RU2200933C2 - Process of blast cutting of thick-walled structures - Google Patents

Abstract

FIELD: blasting operations, blast cutting of metal, concrete and reinforced concrete structures of various forms and dimensions. SUBSTANCE: process of blast cutting of thick- walled structures includes placement of explosive charge on surface to be cut and its initiation carried out simultaneously by means of opposing pulses perpendicular to section over entire length. Auxiliary explosive charge is positioned on side surface of structure in point of anticipated cut and is time-initiated . Auxiliary explosive charge is worked into structure to be cut. Additional auxiliary explosive charge is placed on opposite side surface of cut structure. Explosive charges are initiated simultaneously or with delay. EFFECT: enhanced efficiency of blast cutting of thick-walled structures of various form and profile. 4 cl, 6 dwg

Description

 The invention relates to charges for blasting, namely to explosive cutting of metal, concrete and reinforced concrete structures of various shapes and sizes.

 The known method described in the patent of the Russian Federation 2062162, cl. F 42 D 3/00 under the name "Method for crushing a metal monolith".

 In the metal monolith form holes located along the line of the proposed separation. Explosive charges are placed in the holes, which then explode. The placement of explosive charges and their blasting is carried out at least once in each hole. Holes are formed, including using cumulative charges. Before crushing, the monolith is subjected to local softening or embrittlement along the lines of the proposed separation.

 The disadvantage of this method is its complexity and low efficiency.

 The closest technical solution, selected as a prototype, is the method of cutting structures described in the patent of the Russian Federation 2105946, cl. 6 F 42 V 1/00 entitled "Method for cutting structures and blast wave generator".

 The tape charge of the explosive is placed on the cut surface and is initiated simultaneously along the entire length by counter-directed pulses perpendicular to the section.

 The disadvantages of this method is the lack of charge efficiency in the case of cutting thick-walled flat metal structures, because as a result of unloading waves, the maximum tensile stresses in the zones adjacent to the side surfaces of the object can be less than the dynamic tensile strength and there will be no structural failure. In particular, for reinforced concrete structures, this will lead to concrete spalling, and reinforcing steel bars will not be cut. To reduce the effect of unloading, a significant increase in the mass of explosives in the charge is required or other technical solutions are used.

 The objective of the present invention is to provide a method with increased efficiency of explosive cutting of structures and especially thick-walled metal and reinforced concrete structures of various shapes and profiles.

 The present problem is solved in that in the method of explosive cutting of thick-walled structures, including the placement of the explosive charge on the cut surface and its initiation, carried out simultaneously along the entire length with counter-directed pulses perpendicular to the cut, an auxiliary explosive charge is placed on the side surface in the place of the proposed cut and the agreed initiation of explosive charges.

 In addition, the auxiliary explosive charge is buried in the cut structure or placed on opposite side surfaces of the cut structure.

 In addition, the initiation of explosive charges is carried out simultaneously or with a delay after the operation of the main charge.

 The technical result is expressed in the fact that the simultaneous multi-point symmetric mode of initiation of the main linear explosive charge provides a collision mode of two normal detonation waves along the line of the axis of symmetry of the explosive charge passing along the larger base. As a result of the interaction of shock waves propagating deep into the material of the object, reflected waves and unloading waves, stress waves arise, which lead to the appearance in the plane perpendicular to the surface of the object and passing through the longitudinal axis of charge symmetry (along the larger base) tensile stresses exceeding the dynamic tensile strength of the material destructible object.

 The most important factor determining the effectiveness of any dynamic loading system is the ability to create a triaxial stress state in a certain area of the material of the cut object. The creation of the necessary radial tensile forces directed perpendicular to the plane of the cut significantly increase the cutting ability of the method.

 The simultaneous undermining of the lateral charges simultaneously with the main charge or after some time after its detonation allows the formation of additional radially directed tensile forces and thereby load the unloaded areas adjacent to the side surfaces.

 As a result, complete destruction occurs in the plane of symmetry of the object, which coincides with the longitudinal plane of symmetry of the charge.

 The presence of signs that distinguish the claimed invention from the prototype, allows us to conclude that it meets the criterion of "novelty."

 In FIG. Figures 1 and 2 show variants of charge placement schemes on a cut structure.

 Figure 3, 4 and 5 presents a diagram of the propagation of detonation and shock waves.

 Figure 6 presents a photograph with a cut object.

 The method is implemented as follows.

 The explosive circuit (FIGS. 1 and 2) contains the main linear explosive charge 1 in the form of a tape, side explosive charges 5, initiating multipoint elements 2 (blast wave generators) and delay lines 6, cut object 4, detonator caps 3.

 The explosive circuit is activated using one or more detonator capsules 3. Figure 1 shows an example of two-point initiation of the main charge, when the delay systems of the initiating elements of the charges are blown up simultaneously using, for example, two detonator caps, each of which initiates a delay line only initiating multipoint element on which it is installed. Side charges (one or more on each side surface) are detonated simultaneously with the main charge or with some delay.

 The main and side charges (including charges in the holes) are positioned without gaps with the surfaces of the object being cut 4.

 Consider the operation of the explosive circuit as an example of the placement of lateral charges in the holes (Fig.1, 3).

 With a multipoint simultaneous detonation of the initiating elements 2 located on the edges of the main charge 1 to the longitudinal axis of the charge from two sides, two detonation fronts begin to propagate at a speed D (D, km / s, is the detonation velocity for this explosive) (Fig. 3), which, with multipoint initiation, as a first approximation, can be considered linear (the smaller the initiation step, the more linear the detonation front and vice versa) (Fig. 5).

In this case, two shock fronts with a velocity C extend deep into the material of the object being cut (Fig. 3). The further propagation of detonation fronts along charge 1 (the case is considered when the explosive charge thickness is much smaller than its width, i.e., the charge is assumed to be relatively thin and the charge thickness is not taken into account) leads to their collision along the line of longitudinal charge symmetry (T. A). This leads to further in-depth propagation of the material of the destructible object 4 along the entire length of the axis of the proposed cut, which coincides with the longitudinal axis of symmetry of the explosive charge, of the wave process of interaction of shock waves with a clearly defined boundary. As a result of this interaction, stress waves arise in a plane perpendicular to the surface of object 4 and passing through the longitudinal axis of symmetry of charge 1, which in turn lead to tensile stresses exceeding the dynamic tensile strength of the material of the destroyed object 4 (AA ₁ ). As a result of the fact that tensile stresses arise in a narrow localized zone, the destruction occurs with the formation of a crack that occurs in the plane of symmetry of the object, which coincides with the longitudinal plane of symmetry of the charge. Lateral charges 5 are blown simultaneously with each other at a certain point in time, for example, at the moment of arrival of a shock wave propagating from the main charge to their location (T.A ₃ ) or earlier (Fig. 4).

 It is also obvious that due to the finite dimensions of the object being cut 4, when the shock wave exits to the free lateral surface, spalling effects will occur, especially manifested on the back (end) surfaces of the object being cut. In this case, unloaded regions arise (7, Fig. 5), in which, when only the main upper charge of destruction is undermined, they are either absent or small.

 Using lateral charges 5, effective total radially directed tensile forces arise, which can significantly increase the efficiency of explosive cutting.

 An indirect confirmation of the effectiveness of this method is that the total mass of side charges 5 in the case of their placement in the holes is less than 5% of the mass of the main charge.

Using this method, a steel billet of mild steel (st.10) was cut with a thickness of 460 mm, a length of 800 mm and a width of 800 mm and the following charges were used, made of a plastic aircraft based on RDX:
the main charge is a thickness of 20 mm, a width of 410 mm, a mass of 12.7 kg;
lateral charges - two charges with a total mass of 50 g.

The specific consumption of explosives in this case amounted to about 3 g per 1 cm ² the cross-sectional area of the workpiece or 5.6 kg / t.

 Steel billet was cut into two parts for one blasting (Fig.6).

 The described method can significantly increase the efficiency of explosive circuits for cutting thick-walled structures, for example, steel or reinforced concrete. Moreover, the method allows you to completely cut the structure into two or more in one blast, depending on the number of charges and parts involved. Using this method allows to obtain a smooth (in the case of metal targets) the nature of the cut without the formation of fragments.

Claims (5)

 1. The method of explosive cutting of thick-walled structures, including the placement of an explosive charge on the cut surface and its initiation, carried out simultaneously along the entire length with counter-directed pulses perpendicular to the cut, characterized in that an auxiliary explosive charge is placed on the side surface in the place of the intended cut and carry out coordinated initiation of explosive charges.  2. The method of explosive cutting of thick-walled structures according to claim 1, characterized in that the auxiliary charge of the explosive is buried in the cut structure.  3. The method of explosive cutting of thick-walled structures according to claim 1 or 2, characterized in that an additional auxiliary explosive charge is placed on the opposite side surface of the cut structure.  4. The method of explosive cutting of thick-walled structures according to claim 1, characterized in that the initiation of explosive charges is carried out simultaneously.  5. The method of explosive cutting of thick-walled structures according to claim 1, characterized in that the initiation of an auxiliary explosive charge is carried out with a delay after the explosive charge is triggered.

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