SU1195004A1 - Method of exciting elastic waves in rock body - Google Patents

Abstract

1. A METHOD OF ELASTIC WAVE ELASTICATION IN A MASSIF OF MOUNTAIN BREEDS, including the creation of mechanical stresses in a local area of an array of rocks, characterized in that, in order to increase the excitation stability and control the characteristics of the excited elastic waves, in the local area they create an electrically conductive region with non-conductive less than 2-10 (ohm. m) and affect it with a pulsed quasi-stationary .. magnetic field, and the characteristics of the excited elastic waves are controlled by adjusting the magnitude and length nosti pulse field strength of the exciting magnetic field. 2. A method according to claim 1, wherein the electrically conductive area is created by forming a cavity in which a metal plate with a thickness of 10-50 mm is fixed. 3. A method according to claim 1, characterized in that the electrically conductive region is created by forming a cavity into which a short-circuited electrically conductive coil is placed, the plane of which turns (Lai is parallel to the local area of the array, and then the cavity is filled with a hardening compound. 4. Method POP.1, characterized in that the electrically conducting WELENLUTE region in the form of a wedge, one side of which is located along the local area of the SP, and the other forms an angle of 45 with it. // // 1 /// 4: //// /// // U ///// 7 /// L

Description

(Eng. 7 1 H3o6peTenftie refers to mining and can be used to excite elastic waves while monitoring the properties and state of the rock mass. The purpose of the invention is to increase the stability of the excitation and control the characteristics of the excited elastic waves. Fig. 1 shows a diagram of the implementation of this method Fig. 24 shows possible options for creating an electrically conductive array region; Fig. 5 shows experimentally the dependence of the relative amplitude A of the excited wave on the distance by the method of external causative agent quasist a stationary pulsed magnetic field (inductor) and an electrically conductive region L of the array; Fig. experimentally obtained dependence of the relative amplitude of the elastic wave excited in the array on the discharge voltage of the storage battery capacitors; Fig. 7 - experimental dependence of the relative change in the duration of the elastic pulse arising in the array, from the capacitance of capacitors of the storage node. The method is carried out as follows. In the local part of the array 1, the coaxial region 2 is given with a conductivity of not less (Ohm-m) near which an inductor 3 is positioned at a distance L 0 20 mm, which is discharged in an electric power storage unit 4. The storage unit 4 is, for example, a battery of capacitors. The duration and amplitude of the discharge pulse from the storage node 4 is controlled by the control unit 5 by switching different amounts of capacitors to the digging node 4 and changing the charging voltage on them. As a result of the discharge of the capacitors of the storage node 4 to the inductor 3 coil in the electrically conductive region 2, a pulsed quasi-stationary magnetic field is created, which leads to the appearance of eddy currents in the region of eddy currents, the interaction of the magnetic field with the magnetic field of the inductor 3 the local part of array 1 adjacent to the electrically conductive region 2. The latter leads to the formation of elastic waves in the array 1. The conductivity of the electrically conductive region must be at least 2 10 (Ohm. MH, since otherwise (as shown by experimental studies) the amplitude of the excited elastic waves decreases, as a result of a decrease in the eddy currents induced in region 2. The amplitude of the excited elastic wave is controlled by changing the distance between the inductor 3 and the conducting region 2 in range O - 20 mm, which leads to a decrease in the amplitude of the radiated wave by 15–20 times (Fig. 5). In addition, the amplitude of the excited wave is controlled by changing the discharge voltage of the capacitors of the storage node 4. Increasing the discharge A voltage from 900 to 1600 V leads to an increase in the amplitude of the excited elastic wave by about 6 times (Fig. 6). The duration of the excited elastic pulse is controlled by changing the capacitance of the capacitor node 4 using the control unit 5 to control the duration of the pulse. It is proportional to the square root of the capacitance of the storage capacitors (Fig. 7). . The electrically conductive region is created, for example, by forming a local cavity 6 on the surface of array 1 and fixing a metal plate 7 in it using anchors 8 and 9 and cement mortar 10 (Fig. 2). The optimum thickness of the electrically conductive region is 2-1 1050 mm, since, with a thickness of less than 10 mm, the amplitude of the excited elastic wave drops significantly at low frequencies, where the thickness of the electrically conductive region becomes less than the skin layer: where U is the skin layer thickness; - absolute magnetic permeability; С - conductivity; W - krugoEza frequency.

 3

Increasing the thickness of the electrically conductive region of more than 50 mm is impractical because it does not lead to a further increase in the amplitude of the excited elastic waves and complicates the manufacturing technology of this region.

The diameter of the conductive region d should be 1.2-1.6 times the diameter of the inductor. Reducing the diameter of the electrically conductive region to less than 1.2 diameters of the inductor is impractical because it reduces the amplitude of the excited elastic waves due to the fact that part of the magnetic field energy is dissipated in the surrounding rocks j does not interact with the electrically conductive area of malrs sizes. Increasing the diameter of the conductive region of more than 1.6 E | the inductor does not lead to an increase in the amplitude of the excited elastic waves, but complicates the technology of manufacturing this area. The plate 7 can also be fixed directly on the surface of the array, however, at the same time, the rigidity somewhat decreases.

its in connection with the array which leads to a decrease in the radiated power

The electrically conductive region 2 (Fig. 3) can also be created by forming a cavity 6 on the surface of array 1 into which a short-circuited electrically conducting coil It is placed, the plane of the turns of which is parallel to the free surface of array 1, then filled with a hardening compound 12. The coil is made of metal wire with good wire 950044

revenge, for example, copper, and should according to its geometric and winding characteristics, Kai showed experimental studies to be 5 like inductor coil 3. For example, coil 11 with an inner diameter of 2.5 cm and an outer diameter of 5 cm can contain 50 turns of copper wire with a diameter 2 mm. The fabrication of this electrically conductive region is somewhat more complicated than that described above, however, this method of manufacturing an electrically conductive region makes it possible to excite elastic waves with large 20-30%

5 amplitudes, which is explained by an increase in the inductance of the electrically conducting region, and consequently, the intensity of the magnetic field of self-induction.

0

The electrically conducting region 2 (Fig. 4) can be executed in the form of a wedge 13, one side of which is located along the free surface of the array, and the other forms with

5, its angle is 45, with the linear dimensions of the plane of the wedge parallel to the free surface of the array, should be the same as the area shown in FIG. 2, i.e.

0 is 1.2-1.6 times the diameter of the inductor.

The use of such a form of the electrically conducting region makes it possible to excite an intense shear

5, a wave propagating in the direction normal to the free surface of the array, which is created by the tangential component F, excited by the mechanical force F (Fig. 4).

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Claims (4)

1. METHOD FOR EXCITING ELASTIC WAVES IN A MASSAGE OF ROCKS, including the creation of a local rev. region of the rock mass of mechanical stresses, characterized in that, in order to increase the stability of the excitation and control the characteristics of the excited elastic waves, in the local region create an electrically conductive region with a conductivity of at least 2-10? (Ομ, -μ) '^ act on it by a pulsed quasistationary .. magnetic field, and the characteristics of the excited elastic waves are controlled by controlling the magnitude and duration of the pulse of the intensity of the exciting magnetic field. 2. The method according to p. 1, with the fact that the electrically conductive region is created by forming a cavity in which a metal plate 10 - 50 mm thick is fixed *. 3. The method according to π. 1, characterized in that the electrically conductive region is created by forming a cavity in which a short-circuited electrically conductive coil is placed, the plane of the turns of which is parallel to the local region of the array, and then the cavity is filled with a hardening compound. 4. The method according to p. 1, characterized in that the electrically conductive region is made in the form of a wedge, one side of which is located along the local area of the array, and the other forms an angle of 45 ° with it. FIG. 7