kSIST FprEN ISO 22476-9:2020

SLOVENSKI STANDARD
oSIST prEN ISO 22476-9:2019
01-oktober-2019
Geotehnično preiskovanje in preskušanje - Preskušanje na terenu - 9. del:
Terenski krilni preskus (FVT in FVT-F) (ISO/DIS 22476-9:2019)

Ground investigation and testing - Field testing - Part 9: Field vane test (FVT and FVT-F

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

3.1 General ........................................................................................................................................................................................................... 1

3.2 Symbols ......................................................................................................................................................................................................... 4

4 Equipment ................................................................................................................................................................................................................... 5

4.1 Test configurations .............................................................................................................................................................................. 5

4.2 Vane .................................................................................................................................................................................................................. 8

4.2.1 General...................................................................................................................................................................................... 8

4.2.2 Dimensional requirements ..................................................................................................................................... 8

4.3 Vane shaft and friction reducer .............................................................................................................................................10

4.4 Slip coupling ...........................................................................................................................................................................................10

4.5 Extension rods, protective casings, protection shoe ...........................................................................................10

4.6 Equipment for applying rotation ..........................................................................................................................................11

4.7 Equipment for measuring rotation and torque .......................................................................................................11

5 Selection of test and test configuration .....................................................................................................................................11

5.1 Selection of shear strengths to be measured .............................................................................................................11

5.2 Selection of equipment and procedures related to soil conditions ........................................................13

6 Test procedure .....................................................................................................................................................................................................13

6.1 Equipment checks and calibrations ...................................................................................................................................13

6.2 Position and inclination of thrust machine .................................................................................................................14

6.3 Test depths ..............................................................................................................................................................................................14

6.4 Internal friction torque reading prior to testing .....................................................................................................14

6.5 Methods for reaching the level for insertion of vane ..........................................................................................14

6.6 Insertion of the vane .......................................................................................................................................................................16

6.7 External friction torque reading ...........................................................................................................................................16

6.8 Vane shear test .....................................................................................................................................................................................16

6.9 Internal friction torque reading after the test ......... ..................................................................................................17

7 Test results ...............................................................................................................................................................................................................17

8 Reporting ...................................................................................................................................................................................................................18

8.1 General ........................................................................................................................................................................................................18

8.2 Reporting of test results ...............................................................................................................................................................19

8.2.1 General information ...................................................................................................................................................19

8.2.2 Location of the test .................. ......................................................................................................................... ...........19

8.2.3 Test equipment ...............................................................................................................................................................20

8.2.4 Test procedure ................................................................................................................................................................20

8.2.5 Test results .........................................................................................................................................................................20

8.3 Presentation of test plots ............................................................................................................................................................20

Annex A (informative) Example of field record for field vane test .....................................................................................22

Annex B (normative) Maintenance, checks and calibration .....................................................................................................24

Annex C (informative) Uncertainties in field vane testing ..........................................................................................................27

Annex D (normative) General interpretation and explanation for tapered and rectangular

vanes with H/D ratios differring from 2 ...................................................................................................................................29

Annex E (informative) Interpretation and explanation for a rectangular vane with rounded

corners .........................................................................................................................................................................................................................32

Annex F (normative) Calculation of test depth .......................................................................................................................................34

Annex G (informative) Example of estimation of post-peak behaviour ........................................................................35

Bibliography .............................................................................................................................................................................................................................36

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The field vane test is used to determine the vane shear strength of soils in the undrained condition,

by insertion of a rectangular vane into fine-grained soil and rotating it. During rotation, the torque

and rotation can be measured, depending on the test configuration. From the measured torque and the

dimensions of the vane, the peak shear strength, an indication of post-peak behaviour and the remoulded

shear strength can be derived by limit equilibrium analysis. Soil sensitivity can be ascertained if peak

The tests are carried out in boreholes, in trial pits and with pushed-in equipment. Torque and rotation

are measured either above the ground surface using extension rods; or directly above the vane.

The field vane test is mainly applicable to saturated fine-grained soil. The vane shear strength

determined by the test is commonly corrected before geotechnical analysis, using factors based on

This standard deals with the equipment requirements, execution and reporting of field vane tests for

the measurement of peak and remoulded vane shear strength together with the sensitivity of fine-

grained soils. In addition, post-peak shear strength behaviour can be evaluated. Two types of field vane

test are described; the ordinary field vane test (FVT) and the fast field vane test (FVT-F).

NOTE 1 This part of ISO 22476 fulfils the requirements for field vane tests as part of the geotechnical

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

ISO 10012:2003, Measurement management systems — Requirements for measurement processes and

ISO 14688-1, Geotechnical investigation and testing — Identification and classification of soil — Part 1:

ISO 14688-2, Geotechnical investigation and testing — Identification and classification of soil — Part 2:

ISO 22475-1, Geotechnical investigation and testing – Sampling methods and groundwater measurements

Extension rods that are sleeved inside of protective casings during vane testing.

Borehole that is cased to prevent collapse and minimize friction between the extension rods and soil.

Note 1 to entry: The system typically includes sensors, signal conditioning, AD converter and recording unit.

Test configuration whereby the torque is measured close to the vane. The rotation can be measured

Torque due to friction outside the measuring equipment during rotation excluding torque caused by

shearing of soil. External friction is mainly caused by friction acting on extension rods and it can be

A ring inserted between the vane and the extension rods to reduce friction along uncased extension rods.

Distance from the ground surface or base of (bore)hole or trial pit to mid-height of the vane, measured

Torque due to friction inside the measuring equipment during rotation when there is no torque acting

Sum of the lengths of the extension rods, the vane shaft and the distance to mid-height of the vane,

Equipment to protect the vane while pushing into the soil. It assists with the insertion of the vane

without drilling. Usually, the tip of the protection shoe consists of four plate slots allowing the vane

Tubes that isolate the extension rods from the soil and give support against buckling.

Distance between the bottom of the protective casing/shoe and the mid-height of the vane when pushed

Note 1 to entry: Apparent rotation is the rotation recorded by the rotation measurement equipment.

Mechanism that allows the extension rods to rotate freely while the vane remains stationary.

Vertical distance from the ground surface, reference level or datum to mid-height of the vane.

Note 1 to entry: According to Annex F, the penetration length can be corrected with inclinometer measurements

to correspond the test depth. Otherwise, the test depth is based on the penetration length owing to the

Two types of field vanes test can be distinguished; ordinary field vane test (FVT) and fast field vane

Time from the beginning of application of torque to the vane until the maximum torque is reached.

Extension rods that are not protected by protective casing allowing friction to develop between the

Test configuration whereby the torque is measured above the ground surface. The rotation is applied

Note 1 to entry: Most vanes have a (nearly) rectangular shape. For practical reasons, vanes without protection

shoes often have slightly tapered lower ends of the vane plates or with rounded corners. Some equipment using

uncased extension rods and a slip coupling to separate the rod friction from the torque on the vane are designed

with slightly tapered, sharpened, pointed or conical, vane plates in order to disengage the slip coupling during

Cylindrical element of the vane to which the vane plates are fixed. The vane shaft may be connected

directly to the force or torque measurement equipment in a downhole test or connected to it via

Time between reaching the test depth and beginning of application of the torque to the vane.

Difference between the internal friction torque readings of the measuring equipment prior and after

c Undrained shear Shear resistance of fine-grained soils in the undrained condition kPa

c Post-peak field Post-peak shear strength of soil, selected after desired rotation after kPa

c Remoulded field Shear strength, as measured by field vane test, after remoulding kPa

c Fast field vane Peak shear strength of soil, derived from the maximum torque kPa

l Penetration sum of the lengths of the extension rods, the vane shaft and the dis- m

R Area ratio Cross sectional area ratio of vane and vane shaft compared to circular -

Field vane The ratio between the field vane and remoulded field vane strengths -

T Internal friction Stable output of a measuring equipment during rotation when there Nm

torque reading is no torque acting on the vane and no friction acting on the exten-

T External friction Stable output of a measuring equipment during rotation when there Nm

torque reading is no torque acting on the vane (usually measured prior to the vane

T Maximum torque Torque required to obtain failure in soil around the vane, corrected for Nm

T Maximum Measured torque required to obtain failure in soil around the vane in- Nm

measured torque cluding external friction. The maximum torque (T ) can be calculate

T Post-peak torque Post-peak torque selected after maximum torque, corrected for inter- Nm

T Measured post- Measured post-peak torque selected after desired rotation after Nm

T Torque for Measured constant torque value after remoulding the soil, corrected Nm

T Measured torque The constant measured torque value after remoulding including Nm

for remoulded external friction torque. The torque for remoulded condition is calcu-

The test equipment includes a vane and vane shaft, extension rods, rotation equipment and a rotation/

torque measuring equipment, configured in a number of combinations, see Figure 1.

which are used to increase the insertion or the penetration length that can be achieved and also will

reduce the friction in the system. In addition, borehole casing may be used to allow predrilling prior to

Vane test may be performed in either uphole or downhole configurations. Typical configurations

are illustrated in Figure 1 and locations of torque and rotation measurements, torque transfers and

In the uphole configuration, torque (T) can be measured by a torque wrench or a dial indicator spring

with variable lever arm (W) or by a continuous torque measuring equipment (U) located above ground

surface at the point for insertion of the vane. For reading with an indicator spring, correction is needed

In the downhole configuration, the torque measuring equipment is located close to the vane, but the

rotation can be measured either close to the vane (D*) or above ground surface (D). The rotation unit

In the downhole configuration, the measuring unit can be covered by larger protective casing and the