MXPA98001011A - Method and apparatus for controlled explosion of small load of rock and concrete, by explosive pressurization of the fund of a perforated hole - Google Patents

Abstract

Rock and other hard materials, such as concrete, are fragmented by a small-controlled controlled explosion process. The process is done by pressurizing the bottom of a drilling hole, in such a way that a controlled fracture is initiated and propagated, or any previously existing fractures are propagated near the bottom of the hole. A cartridge containing an explosive charge is inserted into the bottom of a short hole drilled into the rock. The explosive charge is configured to provide the desired pressure at the bottom of the hole, including, if desired, a strong discharge tip at the bottom of the hole, to improve microfracturing. The cartridge stops in place or is docked by a massive berthing bar of high strength material, such as steel. The explosive can be started in a variety of ways, including through a conventional electric explosion cap. The cartridge incorporates an additional internal volume designed to control the application of pressure in the volume of the bottom of the hole by the detonation explosive. The primary method by which high-pressure gases are contained in the bottom of the hole to be released through the opening up through controlled fractures, is through the massive inertial berthing bar that blocks the flow of gas rising through the drilling hole, except for a small line of leakage between the berthing bar and the walls of the drilling hole. This small leakage can be further reduced by the design characteristics of the cartridge and the docking bar. The berthing bar is preferably connected to a beam mounted on a carrier. A preferred embodiment incorporates an advancing mechanism to allow both a drill bit and a small charge explosion apparatus to be used on the same beam for drilling and subsequent loading and activation insertion operations. The main characteristics of the method and apparatus are the relatively low energy of projecting small pieces of rock, and the relatively small amount of explosive required to break the river.

Description

METHOD AND APPARATUS FOR CONTROLLED EXPLOSION OF SMALL LOAD OF ROCK AND CONCRETE. MFnta ^ tt: EXPLOSIVE PRESERVATION OF THE DN PUNCH HOLE FUND The present application claims priority of the U.S. Patent Provisional Joint Joint Application Serial Number: 60 / 001,929 entitled "METHOD AND APPARATUS FOR CONTROLLED EXPLOSION OF SMALL ROCK AND CONCRETE LOAD, BY EXPLOSIVE PRESSURIZATION OF A HOLE FUND DE PERFORACIÓN ", presented on August 4, 1995, which is incorporated herein by reference in its entirety. FIELD OF THE INVENTION The present invention relates in general to small loading techniques for excavating rock and other materials and specifically, for using explosives in small charge explosion techniques to excavate massive hard rock and other hard materials. BACKGROUND OF THE INVENTION Rock excavation is a primary activity in the mining, quarry and civil construction industries. There are a number of important needs not covered in these industries related to the excavation of rock and other hard materials. These include: Reduced cost of rock excavation Increased excavation regimes Increased safety and reduced safety costs Better control over the accuracy of the excavation process. Effective method in acceptable excavation cost in urban and environmentally sensitive areas. Drilling and blasting methods are the most commonly used and most generally applicable means of rock excavation. These methods are not suitable in many urban environments due to regulatory constraints. In production mining, drilling and blasting methods are mainly limited in production regimes, while in the discovery of mines and civil tunnels, drilling and blasting methods are fundamentally limited in advancement regimes due to the cyclical nature of the process Large-scale drilling and explosion. Tunnel boring machines are used for excavations that require long, relatively straight tunnels with a circular cross section. These machines are rarely used in mining operations. Roadhead drilling machines are used in mining and construction applications but are limited to moderately hard, non-abrasive rock formations. Mechanical impact breakers are commonly used as a means of breaking rocks exceeded in size, concrete structures and reinforced concrete. The mechanical impact breaker technology has advanced by increasing the energy of the blow and the impact frequency of the impact tool through the use of high-energy hydraulic systems; and through the use of drill bits with high resistance to fracture and great strength for the tool bit. Mechanical impact breakers can be used in almost any workplace arrangement due to the absence of air currents and their relatively low seismic signal. As a general excavation tool, mechanical impact breakers are limited to relatively weak rock formations that have a high degree of fracture. In harder rock formations (unlimited compressive strengths above 60 to 80 MPa), the efficiency of the excavation of the mechanical impact breakers falls rapidly and the wear of the bit of the tool increases rapidly. Mechanical impact breakers can not, on their own, economically excavate an underground surface in massive hard rock formations. Small charge explosions techniques can be used in all rock formations including hard, massive rock formations. Small charge explosions include methods where small amounts of explosive agents are consumed each time, as opposed to conventional perforation and explosion operations involving episodes that involve drilling multiple hole patterns, load the holes with explosive charges synchronizing in milliseconds the explosion of each individual hole in which tens to thousands of kilograms of explosive agent are used. The small charge explosion can produce flying rock dust that is unacceptable to nearby machinery and structures and can generate unacceptable air currents and noise. In addition, small charge explosion techniques can not be used economically to excavate with the required precision frequently. There is then a need for a method and means of breaking rock efficiently and with flying rock dust at low speed so that the drilling, lagging, dragging and ground support equipment can remain on the work surface during the breaking operations. rock. SUMMARY OF THE INVENTION The objectives of the present invention are to provide an excavation technique that is relatively inexpensive, provides high excavation rates, is safe for personnel, offers a high degree of control and precision in the excavation process, and is acceptable in urban and environmentally sensitive areas.

These and other objects are realized by the present invention which is a device for fracturing a hard material, such as massive rock or concrete, which includes; (i) a cartridge; and (ii) a docking element to hold the cartridge in a hole in the material. The cartridge, which is positioned adjacent one end of the docking element, includes: (i) a cartridge base positioned adjacent the end of the docking element; and (ii) an outer housing of the cartridge attached to the base of the cartridge. A first portion of the outer housing of the cartridge contains an explosive and a second portion of space for controlling the pressure of the gas in the hole. The explosive is placed at a distance from the base of the cartridge to dissipate a detonation shock wave generated during the detonation of the explosive. Typically, the base of the cartridge is sacrificed and is not reusable. The space of the explosive from the base of the cartridge and the use of a sacrificial cartridge base allows reuse of the docking element. The device is especially useful in small load explosion applications where relatively light weight weights are employed to cause material breakage. The space to control the gas pressure in the hole prevents over-pressurization of the gas at the bottom of the hole. The volume of the space preferably varies from about 200 to about 500 percent of the volume of the explosive. The base of the sacrificial cartridge is designed to undergo plastic deformation in response to the attenuated shock wave to the docking element. In this way, damage to the docking element is inhibited and the docking element is reusable. The preferential plastic deformation of the base of the cartridge instead of the docking element results from the fact that the base of the cartridge has a lower elastic resistance than the docking element. Preferably the elastic resistance of the base of the cartridge is not greater than about 75 percent of the elastic resistance of the docking element. The base of the cartridge preferably has a thickness of about 1.2 centimeters to about 5 centimeters, a diameter ranging from about 50 to about 250 millimeters, and a length to diameter ratio ranging from about 0.15 to about 0.6. To substantially optimize the fracturing of the material, the explosive is in close proximity to the bottom of the hole. Preferably, the distance of the explosive from the bottom of the hole is not more than about 15 millimeters. To cause the outer housing of the cartridge to experience a high degree of fragmentation, the thickness of the wall of the outer housing of the cartridge is relatively thin. Preferably, the nose portion of the outer housing located at the opposite end of the outer housing of the cartridge of the base of the cartridge has a thickness ranging from about 0.75 to about 4 millimeters. The cartridge has a length-to-diameter ratio of from about 1 to about 4. The docking element and the base of the cartridge may include guiding means for aligning the base of the cartridge with respect to the end of the docking element. In one embodiment, the guiding element is provided by the use of paired mating surfaces at the end of the deep part of the hole of the docking element and the upper end of the base of the cartridge. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cut-away side view of the present controlled fracture process of small charge explosion after detonating a cartridge containing explosive held at the bottom of a drill hole by a massive berthing bar, showing created a penetration cone type fracture that is typical of unbound hard rock formations.

Figure 2 is a side sectional view of the present controlled fracture process of small charge explosion after detonating a cartridge containing explosive held at the bottom of a drill hole by a massive berthing bar, showing to have conducted a fracture or previously existing fractures that intersect the hole near the bottom. This is typical of bonded or fractured rock formations. Figure 3 is a sectional view of the present small charge explosion process showing the berthing bar and the cartridge in the drilling hole before starting the explosive. Figure 4 is a side elevational view of the cutting of a small charge explosion cartridge and tie rod element showing the cartridge base back design and the configuration of the explosive charge to closely engage the cartridge. bottom of the hole. Figure 5 is a side view of approaching the cutting of a small charge explosion cartridge and a tie rod element showing the design of the cartridge backing base cap and the explosive charge configuration for decoupling the tip of the cartridge. Bottom hole pressure. Figure 6 is a section showing an alternative cartridge configuration in which the explosive charge is uncoupled from the bottom of the hole and in which the explosive charge is mounted on the base contact in order to insulate the tie-bar of any shock of transitory regime. Figure 7 is a sectional view of an alternative berth bar configuration showing a conical transition for coupling the conical transition in the drill hole. Figure 8 is a sectional view of the present small charge explosion process after the explosive has been detonated showing the sealing action of the recoil base cap of the small charge explosion cartridge when the cartridge wall is not breaks near the end of the berthing bar. Figure 9 is a sectional view of the present small bar explosion process after the explosive has been initiated showing the sealing action by the backup sealing ring when the cartridge wall ruptures near the end of the tie bar . Figure 10 illustrates the history of the pressure calculated at the bottom of the hole for the case where the rock does not break, typical of the small load explosion method with the explosive charge initially decoupled from the bottom of the hole.

Figure 11 illustrates the history of the pressure calculated at the bottom of the hole for the case when the rock breaks, typical of the small load explosion method with the explosive charge initially decoupled from the bottom of the hole. Figure 12 illustrates the calculated distribution of gas in the small charge explosion system for the case when the rock breaks where a leak occurs around the berthing bar when the volume of the fracture opens. Figure 13 illustrates the history of the pressure calculated at the bottom of the hole for the case when the rock breaks, typical of the small load explosion method with the explosive charge initially coupled to the bottom of the hole to increase microfracturing. Figure 14 illustrates the history of the pressure calculated at the bottom of the hole for the case when the rock does not break, typical of the load method in the propeller-based hole. Figure 15 illustrates the history of the pressure calculated at the bottom of the hole for the case when the rock does not break, typical of the propellant-based gas injector method. Figure 16 illustrates the gas distribution calculated in the propeller-based gas injector system for the case when the rock breaks where the gas leak occurs past the tip of the barrel when the volume of the fracture opens. Figure 17 shows the present invention in use with a typical carrier having a beam for the small charge explosion apparatus. The small charge explosion device includes an element for drilling a short hole in the rock, - advance; insert a small charge explosion cartridge (SCB-EX) into the hole; and activate the shot. Figure 18 is (1) a sectional side view of a small load explosion apparatus mounted on a feed mechanism which in turn is mounted on the end of an articulation beam assembly and (2) a front view of the advance mechanism showing a rock drill and a small charge explosion device. Figure 19 depicts another embodiment of a device according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED MODALITY The present invention involves breaking rock or other hard material such as concrete, drilling a short hole, placing a cartridge containing an explosive charge in the drilling hole, placing a massive berthing bar in the drilling hole. in contact with the cartridge, and detonate the explosive. This method is a small charge explosion process as opposed to a mechanical method or a multiple hole pattern drilling and blasting method to break the rock. A small charge explosion method means that the rock breaks into small pieces, (typically in the order of 1/2 to 3 cubic meters per shot) as opposed to conventional episodic drilling and blasting operations that involve drilling multiple hole patterns , load the holes with explosive charges, explode by chronometer the explosion of each individual hole, ventilation cycles and lag. The small load explosion includes all methods where small amounts of explosive agents are consumed (typically few kilograms or less) each time. The small charge explosion usually involves shooting holes individually and may include firing several holes simultaneously. The seismic signature of small charge explosion methods is relatively low due to the low amount of explosive agent used each time. The small charge burst underground typically involves removal from about 0.3 to about 10, more preferably from about 1 to about 10 and more preferably from about 3 to about 10 cubic meters of banks per shot using from about 0.15 to about 0.5, more preferably from about 0.15 to about 0.3 and more preferably from about 0.15 to about 0.2 kilograms of explosive agent, depending on the method used. The small surface charge explosion removes an amount of material typically ranging from about 10 to about 100, more preferably from about 15 to about 100, and more preferably from about 20 to about 100 cubic meters of rock bank per shot using from about 1 to about 3, more preferably from about 1 to about 2.5 and more preferably from about 1 to about 2 kilograms of explosive agent, depending on the method used. The cubic meters of bank are cubic meters of rock at the site, not the cubic meters of loose rock discharged from the surface of the rock. The amount of small charge explosive agent per shot preferably ranges from about 0.1 kilograms to about 2 kilograms, more preferably from about 0.1 kilograms to 1 kilogram and more preferably from about 0.1 kilogram to 0.4 kilograms. In the present invention, the main method by which the gas pressures are contained in the bottom of the hole is by a massive reusable berthing bar which confines the pressure in the bottom of the hole controlling inertially and minimizing the retraction of the cartridge during the Rock breaking process. By controlling the geometry of the explosive charge, the bottom of the drilling hole can be pressurized in a more convenient way for efficient breaking in rock formations varying from soft rock, fractured, to hard massive. This small load controlled explosion method is referred to herein as the small charge explosion method or SCB-EX method. This method induces a controlled fracturing of the rock that is considerably more energy efficient than the current method of drilling and blasting or the mechanical methods of rock excavation. The present invention represents a significantly different means for inducing controlled fracturing of the bottom of the hole as the type of fracture of the penetration cone (PCF) of rock fracture. It differs from the injector method in which an explosive charge is placed directly on the bottom of a drilling hole percusively. It differs from the Hole Loading method (ie, described in U.S. Patent Number: 5,308,149 which is incorporated herein by reference) in that (1) a detonation explosive is used instead of a non-detonating propellant; (2) the explosive can be configured to increase microfracturing at the bottom of the hole; (3) the pressure that charges the bottom of the hole is much faster; and (4) the cartridge does not play a role in the combustion of the explosion agent. However, it preserves or improves the major advantages of the Injector and Hole Load methods in which the rock breaks efficiently and the resulting loose rock is so benign that the equipment can remain on the work surface while the rock is breaking. . Break Mechanism If the rock is high strength and massive without extensive bonding, this controlled fracturing can be manifested by a type of primary fracture in the rock referred to as the Penetration Cone (PCF) fracture. The basic characteristics of rock breakage by penetration cone fracture by the small load explosion method is illustrated in Figure 1. Penetration break fracture is based on the initiation and propagation of a symmetric shaft fracture to Starting from the corner of a rapidly pressurized, short drilling hole. Such a fracture initially propagates downward inside the rock, and then turns toward the free surface as surface effects become important, resulting in the removal of a large volume of rock. The residual cone left on the surface of the rock by the initial penetration of the fracture into the rock provides the basis for the name (Penetration Cone Fracture, or PCF) given to this type of fracturing.

If the rock contains junctions or other previously existing fractures intersecting the bottom of the pressurized hole as shown in Figure 2, controlled fracturing will manifest by the opening and extension of these as the primary fractures. In any case, the breaking of the rock is characterized by a controlled fracture caused by properly pressurizing only the drill hole. The Drilling Hole The small load explosion method can be used in a constant diameter drilling hole or a stepped drilling hole. In the case of a stepped drilling hole, the bottom of the hole is drilled to a diameter slightly smaller than the top of the hole. This can be carried out by a pilot hole with a ream hole afterwards. The length of the smallest diameter pilot hole is slightly longer than the small charge explosion cartridge. The main purpose of the stepped hole is to provide additional clearance between the berthing bar and the walls of the drilled hole to make it easier to insert the cartridge with the berthing bar. The stepped hole also allows the cartridge to be inserted with a more precise tolerance fit than would be given in the case with a constant diameter drill hole, since the alignment of the berthing bar with the drill hole is less critical. The bottom quality of the drilled hole is an important feature of the small load explosion process, especially in harder, more massive rock formations. The requirements for the bottom of the hole are a sharp corner and numerous microfractures. This can be done better by percussing drilling the hole with sharp corner drill hole. The corner at the bottom of the hole is where the primary fracture will start in the absence of previously existing fractures. As soon as the hole is pressurized, a tension field develops in the rock around the hole and the maximum tension line runs 45 degrees down the corner of the bottom of the hole. The sharper the corner, the greater the stress concentration and the easier for the primary fracture to start at the corner of the bottom of the hole. Micro-fracturing at the bottom of the hole also promotes the initiation of the primary fracture in the absence of previously existing fractures by weakening the rock around the site where the primary fracture will begin. It has been found that microfracturing is about as effective as notching the corner of the bottom of the hole. It has been observed that drilling the hole with a percussive driller causes a sufficiently high degree of microfracturing at the bottom of the hole, at least in soft to moderately hard rock formations, and microfracturing appears to be increased by increasing the rock driller's energy flow near the completion of the hole drilling cycle. The diameter of the drill hole (taken as the diameter at the bottom of the hole) for the small load explosion method preferably ranges from about 50 millimeters to 250 millimeters, more preferably from about 50 millimeters to 125 millimeters and more preferably from about 75 millimeters. millimeters to 100 millimeters. The ratio of length to diameter (taken as diameter as the diameter at the bottom of the hole) of the drill hole for the small load explosion method preferably ranges from about 4 to 20, more preferably from about 5 to 15 and more preferably from about 5 to 12. If the drill hole is stepped, the ratio of the diameter of the largest edge hole against the smallest pilot hole preferably ranges from about 1.1 to 1.5, more preferably from about 1.15 to 1.4 and more preferably from about 1.15. up to 1.25.Configuration of the explosive charge The basic configuration of the small charge explosion system is shown in Figure 3, which illustrates a short drilling hole, the cartridge containing an explosive charge at the bottom of the hole and a berthing bar for contain the high pressure gases generated when the explosive is detonated, until the rock fragments. The explosive charge, like Figure 3, is designed to give an energy release that will result in a desired average pressure in the volume inside the hole.

This average or equilibrium pressure can be calculated from the formula: p = (7-1) pe (1 + p?) Where p = average gas pressure 7 = specific heat ratio of the explosive product gases p = average gas density e = gas energy per unit mass? = coefficient of co-volume for the gases of the explosive product The mass of explosive charge for the small charge explosion method varies depending on the application.

In underground excavation, the explosive charge mass preferably ranges from about 0.15 to about 0.5, more preferably from about 0.15 to about 0.3, and more preferably from about 0.15 to about 0.2 kilograms of explosive agent. In surface excavations, the mass of the explosive charge generally varies from about 1 to about 3, more preferably from about 1 to about 2.5, and more preferably from about 1 to about 2 kilograms of explosive agent. Either for the configuration of small load explosion just coupled or for decoupling, the average or equilibrium pressure developed in the volume available at the bottom of the hole in the absence of retraction of the berthing bar, fracture or leakage development , based on the equation p = (7-1) pe (1 + p?) preferably ranges from about 100 MPa to 1,200 MPa, more preferably from about 200 MPa to 1,000 MPa and more preferably from about 200 MPa to 750 MPa. In the present method, the explosive charge can be set to direct a strong shock peak at the bottom of the hole as shown in Figure 4. A strong shock peak consists of a strong shock immediately followed by a wave of acute rarefaction such that the rise and fall of pressure occurs for a time that is short compared to the time required for a seismic wave to cross the volume of rock affected by the peak. A shock peak consists of a strong shock followed immediately by a wave of acute rarefaction such that the risk and pressure drop occurs for a time that is short compared to the time required for the seismic wave to cross the volume of rock affected by peak. When the explosive charge is just coupled to the bottom of the hole, a strong shock peak is conducted towards the rock at the bottom of the hole and additional microfractures are induced as the compressive force of the rock is substantially exceeded. The increased microfracture promotes the easier initiation of the primary fracture system. This ability can be demonstrated decisively in very hard massive rock formations where the exploding energy of the drill is limited. The explosive charge can be configured to fit directly only around the corner region of the bottom of the hole to create microfracture only near the corner of the bottom of the hole where it is desired to initiate the main fracture. In the small charge burst charge configuration for very fair coupling of the explosive charge to the bottom of the hole, the amplitude of the shock peak measured at the bottom of the hole preferably ranges from about 1,500 MPa to 5,000 MPa, more preferably from about 2,000 MPa up to 4, 500 MPa and more preferably from about 2,500 MPa to 3,500 MPa. The strong shock peak can be reduced or eliminated by inserting a gap between the end of the explosive charge and the bottom of the hole as shown in Figure 5. This may be desirable in softer, very fractured rock formations where only wants the generation of gas without strong shock component. The resistance of the shock peak that impacts the bottom of the drill hole can be controlled by the size of the gap between the end of the explosive charge and the bottom of the hole. In the small charge explosion burst configuration for an explosive charge decoupled from the bottom of the hole, the length of the gap separating the bottom of the explosive charge from the bottom of the hole ranges preferably from approximately 19 millimeters to 60 millimeters, more preferably from about 10 millimeters or 50 millimeters and more preferably from no more than about 40 millimeters. In the small charge explosion charge configuration for an explosive load decoupled from the bottom of the hole, the amplitude of the shock peak measured at the bottom of the hole preferably ranges from about 600 MPa to 2,000 MPa, more preferably from about 600 MPa to 1,000 MPa. Because of the high pressures, in the range of 100 MPa to 1,000 MPa, required to adequately perform the controlled fracturing of hard rock, or comparable materials, several innovative design and application concepts had to be realized and are the subject of this invention. The pressures developed within an explosive small charge explosive cartridge and applied to the bottom of the hole are less than those generated in conventional drilling and blasting where the explosive charge substantially fills the drilled hole and makes contact with the walls of the drilling hole and exposes the rock in the immediate vicinity of the drilling hole to the full detonation pressure of the explosive. Sufficient gas pressures for the development of the controlled fracture but below those that would break the cartridge can thus be achieved in a controlled manner. The pressures thus developed are kept below those that would deform or damage the end of the berthing bar and below those that would crush the rock around the hole. However, the pressures generated in the small controlled charge explosion process and the rock walls near the bottom of the hole are exposed to pressures comparable to those that occur in the flue pipe of a high performance gun. The small charge explosion cartridge The main functions of the cartridge are: (1) protect the explosive charge during insertion into the drill hole; (2) provide the internal volume necessary to control the pressures developed at the bottom of the hole; (3) Protect the explosive charge of the water in a wet drilling hole and; (4) provide the berthing bar with insulation of any strong shock transient from the explosive charge. The cartridge wall adjacent to the base contact can be designed to expand towards the perforation hole wall without rupture, thus preventing gases from the high pressure explosive product from acting directly on the hole wall or at any fracture (natural or induced) along the wall of the hole. This containment of the gases from the explosive product maintains the gas pressure so that the gasses act predominantly to form and pressurize the desired controlled fractures, such as the penetration cone fracture, which originates in the concentration developed at the bottom of the hole. . It is important to prevent hot gases from escaping through the hole around the steel bar. This gas leak can reduce, by a small amount, both the pressure and the volume of gas available for controlled fracturing of small desired load explosion. Also the exhaust gases can damage the berthing bar by convective heat transfer erosion processes. As noted above, the escape of gases past the reusable berthing bar can be reduced by having a small space between the bar and the wall of the hole. Calculations with a finite difference code indicate that an annular space smaller than 0.38 millimeters in a 76 millimeter diameter drill hole will adequately minimize the escape of high pressure gases. Additional cartridge integrity is obtained by including a tapered tapered base contact in the cartridge as shown in Figures 4 and 5. In these embodiments, the cartridge comprises a conical wall section with a cylindrical exterior and a conical interior and a contact basal sealant with a conical shape that can move inside the conical inner wall of the cartridge. As the berthing rod recedes out of the hole by the pressure of the gases, the basal contact can follow and thus maintain a seal against the gases of the explosive product for a sufficient time to complete the controlled hole bottom fracture process. The amount of recoil that occurs during the time the pressure at the bottom of the hole develops and the rock fragmentation is complete varies preferably from about 5 millimeters to 50 millimeters, more preferably from about 10 millimeters to 40 millimeters and more preferably from approximately 10 millimeters to 20 millimeters. The amount of recoil is mainly controlled by the inertial mass of the berthing system and the history of the pressure developed at the bottom of the hole. Either for the small load explosion burst configuration just coupled or uncoupled, the angle between the base of the cartridge and the wall of the cartridge body on which the base can move during recoil ranges preferably ranges from about 1 degree to 10 degrees, more preferably from about 2 degrees to 8 degrees and more preferably from about 3 degrees to 6 degrees. The cartridge wall is thin in and near the bottom of the hole. It should be thick enough to withstand the process of inserting the cartridge into the drilling hole. But it must be thin enough to fragment when the explosive charge is detonated so as not to leave fragments large enough to cover the fractures initiated in the corner of the bottom of the hole. Either for the small load explosion burst configuration just coupled or decoupled, the thickness of the wall of the outer cartridge housing adjacent to the bottom of the hole preferably ranges from about 0.75 millimeters to 5 millimeters, more preferably from about 0.75 millimeters to 4 millimeters and more preferably from about 0.75 millimeters to 3 millimeters. It may be desirable to design notches in the bottom of the cartridge to ensure that it will fragment when the explosive is detonated. The explosive charge like the one shown in the Figures 4 and 5 are detonated and consumed before the influence of the cartridge walls can be felt. Therefore, the design of the cartridge is determined by other factors but not by any consideration of the detonation combustion of the explosive charge. This contrasts with methods in which non-detonating propellants are used. The cartridge in these methods must be designed to provide some initial confinement to allow the propellant to burn adequately to the desired pressure, thus adding an additional design requirement for the cartridge. Figure 4 shows a small charge explosion cartridge geometry including: the downward end of the hole in the berthing bar; a conical base cap that can slide inside the cartridge wall; an explosive charge that is coupled precisely with the bottom of the hole, a volume of internal relief to control the long-term average pressure of the explosive products; and the backup metal pointing ring in the case where the cartridge walls are broken near the base cover.

Figure 5 shows a small charge explosive cartridge geometry including the end below the hole in the berthing bar; a conical base cap that can slide inside the cartridge wall; an explosive charge that disengages from the bottom of the hole; an internal relief volume to control the long-term average pressure of explosive products; and a backup metal sealing ring in the case where the cartridge wall is broken near the base cap. Figure 6 shows an alternative small charge burst cartridge geometry that includes: the bottom end of the hole in the berthing bar; a conical base cap that can slide inside the cartridge wall; an explosive charge that engages just at the bottom of the hole but is disengaged from the base cap to insulate the tie-bar from strong transient shock regimes, - an internal relief volume to control the long-term average pressure of the products explosives; and a backup metal pointing ring in the case where the cartridge wall is broken near the base cap. The small charge explosion cartridge can be destroyed in one shot. The end of the berthing bar is exposed to a controlled pressure pulse similar to that generated inside the gun that drives the impeller and, if it is protected such as by the conical base cap, sacrificed and by the shock insulation of the hollow between the lower end of the base of the cartridge and the upper end of the explosive, it is unlikely to sustain damage over a large number of activations. Even if the end of the berthing bar adjacent to the cartridge is damaged from time to time, it is a relatively simple, inexpensive operation to replace or repair the damaged end. The cartridge can be inserted into the hole in several ways. The cartridge can be inserted either mechanically by means of a rod or long bar, or by pneumatically inserting a flexible tube and blowing the cartridge to the bottom of the hole by means of a compressed air system with a pressure differential of the order of 1/10 bar. The cartridge can also be inserted directly by attaching the cartridge to the same tie-bar. Berthing and sealing The main method by which gas pressures are contained in the bottom of the hole until they are relieved by the opening of controlled fractures, is by the massive inertial berthing bar that blocks the flow of gas to the bore hole except for a small leakage path between the berthing bar and the walls of the drilling hole. This is illustrated in Figures 6 and 7 showing two variations of the berthing bar.

The width of the annular gap separating the end inside the hole of the berthing bar from the walls of the drilling hole in the activation position preferably varies from approximately 0.1 millimeter to 0.5 millimeter, more preferably from about 0.1 millimeter to 0.3 millimeter and more preferably from about 0.1 millimeter to 0.2 millimeter. This small leakage can be further reduced by design features of the cartridge containing explosive and the berthing bar. The cartridge can be designed with a conical wall, which is thicker closer to the berthing bar, and a conical base cap similarly that can slide within the walls of the cartridge as the docking bar recedes. This type of sealing mechanism can reduce the possibility of premature rupture of the cartridge and leakage of explosively generated gases. A sealing mechanism in the berthing bar can also be used to obtain better or complete sealing near the bottom of the hole. The confinement of the high pressure gases to the bottom of the hole is made by the proper interaction of the inertia of the berthing bar that minimizes the backward movement of the cartridge, the expansion of the cartridge towards the walls of the drill hole without rupture and a small space between the end of the berthing bar and the wall of the hole that almost eliminates the leakage of high pressure gases passing the bar during the short time it takes to start, propagate and complete a controlled fracture. The tip of the berthing bar illustrated in Figure 6 (also the same as that shown in Figures 4 and 5) is designed to be placed in an abrupt step of a stepped drill hole to avoid crushing the small charge explosion cartridge . The tip of the berthing bar illustrated in Figure 7 is designed to be placed in a smooth transition section between the upper portion of the larger diameter drill hole. This type of drill hole can be formed by a special drill hole assembly. The berthing bar is inserted into a drilling hole and the conical section sits in the conical section of the drill hole to form an initially tight seal for the high pressure gases that will be generated at the bottom of the hole. The high pressure gases will cause the berthing rod to back up, thus opening a gap between the conical section of the berthing bar and the conical section of the drill hole. The conical section of the drill hole is less sensitive to splintering and imperfections in the rock than a sharply stepped drill hole such as that shown in Figures 4, 5 and 6 and thus the development of the gap and the high leakage of gases. Pressure can be controlled better. Since the bottom end of the hole in the berthing bar fills most of the cross-section of the drill hole, it provides adequate sealing of gas pressures generated by the propellant charge. When the propellant is properly started and quickly burned at its peak design pressure, only a small fraction of the propellant gases escape into the gap between the berthing bar and the walls of the drill hole. This leakage of residual gas, while not seriously degrading the pressure at the bottom of the hole, can cause damage to the berthing bar over a large number of shots. The design of high pressure gas sealing features at the base of the cartridge or downstream end of the hole in the berthing bar can reduce or eliminate the residual leakage of gases from the explosive product. In addition to, or as an alternative to the sealing and gas content provided by the loading cartridge as described above, sealing can be provided at the end of the tie rod cartridge. You can use any of different sealing techniques, such as V-seal, O-rings, unsupported area seals, welded seals, and so on. Seals can be replaced each time a cartridge is activated or, preferably, the stamps can be reusable. When the main sealing function is provided only by the berthing bar, the design of the cartridge can be considerably simplified. A small charge bursting cartridge and berthing bar can easily be inserted into a hole with such small spaces by drilling a stepped drilling hole with a larger diameter upper portion section, as illustrated in Figure 5 for example. The sealing of the hole can be helped and the weight of the apparatus can be reduced by accelerating the berthing bar towards the bottom of the hole just before turning the propeller on the cartridge. The berthing bar can be accelerated by the hydraulic or pneumatic power source that is used to move the beam or carrier for the small load explosion device, or by any other means that is available. The berthing bar accelerates at a velocity directed towards the bottom of the hole, which is comparable to the opposite directed retraction velocity induced when the propeller is burned. These speeds are of the order of 1.5 to 15 meters per second. The acceleration before the activation must be sufficient to reach the desired speed in a short distance, of the order of a third of a hole diameter (2.54 centimeters or less in a hole of 7.68 centimeters in diameter). This technique is known as "off-battery activation" and is sometimes used in the operation of large guns to reduce recoil forces. Since the recoil speed of the small charge explosion apparatus plays an important role in the process of sealing holes, it is desirable to minimize the rate of recoil. The batteryless activation technique can do this. Alternatively, if the recoil speed is acceptable, this technique can be used to reduce the recoil mass. In the small charge explosion method, the small charge explosion apparatus serves as a large part of the backing mass and thus the weight of the apparatus can be reduced. Weight reduction is an important goal since the carrier and the beam can operate more efficiently with less weight associated with the drilling and small load explosion device. The batteryless activation technique can also be used to assist the sealing operation when the seal is provided by the explosive cartridge. The seal provided by the cartridge usually breaks when the base of the cartridge breaks and separates from the body of the cartridge as the berth bar retracts out of the hole (the cartridge body is held against the walls of the bore hole by the gases of the cartridge). explosive product at high pressure and can not move in relation to the hole). When activated without a battery, the recoil speed of the berthing bar can be reduced and the displacement out of the hole of the berthing bar can be delayed, giving the gases of the high pressure explosive product significantly more time to act on the bottom of the hole and drive the desired controlled fracturing to the term. Performance Comparisons with Other Small Load Methods Figures 3, 8 and 9 illustrate the small load explosion process. Figure 3 shows the system before detonating the explosive. Two possibilities are considered for the behavior of the back of the cartridge. In the first case, shown in Figure 8, the cap of the conical base recesses with the berthing bar and the walls of the cartridge are held against the walls of the drill hole by the gas pressure. In this case, there is no leakage of explosive product gases out of the back of the cartridge. The front end of the cartridge is fragmented, and the bottom of the hole is exposed to the total gas pressure. In the second case, shown in Figure 9, the wall of the cartridge near the base cap has been broken. The high pressure gas has forced some of the material from the wall and the steel backup ring into the gap between the berthing bar and the walls of the drill hole to seal any further gas leakage past the berthing bar. In this case, the walls of the drilling hole near the bottom of the hole are exposed to high pressure gases, which can be advantageous in rock formations that have numerous previously existing fractures. Otherwise the operation of the system is the same as in Figure 8. Figure 10 illustrates the history of the pressure at the bottom of the hole as calculated using a computer code of finite differences. This code models the detonation explosive in the cartridge, the recoil of the berthing bar, the gas leak past the berthing bar and the evolution of a typical fracture volume. Figure 10 shows the bottom hole pressure for the case when the rock does not fracture, as could happen when the hole is drilled too deep. The calculation includes the recoil of the drill rod and some gas leak passing the berthing bar. The calculation has been made for 200 grams of TNT explosive that is initially uncoupled from the bottom of a drill hole of 89 millimeters in diameter. There is a moderate shock peak driven towards the bottom of the hole by explosive products that rapidly expands through the 30 millimeter gap that separates the charge from the bottom of the hole. The pressure at the bottom of the hole starts within 25 microseconds of initiation of the TNT and oscillates rapidly in the small volume available. The recoil of the bar and the gas leak cause the average pressure to decay over time. Figure 11 shows the pressure at the bottom of the hole for the case of the decoupled load when the rock fractures. The calculation includes the recoil of the berthing bar, some gas leakage passing the berthing bar and the fracture volume opening towards the bottom of the hole. Compared to the pressure history in Figure 10, the pressure at the bottom of the hole decays more rapidly in the last part of the pressure history because of the evolving volume of the fracture in which the high pressure gases flow. . Figure 12 shows the history of the gas distribution for the case when the rock breaks. The distribution tracks the gas remaining inside the cartridge's volume, the gas leaking from the base of the cartridge (assuming imperfect sealing action), and the gas injected into the bottom of the hole and fractures in the rock. In this calculation, the base of the cartridge is assumed to have broken after 2.5 millimeters of recoil and the gas leaks out of the gap between the berthing bar and the walls of the drill hole. After 4 milliseconds, 45 grams of gas remain within the original cartridge volume, 18 grams of gas remain within the original cartridge volume, 18 grams have leaked past the berthing bar and 137 grams have been injected into the bottom of the hole and developed fractures. After 4 milliseconds, the fracture has spread over a meter and the rock has been effectively excavated. From the perspective of the gas leak, this is a worst-case situation, since the gap between the berthing bar and the walls of the drilling hole is assumed to be widely open and not blocked by any cartridge material or metal ring sealer backrest. Figure 13 shows the pressure at the bottom of the hole for the case where a load is coupled when the rock breaks. This illustrates a much stronger shock peak driven at the bottom of the hole. While there is little energy associated with this pulse, the effect is to create microfractures in the bottom of the hole. In this case, it would be expected that the initial shock peak would create substantially more microfracturing than the case shown in Figure 11. Figure 14 shows the history of bottomhole pressure for the case of a propellant based on the loading system in the hole as incorporated in the United States Patent Number: 5,308,149 entitled "Method of pressurizing non-explosive drilling holes and apparatus to control the fragmentation of rock and hard compact concrete". The calculation was made for 250 grams of fast burn propeller in the same hole volume as that used for the preceding small load explosion calculations. This pressure history can be directly compared to the history of the small load explosion pressure shown in Figure 10 where the rock does not break and the recoil of the bar and the gas leak cause the average pressure to decay over time . The main difference is the relatively slow speed at which the pressure rises and the absence of any strong shock peak in the driving example. In the case of propellant, there is substantially more recoil of the berthing bar before the pressures increase to the threshold where fractures begin to begin. Figure 15 shows the history of bottomhole pressure for the case of a propeller-based injector system such as that incorporated in United States Patent Number: 5,098,163 entitled "Controlled fracture method and compact rock breaker apparatus. hard and concrete materials. " The calculation was made for 380 grams of fast burn propellant in the combustion chamber of the gas injector. The same bottom hole volume is used as used for the previous small charge explosion calculations. This pressure history can be direccompared to the history of the small charge explosion pressure shown in Figure 10 where the rock does not break and the rod recedes and the gas leak causes the average pressure to decay over time. The main difference is the gas injected into the bottom of the hole blows the back of the gas injector barrier and causes a rapid loss of pressure at the bottom of the hole even when the rock does not break. In the injector method, the propellant gases developed in the combustion chamber must expand down the injector barrier to reach the bottom of the drill hole. When the high-velocity gases find the bottom of the hole, the kinetic energy abrupturns back into internal energy and the gas pressure rises abrup The pressure wave is reflected again in the injector which, in effect, represents a "major leak" for the maintenance of the pressure at the bottom of the hole. There is also an absence of any strong shock peak in the propellant example. Figure 16 shows the history of the gas distribution for the case of the injector when the rock breaks. The distribution tracks the remaining gas within the volume of the gas injector, the gas leaked from the bottom of the hole passing the seal at the mouth of the barrel, and the gas injected into the bottom of the hole and the rock fractures. After 4 milliseconds of pressure at the bottom of the hole, 145 grams of gas remain within the volume of the gas injector, 61 grams have leaked from the volume of the hole and 174 grams have been injected into the bottom of the hole and developed fractures. At this time the fractures have spread to the surface and the rock has been effectively fragmented. The main observation is that 145 of the initial 380 grams of propellant gases remain in the gas injector after the rock fragmentation has finished. This gas must then empty the gas injector and is a major source of noise and energization of flying rock dust. A good comparison of the methods of Injector, charge in the hole (CIH) and small load explosion can be made by evaluating the history of the integrated pressure (impulse) at the bottom of the drilling hole in the case when the rock does not fracture. In this comparison, the recoil of a berthing bar (mass of 772 kilograms) and the gas leakage are included but the evolution of the fracture volume is not allowed. The impulse is calculated for the pressure acting on the bottom of the hole during the same duration of time (approximately 4 milliseconds). The results are shown in Table 1. It is seen that the methods of charge in the hole (CIH) and small load explosion (SCB-HE) manage approximately the same impulse to the bottom of the hole and leak comparable amounts of gas. The small load explosion process (SCB-HE) achieves this with 50 grams less load, mainly as a consequence of the higher proportion of specific heats of the explosive products (7 = 1.3) compared to the products of the propellant (7). = 1.22). The injector method manages significantly less imposed with a substantially higher loading mass. The calculations were repeated, this time allowing the rock to fracture and evolve the volume of the fracture. The results are shown in Table 2. The volume model of the fracture used herein assumes that the fracture propagates at a constant velocity (350 m / s) as soon as the initiation of the threshold is exceeded. Thus the fracture propagates approximately 1.25 meters in the 4 milliseconds in which the pressure is applied and this is considered sufficient to complete the process of fragmentation of the rock. The effect of the shock peak generated in the small load explosion (SCB-HE) method in fracturing is not included in the calculations. However, the amplitude of the peak and the short duration of this shock peak in the coupled HE case is in the proper range to induce substantial microfracturing in the region directly below the bottom of the hole. Characteristics The primary characteristics of the small load explosion method are: 1. Pressurize only the bottom of the hole with pressures high enough to break hard rock. 2. The controlled use of detonation explosives as an energy source. 3. A means of dynamic sealing of the bottom of the hole until the rock breaks. 4. An element to create microfractures at the bottom of the hole only. A key feature of the controlled fracture method, with small load, is the benign nature of the flying rock dust that allows drilling, lagging, grounding and dragging equipment to remain on the work surface during rock breaking operations . A second key feature of the method and apparatus is that they can be used in either dry or water filled holes. An important feature of the small charge explosion process is the removal of crushed rock which is a primary source of dust. Excess dust requires additional equipment and time to control and can in some types of excavation operations, lead to secondary explosions that are a safety risk. In the configuration shown in Figure 3, the only portion of the drill hole exposed to the direct detonation pressures is the same bottom of the hole which represents only a small portion of the total hole surface area.

System components The basic components of the small load explosion system are: beam and carrier assembly - driller mounted on the beam assembly the cartridge and magazine loading mechanism the tie rod and explosive ignition mechanism the cartridge and Explosion cover - the main explosive charge The basic components of the small cargo excavation system are shown schematically in Figure 17. The following paragraphs describe the characteristics considered for the different components. The beam and subcarrier assembly The carrier can be any standard mining or construction carrier or any carrier specially designed to assemble the beam assembly or beam assemblies. You can build special carriers to sink the shaft, recess mining, narrow vein mining and military operations, such as digging trenches, construction of fighting position and placement of demolition cargo. The beam assembly can be composed of any articulated mining beam or standard construction or any modified or customized beam. The function of the beam assembly is to orient and position the drill and the small load explosion device in the desired location. The beam assembly can be used to assemble a feed assembly. The advancer maintains both the rock drill and the small load explosion beam assembly and rotates around an axis aligned with both the rock drill and the small load explosion docking assembly. After the drill drills a short hole in the surface of the rock, the advancer is rotated to align the tie rod assembly for easy insertion into the drill hole. The advancer assembly removes the need for separate beams for the rock drill and the tie rod assembly. The mass of the beam and of the advancer also serves to provide backward movement and stability for the drilling machine and the small load exploding device. The rock drill The drill consists of the drill motor, the drill bit and the drill bit and the drill motor can be pneumatically or hydraulically driven. The preferred type of drilling machine is a percussive drilling machine because a percussive drilling machine creates microfractures at the bottom of the drill hole that act as initiation points for the penetration cone fracture. You can also use rotary drills, diamond drills or other mechanical drills. In these cases the bottom of the hole may have to be specially conditioned to promote the type of penetration cone fracture. Standard drill bits can be used to use and these can be shortened to meet the short hole requirements of the small load explosion method. Mining drills or standard construction drills can be used to drill holes. Percussive drilling bits that increase microfracturing can be used. The sizes of the drilling holes can vary from 2.54 centimeters to 50.8 centimeters in diameters and depths that are typically from 3 to 15 hole depth diameters. Drill bits to form a stepped hole for easier insertion of the tie-bar assembly may consist of a pilot drill bit with a slightly larger diameter drill bit, which is a standard drill configuration offered by drill bit manufacturers. rock drills. Drill bits to form a tapered transition hole for easier insertion of the tie-bar assembly may consist of a pilot drill with a slightly larger diameter flange. The flange and pilot can be specially designed to provide a conical transition from the larger flanged hole to the smaller pilot hole. For the configuration of the berthing bar in which the transition from the enlarged hole to the pilot hole is conical, the angle of the conical section of the berthing bar preferably varies from about 10 degrees to 45 degrees, more preferably from about 15 degrees to 40 degrees and more preferably from about 15 degrees to 30 degrees. Warehouse Mechanism and Charge of Small Load Explosion Cartridge Small load explosion cartridges are stored in a warehouse in the manner of a munitions store of a self-loading cannon. The loading mechanism is a standard mechanical device that retrieves a cartridge from the warehouse and inserts it into the drill hole. The berthing bar described below can be used, as a subcomponent of the loading mechanism, to insert the cartridge into the hole. The loading mechanism will have to cycle a cartridge from the warehouse into the drilling hole in no less than seconds and more typically in 30 seconds or more. This is slow in comparison to modern high-speed gun barge autoloaders and therefore does not involve high acceleration charges in the small explosive burst cartridge. Variants of military self-loading techniques or industrial bottle and container handling systems can be used. The average time between the sequential small charge burst ranges ranges preferably from about 0.5 minutes to 10 minutes, more preferably from about 1 minute to 6 minutes and more preferably from about 1 minute to 3 minutes. The loading mechanism will require moving a cartridge from the magazine to the insertion in the drill hole in a shorter time than the previous draft cycle time. A variant is a pneumatic transport system in which the cartridge is propelled through a rigid or flexible tube by pressure differences of the order of 1/10 bar. The berthing bar and activation mechanism is attached to the main advancing beam mechanism as illustrated in Figure 17. The berthing bar typically extends well into the drill hole. The berthing bar makes firm contact with the cartridge containing explosive to provide close proximity to the electric explosion cap or other explosive initiation method and to confine the cartridge to the bottom of the drill hole as the explosive is detonated. The diameter of the berthing bar is just smaller than the diameter of the drill hole, sufficient to provide space for the bar in the hole. The berthing bar contains the activation mechanism for the explosive cartridge. This activation mechanism can be electrical or optical function. Additional sealing can be provided against escape of the gases from the explosive product at the end of the docking bar cartridge. Any of several conventional sealing techniques such as V-seals, O-rings, unsupported area seals, etc. can be used. The additional sealing would serve to further limit the undesirable escape of gases from the explosive product of the cartridge and the bottom of the hole. Additional sealing of the explosive product gases can be achieved by also accelerating the berthing bar in the hole just before the ignition of the explosive charge so that the inertia of the berthing bar in the hole provides additional forces against displacement. of cartridge out of the hole and the rupture of the consequent cartridge and loss of gases from the high-pressure explosive product. The cartridge and initiator of the small charge explosion The small charge explosion cartridge is an important component of the present invention. Its function is to: act as a storage container for the solid or liquid explosive serve as a means of transporting explosive from the storage warehouse to the excavation site protecting the explosive charge during insertion into the drill hole serving as a combustion chamber for the explosive provide an internal volume to control the pressures developed at the bottom of the hole to protect the explosive charge of the water in a wet drilling hole - to provide the berthing bar with insulation from any heavy load shock passenger regime explosive provide a backup sealing mechanism for the explosive product gases as the explosive is detonated in the drilling hole. In addition to containing the explosive charge, the small charge explosion cartridge as illustrated in the Figures 4, 5 and 6 contains excess internal volume to control the average pressure in the cartridge at the desired level which can be substantially less than if the volume of the total cartridge was filled with solid or liquid explosive. One of the main design criteria for the cartridge is to provide adequate sealing in the drilling hole for the gases of the detonation or explosive product under controlled conditions. The cartridge can be designed to seal adjacent to the tie-bar, around the walls of drilling hole. This will prevent the high pressure gases from leaking between the berthing bar and the walls of the drilling hole, and better contain the gases of the high pressure explosive product at the bottom of the drilling hole. A simple cartridge design with features to ensure proper hole sealing and gas containment of the explosive product is shown in Figure 4. The small charge explosion cartridge can have a combination of suitable geometry and material properties suitable to prevent premature rupture of the cartridge, which results in premature loss of propellant gas pressure, which, in turn, reduces the effectiveness of the controlled fracture process of the desired hole bottom. The design of the cartridge illustrated in Figure 4 satisfies the general requirements by combining a conical wall and similarly a conical base plug, both of which tend to avoid premature failure of the cartridge near the base of the cartridge. The conicity of the wall in the range of 1 to 10 degrees is satisfactory, with the conicity being preferred between 3 and 5 degrees. The cartridge can be made of any strong and collapsible material, including most plastics, metals, and properly constructed composites. The cartridge can be made of a material that can be deformed either elastically and / or plastically, with sufficient deformation before rupture to allow the content of the cartridge to follow both the expansion of the walls of the drilling hole and the recoil of the berthing bar during rapid pressurization of drilling hole and controlled fracture process. The cartridge may also be made of a combustible or consumable material as used in fuel cartridges occasionally used in cannon ammunition. The preferred materials are those that will provide the required sealing and that can be done at the lowest cost per part. In the design shown in Figure 4, a mechanical action is used to reduce some of the geometry and material properties requirements of the first cartridge design. This small charge explosion cartridge is constructed of a folding sleeve and a basal seal cap. The collapsible sleeve is conical to provide greater resistance to premature rupture of the cartridge near its base and to provide an interference seal with the basal seal cap, which is also conical. The basal seal cap can be constructed of any solid material, such as plastic, a metal or a composite. The preferred materials are those that can be made for the lowest cost per part. The base seal cap contains the explosion cap or other initiator required to detonate the explosive charge. The explosion cap is located on the cartridge at the end adjacent to the berthing bar. Its function is to initiate a detonation in the most important explosive charge when activated by an operator command. Standard or novel initiation techniques may be employed. These include instantaneous electric blast caps activated by a direct current pulse or inductively induced current pulse; non-electric explosion caps; thermal ignition; high-energy primers or an optical detonator, where a laser pulse initiates a primary charge sensitive to light. An alternative cartridge design is shown in Figure 6. This cartridge design is similar in construction to the cartridge design shown in Figure 4. This alternative design satisfies the sealing requirements provided by a base that is led into the gap between the cartridge and the cartridge. berthing bar and rock under the action of explosive gas products. The base also includes a means of shock isolation to protect the end of the bar from transient shock regimes from the detonating explosive. As with the other designs of small charge explosive cartridges, the means for initiating the explosive are contained in the base of the cartridge. The explosive charge is loaded into a plastic, metal or heavy paper container that is mounted inside the cartridge to give the explosive charge rigidity and to place it inside the cartridge in order to uncouple the explosive from the walls of the drill hole. The explosive Explosives are used instead of propellants in the present invention. The propellers deflagran or burn subsonically and the rise of pressure is controlled by the geometry of the propeller; the chemistry of the propellant; the charge density of the propellant; stasis or empty space in the cartridge; and the confinement of the cartridge / propeller system between the walls of the drilling hole and the berthing bar. In this control, the bottom of the drill hole can be pressurized to a penetration cone fracture or other controlled fractures start along the maximum tension concentration line at the perimeter of the bottom of the hole. The propellant gases then expand in the fracture (or fractures) and conduct the depth of the fracture (fractures) in the rock and / or to the nearby free surfaces.

An explosive charge, on the other hand, detonates which is a supersonic type of burning that generates strong shock waves. These shock waves can be controlled and directed to pressurize the bottom of the drilling hole in a controlled manner so that the rock around the drill hole will not fracture and crush excessively. By restricting the mass of the explosive, it is possible to achieve a desired average pressure in the volume of the bottom hole.

By configuring the geometry of the explosive charge, strong shock waves can be prevented from sticking to the bottom walls of the hole or directing the bottom of the hole to induce microfractures where they can act as initiation sites for the main fracture. The explosives that could be used in the present invention can be solid, liquid or in the form of a slurry. Examples of solid explosives are: dynamitas ammonium nitrate TNT - Composition 3 Composition 4 Octol Examples of liquid explosives are: nitromethane - hydrazine Examples of explosives in gaseous pulp are: ammonium nitrate / fuel oil water gels emulsions - mixtures of nitrate ammonium and nitromethane the explosive can be sensitized so that there is a "sensitive cap" (capable of being initiated by an explosion cap number 8) either when embarking or just before use by injecting sensitizer into the explosive. The explosive may also have agents added to reduce the amount of toxic byproducts generated during combustion. APPLICATIONS This method of breaking soft, medium and hard rock as well as concrete has many applications in the mining, construction and quarry industries and for military operations. These include: tunnels * excavation of caverns deepening of wells exploitation of the pit and tunnel in mining long-wall mining, chamber mining and pillar i ** - methods of recess (contraction, cutting and filling and narrow vein) > • selective mining + exploitation of undercutting for tillage mining in vertical crater removal (VCR) exploitation at the haul point for collapse of blockage and contraction shrinkage > - Secondary rupture and reduction of oversized size ^ Cut trenches Backhook drilling - Rock cuts > - precision explosion - demolition > - open-air cleaning *** • open-pit explosion > - breaking and exploitation by banks in rock quarries > - construction of fighting positions and shields of personnel in rock i ** - reduction of natural and man-made obstacles for a military movement. The general breakthrough mechanism of penetration cone fracture for the small load explosion method using a berthing bar to inertially contain a cartridge containing an explosive charge at the bottom of a short drill hole is shown schematically in Figure 1 A cartridge 1 is inserted into the bottom of a short hole 2 drilled in the hole in the surface of the rock 3. An inertial berthing bar 4 is placed in the hole to contain the high pressure gases generated by an explosive charge contained in the cartridge 1. The gases fill the volume 5 and pressurize the bottom of the hole 2 until a type of fracture of the penetration cone of the fracture 6 is carried down towards the rock 7. The fracture 6 intersects the surface of the rock 3, the rock bounded by the fracture 6 and the surface of the rock 3 is effectively fragmented. Figure 3 shows the small charge explosion system placed in a drill hole before activation. A short hole 15 is drilled in the surface of the rock 16 and a cartridge 17 is inserted in the bottom of the hole 15. The cartridge 17 is inserted in the bottom of the hole 15. The cartridge 17 can be inserted by attaching it to the end of a bar. berthing 18 that is prevented from crushing the cartridge 17 stopping it on the step 19 formed near the bottom of the drilling hole 15. The base of the cartridge 20 is joined to the end of the berthing bar 18 and can back up with the berthing bar 18 under the action of high pressure gases generated by the explosive charge 21. An explosive initiation system 22 is located coaxially in the tie-bar and is used to initiate the explosion cover 23 located in the base 20 of the cartridge 17. A tube 24 contains the explosive charge 21 within the cartridge 17 Because the cartridge 17 contains excess volume 25, the small charge explosion method can be used either in a gas filled hole or filled with water. In a hole filled with water, the cartridge 17 will displace most of the water from the bottom of the hole 15. In this configuration, the explosive charge 21 is directly coupled to the bottom of the cartridge 17 in order to drive a strong shock peak towards the rock 26 at the bottom of the hole 15 to increase microfracturing at the bottom of the hole 15. For best results, at least about 50 percent of the area of the nose portion of the outer housing of the cartridge that makes contact with the bottom of the hole makes contact with the explosive. The preferred contact area is the outer ring of the nose portion so as to better induce microfracturing at the bottom of the hole in the annular region around the corner of the bottom of the hole. Figure 4 shows a small charge explosion cartridge 27 placed at the bottom of the drill hole 28 and supported by a tie bar 29. The tie bar 29 is prevented from squashing the cartridge 27 by a step 30 in the drilling hole. The cartridge 27 is composed of a body 31 and a tapered base plug 32 and a metal backup seal ring 33. The base 32 of the cartridge 27 has a concave rear surface 34 to assist in locating the tie bar 29 to maintain alignment approximate central An explosive charge 35 is maintained centrally in the base 32 of the cartridge 27. The explosive charge 35 does not completely fill the cartridge 27. The cartridge 27 also contains an internal volume 36 that allows the combustion products of the explosive to expand and control the pressure average in the cartridge 27. The explosive charge 35 is additionally contained in a cover or container 37 to give the explosive charge 35 structural support. The explosive charge 35 is closely coupled to the bottom of the cartridge body 31 so as to drive a strong shock peak towards the bottom of the bore hole 38. The base 32 contains an electrical coil 39 which is connected to an exploded cover 40 which it is used to initiate the explosive charge 35. A second electric coil 41 is contained in the tie-bar 29 and is connected to an external activation circuit (not moved). A pulse of current is generated in the coil 41 and induces a current in the coil 39 which is eficient to initiate the explosion cover 40. Thus the tie bar 29 does not need to be in intimate contact with the base of the cartridge 32. Figure 5 shows a small charge explosion cartridge 42 containing an exploitative charge 44 that is not coupled to the bottom of the cartridge body 45 but separated by a recess 46. The recess 46 conventionally reduces the peak pressure of the driven shock peak. at the bottom of the hole 47. Otherwise, the cartridge 43 is substantially equal to the cartridge shown in Figure 4. The berth bar 48 is shown with a step 49 to prevent the berth bar 48 from squashing the cartridge 43. end of the berth bar 48 ee convex 50 to help align it with the concave bay 51 of the cartridge. The primary element of sealing the gaees generated by the exploitative load 44 is the end-berthing bar 48 that fills more of the cross-section of the bottom of the drill hole 52, leaving only a gap of free space 53 for the high-pressure gases eecapen. The additional sealing of this high-pressure item is carried out by the metal sealing ring 54 and portion of the cartridge body 45 and the base of the cartridge 55 which are forced into the gap 53 by the high-pressure gases. Figure 6 shows an alternative version of a small charge explosion cartridge 56 incorporating a shock isolation mechanism 57 which is designed to assist in decoupling the transient shock regime generated by the explosive charge 58, from the fuel cap. 59 of cartridge 56. Otherwise, the cartridge 56 is substantially the same as the cartridges shown in Figures 4 and 5.

Figure 7 shows an alternative configuration of the lower end of the berthing bar in the hole. There is no cartridge in it. The tie bar 60 has an elongated tip 61 with a conical section 62. The drilling hole has a larger diameter upper section 63 which is transposed to a smaller diameter lower section 64 by a conical section 65. This type of drilling hole can be formed by a Special drilling bore assembly. The berth bar 60 is inserted into the drill hole and the conical section 62 is fed into the conical section 65 of the drill hole to form an initially sealed seal for the high pressure gasses that will be generated at the bottom of the hole. High-pressure gasses will cause the berth bar 60 to back off, thus opening a gap between the conical section 65 of the drill hole. The conical section 65 of the drill hole is less sensitive to splintering and imperfections in the rock than a sharply staggered drill hole as shown in Figures 4, 5 and 6 and to the de-spiral of the well and the leak of the high-pressure gases. ee can control it better. Eeta bar tie configuration can be used with any cartridge configuration shown in Figures 4, 5 and 6. Figure 19 depicts another embodiment of a small charge explosion cartridge 200 according to the present invention. The cartridge 200 includes a sacrificial cartridge base 204, an outer cartridge housing 208, an inner cartridge housing 212, an explorer 216 and a detonating cord 220. The detonating cord 220 includes a detonation initiator 224, a secondary induction 228, and a conductor 232 for connecting the secondary induction coil 228 and the knock initiator 224. A tie-bar 236 includes means for sealing the cartridge 200 in the bore 240 (ie, the gap between the boom berthing and the side of the hole) and the primary induction coil 244 in electrical contact with the secondary induction coil 228 to initiate the detonation of the exploit. The cartridge 200 includes a free volume 248 formed by the outer housing of the cartridge 208, the base of the cartridge 204, and the inner housing of the cartridge 212. The inner housing of the cartridge 212 also includes a free volume 252 located between the explosive 216 and the cartridge base 204. The free volume 252 allows the detonation exploding pressure to be attenuated by expansion to the point where it does not overload the base of the cartridge 204 and transmits excessive shock energy to the tie bar 236. The free volumes 248 and 252 they constitute the majority of the total free volume at the bottom of the hole 240. Preferably, the free volume 252 varies from about 20 haeta to about 100 percent of the volume of the explosive 216. It is preferred that the total of the free volume 252 and the free volume 248 vary from about 2 to about 5 times that of the volume of the explosive 216. The free volume 252 preferably represents at about 17 haeta about 50 percent of the total volume of the inner housing of the cartridge 212. The sum of the free volume 252, the free volume 248, and the explosive 216 equals the total volume available for the gae generated when the explosive is consumed 216. As will be appreciated, the free volume augmented with the clearance between the outer housing the cartridge 208 and the surface of the hole 240 provides another small volume in addition to the total free volume at the bottom of the hole. The base of the cartridge 204 protects the end inside the reusable 256 hole of the berthing bar from permanent damage during the detonation of the explosive, contains part of the initiator system, and helps seal the bottom of the hole by occupying most of the area in cross section of the hole. The base of the cartridge preferably has a resilient strength less than the elastic resistance of the berthing bar so that the base of the cartridge undergoes plastic deformation as a re-peg to the detonation of the explosive before the berthing bar.

Preferably, the elastic strength of the base of the cartridge is not greater than about 75 percent of the elastic resistancy of the berthing bar. The base of the cartridge can be composed of a variety of cheap materials, including steel, aluminum, plastic, compueetoe, and eimilaree. The thickness "t" of the base of the cartridge preferably varies from about 1.27 haeta to about 5 centimeters. The diameter of the base of the cartridge has a diameter ranging from about 50 to about 250 millimeters and has a length to diameter ratio ranging from 0.15 to about 0.6. The shape of the cartridge baee 204 serves for numerous purposes. By way of example, the outer end 260 of the cartridge base has the same shape as the end 256 of the tie bar 236 so that the tie bar 236 can be aligned with the cartridge 200 to allow the induction coil primary 244 is electrically coupled to the second induction coil 228. As shown, the preferred shape of the outer end 260 of the base of the cartridge and end 256 of the docking means is curved. The base of the cartridge is conical in shape where the balee of the cartridge connects with the outer housing of the cartridge 208. Accordingly, the portion of the outer housing of the rubber 208 adjacent to the conical portion of the cartridge baee decreases from diameter in the angle as the decrease in diameter of the conical portion of the base of the cartridge. During detonation of the exploive, the conical portion of the cartridge was the outer housing of the cartridge against the sides of the hole 240, sealing therewith the cartridge 200 at the bottom of the hole. The outer housing of the cartridge 208 has a cylindrical shape and seals the inner part of the cartridge 200 from any water or other liquid in the hole 240. As noted above, the outer housing of the cartridge contains the free volume needed to control the average spike preelection. at the bottom of the hole and thereby prevent over-purification of the bottom 223 of the drilling hole. To improve rerouting, the outer housing of the cartridge should be fragmented when the explorer detonates to inhibit large part of the housing from blocking or preventing the gae from flowing in the open fracture at the bottom of the hole. The outer housing of the cartridge may be composed of various materials, including steel, aluminum or plastics. Lae dimeneionee of the cartridge depend on the specific application. The thickness of the wall of the outer housing of the cartridge preferably ranges from about 0.75 to about 5 millimeters in underground excavation applications and from about 0.75 to about 5 millimeters in surface excavation applications. Preferably the nose portion 221 of the outer housing of the cartridge located at the opposite end of the outer housing of the cartridge from the cartridge bed has a groeor ranging from approximately 0.025 haeta to approximately 0.076 centimeter in underground excavation applications and from approximately 0.025 to 0.076. in surface excavation applications. The cartridge 200 has a maximum diameter ranging from about 50 to about 250 millimeters in underground excavation applications and of approximately 50 hectares approximately 250 millimeters in surface excavation applications. The cartridge has a length to diameter ratio of approximately 1 haeta about 4. The inner housing of the cartridge 212 contains the exploit and places the explosive in the hole 240. In other words, the inner housing of the cartridge places the explosive (i ) away from the side walls of the drilling hole 240, (ii) away from the base of the cartridge 204, and (iii) maintains the separation between the exploit and the bottom of the hole. As in the case of the outer housing of the cartridge, it is important that the inner housing of the cartridge be fragmented when the explosive is detonated so that there are no large pieces to block or prevent the flow of gae towards the open fracture at the bottom of the hole. The inner housing of the cartridge can be of a variety of materials, including steel, aluminum or plastic, and has a preferred wall thickness that varies from about 0.2 to about 1 millimeter. The exploit can be any number of the explosive materials noted above. In the case of liquid explorae, a separation wall or membrane is required in the upper portion 264 of the explosive to keep the explosive in the lower portion of the inner housing of the cartridge. The mass of the explosive 216 preferably ranges from about 0.15 to about 0.5 kilograms in excavation applications below ground and from about 1 haeta to about 5 kilograms in surface excavation applications. The detonation assembly 220 has several subcomponents as noted above. The initiator 224 is preferably a cover number 6 or number 8 or another dietary initiation detonation. The secondary induction coil preferably has a diameter of cable that is eminent for carrying electric current pule ranging from about 1 to about 5 amps. The primary induction coil 244 preferably has a wire diameter eficient to carry a pulse of electric current ranging from about 20 to about 200 amps. For best results, the maximum distance ("d") between the primary and secondary induction coils is preferably no greater than about 3 millimeters. An activation box energizes the primary induction coil 244 with a surge of current that induces a current in the secondary induction coil 228. The spatial positions of the six components in the cartridge 200 are important for the optimum performance of the cartridge. The distance "di" between the bottom of the inner housing of the cartridge 212 and the bottom of the outer housing of the cartridge 208 determines the amount of fracturing in the rock induced by the cartridge. The maximum degree of fracturing is realized when the distance "di" is substantially 0 and the outer housing of the cartridge makes contact with the bottom of the hole 240. Preferably, "di" is not greater than about 15 millimeters. The distance "d2" from the bottom of the outer housing of the cartridge to the bottom of the hole 240 is preferably kept as low as possible and that the outer housing of the cartridge is depressed at the bottom of the hole by the force of insertion of the cartridge into the hole . As will be appreciated, the outer housing of the cartridge can sustain significant damage during insertion, including rupture. Preferably, the "d2" diet is no more than about 15 millimeters. The distance "d3" is the free space distance between the outer housing of the cartridge and the side wall of the drilling hole 240. The distance "d3" is preferably sufficient to allow the cartridge to be easily inserted into the bottom of the hole and to hold significant damage as noted above. The distance will vary, of course, with the wear and over-excavation of the drill bit in different types of rocks. Preferably, the diet "d3 varies from about 0.2 haeta to about 3 millimeter.The berthing bar 236 has a sufficient height to withstand a substantial portion of the recoil of the bale of the cartridge 204 which results from the detonation of the exploiter 216. Preferably the bar berthing has a peeo that varies from approximately 25 to approximately 1, 000 kilogram. The diameter of the berthing bar is sufficiently large to form a seal between the sides of the berthing bar 236 and the sides of the hole 240 to inhibit the escape of gas from the detonation of the explosive 216 from the bottom of the hole. Preferably, the diameter of the tie bar 236 ranges from about 50 to about 250 millimeters in excavation applications underground and from about 50 to about 250 in excavation applications. Typically, the berthing bar has a cross-sectional area that is at about 95 percent of the tranevereal cut-hole area. To protect the end 256 of the berthing bar 236 from the damage caused by the recoil of the cartridge bae of the detonation of the explosive 216, the explorer 216 is placed at a distance "d4" from the cartridge bay to die the wave of detonation shock. For improved rereading, the distance "d4" preferably ranges from about 0.12 to about 7.6 centimeters. Figure 20 depicts another embodiment of a small charge explosion cartridge 300 according to the present invention. Unlike the cartridge 200 of the previous embodiment, the cartridge 300 does not have an inner cartridge housing. Instead, the explorer 304 is located in the nose portion 308 of the outer housing of the cartridge 312. As noted above, a separation wall 316 is intended to remove the explosive, especially liquid explosives, from the free volume 320 of the cartridge. Preferably, the free volume 320 repre sents from about 50 to about 75 percent of the total volume of the outer housing of the cartridge. The explosive occupies the total remaining volume of the outer housing of the cartridge.

Figure 8 shows the small load exploit system after activation in the situation where the cartridge wall 66 does not break near the end of the tie bar 67. The explosive has been started and the depressurized presses are forced to the bar. docking 67 and the baee plug of the cartridge 68 recedes as the walls of the cartridge 66 expand against the bore hole wall 69. The front portion of the cartridge has been fragmented causing the hole to be filled with gaees of the explosive product initiating a fracture controlled 70 at or near the bottom of the drilling hole 71. The pressure forces taper of the plug 68 against the taper of the cartridge wall 72 during retraction to maintain a dynamic seal as it occurs and ruptures rock. . Figure 9 shows the small load exploding seventh after activation in the situation where the cartridge wall 73 breaks 74 near the end of the tie rod 75. The cartridge wall 73 near the plug of the base ee aeume The broken gas 74 and the gases of the high-pressure explosive product then force the metal back-up ring 77 into the gap 78 between the end of the tie-bar 75 and the wall of the bore hole 79, sealing the element against leakage. gae from the bottom of the hole.

The performance of the small charge explosion method for the case of a deepening explosive charge is shown in Figure 10 by the history of the pressure calculated at the bottom of the drill hole. The calculation is for the case when the rock does not fracture. The pressure 80 is shown as a function of time 81. A preemption peak 82 ee immediately generates as a result of the expansion of the explosive products through the gap (see Figure 5). The pressure oscillates 83 as the gas generated by the explosive products moves backward and forward in the available volume. The pressure decays over time as the berthing rod recedes (increasing the available volume) and as the gae leaks pass the berthing bar. The pressure ee mueetra at the bottom of the hole for about 4 milli-seconds. The performance of the small charge explosion method in the case of an uncoupled explosive charge is shown in Figure 11 by the ice of the calculated pressure at the bottom of the drill hole. The calculation is for the rock when the rock breaks. The pressure 85 is shown as a function of time 86. A pressure peak 87 is immediately generated as a result of the expansion of the product exploded through the gap (see Figure 5). The pressure oscillates 88 as the gae generated by the explosive products moves backwards and forwards in the available volume. The pressure declines 89 over time as the berthing bar recedes (increasing the available volume); as the gas leaks pass the berthing bar and as the gas flows into the developing fracture system. The pressure ee shows at the bottom of the hole for approximately 4 milliseconds. The calculated distribution of gas within the small charge exploit cartridge and the bottom of the hole is shown in Figure 12. The calculation is for the case when the rock fractures and correeponds to the ice of the precession shown in Figure 11. The mass of the remaining gas in the volume of the cartridge 90, the mass of the gas leaked from the system 91 and the mass of the gas injected into the bottom of the hole and the fracture number 92 are measured as a function of time 93. Deepuée of the initiation, The gases of the explosive product expand to fill the entire cartridge and the volume of the bottom of the hole. When the pressure reaches a critical threshold (of the order of 30 percent of the compressive resistance of the rock), a fracture begins. The gae continues to flow from the cartridge to the expanding fraction seven. At the same time, in this calculation, the cartridge wall near the cap of the cartridge base is assumed to be broken after the 2.5 millimeter retraction is preempted, allowing the gas to escape through the gap between the tie bar and the wall of the docking hole. The gaeto of the mass of gae ee aeume that leaks in the condition of aeonic drowning that is dictated by the cross-sectional area of the gap and the velocity and density of the local gas eonid. After 4 milli-seconds, the fracture will have reached the surface of the surface of the rock and the fragmentation of the rock is considered complete. As it will be seen, a small fraction of the gae has escaped from the system (18 grams of the original 200 grams) have been injected into the bottom of the hole and severed from the fracture. The performance of the small load exploratory method for the reduction of an exploratory load is coupled in the Figure 13 by the calculated pressure beam at the bottom of the drill hole. The calculation is for the rock when the rock breaks. The pressure 94 is shown as a function of time 95. A strong pressure peak 96 is immediately generated as a result of the reflection of the detonation wave from the explosive in contact with the bottom of the cartridge (see Figure 4). The pressure oscillates 97 as the gas generated by the exploded product moves backward and forward in the available volume. The pressure declines 98 over time as the berthing bar recedes (increasing the available volume); as the gas leaks from the berthing bar and the gae flows towards the fracture system under development. The pressure is displayed at the bottom of the hole from approximately 4 milliseconds. The realization of a non-explosive method of loading in the hole using a propellant of the drilling hole in Figure 14 by means of the calculated pressure at the bottom of the drilling hole. The calculation ee for the fall when the rock does not fracture and can be compared to the example of the small load exploit of Figure 10. The preemption 99 is shown as a function of time 100. There is a dietinta lack of a peak of pressure and pressure increases relatively slowly compared to the small load explosion method. The pressure declines 101 over time as the berthing bar recedes (increasing the available volume); and as the gas fugae pass the berthing bar. The pressure dies at the bottom of the hole for approximately 4 milli-seconds. The realization of a gas injector device using a propulsive device in Figure 15 by means of the ice of the calculated pressure at the bottom of the drilling hole. The calculation ee for the case when the rock does not fracture and can be compared with the example of small load explosion of Figure 10 and the example of the Load in the hole of Figure 14. The pressure 102 is demoted as a function of time 103. There is a distinct lack of a pressure peak and the pressure rises relatively slowly compared to the small load exploit method. The pressure declines 104 over time as the berthing bar recedes (increasing the available volume); and as the gas leaks stop the berthing bar; and as the gas blows back from the barrel of the gas injector. The ee mueetra preeion at the bottom of the hole for about 4 milliseconds. The gas distribution calculated within the seventh gas injector and the bottom of the hole is shown in Figure 16. The calculation is for the case when the rock fractures. The mass of the gas in the injector volume of gae 105, the mae of the leaked gae of the system 106 and the mass of the gas injected towards the bottom of the hole and the seventh of fracture 107 ee mueetra as a function of time 108. Approximately 4 milieecond After the precession has been at the bottom of the hole, a fracture will have reached the surface of the face of the rock and the fragmentation of the rock can be considered complete. As you can see, a significant fraction of the gas has leaked from the system (61 grams of the original 380 grams). Much of the gas (145 grams of the original 380 grams) remains inside the gae nozzle. The gae reetante in the gae deepuée injector that the fragmentation of the rock can be the source of much of the current of air and energy rock dust rock frequently associated with this method. A possible rock excavation seventh based on the use of a small load exploratory beam in figure 17. There are joint beam 108 and 109 joined to a mobile subcarrier 111. The beam assembly 108 has a small load explosion apparatus 111 mounted on it. The beam assembly 109 has an optional mechanical impact breaker 112 and a backhoe attachment 113 to move broken rock from the work surface to the 11th trane conveyor 114 which pans the broken rock through the excavator to a haulstone (not shown). A typical advancer mechanism for the small charge explosion apparatus is shown in Figure 18. The advance mechanism 115 connects the small charge explosion apparatus 116 to the hinge beam 117. A rock driller 118 and an insertion mechanism Small charge explosion 119 are mounted on the advancement 115. The beam 117 places the advancing assembly on the surface of the rock so that the rock drill 118 can drill a short hole (not shown) on the surface of the rock (not shown). When the rock drill 118 is removed from the hole, the advancer 115 rotates about the shaft 120 by a hydraulic mechanism 121 so as to align the inerting mechanism SCB-EX 119 with the axis of the drill hole. The small load explosion insertion mechanism 119 is then inserted into the drill hole and the small load is raised for ignition.

Claims (21)

1. A diepoeitive to fracture a hard material, comprising: a cartridge; and a docking element for retaining the cartridge in a hole in the material, the docking element having a first elastic rebound, the cartridge being located adjacent one end of the docking element and including: a cartridge base positioned adjacent to the end of the docking element, the base having the cartridge a second elastic resistance less than the first elastic re-appointment; and an outer cartridge housing attached to the cartridge bed, a first portion of the outer housing of the cartridge contains an explosive and a second portion a space for controlling the gas pressure in the hole, wherein the explorer is placed at a distance of the base of the cartridge to dissipate a detonation shock wave generated during the detonation of the explosive to protect the docking medium from the detonation shock wave.

The device of Claim 1, wherein the base of the cartridge has a thickness ranging from about 50 to about 250 millimeters.

3. The device of claim 1, wherein the anchoring element has a first elastic resistance and the base of the cartridge a second elastic resistance and the second elastic resistance is not more than about 75 percent of the first elastic resistance.

4. The device of claim 1, wherein the belay element has a first elastic resistance and the base of the cartridge a second elastic resistance and the second elastic reheat is less than the first elastic re-tension so that the base of the cartridge is deformed. plastically as a response to the detonation shock wave before the docking element.

The device of claim 1, wherein the base of the cartridge is tapered and the portion of the outer housing of the cartridge adjacent to the base of the tapered cartridge for eellaring the cartridge in the hole when the cartridge baee recedes from the wave of detonation shock.

6. The device of claim 1, wherein the nose portion of the outer housing of the cartridge located at the opposite end of the outer housing of the cartridge from the base of the cartridge has an amount ranging from about 0.75 to about 5 millimeters.

7. The device of claim 1, wherein the explosive is selected from the group that connects in a mixture of ammonium nitrate and nitromethane, dynamite, composition 3, Composition 4, Octol, explosives in emulsion, explosive in water gel, and gelignite. The device of claim 1, wherein the space has a volume of space and the explosive a volume of explosive and the volume of the space varies from about 200 haeta to about 500 percent of the exploit volume. 9. The diepoeitive of claim 1, wherein the explo- sive is eepara from the bottom of the hole by a diet not greater than about 15 millimeters. The device of claim 1, wherein the distance varies from about 1.27 haeta to about 7.62 centimeter. 11. The diepoeitive of claim 1 wherein at least one of the docking element and the base of the cartridge includes guiding elements for aligning the base of the cartridge with respect to the end of the docking element. The device of claim 11, wherein the docking element includes a primary inductance coil and the base of the cartridge a secondary inductance coil, the primary and secondary inductance coils being electrically coupled together to initiate the detonation of the exploit. . 13. The die of claim 1, wherein the cartridge has a length to diameter ratio ranging from about 1 to about 4. The die of claim 1., which further comprises: a sealing element for sealing the cartridge at the bottom of the hole to pressurize the bottom of the hole and form a fracture from a machine at the bottom of the hole. 15. The diepoeitive of claim 1, wherein the balee of the cartridge has a length-to-diameter ratio ranging from about 0.15 haeta to about 0.60. 16. The diepoeitive of claim 1, wherein the space has a volume of space and the volume of space varies from about 50 haeta to about 75 percent of the total volume of the outer housing of the cartridge. 17. An explosive device for fracturing a hard material, the exploitative device being placed in a hole in the hard material, the device comprising: a cartridge base; an outer housing of the cartridge having a base portion attached to the base of the cartridge and a nose portion, the nose and nose portion being positioned at opposite ends of the outer housing of the cartridge, including the outer housing of the cartridge an explosive in contact with the nose portion and an open space to control the pressure of the gas in the hole, where, when the device is placed in the hole, the nose portion comes into contact with the bottom of the hole. 18. The explosive device of claim 17, wherein at least about 50 percent of the area of the nose portion contacting the bottom of the hole contacts the explosive. 19. An explosive device for fracturing a hard material, the explosive device being placed in a hole in the hard material, the device comprising: a berthing bar extending towards the hole of a point outside the hole; a cartridge base in contact with a free end of the berthing bar, the free end of the berthing bar being located in the hole, - and an outer housing of the cartridge including an explosive separated from the base of the cartridge to dissipate a Shock shock wave generated during detonation of the exploive to protect the beating bar from the detonation shock wave and a space to control the pressure of the gas in the hole. The explosive device of claim 19, wherein the base of the cartridge has a length to diameter ratio ranging from about 0.15 to about 0.60 millimeter. 21. The exploitative diepoeitive of claim 19, wherein the dietary ratio between the explosive and the base of the cartridge varies from about 1.27 to about 6.35 centimeters. 23. The explosive device of claim 19, further comprising: an internal cartridge housing positioned within the outer housing of the cartridge and contacting the base of the cartridge, the inner housing of the cartridge containing the explosive and a clearance between the cartridge. exploeivo and the cartridge baee. 24. The explosive device of the claim 23, wherein the inner housing of the cartridge has a wall thickness ranging from about 0.2 haeta to about 1 millimeter. 25. The explosive device of claim 19, further comprising: an elliptical element for sealing the explosive device at the bottom of the hole to preeurise the bottom of the hole and form a fracture from a corner of the bottom of the hole. 26. The explosive device of claim 23, wherein the inner housing of the cartridge has a volume and the volume of the free space varies from about 17 to about 50 percent of the volume of the internal cartridge housing. SUMMARY Rock and other hard materials, such as concrete, are fragmented by a small controlled charge exploratory process. The process is carried out by pressurizing the bottom of a drilling hole, in such a way that a controlled fracture starts and spreads, or propagates any previously existing fractures near the bottom of the hole. A cartridge containing an explosive charge is inserted into the bottom of a short hole drilled into the rock. The explosive charge is configured to provide the predetermined pressure at the bottom of the hole, including, in this case, a strong charge tip at the bottom of the hole, to improve microfracturing. The cartridge is stopped in place or is docked by a heavy berthing bar of high re-heat material, such as steel. The explosive can be started in a variety of ways, including through a conventional electric explosion cap. The cartridge incorporates an additional internal volume designed to control the application of pressure in the volume of the bottom of the hole by the detonation explosive. The primary method by which high-pressure gases are contained in the bottom of the hole until they are released through the opening ee by the controlled fracture, by means of the massive inertial berthing bar that blocks the flow of gae emanating from the drilling hole, except for a small line of leak between the berthing bar and the wall of the drill hole. Eeta small leakage can be further reduced by the design features of the cartridge and the tie rod. The berthing bar is preferably connected to a beam mounted on a carrier. A preferred embodiment incorporates an advancing mechanism, to allow both a drill bit and a small load explorer to be used on the same beam for drilling and the subequent loading and activation insertion operations. The principal characteristics of the method and apparatus are the relatively low energy of the projection of small pieces of rock, and the relatively small amount of explosive required to break the rock. * * * * *