US3222872A - Method of strengthening and sealing rock - Google Patents

Method of strengthening and sealing rock Download PDF

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Publication number
US3222872A
US3222872A US107175A US10717561A US3222872A US 3222872 A US3222872 A US 3222872A US 107175 A US107175 A US 107175A US 10717561 A US10717561 A US 10717561A US 3222872 A US3222872 A US 3222872A
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United States
Prior art keywords
rock
sealing
holes
medium
binding
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Expired - Lifetime
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US107175A
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English (en)
Inventor
Langefors Ulf Marten
Brannfors Sten Harald
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Nitroglycerin AB
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Nitroglycerin AB
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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
    • E21D9/001—Improving soil or rock, e.g. by freezing; Injections

Definitions

  • the present invention relates to the strengthening and/ or tightening, or sealing of rock by so-called injection or spreading of a binding or sealing medium either in cracks or faults inside the rock or over parts of a rock surface uncovered by blasting.
  • a binding or sealing medium is usually effected by pumping in some hydraulic cement composition, such as Portland cement slurry or concrete through drill holes, especially prepared for that purpose.
  • some hydraulic cement composition such as Portland cement slurry or concrete
  • drill holes especially prepared for that purpose.
  • the injection medium is, of course, allowed to bind before further work is done on the rock.
  • the present invention has for its main object to con siderably improve the possibilities for effectively spreading injection or sealing materials in order to strengthen and/or seal the rock. According to the invention this improvement is achieved by utilizing the gas pressure from a detonating blasting charge for spreading the binding or sealing medium. Secondarily the temperature rise occurring at the detonation of the explosive can be used to facilitate the distribution of the binding or sealing medium.
  • the invention can be applied both for the injection of a binding or sealing medium in advance and for spreading the medium in direct connection with such blasts which have for their purpose to uncover fresh rock surfaces.
  • the invention supplements or replaces in a very favorable manner the subsequent application of a covering layer mentioned in the introduction, since according to the invention the binding or sealing medium is driven into the cracks in the remaining rock surface with considerable force and thus effectively binds the latter to a considerable depth. Therefore, also in this case, the treatment may be referred to as a kind of injection although a part of the binding or sealing agent will then, of course, 'be lost because some of the agent will become distributed over the surfaces of such blocks or pieces of the rock which are removed by the blast.
  • the application of the invention in direct connection with the removal of rock by blasting may in certain cases advantageously replace the strengthening of the rock by injection before the blasting work is started.
  • a binding or sealing medium in connection with the blasting away of the rock according to the present invention the adhesion of the medium first begins when the cracks are subjected to the pressure of the gases of explosion and are thus expanded, and the subsequent hardening or solidification of the medium generally occurs first when the blasting process has already taken place and the cracks have contracted again. This, however, requires that the hardening or solidifying process take place rapidly.
  • the binding or sealing medium and the blasting charge may each be introduced as separate units into a drill hole, whereupon the blasting charge is caused to detonate, or the binding or sealing medium and the blasting charge may be introduced together into a drill hole as a single unit prepared in advance.
  • the magnitude of the blasting charge must, of course, be adapted to the desired effect, which in case of a preparatory injection may consist solely of the spreading or blowing in of the medium into existing holes and cracks, but it may also include the blasting of communicating cracks between a drill hole and the natural crack formations in the rock, so that the need for a separate blast in the hole before the injection proper is entirely eliminated.
  • the blasting charge can be utilized for positively detaching material from a rock surface while, at the: same time, it causes a spreading of the binding or sealing medium not only over considerable parts of the rock surface exposed by blasting but also into cracks and faults in such surface.
  • the invention may, of course, very well be applied in its primary form together with a fluid injection medium e.g. in the form of a cement slurry or concrete, which should then preferably be of the rapid hardening type.
  • a fluid injection medium e.g. in the form of a cement slurry or concrete, which should then preferably be of the rapid hardening type.
  • a blasting charge to spread a hydraulic binding medium such as cement also in a pulverulent form.
  • the medium may, if desired, be compressed beforehand into a solid body or briquette which is pulverized during the explosion in the blasting.
  • a hydraulic binding medium of this kind can then be caused to bind and harden rapidly in the cracks and holes of the rock by the addition of water produced by the detonation of the explosive, or deriving from the natural supply of water which can be counted on from the water veins in the rock itself.
  • the charge itself may be supplemented either by the addition of a water capsule which is split up by the explosion, or by submerging the charge in water before it is inserted into the hole, the water then suitably being absorbed in an ample quantity in a porous paper wrapping, for example, surrounding the binding medium unit itself.
  • the water may, of course, be replaced by some other additional liquid agent which causes binding and hardening.
  • the hydraulic binding medium may be substituted by a partially polymerized synthetic resin composition and the water by a hardener or accelerator to rapidly cause complete polymerization of the same.
  • sealing media in the form of particular, hydrophilized asphalt compositions, thermo-plastics or similar materials, the viscosity of which may be reduced by the heat produced during the explosion, so that the material can easily flow into thin cracks, etc. under the pressure exerted by the gases of explosion.
  • sealing media may, of course, also be shaped into briquettes or solid bodies which are disintegrated by the detonation.
  • FIG. 1 is a sectional elevation taken through part of a rock in which a tunnel is in course of construction by blasting;
  • FIG. 2 shows to an enlarged scale a vertical section through a fragment of a tunnel back or root
  • FIG. 3 is a longitudinal section through a drill hole containing a charge which consists of an explosive and a binding or sealing medium, and
  • FIG. 4 shows a cross-section through another drill hole having inserted thereinto a charge comprising both a dry binding medium, a liquid capsule and a central blasting charge.
  • FIG. 1 shows, on the top lefthand side, a typical example of an injection drill hole 1, through which a binding or sealing medium for local tightening or strengthening of the rock can be injected into a rock portion containing numerous cracks as indicated, in the Vicinity of the lower end of the drill hole.
  • a downwardly directed injection hole of this kind one may advantageously use the most simple form of application of the inventive process which consists in first pouring a certain quantity of fluid concrete or cement slurry into the hole and then submerging into the fluid contents of the hole a blasting charge, which is subsequently fired, so as to both blast apart the walls of the drill hole to establish communication between the hole and the adjacent natural cracks in the rock, and also spread the concrete or cement slurry into the cavities and cracks in the weak part of the rock with considerable force.
  • a fluid medium such as the cement slurry or concrete mass mentioned
  • injection may more suitably be carried out with sealing media in solid or at least plastic form so that the medium may be introduced into the drill hole in pieces of suitable shape to surround the blasting charge proper.
  • a procedure as well as charging the drill hole with a prefabricated composite charge containing both an explosive and a suitable quantity of sealing mass may, of course, always be used for injection irrespective of the location of the drill hole.
  • the tunnel 2 indicated in FIG. 1 is in course of being extended in an upward direction and a series of substantially horizontal drill holes 3 have therefore been provided in that part of the rock which forms the back or roof of the tunnel.
  • charging units preferably prepared in advance and of a type which will be more particularly described hereinafter with reference to FIGS. 3 and 4 are inserted into these drill holes 3.
  • the purpose of these charges is not only to detach material from the tunnel back, but at the same time they should produce a strengthening of the new roof surface in the tunnel uncovered by the blast, by spreading a binding or sealing medium both over considerable parts of the fresh rock surface to be exposed and also into such cracks and cavities in said fresh surface which already exist or are produced as a result of the blast.
  • FIG. 2 shows in an enlarged scale a fragment of a tunnel roof surface newly uncovered by blasting.
  • the thickened radiating lines and contours 4 indicate the surfaces and cracks over which the binding or sealing medium is spread by the charge 5, indicated by dash-and-dot lines.
  • FIG. 3 there is shown in shortened longitudinal section a drill hole 6 with a sealing charge intended for simultaneous blasting away of the rock.
  • This composite charge which is inserted into the hole in the usual manner inside a stemming 7, is in the form of a rod which may, if desired, be assembled from a number of sections, and which consists of an outer tubular casing 8 formed by a binding or sealing medium and an inner core of an explosive substance 9.
  • the two parts 8 and 9 of the charge may, of course, be stored and transported to the working site separately to be assembled to a unit first when inserted into the drill hole, but the parts of the charge may also be combined in a single unit already at the factory producing the explosive.
  • tubular casing 8 may be moulded from a quick-setting hydraulic cement in a dry, powdered state, for example, but compressed to form a kind of briquet (of course without any addition of water).
  • the casing 8 may be moulded of a thermo-plastic resin or a similar composition, such as hydrophilized asphalt.
  • the binding or sealing medium may also be introduced into the drill hole at the working site without being preshaped to tubular bodies.
  • the sealing medium if in the form of a dry cement powder, may be blown or stamped into the drill hole and the filling or plug formed thereby be hollowed to receive the explosive charge.
  • Stamping and hollowing may, of course, also be used in connection with binding or sealing media in plastic form, and is sometimes the most convenient method, the more since it is not absolutely necessary to locate the explosive substance 9 centrally in the filling or tube of the sealing agent. In certain cases an eccentric location of the explosive may even be advantageous in order to produce a more controlled distribution of the binding or sealing material in certain predetermined directions.
  • the seal forming material to be spread out should be distributed as evenly as possible longitudinally of that part of the drill hole which is intended to receive the explosive. This is the reason why a substantially tubular body of sealing medium is preferred but on the other hand, if such moulding of the medium is not desirable, for instance because it would be rather expensive, one may equally well use an explosive charge divided into several pieces and place the sealing medium between such pieces spaced in the drill hole.
  • FIG. 4 shows a slightly modified type of composite charge in a drill hole 10, this latter charge consisting of a central core 11 of an explosive substance surrounded by a capsule 12 containing a liquid such as water and a tubular outer casing 13 of a binding medium, such as a hydraulic cement in dry form.
  • the liquid capsule 12 may be constructed of a plastic material or the like for example, and it is, of course, intended to burst at the blast so that the liquid therein mixes with the dry cement derived from the outer casing 13 disintegrated by the explosion.
  • a method of creating a layer of sealing material across a broad area of an earth formation comprising:
  • said predetermined distance between said holes being such that the pressure created by detonation of said explosive material is sufiicient to form interconnecting fractures between said holes and distribute said sealing material throughout said fractures between said holes, whereby a practically continuous layer is formed across the earth formation by said sealing material.
  • a method of blasting to expose a broad area of earth formation and simultaneously seal the surface thereof comprising:
  • said predetermined distance between said holes being such that the pressure created by the detonation of the explosive material is sufficient to break away the unwanted formation and distribute a practically continuous layer of sealing material on the face of the formation between the holes, whereby the exposed surface of the formation is sealed by said sealing material.
  • a method of blasting to expose a broad area of rock formation and simultaneously strengthen the surface thereof comprising:
  • said predetermined distance between said holes being such that the pressure created by the detonation of the explosive material is sufiicient to break away the unwanted formation and distribute said strengthening medium into cracks adjoining the remaining face between the holes, whereby the exposed surface of the formation is strengthened by said sealing material.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Soil Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Drilling And Exploitation, And Mining Machines And Methods (AREA)
  • Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
US107175A 1960-05-05 1961-05-02 Method of strengthening and sealing rock Expired - Lifetime US3222872A (en)

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SE04474/70A SE358690B (forum.php) 1960-05-05 1960-05-05

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GB (1) GB951959A (forum.php)
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3397756A (en) * 1965-07-29 1968-08-20 Du Pont Reduction of explosive shock and noise by dispersion of water particles
FR2077626A1 (forum.php) * 1970-01-29 1971-10-29 Mawhood Eric
US4370077A (en) * 1980-08-04 1983-01-25 Colgate Stirling A Method of pressurizing and stabilizing rock by periodic and repeated injections of a settable fluid of finite gel strength
EP0131678A1 (de) * 1983-02-26 1985-01-23 MC-Bauchemie Müller GmbH & Co. Verfahren zum Verfestigen von Bodenformationen durch Bodenverdichtung
CN114059605A (zh) * 2020-07-31 2022-02-18 国网河南省电力公司新密市供电公司 电力塔基础沉降注浆修复方法

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US442678A (en) * 1890-12-16 Method of blasting
US748935A (en) * 1904-01-05 Blasts n g-cartridge
US1480674A (en) * 1921-03-07 1924-01-15 Diescher & Sons S Drilling wells
US1592104A (en) * 1922-08-26 1926-07-13 Hallvarson Peter William Lining device
US1734670A (en) * 1923-09-05 1929-11-05 Haskell M Greene Means for cementing oil, gas, and water wells
US1934701A (en) * 1931-01-31 1933-11-14 Charles R Edwards Method and apparatus for cementing
US1987958A (en) * 1932-02-16 1935-01-15 Deutsche Werke Kiel Ag Method and means for filling in concrete, rocks, and the like
US2229264A (en) * 1938-03-10 1941-01-21 Louis S Wertz Process of densifying concrete structures
US2627169A (en) * 1946-07-15 1953-02-03 Koehring Co Method of producing stabilization in soil masses
US2689008A (en) * 1951-06-15 1954-09-14 Standard Oil Dev Co Method for cementing wells
US2718264A (en) * 1951-07-25 1955-09-20 Exxon Research Engineering Co Method of squeeze cementing in cased boreholes
US2911046A (en) * 1956-07-05 1959-11-03 William J Yahn Method of increasing production of oil, gas and other wells
US3108443A (en) * 1959-07-07 1963-10-29 Schucrmann Fritz Method of fixing anchor bolts in the drill holes

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US442678A (en) * 1890-12-16 Method of blasting
US748935A (en) * 1904-01-05 Blasts n g-cartridge
US1480674A (en) * 1921-03-07 1924-01-15 Diescher & Sons S Drilling wells
US1592104A (en) * 1922-08-26 1926-07-13 Hallvarson Peter William Lining device
US1734670A (en) * 1923-09-05 1929-11-05 Haskell M Greene Means for cementing oil, gas, and water wells
US1934701A (en) * 1931-01-31 1933-11-14 Charles R Edwards Method and apparatus for cementing
US1987958A (en) * 1932-02-16 1935-01-15 Deutsche Werke Kiel Ag Method and means for filling in concrete, rocks, and the like
US2229264A (en) * 1938-03-10 1941-01-21 Louis S Wertz Process of densifying concrete structures
US2627169A (en) * 1946-07-15 1953-02-03 Koehring Co Method of producing stabilization in soil masses
US2689008A (en) * 1951-06-15 1954-09-14 Standard Oil Dev Co Method for cementing wells
US2718264A (en) * 1951-07-25 1955-09-20 Exxon Research Engineering Co Method of squeeze cementing in cased boreholes
US2911046A (en) * 1956-07-05 1959-11-03 William J Yahn Method of increasing production of oil, gas and other wells
US3108443A (en) * 1959-07-07 1963-10-29 Schucrmann Fritz Method of fixing anchor bolts in the drill holes

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3397756A (en) * 1965-07-29 1968-08-20 Du Pont Reduction of explosive shock and noise by dispersion of water particles
FR2077626A1 (forum.php) * 1970-01-29 1971-10-29 Mawhood Eric
US4370077A (en) * 1980-08-04 1983-01-25 Colgate Stirling A Method of pressurizing and stabilizing rock by periodic and repeated injections of a settable fluid of finite gel strength
EP0131678A1 (de) * 1983-02-26 1985-01-23 MC-Bauchemie Müller GmbH & Co. Verfahren zum Verfestigen von Bodenformationen durch Bodenverdichtung
CN114059605A (zh) * 2020-07-31 2022-02-18 国网河南省电力公司新密市供电公司 电力塔基础沉降注浆修复方法

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SE358690B (forum.php) 1973-08-06
GB951959A (en) 1964-03-11

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