SU1451270A1 - Method of monitoring compressibility of hardening fill-up body - Google Patents

Abstract

The invention relates to the field of measuring the deformation properties of hardening filling arrays. The goal is to simplify and reduce the time needed to control the compressibility of a hardening solid under the action of rock pressure. In the process of building the filling array, measuring electrodes are placed in it. The electrical parameters of the array are measured by electrochemical converters. Compressibility is determined by the correlation dependence D 0 1570 (P - K / S-IP) at K

Description

The invention relates to the measurement of the deformation properties of hardening backfill arrays and can be used in the development of mineral deposits with the laying of the goaf.

The purpose of the invention is to simplify and shorten the time to control the compressibility of a hardening mass under the action of rock pressure.

Figure 1 shows the electrochemical converter, a general view; Fig. 2 is a schematic diagram of the measurement; FIG. 3 shows the relationship between shrinkage of the samples and discharge current for various personal pressures P.

The electrochemical converter consists of a polyvinyl chloride tube 1 with a diameter of 50 mm, from the outer side on which graphite rods 2 are glued on diametrically opposite sides, and inside the tube with the help of holders 3 there is attached a zinc tube 4.

Measurement of electrical parameters of the bookmark is carried out according to the scheme shown in Fig.2. Graphite electrodes 5-8 and zinc tube 4 through button 9 are connected in turn to microammeter 10 having a shunt 11.

Fig. 3 shows the correlation dependence between shrinkage of the bookmark (of this particle size distribution and the discharge current of the electrochemical converter I. The latter is placed in the filling mixture. The correlation dependence was obtained experimentally for different values of rock pressure.

The method is carried out as follows.

In the process of forming a hardening backfill array, the electrochemical converter (Fig. 1) is placed in the test medium by lowering it into the backfill solution. From the transducer, electrically the wires are conducted to the measuring point. During the production of measurements, the conductors are connected to the measuring circuit (Fig. 2). The measurement result is the magnitude of the effective value of the discharge current 1p.

The amount of shrinkage is determined by the formula

L 0.1570 (R - I 1p)

with k (5 - 11,5) Mlla,.

P (5 - 25) MPa,

where L is the compressibility of the backfill array;

IP discharge current of the electrochemical converter; P is the magnitude of the rock pressure; S is the surface area of the electrode; K - electrochemical coefficient

The value varies from 5 to 25 MPa due to the fact that the depth of development of underground mines is in the range of 200 to 1000 meters.

The electrochemical coefficient K varies from 5 to 11.5 m-MPa / A with a change in the grade of cement used in the tab, from 200 to 500.

From the point of view of electrolytic properties, the hardening stuffing material is presented in the form of a matrix electrolyte, i.e. electrolyte, located in the pores of a solid, electrolyte. The electrical conductivity of the solid phase is several orders of magnitude lower than the electrical conductivity of the electrolyte, therefore the solid phase is considered non-conducting. The fluid as a result of capillary forces is not fluid, but has the properties of an electrolyte in which there is no convection. The interconnectedness of the mechanical and physical structures underlies the action of the method in question.

If an electrode is placed in such an electrolyte in the process of its formation from materials with different values of normal potentials, an electromotive force arises on the electrodes (electromotive force, the magnitude of which depends on the type of electrodes and the electrical parameters solidifying it). by pressing the button 9. From the point of view of the inertia of the measuring system of a magnetoelectric indicator (ampere-voltmeter P-4311), it should be assumed that the deviation of the instrument arrow is proportional to the effective value of current for a certain period of time.

The purpose of the shunt is to obtain the highest value of the discharge current, the concentration polarization effect is most fully manifested and the information content of the measurements increases. In this connection, the value of the shunt should be minimal, at which the sensitivity of the device ensures a confident fixation of the measured value.

The magnitude of the electric current is determined by the course of electrokinetic processes on a graphite electrode. Here is the cathodic recovery of hydrogen ions.

N

H

40Н

and water molecules 2H-2P + 0 / + 4e

When an external measuring instrument is connected to the electrodes as a result of the passage of current at the boundary of the graphite electrode, hydrogen and OH ions will be generated at the first time instant. The graphite electrode has a very low adsorption capacity with respect to hydrogen; therefore, the active electrode surface is shielded with a hydrogen film and the further current flow is associated with the dissipation of hydrogen in the pores of the filling material. The diffusion coefficient D entering the first Fick law will depend on the degree of moisture in the surrounding pores, therefore the discharge current is equal to

f P -DS grad With,

where Ip is the magnitude of the discharge current; C - the concentration of regulatory substances in this case is proportional to the moisture content of the bookmark; S is the surface area of the electrode;

D diffusion coefficient. The required period for measuring the compressibility of filling arrays is due to

51270

is driven by field development technology. For example, when mining ore reserves in secondary chambers, the compressibility control of the filling mass in the first-stage chambers shows the effectiveness of rock pressure control, i.e. The high compressibility indicates the beginning of displacement of the overburden and the need to use a higher quality bookmark in the neighboring chambers. Spec. . deadlines for such control in the range of 1 to 6 months.

When mining ore under protected objects, the compressibility of hardening arrays should strictly comply with the calculated standards and be confirmed by regular experimental measurements after 1-1.5 months.

ten

15

thirty

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Claims (1)

Invention Formula A method for controlling the compressibility of solidifying filling arrays, including placing measuring sjjeMeHs in a filling array in the process of its erection, which differs from the fact that the electrical parameters of the array are produced by electrochemical converters, and compressibility is determined by the correlation dependence X 0.1570 (P - I 1p), with K (5 - 11.5) - MPa, P (5 - 25) MPa, where A 35 40 compressibility of the backfill; IP is the discharge current of the electrochemical converter; P is the magnitude of the rock pressure; S is the surface area of the electrode; K - electrochemical coefficient. t Itgl so W 60 80 t y.MKa Fiv.Z