Abstract: A formation is blasted with one or more arrays of elongated, chemical, explosive charges so as to produce relatively low levels of ground vibration. The orientation and velocity of propagation of explosion in each charge and the velocity of propagation of vibration in the formation are such that, at a selected outlying location, the onset of vibration from explosion of the first negligably small increment of the charge arrives a finite time before that from explosion of the last negligably small increment. The charges of each array are fired in accurately-timed sequence, with the times between initiations chosen so that, at the outlying location, the onset of vibration from explosion of the last small increment of each charge, except the last charge, arrives a negligably small increment of time before the onset of vibration from explosion of the first small increment of the succeeding charge.

Abstract: A blasting agent is disclosed for use in a borehole having a pressure resistant closure. The blasting agent is used in combination with a primary initiating system comprised of a detonator and an initiator for the detonator. The blasting agent is preferably a semi-fluid explosive material having a predetermined sensitivity. The sensitivity is related to the borehole diameter and the initiating system's strength, wherein the blasting agent upon initiation is transformed into explosive products by means of reaction front which consumes substantially all the blasting agent as the reaction front passes through the blasting agent. The reaction front has an average velocity of propagation of beween 200 meters/second and 1,000 meters/second for at least 30% of the total length of blasting agent located in the borehole. Another aspect of the invention is a method of blasting wherein the average velocity of propagation of the explosive front in the blasting agent is in a range of between 200 m/sec and 1,000 m/sec.

Abstract: A blasting agent is disclosed for use in a borehole having a pressure resistant closure. The blasting agent is used in combination with a primary initiating system comprised of a detonator and an initiator for the detonator. The blasting agent is preferably a semi-fluid explosive material having a predetermined sensitivity. The sensitivity is related to the borehole diameter and the initiating system's strength, wherein the blasting agent upon initiation is transformed into explosive products by means of reaction front which consumes substantially all the blasting agent as the reaction front passes through the blasting agent. The reaction front has an average velocity of propagation of between 200 meters/second and 1,000 meters/second for at least 30% of the total length of blasting agent located in the borehole. Another aspect of the invention is a method of blasting wherein the average velocity of propagation of the explosive front in the blasting agent is in a range of between 200 m/sec and 1,000 m/sec.

Abstract: To prevent the rapid escape of high-pressure explosion gases when an explosive charge is initiated in a borehole, the hole is stemmed with chunks of readily liquefiable and/or vaporizable solid material, preferably chunks of ice and/or chunks of dry ice, piled up one upon the other so as to form a columnar bed of pre-solidified stemming material. The column remains in place during the explosion, and thereafter disappears by melting and/or subliming on absorbing heat from the surrounding formation. A preferred stemming column comprises a combination of ice chunks and chunks of dry ice, e.g., wherein the ratio of dry ice to ice in the column decreases with distance from the explosive charge.

Abstract: An apparatus for injecting a lubricating liquid, e.g., water, into a conduit as an annular layer around a flowing Bingham solid, e.g., a water gel or water-in-oil emulsion explosive, to facilitate the flow of the Bingham solid has an annular passageway from which the lubricating liquid flows into a cylindrical chamber containing the flowing Bingham solid. The annular passageway has a constricted throat portion of adjustable width, which, along with the flow rates of the Bingham solid and the lubricating liquid, is adjusted to produce a thin film of lubricant which allows lubricated plug flow of the Bingham solid in a descending section of conduit under the propelling force of gravity alone. Low drag permits the delivery of Bingham solid explosives into very deep vertical holes with no increase in the required pumping pressure.

Abstract: An apparatus for injecting a lubricating liquid, e.g., water, into a conduit as an annular layer around a flowing Bingham solid, e.g., a water gel or water-in-oil emulsion explosive, to facilitate the flow of the Bingham solid has an annular passageway from which the lubricating liquid flows into a cylindrical chamber containing the flowing Bingham solid. The annular passageway has a constricted throat portion of adjustable width, which, along with the flow rates of the Bingham solid and the lubricating liquid, is adjusted to produce a thin film of lubricant which allows lubricated plug flow of the Bingham solid in a descending section of conduit under the propelling force of gravity alone. Low drag permits the delivery of Bingham solid explosives into very deep vertical holes with no increase in the required pumping pressure.

Abstract: Missiles located in the deeper (hard rock) portion of a shaft or tunnel are protected from damage during a nuclear attack by a mass of ice, preferably trumpet-shaped, located in the outermost portion (e.g., 600-900 meters). When missile egress is required, an ice-supported passageway is bored through the ice, preferably by melting. The trumpet shape assures a straight path for missile egress even if the shaft or tunnel should become transversely displaced by a cratering explosion against the surface.

Abstract: Producing a fracture network in deep rock, e.g., in an ore body, by detonating explosive charges sequentially in separate cavities therein, the detonations producing a cluster of overlapping fracture zones and each detonation occurring after liquid has entered the fraction zones produced by previous adjacent detonations. High permeability is maintained in an explosively fractured segment of rock by flushing the fractured rock with liquid, i.e., by sweeping liquid through the fracture zones with high-pressure gas, between sequential detonations therein so as to entrain and remove fines therefrom. Ore bodies prepared by the blast/flush process with the blasting carried out in substantially vertical, optionally chambered, drilled shot holes can be leached in situ via a number of holes previously used as injection holes in the flushing procedure and a number of holes which are preserved upper portions of the shot holes used in the detonation process.

Abstract: A fracture that conducts fluid within the confines of an underground rock formation without the need for particulate proppant materials to hold opposing fracture faces apart is created by a method in which a long portion of a hole drilled into the formation has its axis slanted with respect to the directions of the principal stresses, and is pressurized rapidly over its entire length with fluid, preferably by detonating an explosive therein.A hypothetical fracture plane is defined as that plane containing the axis of the hole which is under the least compressive normal stress. When the orientation of the hole axis is such that there is a substantial shear stress on the hypothetical fracture plane, but the normal stress thereon does not greatly exceed the minimum principal stress, the fracture created lies close to the hypothetical fracture plane, and is conductive to fluids.

Abstract: In a method of anchoring a reinforcing member such as a rock bolt in a hole, e.g., in a mine roof,wherein two separate components of an inorganic cement grouting system are mixed, preferably in the hole, e.g., by the rotation of the reinforcing member, whereby the components react to form a hardened grout around the reinforcing member, the two components of the system delivered into the hole are: (1) a slush or sludgy mass of a particulate inorganic cement, e.g., an hydraulic cement, and a liquid which is nonreactive therewith, preferably a hydrocarbon, and (2) a liquid, e.g., water, which is reactive with the cement; and a particulate aggregate such as sand preferably is present in the cement slush and/or the reactive liquid. The inorganic cement constitutes more than 10 percent, and the weight of any aggregate present is no more than about 80 percent, of the total weight of the two components. The two components preferably are delivered into the hole separately, e.g.