ASTM D6230-98(2005)
(Test Method)Standard Test Method for Monitoring Ground Movement Using Probe-Type Inclinometers
Standard Test Method for Monitoring Ground Movement Using Probe-Type Inclinometers
SIGNIFICANCE AND USE
An inclinometer is a device for measuring deformation normal to the axis of a pipe by passing a probe along the pipe and measuring the inclination of the probe with respect to the line of gravity. Measurements are converted to distances using trigonometric functions. Distances are summed to find the position of the pipe. Successive measurements give differences in position of the pipe and indicate deformation normal to the axis of the pipe. In most cases the pipe is installed in a near-vertical hole. Measurements indicate subsurface horizontal deformation. In some cases the pipe is installed horizontally and the measurements indicate vertical deformation.
Inclinometers are also called slope inclinometers or slope indicators. Typical applications include measuring the rate of landslide movement and locating the zone of shearing, monitoring the magnitude and rate of horizontal movements for embankments and excavations, monitoring the settlement and lateral spread beneath tanks and embankments, and monitoring the deflection of bulkheads, piles or structural walls.
SCOPE
1.1 This test method covers the use of inclinometers to monitor the internal movement of ground. The test method covers types of instruments, installation procedures, operating procedures and maintenance requirements. It also provides formulae for data reduction.
1.2 The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate health and safety practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D6230 − 98(Reapproved 2005)
Standard Test Method for
Monitoring Ground Movement Using Probe-Type
Inclinometers
This standard is issued under the fixed designation D6230; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope axis of the pipe. In most cases the pipe is installed in a
near-vertical hole. Measurements indicate subsurface horizon-
1.1 This test method covers the use of inclinometers to
tal deformation. In some cases the pipe is installed horizontally
monitor the internal movement of ground. The test method
and the measurements indicate vertical deformation.
covers types of instruments, installation procedures, operating
procedures and maintenance requirements. It also provides 3.2 Inclinometers are also called slope inclinometers or
formulae for data reduction. slope indicators. Typical applications include measuring the
rate of landslide movement and locating the zone of shearing,
1.2 The values stated in SI units are to be regarded as the
monitoring the magnitude and rate of horizontal movements
standard. The inch-pound units given in parentheses are for
for embankments and excavations, monitoring the settlement
information only.
and lateral spread beneath tanks and embankments, and moni-
1.3 This standard does not purport to address all of the
toring the deflection of bulkheads, piles or structural walls.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Apparatus
priate health and safety practices and determine the applica-
4.1 The probe type inclinometer uses sensors inside a probe
bility of regulatory limitations prior to use.
to indicate the orientation of the probe relative to the pull of
gravity. The complete system consists of:
2. Referenced Documents
4.1.1 A permanently installed pipe, called casing, with test
2.1 ASTM Standards:
method grooves. The casing is made of plastic, aluminum
D653 Terminology Relating to Soil, Rock, and Contained
alloy, or fiberglass.
Fluids
4.1.2 The Probe—Most probes use force balance acceler-
D4622 Test Method for Rock Mass Monitoring Using Incli-
ometers which give a voltage output that is proportional to
nometers (Discontinued 2000) (Withdrawn 2000)
inclination of the probe. Biaxial probes contain two sensors
oriented 90° apart to permit readings in orthogonal directions
3. Significance and Use
at the same time.
3.1 An inclinometer is a device for measuring deformation
4.1.3 A portable readout unit with power supply for the
normal to the axis of a pipe by passing a probe along the pipe
sensors and display to indicate probe inclination. The readout
and measuring the inclination of the probe with respect to the
unit may have internal memory to record data.
line of gravity. Measurements are converted to distances using
4.1.4 An electrical cable connecting the probe and readout
trigonometric functions. Distances are summed to find the
unit with distance markings. Fig. 1 shows a typical set of
position of the pipe. Successive measurements give differences
components.
in position of the pipe and indicate deformation normal to the
5. Procedure
5.1 Installation of Casing in a Borehole:
This test method is under the jurisdiction ofASTM Committee D18 on Soil and
5.1.1 Select casing materials that are compatible with the
Rock and is the direct responsibility of Subcommittee D18.23 on Field Instrumen-
tation.
environmental conditions at the installation. Select casing size
Current edition approved Nov. 1, 2005. Published December 2005. Originally
consistent with the specific measurement requirements and
approved in 1998. Last previous edition approved in 1998 as D6230 – 98. DOI:
conditions for the job. Store casing materials in a safe, secure
10.1520/D6230-98R05.
place to prevent damage. Sunlight may damage plastic casing.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
HighandlowpHmaydamagemetalcasing.Notethataspecial
Standards volume information, refer to the standard’s Document Summary page on
probe may be required for non-vertical boreholes.
the ASTM website.
5.1.2 Assemble all components required for the casing,
The last approved version of this historical standard is referenced on
www.astm.org. including casing, joints, connectors, and end cap. Examine
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6230 − 98 (2005)
backfill is preferable unless the surrounding ground is too
pervioustoholdthegrout.Placegroutwithatremie.Buoyancy
must be overcome with grout backfills. Add a weight to the
bottom of the inclinometer casing, temporarily place clean drill
pipe inside the casing, or place the first 3 m (10 ft) of grout
aroundthebottomofthecasingandletitset,thencompletethe
grouting. Place sand and gravel backfills slowly and with
techniques to prevent leaving large voids in the backfill. Such
voids can later lead to erratic readings. Place backfill and
withdraw drill casing or augers in sequence to prevent any
squeezing off of the borehole. Withdraw drill casing and
hollow-stem augers without rotation to prevent damage to the
inclinometer casing. Use measures to prevent backfill from
spilling into the inclinometer casing.
5.2 Installation on The Ground Surface of Horizontal Cas-
ing:
NOTE 1—A practical limit for installing horizontal casing is about 100
m. Beyond 100 m cable friction makes it difficult to pull the inclinometer
FIG. 1 Typical Components of Inclinometer System
probe through the casing. Special TFE-fluorocarbon inserts on the cable
alleviate the problem to some degree.
5.2.1 Select casing materials that are compatible with the
each component for defects. Do not use defective components
environmental conditions at the installation. Select casing size
since they may later cause problems with readings that are
consistent with the specific measurement requirements and
difficult to diagnose and impossible to correct. Keep all
conditions for the job. Store casing materials in a safe, secure
components clean and free of foreign matter during assembly.
place to prevent damage. Sunlight may damage plastic casing.
Follow the manufacturer’s instructions for assembly of the
HighandlowpHmaydamagemetalcasing.Notethataspecial
casing. If required, use sealing mastic and tape to seal all
probe is required for horizontal casing. If one end of the casing
couplings to prevent later flow of soil particles into the casing.
istobeburiedthentheendcapcontainsapulleytocarryawire
Thisisespeciallyimportantwhenusinggrouttosealthecasing
that is used to pull the probe into the inclinometer casing.
in the hole. Exercise care to keep the casing grooves free of
Special care must be taken to insure that the pulley is correctly
obstructions. When assembling couplings, use procedures to
assembled, free to turn and has the wire in place. Take
prevent spiraling of the casing grooves. Twist adjacent cou-
precautions at all times during installation to keep the wire
plings in alternate directions before fixing to minimize spiral-
clean.
ing. Examine the casing during assembly to confirm that
5.2.2 Create a near-level surface over the length where the
spiraling is not occurring. Place a cap on the bottom end and
casing is to be installed. Cover with a bed of at least 50-mm
seal it to prevent inflow.
(2-in.) deep and 300-mm (12-in.) wide of clean sand, pea
5.1.3 Create the borehole using procedures to keep it
gravel or a lean grout.
aligned within the range of the readout equipment. Extend the
5.2.3 Assemble all components required for the casing,
borehole at least 5 m (16 ft) beyond the zone of expected
including casing joints, connectors, and end cap. Examine each
movement. It may be necessary to use casing, hollow-stem
component for defects. Do not use defective components since
augers, or drilling mud to keep the hole open and stable. Flush
theymaylatercauseproblemswithreadingsthataredifficultto
the hole until clear of drilling cuttings.
5.1.4 Insert the casing into the borehole. Establish the diagnose and impossible to correct. Keep all components clean
and free of foreign matter during assembly. Follow the manu-
reference orientation for the casing and align one set of groves
with this reference.This orientation is commonly referred to as facturer’s instructions for assembly of the casing. If required
usesealingmasticandtapetosealallcouplingstopreventlater
the A direction. It should align with the direction of greatest
anticipated movement. Add clean water to the casing if flow of soil particles into the casing. This is especially
important when using grout to seal the casing in the borehole.
necessary to overcome buoyancy. Use care to minimize any
twistofthecasingduringinstallation.Careshouldbeexercised Exercise care to keep the casing grooves free of obstructions.
When assembling couplings, use procedures to prevent spiral-
to maintain orientation without twisting from the first piece of
casing to the last. Twisting the top of the casing may cause ing of the casing grooves.Twist adjacent couplings in alternate
directions before fixing to minimize spiraling. Examine the
spiraling of casing at depth.
5.1.5 Backfill the annular space between the borehole wall casing during assembly to confirm that spiraling is not occur-
ring.
and the inclinometer casing with a suitable filling material.
Borehole can be pre-grouted or post-grouted. If post-grouted, 5.2.4 Place the casing onto the bed and adjust its position
grouting can be through a tremie placed in the annulus of the until it is within the tolerances required by the readout device.
inclinometer casing and the borehole’s walls or via an internal Establish the reference orientation for the casing and align one
tremie connected to a one-way bottom grout valve. Options set of groves with this reference. This orientation is commonly
includecementgrout,sandandpeagravel.Aleancementgrout referred to as the A direction. It aligns with the direction of
D6230 − 98 (2005)
greatest anticipated movement. Visually check for and remove readings. Repeat the procedure to the top of the casing to
any spiraling. Determine that the pull cable is in position and complete the traverse. Remove the probe from the casing,
moves freely through the inclinometer casing. rotate it 180°, and lower it to the bottom of the casing. Start
5.2.5 Use hand tools or light construction equipment to readings for this traverse from exactly the same depth as the
place clean sand, pea gravel or lean grout evenly, at least first traverse and make each reading at exactly the same depth
150-mm (6-in.) wide, on both sides of the casing. Cover the as the first traverse. For biaxial probes, two traverses complete
inclinometer casing with at least 50 mm (2 in.) of clean sand, the set of readings. For uniaxial probes, two more traverses
pea gravel or lean grout. Place fill over casing in 150-mm must be made for the B direction the same way as for the A
(6-in.) lifts. Fill for the first lift should not contain any particles direction.
larger than 25 mm (1 in.). If compaction is required, use hand
5.4.2 Check the set of readings by summing the readings for
compactors for the first two lifts.
the A and A' directions at each depth and the readings for the
B and B' direction. These sums are called check-sums and
5.3 Calibration:
should equal a constant value that is a characteristic of the
5.3.1 Inclinometers are factory calibrated and supplied with
probe. Refer to the manufacturer’s literature for information on
a calibration factor, K, that is specific to the probe and the
allowable variation in the check-sum. A single deviation in a
readout unit. Some manufacturers provide standardized read-
check-sum probably indicates a bad reading. Erratic behavior
out units that can be used with multiple probes. However it
of the check-sums generally indicates a poor electrical connec-
should be noted that electronic variations in the readout
tion or a malfunctioning probe or readout.
equipment may cause conditions where different probes will
give different readings. It is recommended that a calibration
5.5 Initial Readings:
check be performed any time a probe and readout unit
5.5.1 Makeinitialobservationsafterallowingsufficienttime
combination is changed. For applications involving small but
for the grout around the casing to set or for the backfill to
important changes over several years, recalibrate the instru-
stabilize. Since computation of all displacements is based on
ment to the precision of the device at least once per year.
theinitialreadings,itisimportanttohaveavalidset.Verifythe
5.3.2 Perform a calibration check before each set of incli-
initial set of readings with at least two sets of readings, taken
nometer readings. Field checks can be made using a test stand,
on the same day. Check these readings for stability of the
a test casing, or a section of field casing in material that does
check-sums and for displacement within the accuracy of the
not move. Test stands are available from most manufacturers.
equipment. Repeat observations until satisfactory agreement is
They employ a short piece of inclinometer casing preset at a
obtained. From all initial readings taken, one set should be
fixed angle. The test stand must be set on a stable base and
selected for use as the reference set for all subsequent readings.
properly aligned by the manufacturer’s instructions. A test
Take readings on any spiral with a spiral sensor if corrections
casing is a short piece of casing installed in a fixed position
for twist are desired, or if there is potential for twist in the
with the grooves at angles of 0 to 10° from the vertical. A
casing of sufficient magnitude to affect the computed displace-
section of field casing that is placed in fixed material can be
ments of the casing.
used to check calibrations. This last method is the least
5.5.2 Thetopposition(x,yandz)oftheinclinometercasing
preferable since most field casings are near-vertical (or near-
must be located by survey at the same time initial readings are
horizontal). Calibration checks on vertical casing can indicate
made by survey to the accuracy of the inclinometer readings.
malfunctioning equipment but cannot provide an accurate
Later changes in the top position of the casing can be used to
calibration.
check the inclinometer readings or to correct for movement of
5.3.3 Perform a calibration c
...
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