RU2437057C1 - Apparatus for measuring deformation and stress in ice cover - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: apparatus for measuring deformation and stress in ice cover has a base and a post for a quartz azimuthal strainmetre, made in form of hollow rigid cylinders with a bottom with a semi-spherical shape. Such a configuration minimises concentration of stress when frozen in ice. Three parametric sensors are placed on the base, each mounted inside a cylinder at two points lying diametrically opposite in the horizontal plane. The axes of sensitivity of the sensors is directed are directed at angles 120° and coincide with the direction of the axes of sensitivity of the quartz bars of the strainmetre. In each post, frozen at the free ends of the quartz bars below the ice surface, a parametric sensor is mounted inside a cylinder at two points lying diametrically opposite in the horizontal plane. The axis of sensitivity of each sensor on a post coincides with the axis of sensitivity of its quartz bar and the axis of sensitivity of one parametric sensor mounted on the base.

EFFECT: possibility of determining principal deformations and primary stress while simultaneously determining the bearing of the source of ice deformation, determining modulus of elasticity of the ice, determining the anisotropic state of the ice and determining attenuation of stress in the ice cover.

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Description

The invention relates to the field of research of the physicomechanical properties of ice and, in particular, ice engineering, and is intended to measure the relative deformations and stresses of the ice sheet caused by natural phenomena and technical influences.

Known quartz rod linear deformometers for measuring the relative deformations of the earth's crust caused by tidal waves and earthquakes [1, 2]. Such devices are installed in specially constructed mines, where climatic effects on the operation of the device are practically absent. In this case, one end of the rod is embedded in a concrete base, and the free end rests on the suspension support at the other base. Both bases are embedded in the rocky soil of the mine.

The disadvantages of the device are the inability to determine the main deformations of the soil and the lack of compensation for temperature fluctuations in the air. In addition, the incorporation of a quartz rod in a concrete base and the method of mounting the base in the ground are unacceptable for the ice operating conditions of the device.

A device for measuring ice deformation [3] is known, which comprises a quartz rod, one end of which is rigidly connected to a base frozen in ice. At the free end of the rod, a stand with a thermocompensation rod, on which the transducer of displacements of the free end of the quartz rod is mounted, is frozen. The disadvantage of this device is the inability to determine the main deformation in the plane of the ice and thereby determine the ellipse of deformation and the azimuth of the source of ice deformation.

A known pressure sensor [4] in ice, made in the form of an elastic hollow ball, in which parametric transducers are located in three mutually perpendicular directions, each of them is fixed at two points located diametrically opposite on the inner wall of the ball. Using such a device, it is possible to determine the stress ellipse in the ice cover and the azimuth to the stress source. The disadvantage of the pressure sensor is the inability to determine ice deformations.

A device for measuring ice deformation [5], taken as a prototype, which is equipped with three quartz rods mounted in a pedestal, frozen in ice. The rods diverge at angles of 120 ° towards the racks, also frozen into ice. Thermal compensation rods with parametric sensors for moving the free ends of the rods are fixed on the racks. This installation of the rods and fixing their ends provides the determination of the main deformations in the plane of the ice and the azimuth of the source of ice deformation in continuous operation based on the following formulas:

where ε _φ is the strain in the direction that forms the angle φ with the X axis of an arbitrarily chosen coordinate system X, Y: ε _I and ε _II are the principal deformations (maximum and minimum) in the direction of the main axes I and II, which form the angles φ ₀ with the X axis and (φ ₀ -π / 2), respectively.

;

;

where ε ₁ , ε ₂ , ε ₃ are the measured strains on each bar. In addition, the device is equipped with a device that allows calibration without interruption of the work of the strainmeter. This provides a hydraulic transformer located on a pedestal, with three working rods resting on clamps with the ends of quartz rods clamped in them. The clamps themselves are pressed by four flat springs to the stops rigidly fastened to the pedestal. The fourth master rod located in the upper part of the torque converter is inserted into the torque converter chamber with a micrometer screw. Thus, a calibration signal is supplied in the form of a step to all three rods. The disadvantage of the prototype is that the device is not designed to measure stresses in ice.

The aim of the invention is the provision of determining the stress-strain state of ice based on the simultaneous measurement of principal stresses and principal strains together with the determination of the azimuth of the source of ice deformation; determination of the elastic modulus of ice; determination of the anisotropic state of ice; determination of attenuation of stresses in the ice cover.

This result is achieved in that the pedestal and racks are made in the form of hollow rigid cylinders with a hemispherical bottom. This configuration minimizes the concentration of stresses when they are frozen in ice. Three parametric sensors are located in the pedestal below the ice surface, each of which is fixed inside the cylinder at two points located diametrically opposite in the horizontal plane. In this case, the sensitivity axes of the sensors diverge at angles of 120 ° and coincide with the direction of the sensitivity axes of the quartz rods of the device. This installation of parametric sensors in the pedestal provides the determination of the main stresses and azimuth of the source of the stress state of ice in the ice plane on the basis of the following formulas:

,

,

where σ _ψ is the stress in the direction that forms the angle ψ with the X axis of the arbitrarily chosen coordinate system X, Y: σ _I and σ _II are the principal stresses (maximum and minimum) in the direction of the main axes I and II, which form the angles ψ ₀ with the X axis and (ψ ₀ -π / 2), respectively.

;

;

where σ ₁ , σ ₂ , σ ₃ are the measured voltages at each parametric sensor installed inside the pedestal.

From the measured principal stresses and strains, the elastic moduli of ice are determined:

;

;

,

,

where E _I , E _II are the elastic moduli in the direction of the maximum and minimum stresses and strains, respectively. It also makes it possible to characterize the anisotropy of the ice cover.

In each rack, frozen at the free ends of quartz rods, a parametric sensor is mounted below the ice surface, mounted inside the cylinder at two points located diametrically opposite in the horizontal plane. In this case, the sensitivity axis of each sensor located in the rack coincides with the sensitivity axis of its quartz rod and the sensitivity axis of one parametric sensor installed in the pedestal. This arrangement of parametric sensors in the pedestal and in the racks provides the determination of the attenuation of stresses on the basis of the device.

Figure 1 shows a sectional view of the device along one of the three quartz rods 1. Pedestal 2, made in the form of a hollow rigid cylinder with a hemispherical bottom, is frozen into ice cover. Parametric sensor 3 is installed inside pedestal 2 (two other sensors are not indicated), mounted inside the cylinder at two points located diametrically opposite in the horizontal plane. At the free end of the quartz rod 1, stand 4 is frozen in the form of a hollow rigid cylinder with a hemispherical bottom. Inside the rack 4, a parametric sensor 5 is mounted, fixed inside the cylinder at two points located diametrically opposite in the horizontal plane. A plate 6 is fixedly mounted on the pedestal 2, to which a hydraulic transformer 8 is attached with bolts 7 with a micrometer screw 9 resting against the reference rod 10, inserted through the oil seal 11 into the torque converter chamber 12. The chamber 12 is filled with a working fluid. A working rod 14 is inserted into it through an oil seal 13 (one of three working rod is shown). The working rod abuts against the end of the quartz rod 1 fixed in the movable clamp 15. The clamp 15 is pressed by two horizontal and two vertical flat springs 16 (one vertical spring 16 is visible) to the stop 17 with the help of a strap 18, which is attached to the plate 6 and the stop 17 when bolts 19. The stop 17 is rigidly connected to the plate 6. The quartz rod 1 with its free end is directed towards the rack 4, frozen in ice. A thermocompensation rod 20 is attached to the rack 4, equipped with a parametric sensor 5. A parametric displacement sensor 21 of the free end of the rod is fixed to the end of the rod 20.

Figure 2 presents a top view of the pedestal with a plate 6, a hydraulic transformer 8, a micrometer screw 9, three working rods 14, which abut against the ends of three quartz rods 1, mounted in movable clamps 15. Clamps 15 are pressed by horizontal flat springs 22 (three are visible upper horizontal flat springs) to the stops 17 by means of straps 18 with bolts 19. The free ends of the rods 1 diverge at angles of 120 ° to the posts 4 in accordance with figure 1.

The operation of the device is as follows. Pedestal 2 with three parametric sensors 3 and a plate 6 fixed on a pedestal is frozen in ice. A hydraulic transformer 8 with a micrometer screw 9 is mounted on the plate 6 with bolts 7, abutting against the master rod 10, inserted through the oil seal 11 into the torque converter chamber 12. The rods of quartz pipes 1 are fixed in movable clamps 15, which are pressed by flat vertical springs 16 (Fig. 1) and horizontal springs 22 (FIG. 2) to the stops 17 with the help of strips 18 with bolts 19. The free ends of the three rods 1 are directed towards the three racks 4, inside which are located one parametric sensor 5. On the racks are fixed with a thermal expansion rods 20 and displacement transducers 21 of the free ends of the quartz rods. Thermal compensation rods 20 can eliminate the error that occurs with the own temperature deformation of the rods. Electrical signals from three displacement transducers 21 of the free ends of the quartz rods 1, from three parametric sensors 3 located in pedestal 2, and from three parametric sensors 5 located in racks 4, are fed to the recording equipment (not shown in Figs. 1 and 2) . Based on these signals, the main deformations, the main stresses, the elastic moduli, and the anisotropic state of ice are determined in accordance with the above formulas.

Monitoring the sensitivity of the device is as follows. The master rod 10 is inserted through the gland 11 with a micrometer screw 9 into the chamber 12 of the torque converter 8 by the selected value (for example, by the value leading to the appearance of a signal on the rods of the strainmeter 10 μm). The torque converter 8 is fastened to the plate by 6 bolts 7. In this case, the three working rods 14 through the oil seals 13 will extend and move the movable clamps 15 with the ends of the quartz rods 1 spring-loaded with four flat springs 16 and 22, which will provide the appearance of control signals in the form of steps on the recorder . Further, when the master rod 10 is withdrawn from the chamber 8, when the micrometer screw 9 is unscrewed, the clamps 15 with flat springs 16 and 22 return to their original position and are pressed against the stops 17, and the recording on the recorder returns to its previous level.

The technical and economic effect is manifested:

- to improve the accuracy of measuring the stress-strain state of ice, namely the determination of the main deformations and principal stresses while simultaneously determining the azimuth of the source of ice deformation by one device;

- in determining the elastic moduli of ice from the main deformations and principal stresses and determining the degree of anisotropy of ice;

- in determining the attenuation of stresses in ice on the basis of the device.

Information sources

1. Latynina L.A. Analysis of the work of a rod strain gauge. USSR Academy of Sciences, Institute of Physics of the Earth, No. 4218-72, dep., M., 1977

2. Latynina L.A., Karmaleeva P.M. Deformographic measurements), Moscow: Nauka, 1978.

3. Smirnov V.N., Shushlebin A.I. Device for measuring ice deformation. - Auth. St. No. 712744. Published on January 30, 1980, Bull. Number 4.

4. Smirnov V.N., Shushlebin A.I., Altshuler G.G. Pressure meter. Auth. St. No. 561887. Published 06/15/77 Bul. Number 22.

5. Smirnov V.N., Shushlebin A.I. Device for measuring ice deformation. Auth. St. No. 1784888. Published December 30, 1992 Bul. No. 48 (prototype).

Claims (1)

A device for measuring deformations and stresses of the ice sheet containing a pedestal on which is located a hydraulic transformer with three working rods resting on three movable clamps with three quartz rods clamped in them, the clamps themselves are pressed by four flat springs to the stops fastened with the pedestal, the fourth setting the rod is inserted into the torque converter chamber with a micrometer screw, the rods from the pedestal diverge to three posts at angles of 120 °, three thermocompensation pieces are fixed to the posts with motion sensors of the free ends of the rods, the pedestal and racks are frozen in ice, characterized in that the pedestal and racks are made in the form of hollow rigid cylinders with a hemispherical bottom, three parametric sensors are installed inside the pedestal, each of which is fixed at two points inside the pedestal, located diametrically opposite in the horizontal plane, with sensitivity axes oriented at angles of 120 ° relative to each other and coinciding in direction with quartz rods, in a rack ax is located along one parametric sensor fixed at two points located diametrically opposite in the horizontal plane and sensitivity axes oriented in accordance with its quartz rod and one parametric pedestal sensor.

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