Users’ Manual
EDS-71V/P Single point borehole extensometer
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12
CAUTION:
Never rotate shaft of displacement sensor in respect to the outside body. This will permanently
damage the sensor. During checking pull / push shaft only axially. A pin has been provided at
end of displacement sensor that sits flush in a groove in sensor body.
3.3 Procedure
3.3.1 Refer to figure 2-1 and 2.2. Remove cover (19) and take out polythene bag that contains requisite
quantity of reference buttons (15), link plates (16), sensor tightening nut (17), locknuts (18), M6 x
100 or 125 mm or 150 mm cheese head screw (24) depending upon type of housing and locking
nuts (25).
3.3.2 Remove guide plate (6) with 2 mm Allen key and hollow bolts (12) from holes marked 1, G and V
from flanged housing (5) and place latter flat on clean ground around 1 m away from borehole.
CAUTION:
Always mark a line between flanged housing (5) and adopter cum guide plate (6) before
dismantling so that it can be aligned properly while assembling the sensor (20).
3.3.3 Cut grout and air vent tubes (
Φ
12 mm outside dia.x 1 mm thick supplied in coil form) to required
length. Generally, lower end of grout tube is kept at a level higher than anchor. Grout should cover
anchor to mouth or be around 1 m from face of borehole whichever distance is less. To determine
length of grout tube, ensure that around 1.5 m is required outside the reference plate (14) for ease
in attaching it to grout pump. Air vent tube should be projected around 0.3 m is outside reference
plate (14). Lower end of air vent tube should always be at a higher level than lower end of grout
tube. While inserting anchor in borehole, lowest end of grout tube is tied with a cable tie to the
connecting rod
NOTE:
In upward to horizontally sloping borehole, grout tube should be about 2 m longer than
specified depth of anchor and taped around 100 mm below far end of anchor. Tape grout tube
every 2 m with a PVC tape to plastic tube of connecting rod assembly to prevent it from
swinging loose.
NOTE:
In upward to horizontally sloping borehole, air vent tube should be about 1.5 m longer than
specified depth of anchor and taped around 100 mm above far end of anchor. Tape air vent
tube every 2 m with a PVC tape to the nylon tube of connecting rod assembly to prevent it
from swinging loose. Top end of air vent tube should be at a level higher than anchor.
CAUTION:
In upward to horizontally sloping borehole, care should be taken that air vent tube is taped
around 100 mm beyond rear end of anchor and should not get detached. This is very
necessary for the grout to fill in up to end of anchor.
3.3.4 Guide grout tube through hollow bolt (12), washer (11) and rubber bush (10) of hole marked G at
bottom of flanged housing and corresponding holes on guide plate (6) and reference plate (14),
the grout tube is around 1.5 m outside the reference plate. Similarly, guide the air vent tube through
hollow bolt of hole marked V at bottom of flanged housing; the vent tube is around 0.3 m outside
the reference plate (14).
3.3.5 Tighten corresponding hollow bolt (12) with spanner size 21 mm and long hollow bolt (7) to firmly
grip nylon grout and air vent tubes but not to squeeze them.
CAUTION:
Always tight hollow bolts (12) 2 nos. firstly and then long hollow bolt (7) at the end.
CAUTION:
In upward to horizontally sloping borehole, be particularly careful in tightening the hollow bolts
(12) properly as grout may leak through into the reference head assembly during the grouting
