US3483745A - Borehole extensometer - Google Patents

Borehole extensometer Download PDF

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Publication number
US3483745A
US3483745A US417741A US3483745DA US3483745A US 3483745 A US3483745 A US 3483745A US 417741 A US417741 A US 417741A US 3483745D A US3483745D A US 3483745DA US 3483745 A US3483745 A US 3483745A
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Prior art keywords
wire
borehole
movement
anchor
spring
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Expired - Lifetime
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US417741A
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English (en)
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Horst Ublacker
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Patrick Harrison Inc
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Patrick Harrison Inc
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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
    • E21B49/006—Measuring wall stresses in the borehole

Definitions

  • An anchor is secured within the borehole.
  • A. spring mounted upon this abutment and is biased outwardly with respect to-dhe borehole and is connected to the 'wire to tense the wire and to resiliently stretch it.
  • a movement of the melt structure through which the borehole extends, causes movement of the anchor with respect to the abutment to initiate simultaneous defiection'of the wire and spring.
  • the wire and spring deflect together as a common system and the final basic feature involves a means for measurement of the resulting movement at a point adjacent to "the connection of the wire and spring. This movement, .can be corrected to establish the true movement of the; anchor with respect to the abutment by ascertaining the combined elastic characteristics of the wire and spring.
  • This invention relates to methods and apparatus for measuring changes in the depth or reach of a borehole to indicatetthe movement of a rock mass along'the axis of the borehole, as between selected locationswithin the borehole and the earth or rock face at the entrance or mouth of the hole.
  • the invention will be hereinafterreferred to as a borehole extensometer, or simply as an extensometer.
  • the present invention is an improvement over conventional types of extensometers which are used measure earth'movements.
  • a common type of extensometer consists of a rigid rod having one end anchored in a borehole, as by grouting, so that movements of the other end may be measured by instruments anchored to an abutment at the mouth of the borehole.
  • Another type consist of a wire having one end anchored within the hole and the other end passed'iover a pulley and loaded with weights to pre-tension' 'the wire.
  • a movement indicating device is associated with this wire at a suitable point adjacent to the mouth of the borehole.
  • Another type of wire extensometer substitutes a spring for weights to pre-tension the wire, and includes a manual adjustment device adapted to move the spring longitudinally with respect to the wire to the selected pre-tension before measuring the movement of the wire.
  • a manual adjustment device adapted to move the spring longitudinally with respect to the wire to the selected pre-tension before measuring the movement of the wire.
  • the present invention was conceived and developed to overcome these disadvantages and comprises, in essence, an improved wire extensometer of a spring-loaded type which combines :the spring action of the wire itself with the pull of a tensioning spring to provide a system which required no setting or adjustments and gives a continuous dynamic action to. indicate the movement of rock within a borehole.
  • a further object of; the invention is to provide a borehole extensometer which may be easily arranged as a composite device to measure the deflection at several positions in a single borehole, and such an embodiment of'the invention is hereinafter described.
  • FIGURE 1 is a diagrammatic longitudinal sectional view of a borehole within a rock mass having the improved extensometer "mounted wihin the hole and with anchors being placed at three positions with the hole, and with the measuring head being mounted upon an abutment at the mouth of the hole.
  • FIGURE 2 is an enlarged longitudinal sectional view through a portion of the borehole, illustrated at FIG. 1, including a longitudinal sectional view through an intermediate anchor box.
  • FIGURE 3 is a transverse sectional view of the anchor box per se, as taken from the indicated line 3-3 at FIG. 2
  • FIGURE 4 is an enlarged longitudinal sectional view at the mouth of the borehole and a longitudinal sectional view through the measuring head of the apparatus.
  • FIGURE 5 is a transverse sectional view as taken from the indicated line 55 at FIG. 4.
  • FIGURE 6 is a longitudinal sectional view of a portion of the showing at FIG. 4, as taken on-the indicated line 6-6 at FIG. 5, but on an enlarged scale and with the view being broken and staggered to conserve space.
  • FIGURE 7 is a longitudinal sectional 'view, similar to FIG. 2, but showing an alternate type of anchor.
  • FIG. 1 shows a composite arrangement, of an extensometer where three points are measured in a borehole 1.
  • the hole 1 is bored therein to a selected depth location.
  • Selected anchor positions. I, II and III are located within this hole where anchc r boxes 2 are located.
  • Measuring wires 10 are connected to each anchor box to extend from the mouth ofthe hole to the measuring head 11.
  • the measuring head 11, as hereinafter further described, is set upon a prepared abutment a at the mouth of the hole. Deflections of the system are indicated at the head 11 and may be read either visually or through an electrical system at a remote location, as by signal conduits 35 extending to a conventional type of readout device 36, as will be further described.
  • the anchor box 2 illustrated in detail at FIGS. 2 and 3, is formed as a short tubular member having a heavy rod spiralled and welded to the outer surface to form a gripping spiral 3 which facilitates securely holding the box in position within the hole.
  • the end of each box 2 is turned to form a pipe lock 4 for connection with a protective tubular casing 5.
  • Sections of the casing 5 extend between the several boxes 2 to provide for a fully protected system in the borehole and to facilitate proper location of the anchor boxes 2 when they are inserted into the bore.
  • the annular space between the casing and boxes and the hole wall is filled with grout to cement the boxes 2 in place.
  • the outer surface of the casing 5 is oiled or otherwise treated so that it will not stick to the grout cement and that this casing is generally a thin-walled member of little strength, easily crumpled or pulled from the outlet boxes 2 and will in no way affect the rock movements and the accompanying movements of the anchor boxes.
  • Each anchor box is formed with an internal, transverse shoulder which supports a transversely disposed disc 6.
  • a clamp bolt 7 is extended through an orifice within the disc and is held in position as by a lock nut 8 at the opposite side of the clamp.
  • a wire clamp 9 secured to the bolt 7 is adapted to hold the end of the measuring wire 10 extending to the box, as clearly illustrated at FIG. 2.
  • a suitable orifice is located onthe disc 6 for each wire 10 passing through the anchor with the orifice, or orifices, being in an arrangement which will not interfere with the clamp bolt 7 or its wire 10.
  • a low-friction toroidal button f is mounted in each orifice so that other wires 10 may pass through the button and through the anchor box 2 with no significant frictional effect at the point of contact with the button f,
  • the measuring head 11 is mounted upon a flange 12 which is affixed to the abutment a at the mouth of the hole 1, as by a ring of anchor bolts b.
  • a tubular housing 13 is afiixed to this flange and projects into the mouth of the hole with an end plate thereon supporting rollers 14 which position and align the wires 10 emerging from the hole 1 for connection with tensioning components on the measuring head, as will be described.
  • This housing 13 is encased within a nipple 15 which extends beyond it a short distance and connects with the casing 5 to completely encase the wire system within the borehole 1.
  • a second short tubular housing 16 is attached to the flange 12 to project outwardly therefrom, and it includes an inturned flange 17 at its outer end.
  • a support disc 18 is aflixed to the flange 17 as by a ring of screws, as illustrated. This disc encloses the passageway into the cased hole and also carries the spring tensioning members on its outer face, as will be hereinafter described.
  • the outer housing 16, the disc 18 and the Spring tensioning members are all enclosed within a cover housing 19 which is secured to the flange 12 by a ring of bolts. This housing 19 is installed only after the system is set and adjusted; however, a glass window 20 is located i-n-.'th is housing 19 for visual observations of the instruments therewithin.
  • Three nibvement-indicating instruments to hold the three wires 10 extending into the borehole, are mounted upon the outer face of the support disc 18, each being in axial alignment with its respective Wire 10.
  • Each unit is carried in a base tube 21 with the three tubes 21 outstanding from the support disc 18 in .a triangular arrangement, as with the.th reebeing oriented at 120-degree positions from a common axis point.
  • Each tube is secured to the support disc in a socket-like orifice with a short I threaded end of the tube projecting through the disc and being secured thereto by a lock nut.
  • Each base tube 21 also includes a slide bushing 23 at its outer end and a longitudinal slot 24 at an intermediate reach.
  • the bushing 23 is adapted to slidably hold a tubular retainer rod 25 within the base tube 21, and the rod 25 is connected to the wire 10 and is spring loaded to hold the Wire under tension.
  • the movement of this rod 25 with respect to the base tube is indicated by a caliper arm 26 which is secured to the rod 25 as by a connecfiing screw 28 and outstands from the rod 25 to extend through the slot 24.
  • the caliper arm 26 carries an insertion core 22a of an electric transducer 22 of any conventional type capable of measuring small deflections. This transducer is mounted upon a longitudinally disposed flange k attached to the base tube 21, the mounting being in a slot in the flange to permit longitudinal adjustments of the'transducer 22.
  • the attachment of the transducer to flange k is as by a bolt m which extends through the flange slot and also supports a dial gage 29, the pin 29a of the dial gage abutting against the caliper arm 26 above th c'jonnection of the core 22a. It follows that the dial gage 29 and transducer 22 will both record movement of the arm 26 and that both will be adjusted and zeroed simultaneously by movement of the bolt m in the slot of flange k. V
  • Each retainer rod 25 extends through and beyond the base tube 21, and its outer end is threaded as at 30 to receive holding and locking nuts 31.
  • a helical compression spring 32 is positioned upon the rod 25 between the end of the base tube 21 and the nuts 31, whereby the spring 32 urgesthe retainer rod outwardly to pull the wire 10 attached to it.
  • the wire extends through the retaining rod and is connected to an outer clamp 34 which also includes an abutmerit which is screwed into position in a threaded socket at the outer end of the rod, the two clamps 33 and 34 providing a secure anchorage for the wire when it is held under a substantial tension.
  • An electrical signal wire 35 extending through the housing 19 connects the electrical transducers 22 to the readout device 36, and in the installation of theelectrical circuits, it is to be noted that the housings and electrical lines may be suitably insulated and protected from weather and other factors.
  • the illustrated arrangement of the apparatus is capable of determining the movement in the borehole at positions I, II or III With respect to the abutment a at the mouth of the borehole.
  • the wires 10, anchored in the borehole at separate positions, and secured to individual movement indicators, operate independently of each other. Iridividual readings can be taken by means of a switchingunit, not shown, which switches each circuit 35 into the readout unit 36 in a selected sequence. Multiple readout units 36 or a multiple channel readout unit 36 may also be used to permitsimultaneous readings. Direct reading of the movement of the end of a wire at the mouth oa hole is also possible, for the dial gages 29 can be observed through the window 20. The measuring accuracy of the dial gages is between 0.1 and 0.01 millimetenThe use of an electrical transducer of a suitable type permits an accuracy of 0.0025 millimeter, and such sensitivand precise measurements can be made continuously if desired.
  • the mechanism formed in accordance with the invention may be substantially air-tight if desired.
  • the housing 19 may be insulated to protect the apparatus from temperature changes at the mouth of the borehole where the apparatus is exposed.
  • the expansion or contraction effect due to temperature changes to the portion of the apparatus extending outwardly from the flange 18 will not be significant, for that portionof the syste'rn is self-compensating insofar as wedge locks 53 which may be mounted in suitable inclined grooves about the periphery of the anchor 52.
  • the wires 10 are connected to or pass through this anchor in substantially the same manner as heretofore described.
  • a disc 56 includes a suitable orificef'for the end of a wire 10 to extend therethrough and be held in a lock 59 and another orifice to hold a button fwhere another wire extends completely through the anchor" for connection with an anchor deeper in the hole.
  • the observed movement of a wire 10 at the mouth of a hole is not the true measurement of the movement of the anchor within the hole with respect to the" abutment position.
  • the wire 10 and the spring 32 function in unisonlas components of a single elastic system, and where a long .wire is used, such as 100 meters, the wire may be cornparatively more flexible than the spring. Accordingly, the movement readings obtained by the dial gage and by the transducer 22 must be corrected to determine the true distance movement of a point within the borehole with respect to the abutment.
  • Apparatus for measuring rock movement in a borehole comprising: an anchor means adapted to be secured in the borehole at a selected position therein and to hold the end of a wire; a small-diameter stretchable wire secured to the anchor means and adapted to extend to the mouth of the borehole; an abutment at the mouth of the borehole; a base member carried upon the abutment traversing the mouth of the borehole; a base tube-outstanding from the base member and being axially aligned with the wire extending therethrough; a retainer rod telescopically slideable within the base tube, extending outwardly therefrom with the inner end thereof connecting with the wire; a helical spring telescopically embracing the outward end portion of the retainer rod having its inner end abutting against the base tube and its outer end connected to the end of the rod, said spring being thereby held in compression and biased away from the -borehole; means for connecting the wire With the anchor means with sufiicient tightness to stretch the

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geophysics And Detection Of Objects (AREA)
US417741A 1963-12-23 1964-12-11 Borehole extensometer Expired - Lifetime US3483745A (en)

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Application Number Priority Date Filing Date Title
AT1033263A AT255146B (de) 1963-12-23 1963-12-23 Verfahren und Vorrichtung zum Messen von Längenänderungen in Gebirgen

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Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3635076A (en) * 1969-07-29 1972-01-18 Carnegie Inst Of Washington Strain-sensing device
US4159641A (en) * 1974-09-03 1979-07-03 The United States Of America As Represented By The Secretary Of The Interior Vibrating wire stress meter
US4291581A (en) * 1980-05-01 1981-09-29 Jacoby Charles H Monitoring earth/rock movements
US4327590A (en) * 1978-12-21 1982-05-04 Gesellschaft Zur Forderung Der Forschung An Der Eidgenossischen Technischen Hochschule Method and apparatus for determining shifts at terrain and in structures
US4382335A (en) * 1981-06-09 1983-05-10 The United States Of America As Represented By The United States Department Of Energy Head assembly for multiposition borehole extensometer
US4542655A (en) * 1984-05-09 1985-09-24 University Of Alabama Borehole stress-meter and method and apparatus for the installation thereof
WO1986006830A1 (en) * 1985-05-13 1986-11-20 University Of Alabama Borehole stress-meter and method and apparatus for the installation thereof
EP0188798A3 (en) * 1985-01-24 1987-12-23 Gesellschaft Zur Forderung Der Industrieorientierten Forschung An Den Schweizerischen Hochschulen Und Weiteren Institutionen Method for the assembling of a tubing for measuring purposes
US4719803A (en) * 1987-04-20 1988-01-19 Roctest Ltee/Ltd. Borehole extensometer for monitoring relative mass displacements
US5377548A (en) * 1990-04-23 1995-01-03 Universite De Sherbrooke Method of instrumenting an already erected concrete structure and the so-instrumented structure
RU2193658C2 (ru) * 2000-04-11 2002-11-27 Государственный научно-исследовательский институт горной геомеханики и маркшейдерского дела - Межотраслевой научный центр (ВНИМИ) Устройство для определения деформаций массива горных пород
RU2272993C1 (ru) * 2004-10-04 2006-03-27 Борис Петрович Агудалин Устройство для определения смещений слоев горных пород или элементов инженерно-строительных сооружений
RU2376470C1 (ru) * 2008-07-24 2009-12-20 Государственное образовательное учреждение высшего профессионального образования "Санкт-Петербургский государственный горный институт имени Г.В. Плеханова (технический университет)" Устройство для измерения деформации шпуров
US10925812B2 (en) 2011-03-24 2021-02-23 Amorepacific Corporation Urethane foam for use in impregnating cosmetic composition

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU163770A1 (ru) * Прибор для контроля за осадкой кровли
US1661718A (en) * 1927-02-02 1928-03-06 Donald C Davis Hardness-testing device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU163770A1 (ru) * Прибор для контроля за осадкой кровли
US1661718A (en) * 1927-02-02 1928-03-06 Donald C Davis Hardness-testing device

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3635076A (en) * 1969-07-29 1972-01-18 Carnegie Inst Of Washington Strain-sensing device
US4159641A (en) * 1974-09-03 1979-07-03 The United States Of America As Represented By The Secretary Of The Interior Vibrating wire stress meter
US4327590A (en) * 1978-12-21 1982-05-04 Gesellschaft Zur Forderung Der Forschung An Der Eidgenossischen Technischen Hochschule Method and apparatus for determining shifts at terrain and in structures
US4291581A (en) * 1980-05-01 1981-09-29 Jacoby Charles H Monitoring earth/rock movements
US4382335A (en) * 1981-06-09 1983-05-10 The United States Of America As Represented By The United States Department Of Energy Head assembly for multiposition borehole extensometer
US4542655A (en) * 1984-05-09 1985-09-24 University Of Alabama Borehole stress-meter and method and apparatus for the installation thereof
US4739652A (en) * 1985-01-24 1988-04-26 Gesellschaft zur Forderung der industrieorientierten Forschung an den Schweizerischen Hochschulen und weitern Institutionen Method of, and tubing and support apparatus for, arranging a tubing assembly for measuring purposes
EP0188798A3 (en) * 1985-01-24 1987-12-23 Gesellschaft Zur Forderung Der Industrieorientierten Forschung An Den Schweizerischen Hochschulen Und Weiteren Institutionen Method for the assembling of a tubing for measuring purposes
WO1986006830A1 (en) * 1985-05-13 1986-11-20 University Of Alabama Borehole stress-meter and method and apparatus for the installation thereof
US4719803A (en) * 1987-04-20 1988-01-19 Roctest Ltee/Ltd. Borehole extensometer for monitoring relative mass displacements
US5377548A (en) * 1990-04-23 1995-01-03 Universite De Sherbrooke Method of instrumenting an already erected concrete structure and the so-instrumented structure
RU2193658C2 (ru) * 2000-04-11 2002-11-27 Государственный научно-исследовательский институт горной геомеханики и маркшейдерского дела - Межотраслевой научный центр (ВНИМИ) Устройство для определения деформаций массива горных пород
RU2272993C1 (ru) * 2004-10-04 2006-03-27 Борис Петрович Агудалин Устройство для определения смещений слоев горных пород или элементов инженерно-строительных сооружений
RU2376470C1 (ru) * 2008-07-24 2009-12-20 Государственное образовательное учреждение высшего профессионального образования "Санкт-Петербургский государственный горный институт имени Г.В. Плеханова (технический университет)" Устройство для измерения деформации шпуров
US10925812B2 (en) 2011-03-24 2021-02-23 Amorepacific Corporation Urethane foam for use in impregnating cosmetic composition

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AT255146B (de) 1967-06-26

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