SU785487A1 - Method of detecting the variation of the strained state of salt rock body - Google Patents

Description

I

The design refers to the mining industry; it is intended for the determination of the indirect electrometric method of the average strength of the pillars with a chamber system for the development of mineral deposits.

The known method of O1 phylogenesis is a change in the stressed state of a mountain massif, based on the measurement of elect. the conductivity of rocks, in which the depth of the sample array | and shot wells.

The disadvantage of this cnocog a is the mandatory drilling of wells.

There is also known a method for determining the change in stress state. an array of SALT rocks, including the determination of its electrical resistance.

However, the ACCURACY and the measuring range of the method are limited.

The purpose of this invention is to improve the accuracy and the expansion

measurement range of the stress state of the mountain range.

This goal is achieved by the fact that the array is subjected to the action of an electric FIELD ultrasonic frequency to determine the depth of the destroyed zone, and the change in the stress state is judged by the relative change in the carrier part of the rear sight.

Also, the goal is achieved by the fact that the frequency of the current pulse is 10 KHz.

FIG. Figure 1 shows a graph illustrating the effect of the electric FIELD frequency (i) on the value of the specific resistance of rock salt / p samples at different intensity of their mechanical loading, was equal to (102. 127, 153, 179 and 205); in fig. 2 is a graph in which

It is shown how the intensity of mechanical loading (o, expressed in% of the breaking load) affects the value of resistivity for

samples of different shapes of the one {se sylvinite pooooi, with a ratio of ctxjpoH height (h) to diameter (d) equal to 0.5 and 2; -on 4ig. Fig. 3 is a graph of the effect of creep on the electrical deactivation of rock salt, which was affected by a constant load of 4O% of the compressive strength; FIG. 4 is a graphical dependence of the electrical resistance for samples of various rocks on the frequency of the electric field.

 From the graph (Fig. 1) it can be seen that: by increasing the frequency of the electric field, the variation of the electrical resistance due to a change in the stress state decreases so much that, in the ultrasound frequency region, the electrical resistance ceases to be dependent on the strength of the stress state,

From the graph (Fig. 2), it can be seen that in high samples, the change in electro / resistance with increasing pressure is much more intense than in low samples.

The electrical resistance of samples of various shapes characterizes the electrical resistance of an array of rocks at different distances from the exposed surface. Consequently, the nature of the interconnection of the electrical and mechanical properties of the studied volume of rock is significantly affected by the boundary conditions. As seen from the graph (Fig. 3), with the same mechanical loading, the value of electrical resistance (R) with increasing time (ft) decreases significantly. Therefore, electrical resistance is a dependent value not only of the magnitude of the mechanical intensity, but and from the time of its action.

In the region of ultrasonic frequencies, the curves coincide (Fig. 4). From here follows the fact that in the region of ultrasonic frequencies it is electric. The field For the composition of homogeneous rocks is insensitive.

From the foregoing it follows that taking measurements using

electrometry at the ultrasonic frequency of the electric field extends the measurement range up to stresses close to destructive, at

this eliminates measurement errors due to variability in rock composition and the manifestation of creep.

From the graphs it follows that the optimal pulse frequency

the electric field for the study of salt rocks is 10 kHz. When measuring electrical resistance at a lower frequency

field, errors are due to imperfect composition, and at a frequency of less than 5 kHz, errors arise due to creep of rocks.

Measurements at high frequencies of the electric field are impractical because the sounding depth decreases with increasing frequency of the electric field.

Claims (2)

1. A method for determining the change in the stress state of an array of solar rocks, including the determination of its electrical resistance, characterized in that, in order to increase accuracy and expand the measurement range, the array is subjected to an ultrasonic frequency electric field to determine the depth of the destroyed zone, and the change in stress state is judged by the relative change in the width of non-part pillar. 2, the method according to p. I, about tl and h ayusch and the fact that the pulse frequency is equal to 1O kHz .., Information sources, taken into account in the examination 1. Arsh E.I. Radio wave measurements in coal mining and exploration. Kr.j, Technique, 1967, p. 132-140, 2. USSR author's certificate N9 421773, cl. E 21 C 39/00, a2.O8.72. О / о 20 30 40 50 60 70 tf,%