RU95112U1 - DEVICE FOR MEASURING CRACK DIMENSIONS IN CONSTRUCTION STRUCTURES - Google Patents

Abstract

 1. A device for measuring the size of cracks in building structures, containing a flask with a translucent liquid and a measuring tube connected to it by a flexible tube, characterized in that the flask is made of elastic material and placed between two angles designed to be fixed on the wall on both sides of the crack; a light source is installed in one end of the measuring tube, and a photodetector in the other. ! 2. The device according to claim 1, characterized in that the flask is made in the form of a bellows. ! 3. The device according to claim 1, characterized in that the flask is made in the form of a membrane chamber.

Description

The utility model relates to measuring technique, in particular, to measuring linear dimensions and displacements and can be used as a sensor in the inspection and monitoring of building structures.

When examining building structures, the most critical step is the study of cracks, the identification of their size and development dynamics. They can be caused by a variety of reasons and have various design features.

The measurement of the linear dimensions of welds and cracks in building structures has a number of features (Gorpinchenko VM, Egorov MI Monitoring the serviceability of particularly critical, complex and unique structures. Industrial and civil construction, No. 10, 2004.). First, for a number of building structures, determining the direction of deformation is crucial, which determined the use of two-coordinate sensors, although an integral indicator characterizing the dynamics of crack opening is no less often used. Secondly, installing and fixing the sensors on the walls is a laborious process, therefore, regardless of the frequency of observations, the sensors are installed for a long time. Since several tens of sensors may be required for one building at a time, their cost becomes a determining parameter.

Known devices for measuring linear displacements with an error of less than 0.1 mm, using inductive, capacitive or optical methods (for example, A.S. RU 2367902 C1, 5 G01B 7/00, 09/20/2009, A.S. RU 2131591 C1, G01H 11/02 06.10.1999, magnetic, inductive and other sensors from Baumer, Honeywell, Balluff, encoders Kuebler, optical sensors from Fotek, Renishaw). Possessing comparable parameters, these groups of sensors develop in parallel along the path of reducing the measurement error and expanding the measured range. But no matter what measurement method is used, an improvement in the basic characteristics inevitably leads to a complication of the sensor and an increase in its cost, which is the main disadvantage.

The closest analogue is the prototype of the claimed device is a deflection meter P1 ("Manual on the inspection of building structures of buildings" JSC "TSNIIPROMZDANIY", Moscow, 1997). It contains a vessel with tinted liquid and a measuring tube with a scale connected by a rubber tube. By the change in the liquid level in the measuring tube during its movement (in a vertical position) along a controlled horizontal surface (ceiling, floor), the amount of deflection is measured. For ease of movement, a wheel is attached to the measuring tube from above (for measuring the deflection of the ceiling).

The disadvantage of this device is the low accuracy of the measurements and the limitation of its scope by measuring only vertical deviations.

The technical problem solved by this utility model is to eliminate these drawbacks - increasing the accuracy (sensitivity) of the device and giving it the ability to measure linear displacements in any direction.

The technical result is the creation of a simple and high-precision meter of linear dimensions of welds and cracks in building structures, which has low energy consumption, high speed and the ability to long-term work in standalone mode.

The stated technical problem is solved by the fact that the flask is made of elastic material, filled with a translucent liquid and placed between two corners (racks), designed for rigid fixing on different sides of the crack; in one end of the measuring tube connected to the bulb with a rubber tube, a light source is installed - an LED or a laser, and in the other - a photodetector that registers the height of the liquid column by changing its transparency .. The bulb can also be made in the form of a bellows or a membrane chamber.

Figure 1 shows the appearance of the inventive device, and figure 2, a, b - options for its use as a two-coordinate sensor.

The device comprises (Fig. 1) two angles 1, rigidly fixed with their ends on different sides of the crack perpendicular to the wall, an elastic flask 2 with a translucent (tinted) liquid placed between them and a measuring tube 3 connected to the flask with a flexible tube 4; at the ends of the measuring tube mounted light emitter 5 and a photodetector 6.

Corners 1 are designed for fastening the flask 2 and transfer to it the deformational displacements of the crack.

The flask 2 can be performed in any shape depending on the design features of the mounting location. As a flask, for example, a rubber bulb, an enema, or a plastic bag can be used. For high-precision measurements, deformation gauge chamber designs such as a bellows, a membrane chamber, etc. can also be used.

Measuring tube 3 is made of opaque material to exclude the influence of external illumination. The flexible tube 4 is mounted at the bottom of the measuring tube on its side surface. The internal diameter of the measuring tube determines the sensitivity of such a displacement sensor, since for a cylinder the height is inversely proportional to the square of its diameter d. If the contact pad of the corner is round with diameter D, then the coefficient of conversion of the transverse displacement of the crack l (measured parameter) to the height of the liquid column h is equal to:

The minimum tube diameter is limited by the diameter of the used light emitters 5 and photodetector 6. When using standard LEDs of the AL307 series with a diameter of 3 mm. a hundredfold increase in l can be obtained with a contact pad diameter of only 30 mm, and for AL 117 diodes it will decrease by another four times. The height of the liquid column can be adjusted by the degree of transparency of the liquid (degree of turbidity).

The flexible tube 4 can be made of any material, its length is determined only by the convenience of mounting the measuring tube.

The emitter 5 can also be made in the form of a laser - this eliminates the scattering of light.

The photodetector 6 may be made in the form of a photodiode or a phototransistor.

The device operates as follows.

Cement mortar or mounting glue on both sides of a crack or seam are fixed perpendicular to the plane of the wall two metal corners (figure 1). A flask with a measuring tube and liquid is installed between them. During initial installation, the liquid level in the measuring tube should be in the middle of its length. This is ensured by the introduction of gaskets between the corner and the flask, or a special pressure plate fixed on the corner with an adjusting screw. When the sides of the crack are displaced, a change in the position of the fixed corners leads to deformation of the flask, a change in the height of the column of the colored liquid, and, consequently, a change in its transparency. The transparency of the liquid column is detected by a photodetector. The sensitivity of the sensor is determined by the shape of the bulb and the area of the corners, so the sensor is calibrated with the corners.

The chambers of deformation type manometers - bellows, membrane chambers can also be used as flasks. The effect of a multiple increase in sensitivity due to the difference in the diameters of the chamber and the measuring tube is preserved for such cameras.

Thermal expansion of the liquid is the main source of measurement error - a typical situation for almost all sensors. To eliminate this effect, a temperature measurement is also necessary at the same time as measuring strain. As a temperature sensor, the claimed device itself can be used, but without corners deforming the flask.

A remarkable feature of the claimed utility model is the ability to measure strains in any of the selected directions, as well as an integral one, independent of the direction of the crack. This is achieved by changing the shape of the corners used (figure 2). To measure displacements in only one direction, the contact surface of one of the corners should be made in the form of a plate with a smooth surface, ensuring deformation of the bulb in the direction perpendicular to the plane of the plate and sliding in all the others (Fig. 2, a, b).

The inventive utility model has the following advantages:

- the sensor is easily modified for any crack configuration;

- high sensitivity;

- possible changes in the elasticity of the flask (in frost) do not affect the readings of the device, but only change the magnitude of the compression force;

- low energy consumption, especially when working in pulsed mode;

- low inertia of the system;

- simple compensation of temperature departures.

The simplicity of manufacture and low cost of the device allows you to count on a much wider application than existing analogues.

Claims (3)

1. A device for measuring the size of cracks in building structures, containing a flask with a translucent liquid and a measuring tube connected to it by a flexible tube, characterized in that the flask is made of elastic material and placed between two angles designed to be fixed on the wall on both sides of the crack; a light source is installed in one end of the measuring tube, and a photodetector in the other. 2. The device according to claim 1, characterized in that the flask is made in the form of a bellows. 3. The device according to claim 1, characterized in that the flask is made in the form of a membrane chamber.