4) around or even falls
back, failure has occurred and maximum shear strength has been attained in the
clay at the vane.
6. Holding handle firmly, allow it to return to zero-position.
DO NOT ALLOW THE HANDLE TO SPRING BACK as damage to mechanism
could occur.
7. Note the reading on the graduated scale.
DO NOT TOUCH OR IN ANY WAY DISTURB THE POSITION OF THE GRADUATED
RING UNTIL THE READING IS TAKEN.
8. Record the reading together with position of hole and depth.
9. Tum the graduated scale counter-clockwise back to 0 position.
10. To determine the remolded shear strength, the following procedure is used: Tum
the vane quickly at least 25 revolutions. Zero the scale and take at least two
measurements by turning the instrument as slowly as possible. The minimum value
is considered the correct one.
11. Push the vane down to next position. If necessary add on another extension rod.
12. Repeat the above measurement procedure (3-10).
13. When the last reading is taken pull the vane up. If the clay is comparatively soft, this
can be done by hand, gripping the handle. In harder clays, some mechanical device
might be necessary. It is then advisable to remove the instrument and pull the rods
directly.
Special Procedure
When measuring the shear strength at greater depths, friction between the clay and
the extension rods can be appreciable and must be taken into consideration.
To measure this friction, extension rods and a vane-shaft without vane (dummy) are
pushed into the ground to the depths required for shear force measurements. Friction
is then measured in the same way as when using vanes (above 3-9). The friction-value
obtained is deducted from the measured shear strength to determine the actual shear
strength.
To penetrate through firm layers, a preboring using a rod with the same diameter as the
vane may be helpful.
Warranty
Humboldt Mfg. Co. warrants its products to be free from defects in material or
workmanship. The exclusive remedy for this warranty is Humboldt Mfg. Co.,
factory replacement of any part or parts of such product, for the warranty of this
product please refer to Humboldt Mfg. Co. catalog on Terms and Conditions
of Sale. The purchaser is responsible for the transportation charges. Humboldt
Mfg. Co. shall not be responsible under this warranty if the goods have been
improperly maintained, installed, operated or the goods have been altered or
modified so as to adversely affect the operation, use performance or durability
or so as to change their intended use. The Humboldt Mfg. Co. liability under
the warranty contained in this clause is limited to the repair or replacement of
defective goods and making good, defective workmanship.
Humboldt Mfg. Co.
875 Tollgate Road
Elgin, Illinois 60123 U.S.A.
Testing Equipment for
HUMBOLDT
www.humboldtmfg.com
U.S.A. Toll Free: 1.800.544.7220
Voice: 1.708.456.6300
Fax: 1.708.456.0137
Email: hmc@humboldtmfg.com
Construction Materials
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