US3397756A - Reduction of explosive shock and noise by dispersion of water particles - Google Patents

Reduction of explosive shock and noise by dispersion of water particles Download PDF

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US3397756A
US3397756A US475719A US47571965A US3397756A US 3397756 A US3397756 A US 3397756A US 475719 A US475719 A US 475719A US 47571965 A US47571965 A US 47571965A US 3397756 A US3397756 A US 3397756A
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noise
explosive
chamber
charge
water
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US475719A
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English (en)
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Alday B Andrews
David L Coursen
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EIDP Inc
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EI Du Pont de Nemours and Co
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Priority to US475719A priority Critical patent/US3397756A/en
Priority to GB33717/66A priority patent/GB1130991A/en
Priority to FR71329A priority patent/FR1488000A/fr
Priority to DE19661571276 priority patent/DE1571276A1/de
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42D—BLASTING
    • F42D5/00—Safety arrangements
    • F42D5/04—Rendering explosive charges harmless, e.g. destroying ammunition; Rendering detonation of explosive charges harmless
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
    • B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
    • B21D26/06—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure by shock waves
    • B21D26/08—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure by shock waves generated by explosives, e.g. chemical explosives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K20/00—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
    • B23K20/06—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating by means of high energy impulses, e.g. magnetic energy
    • B23K20/08—Explosive welding
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42D—BLASTING
    • F42D5/00—Safety arrangements
    • F42D5/04—Rendering explosive charges harmless, e.g. destroying ammunition; Rendering detonation of explosive charges harmless
    • F42D5/055—Silencing means for blasting operations

Definitions

  • the prior art also discloses noise-reducing structures which attenuate noise created by detonation of an explosive contained therein.
  • Such structures are enclosures which can be reused a great many times. Said structures not only confine missiles but also reduce the noise created by detonations to a level which is not objectionable in the space outside said structure.
  • a distinguishing characteristic of detonation as a noise source is the exceedingly high rate of reaction and the almost instantaneous generation of a sharp shock front and intense sound pulses, as compared with defiagration reactions which, relatively, are much slower combustion or burning processes.
  • the noise source is at the point of detonation, whereas deflagr'ations inherently are low in noise level until the pressure built up over a relatively long reaction period by combustion reactions suddenly is released, as by deliberate venting or by acciden al rupture of the container. with the generation of a sharp intense sound pulse, perhaps 'at an objectionable or hazardous level.
  • Gas-venting means employed in structures of the prior art preferably are fixed, gas-type mufilers which provide 'a tortuous path for the explosion gases as they pass out of the structure to the space outside.
  • Noise reducing structures of the type described above for use with detonating explosives are both practical and effective in mufiiing noise created in small-scale testing work, for example with less than pounds of detonating explosive, and in explosion-powered metalworking operations carried outwith similar quantities of explosives. Indeed, the principles disclosed for design of said noise-reducing structures also are applicable for much larger structures which, however, required very massive pressu-reand shock-resistant steel walls which are both difiicult and costly to construct, operate, and maintain.
  • the cladding of large metal plates entails the use of relatively large quantities of detonating explosive. Detonation of charges of hundreds or even thousands of pounds of high explosive on a repetitive basis for the cladding of large metal plates by the aforementioned explosioncladding process may be carried out in the open in a sparsely populated, isolated location where the shock and noise created ⁇ by said detonations is not objectionable. As a practical matter, however, the transport of men, materials, and equipment to and from such a suitably isolated area is impracticable because it is time consuming and excessively costly.
  • the need for quantities of massive metal plates of clad construction can be satisfied practically and economically only by use of a suitable noise-controlling, explosion-cladding facility located near both the sources of supply of the metal plates to be clad and the mechanical shops where said plates can be prepared for cladding and for processing after cladding.
  • the cladding facility also will be reasonably close to the shops in which the clad plates are to be fabricated into equipment.
  • This invention provides a simple, effective and inexpensive means for reducing the shock and noise caused by detonation of explosives.
  • the structures of this invention can repeatedly mufile noise and shock of large masses of explosives without significant damage thereto.
  • the process of this invention is a process for reducing the shock and noise caused by detonation of a main explosive charge which comprises interposing a body of finely divided particles of water in the path of the shock wave from said main charge, said water being propelled into said path by a dispersing explosive charge spaced apart from the main charge.
  • the noise-reducing structure provided in accordance with this invention, and in which the process of this invention preferably is practised, comprises a stable subterranean chamber, a tunnel connecting said chamber to a portal, at least one body of water disposed in said tunnel, and at least one explosive charge positioned to disperse said water in said tunnel.
  • the portal of the tunnel is provided with a massive movable closure, preferably having a mass of at least about 100 tons.
  • the process of this invention can be used to shield any detonation and is not limited to subterranean operations.
  • a charge the detonation of which is to be shielded, can be surrounded with a quiescent annulus of water with at least one explosive charge positioned therein. Detonating the dispersing charge in the water annulus creates an annular body of dispersed water particles that dissipates, modifies and reduces the harmful and destructive effect of the shock wave passing therethrough.
  • the process is carried out in a subterranean cavity wherein the explosively generated water dispersion modifies the shock wave emanating from the cavity, preferably to reduce the sound level to below 130 decibels at any position 400 feet or more from the cavity portal.
  • the amount of water which must be dispersed in the path of the shock wave to be muffled increases with the amount of mufiling desired and with that part of the emanating shock wave which is to be blocked by the water dispersion as contrasted with other means, e.g., in subterranean shooting, by overburden.
  • the minimum amount of water is that necessary to effect the muffiing desired while, as a practical matter, the maximum is that for which the charge required for dispersal causes a shock no greater than the muffled shock wave from the main detonation.
  • the amount of water dispersed is about from to 100 times the weight of explosive detonated in the main charge.
  • the water is explosively dispersed by a dispersing charge.
  • the minimum charge is that necessary to get the dispersion, hence the muffling, desired while, for practical purposes, the maximum is that which creates a shock wave no greater than the muffled main shock wave.
  • a dispersing charge of one pound of explosive for about from 100 to 15,000 pounds of water is used.
  • a preferred amount is about one pound of an explosive for each 1500 pounds of water.
  • the dispersed water preferably should occupy a substantial volume and usually be disposed at least 10 .feet along the path of the main shock wave. Also, for optimum dispersion, the dispersing explosive charge should be distributed through the body of water.
  • an elongated body e.g., a trough or large easily fractured tube of water along one or both sides of the tunnel leading to the portal.
  • the dispersed water is positioned apart from the main explosion, for example, to 200 feet therefrom depending on the type of shooting involved.
  • the dispersing explosion is timed to occur shortly prior to passage of the shock wave generated by detonation of the main charge so that maximum dispersion of water is achieved at the time of passage of said main shock wave.
  • said noise similarly may be muffied by forming a second and smaller mass of dispersed water positioned between said first mass and the observation point.
  • the dispersing charge furthest from the main charge create a shock Wave no greater in intensity than that of the shock wave from the preceding charges which it mufiles, i.e., the shock wave from the main charge and any preceding dispersing charges.
  • FIGURE 1 is a view in sectional elevation of a subterranean noise-reducing structure of the present invention
  • FIGURE 2 is a plan view of a subterranean noise reducing structure of FIGURE 1, and FIGURE 2A is an enlarged cross-sectional elevation of the tunnel portion of the structure of FIGURES l and 2 at position A-A.
  • FIGURE 3 is an enlarged side view of a movable plug closure as shown in FIGURE 1;
  • FIGURE 4 is an end view of the movable plug closure shown in FIGURES l and 3.
  • FIGURE 5 is an enlarged plan view of a movable plug supported on two railroad gondola cars.
  • FIGURE 6 is a graph relating chamber diameter to mass of explosive to be detonated therein, as described hereinbelow.
  • FIGURE 1 is a cross-sectional elevation of one embodiment of a structure of the present invention and certain appurtenances thereto, 1 represents a substantially homogeneous natural rock mass, for example, a granite gneiss; 2 is a stabilized subterranean chamber, as defined herein, excavated from and surrounded by rock mass 1; 3 is a mass of sand placed on the fioor of chamber 2 substantially in the center of the floor area; 4 is a metal plate resting on said mass 3 in a position ready for cladding; 5 is a tunnel connecting chamber 2 to portal 7 which provides entry to tunnel 5; 6 is a trench in the floor of tunnel 5, designed to be filled with water, and positioned along the wall of tunnel 5 inside portal 7, which is fitted with rib-reinforced steel arch and liner 8 which, in turn, is anchored in place by steel roof bolts 9 and cement grout fill (not shown) between ribbed arch 8 and the wall
  • FIGURE 2 is a plan view of a noise-reducing structure of the present invention and certain appurtenances thereto wherein the numbered parts have the same significance as in FIGURE 1 above.
  • FIGURE 3 is an enlarged side view of movable plug 11 mounted on gondola cars 13 and rail trucks 14, wherein flange 18 is shown between the body of movable plug 11 and its gasketed tongue 12.
  • FIGURE 4 is an end view of plug 11 showing flange 18, gasketed tongue 12, supporting and reinforcing structural steel members 19, and the ends of rails 16 which support said cars and movable plug assembly.
  • FIGURE 5 is an enlarged plan view of the assembly of movable plug 11 and gondola cars 13 mounted on rail trucks 14.
  • the subterranean chamber, e.g., 2 in FIGURE 1, of the noise-reducing structure of the present invention must retain its structural size and shape after repeated detonation of explosives therein. If the walls, floor, and ceiling are damaged or portions thereof are loosened or dislodged by one or more blasts, the chamber in an extreme case may be subject to catastrophic collapse, or at least it may become hazardous for further use, for example, due to the danger of rock falls on personnel, on equipment, and on the explosive charges or assemblies placed within said chamber. That is to say, the chamber must retain its structural integrity throughout a period of continued use. Such a chamber is designated herein as a stable subterranean chamber.
  • the stability of the chamber will be related to the physical characteristics of the material surrounding the chamber, to the properties of the explosive charge to be detonated therein, to the size of the chamber with respect to the energy of the detonating explosive, and to the placement of the explosive charge with respect to the walls of the chamber.
  • Critical stresses as used herein are stresses produced by explosiomgenerated pressure pulses above which non-elastic effects including plastic flow, crushing and cracking of rock occur.
  • the pressure pulse propagates through the medium without fracturing it, the pressure pulse being absorbed and dispersed in the surrounding medium.
  • the decoupling ratio for a spherical charge in a spherical cavity can be estimated from the equation:
  • R p C D V37 RQ 401 wherein D is the decoupling ratio, R is the cavity radius, R is the charge radius, p is the density of the rock, o is the velocity of sound in the rock, D is the detonation velocity of the explosive, a is the tensile failure stress of the rock, and 'y is the ratio of specific heat of the detonation products at constant pressure to that at constant volume.
  • the stabilized chamber in a structure of the present invention need not be spherical in shape. If the mass of explosive is distributed over a planar area, as exemplified in the process of US. Patent 3,137,937, said chamber 2 of FIGURE 1 will be a room having a substantially rectangular floor of length and width proportional to the areal dimensions of the largest explosive charge to be detonated therein, and a domed ceiling of such height as to exceed the design radius determined in the manner described hereinbefore.
  • the size of the chamber or cavity also varies with the particular explosive used, usually it falls Within 20% of that calculated for dynamite as illustrated in FIGURE 6, being lower for low velocity, lower weight-strength, less brisant explosives and higher for high-velocity brisant explosives such as torpex.
  • the mass of granite rock surrounding said subterranean chamber generally should be at least three times as thick as the chamber diameter, and for limestone about 1% times as thick, for the largest masses of explosive to be detonated in said chamber of a noise-reducing structure of this invention.
  • the mass of rock may be much thicker, and in addition usually is overlayed with a burden of rubble, soil and vegetation.
  • the metal-cladding assembly with explosive charge in place is supported on a bed of sand 3 in FIG- URES 1 and 2, about 12" thick and approximately in the center of the floor area of chamber I.
  • Said sand when smoothly leveled, provides a uniform support for metal plate-cladding assemblies placed thereon, and also protects the chamber floor from damage due to repeated blasts.
  • the center of mass of the explosive charge will be no closer to the chamber side wall and ceiling than the design cavity radius determined as described hereir1- before. It will be apparent that the design principles which govern the shape and size of a structure of the present invention also establish the maximum explosive charge which permissibly is detonated within said structure,
  • the second element in the preferred structure of the present invention is a passageway or tunnel leading from said subterranean chamber 2 to the entrance portal 7 in attached FIGURE 1.
  • the minimum length of the tunnel is established by the requirements for chamber overburden, i.e., the length of said tunnel must be great enough to provide at least the minimum thickness specitied hereinabove for the mass of rock which surrounds said subterranean chamber.
  • the tunnel Will be of greater than minimum length. Practically, the length of the tunnel will be governed by the topography of the area and will be limited by the high cost of driving excessively long tunnels and providing service facilities thereto.
  • the tunnel is of such width and height as to permit easy transport of materials into chamber 2, but the width and height of said tunnel generally will be less than the width and height of said chamber.
  • an irregular surface of said tunnel wall is preferred. The irregularities serve to attenuate the shock waves, especially those which are reflected from the face of plug 11 back to the rear chamber wall, and are then re-refiected to portal 7. Such wall roughness need not exceed of the tunnel diameter.
  • the tunnel floor generally will be approximately level and on grade with the floor of chamber 2, and may be equipped with rails for rail transport of materials, may contain electric power service lines, firing lines, instrument lines, ventilation ducts and the like, none of which are shown in the appended figures.
  • Water is preferably dispersed in tunnel 5.
  • trenches 6 are positioned longitudinally in the floor of tunnel 5, preferably at the sides thereof, as illustrated in FIGURES 2 and 2A.
  • Said trenches serve as containers for water which is explosively dispersed substantially coincidentally with the detonation of the mass of explosive in chamber 2 of a structure of this invention.
  • the trenches will have a capacity of about 3000 gallons of water for large blasts, say 1200 pounds of high explosive, in a structure of this invention. Less water will be required for smaller amounts of explosive.
  • the water is dispersed within a segment of the tunnel volume by the detonation of explosive cord, or, alternately small charges spaced along the water to be dispersed, e.g., every 3 or 4 feet.
  • the amount of explosive charge, based on the explosive therein, is within the ranges previously indicated.
  • water may be contained in flexible plastic tubes which rest on the floor over suitable lengths of detonating cord which will rupture said containers and disperse the water contained in said plastic bags.
  • Other containers such as long troughs may be used, but may be subject to mechanical damage from blast effects.
  • Mechanical means of providing a massive spray generally provide inadequate dispersion of the large amount of water in the short interval of time most suitable for noise control in the structure and by the method disclosed herein.
  • Tunnel 5 of FIGURES 1 and 2 and 2A terminates in portal 7.
  • This portal may be cut in the solid massive rock if said rock is unfractured. If the rock surrounding the portal is not homogeneous and sound, the portal is reinforced by a steel arch or lining 8 bolted and grouted into place as shown in FIGURE 1.
  • the portal, or steel liner thereof, will have as its outer periphery a lip 10 extending from top to floor level, said lip mating with the tongue 12 of movable plug closure means 11 when said plug is moved into closure position against portal 7.
  • a preferred element in a noise-reducing structure of this invention is a closure means for the tunnel.
  • Closure may be achieved by mounting a blast door across the inner end of the tunnel and supporting it by the chamber walls, or by a blast door positioned across the tunnel at a point intermediate the chamber and the portal, and by providing a suitable auxiliary passageway for exit of the gases generated by explosion of the metal-cladding explosive charge in chamber 2.
  • a preferred clousure means is a movable plug 11 in FIGURE 1 which also is shown in more detail in FIGURES 1, 2, 3, 4, and 5, wherein the numbers correspond to the parts identified hereinbefore.
  • plug 11 In use, after placing the explosive charge in chamber 2 of FIGURE 1, plug 11 is moved into place so that the gasketed surface of tongue 12 makes firm contact with lip 10 of arch 8, the brakes on the railway trucks 14 are firmly set by pneumatic pressure, or hydraulic pressure, applied by a conventional brake cylinder. Any small opening remaining at the bottom of the portal below the movable plug 11 is closed by banking plastic bags of water, earth, sand, or like particulate material in the free space below said plug. Closure of the portal area must be at least complete, and preferably will be greater than 97% complete.
  • the explosive charge 4 is fired conventionally by use of electric blasting caps or by detonating fuse initiated from outside the plugged tunnel.
  • a noise-reducing structure of the instant invention must be much more effective for a given weight of detonating explosive if the inhabited area is 1,000 feet from said structure than if it is 10,000 feet from said structure.
  • factors related to weather conditions such as wind direction, velocity and temperature variations with altitude, humidity, and topography of the immediate area also affect the intensity of blast waves transmitted to the inhabited sensing area.
  • it is necessary only to know that a given level of noise in the immediate vicinity of a structure of this invention will not be objectionable after transmission, under the most favorable environmental circumstances therefore, to the nearest inhabited area.
  • the process and structure of this invention are particularly illustrated with respect to explosion clad- 9 ding, they are equally well suited for any application in which it is desired to mufiie the detonation of an explosive. Other examples of such applications are explosion forming, hardening and other metal working operations, as well as explosive testing.
  • the process of this invention also advantageously modifies the pressure profil'e of the blast wave in that it is particularly effective irr" removing high frequency sound leaving low frequency components of the blast wave which are much less objectionable.
  • Example I 'A tunnel 300 ft. long is driven into a ridge of granite gneiss.
  • the first 50 ft. of the tunnel has an 8-ft. high x 8-ft. wide cross-section, the next 100 ft. an 8-ft. high x l-ft. wide cross-section, the next 100 ft. similar to the initial section, and the final section, the stabilized firing chamber, has a 16-ft. high x -ft. wide cross-section and a domed ceiling.
  • the trenches 6 on both sides of the tunnel floor along the first 100 feet from portal 7 are filled with water and together hold about 3000 gallons.
  • the explosive system inside the portal 7 comprises ,an electric blasting cap, a SO-ft. length of 2 gr../ft. LEDC (i.e., 2 gr./ft. PETN/ft. of low energy detonating cord- LEDC), an LEDC cross tie connected to two 400 git/ ft.
  • an electric blasting cap i.e., 2 gr./ft. PETN/ft. of low energy detonating cord- LEDC
  • an LEDC cross tie connected to two 400 git/ ft.
  • Example 2 In this example, a 1250 pound charge of -20 amatol explosive is detonated within a structure of'this invention comprising a 300 ft. tunnel in a ridge of granite gneiss.
  • the first 250 ft. has a l2-ft. high x l2-ft. wide cross-section and the final 50 ft. has 14-ft. high x 18-ft. wide crosssection and a domed ceiling.
  • the tunnel has a wall roughness of about 10% of its width. Water for the water spray is contained in two pairs of 16 in. diameter polyethylene
  • Example 3 This example further illustrates the cumulative effects achieved by combination of the several elements of the noise-reducing structure of the present invention.
  • Example 2 The chamber and tunnel are as in Example 2 above, the movable plug closure 11 is as described hereinbefore and shown in the drawings, and the means foriproviding the massive water dispersion are as in Example 2 above.
  • a 500 lb. charge of amatol explosive is fired in each test, the sound measurement being made at the reference point 400 feet from tunnel portal 7.
  • the results of the'sound measurements for each of the test firings are shown in the following table:
  • a process for reducing the shock and noise caused by detonation of a main explosive charge which comprises interposing a body of dispersed water particles in the path of the shock wave from said main explosive charge, said water being propelled into said path by a dispersing explosive charge spaced apart from the main charge.
  • a process for reducing the shock and noise emitted from the portal of a subterranean cavity and caused by detonation of a main explosive charge therein which comprises interposing a body of dispersed water particles in the path of the shock Wave fromsaid main explosive charge as it passes to said portal, said water particles being formed and propelled into said path by a dispersing eX- plosive charge disposed in water placed between said main explosive charge and said portal.
  • a noise-reducing structure which comprises a stable subterranean chamber, a tunnel connecting said chamber to a portal, at least one body of water disposed in said tunnel and at least one explosive charge positioned in said Water to disperse said water in said tunnel.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Drilling And Exploitation, And Mining Machines And Methods (AREA)
  • Excavating Of Shafts Or Tunnels (AREA)
US475719A 1965-07-29 1965-07-29 Reduction of explosive shock and noise by dispersion of water particles Expired - Lifetime US3397756A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US475719A US3397756A (en) 1965-07-29 1965-07-29 Reduction of explosive shock and noise by dispersion of water particles
GB33717/66A GB1130991A (en) 1965-07-29 1966-07-27 Noise reduction
FR71329A FR1488000A (fr) 1965-07-29 1966-07-28 Procédé pour la réduction du bruit résultant de la détonation de charges explosives
DE19661571276 DE1571276A1 (de) 1965-07-29 1966-07-29 Verfahren zur Daempfung des bei der Detonation einer Sprengladung in einem begrenzten Raum entstehenden Schalls

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US475719A US3397756A (en) 1965-07-29 1965-07-29 Reduction of explosive shock and noise by dispersion of water particles

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GB (1) GB1130991A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3638754A (en) * 1970-12-16 1972-02-01 Du Pont Pressure and sound shield for blast excavation of tunnels and the like
US3823793A (en) * 1972-10-02 1974-07-16 Asahi Chemical Ind Semi-sealed silencer structure
US4192553A (en) * 1978-04-03 1980-03-11 Occidental Oil Shale, Inc. Method for attenuating seismic shock from detonating explosive in an in situ oil shale retort
US4201419A (en) * 1978-08-21 1980-05-06 Occidental Oil Shale, Inc. Control of airblast during explosive expansion in an in situ oil shale retort

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9522880D0 (en) * 1995-11-08 1996-01-10 Parkes John H Improvements in and relating to suppressing explosions

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE520488A (de) * 1953-04-10
DE81320C (de) *
US232640A (en) * 1880-09-28 Method of blasting
GB624771A (en) * 1945-11-07 1949-06-16 Anders Henrik Carl Jespersen Method of blowing-up air raid shelters and the like buildings
BE515909A (fr) * 1952-11-29 1952-12-15 Perfecta Porte-bouteilles
US3222872A (en) * 1960-05-05 1965-12-14 Nitroglycerin Ab Method of strengthening and sealing rock

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE81320C (de) *
US232640A (en) * 1880-09-28 Method of blasting
GB624771A (en) * 1945-11-07 1949-06-16 Anders Henrik Carl Jespersen Method of blowing-up air raid shelters and the like buildings
BE515909A (fr) * 1952-11-29 1952-12-15 Perfecta Porte-bouteilles
BE520488A (de) * 1953-04-10
US3222872A (en) * 1960-05-05 1965-12-14 Nitroglycerin Ab Method of strengthening and sealing rock

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3638754A (en) * 1970-12-16 1972-02-01 Du Pont Pressure and sound shield for blast excavation of tunnels and the like
US3823793A (en) * 1972-10-02 1974-07-16 Asahi Chemical Ind Semi-sealed silencer structure
US4192553A (en) * 1978-04-03 1980-03-11 Occidental Oil Shale, Inc. Method for attenuating seismic shock from detonating explosive in an in situ oil shale retort
US4201419A (en) * 1978-08-21 1980-05-06 Occidental Oil Shale, Inc. Control of airblast during explosive expansion in an in situ oil shale retort

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DE1571276A1 (de) 1970-10-15
GB1130991A (en) 1968-10-16

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