CN204479217U - Rockbolt stress proving installation - Google Patents

Abstract

The utility model discloses a force testing device for anchor rods, which is characterized in that it mainly comprises: a foam metal plate, an upper backing plate, a lower backing plate and a distance measuring instrument, the foam metal plate is located between the upper backing plate and the lower backing plate, The three are bonded together by an adhesive; the foamed metal plate is made of foamed metal material, and the whole is a flat plate structure, which is square or circular in shape and has a circular hole in the center. It is gradually flattened under increasing load. According to the compression characteristics of the foam metal material, using the determined relationship between the load and the deformation, the measurement of the load is converted into the measurement of the displacement, and then the axial force of the anchor rod or anchor cable is obtained. The utility model makes the measurement of the axial force of the anchor rod simple and feasible, and greatly reduces the measurement cost.

Description

Anchor force test device

technical field

The invention relates to the field of health detection of anchorage structures in underground engineering, in particular to a force testing device for anchor rods or anchor cables.

Background technique

In recent years, bolts have been widely used in the field of underground engineering support, and have played an important role in reducing support costs and accidents. Because the bolt is buried inside the surrounding rock, it is a concealed structure, and its health diagnosis and evaluation of its support function are difficult. In order to evaluate the supporting function and health state of the bolt, the axial force at the outer end of the bolt is generally taken as an important evaluation index, but the measurement of the axial force of the bolt is very difficult. At present, the methods of measuring the axial force of bolts at home and abroad mainly include: strain measurement method, pressure sensor measurement method and vibrating wire bolt dynamometer.

The strain measurement method refers to: before the bolt is installed, strain gauges or optical fiber gratings are arranged in the axial direction of the bolt. After the bolt is stressed, a certain deformation occurs, and the axial strain of the bolt can be measured, and the anchor is calculated according to the measured strain. Axial force of the rod. The strain gauges and fiber optical grids used in this method are easily damaged, easily affected by external electromagnetic and temperature, have high requirements on the surrounding environment, and the measurement results are unstable. Generally, the measurement results can only be used as a reference. In addition, the cost of the fiber grating strain measurement system is relatively high.

The pressure sensor measurement method refers to: a piezoelectric sensor is pre-installed at the anchor tray, and the axial force of the anchor is measured through the piezoelectric sensor. The measurement accuracy of this method can be guaranteed, but the cost is high. The cost of a single piezoelectric sensor reaches tens of thousands of yuan. If it is not recycled, it will cause great waste. If it is recycled, it will cause the bolt to fail and threaten the safety of the project.

The vibrating wire anchor dynamometer first transmits the deformation of the anchor rod to the vibrating wire, thereby changing the vibration frequency of the vibrating wire. By detecting the frequency of the vibrating wire, the deformation of the vibrating wire can be obtained, and then the deformation of the anchor rod can be obtained, and then the axial force of the anchor rod can be obtained. This method needs to weld the two ends of the vibrating wire on the anchor rod in advance, which not only complicates the operation, but also makes it difficult to guarantee the welding quality, and also greatly increases the difficulty of installing the anchor rod.

Contents of the invention

The object of the present invention is to provide a kind of bolt axial force testing device with simple structure, and its technical solution is:

A bolt force testing device, characterized in that it mainly includes: a foam metal plate, an upper backing plate, a lower backing plate and a distance measuring instrument, the foam metal plate is located between the upper backing plate and the lower backing plate, and the three are bonded together Bonded together with an agent to form a combined board, the centers of the three are located on the same axis; the foamed metal board is made of foamed metal material, the overall structure is a flat plate, the shape is square or circular, and a circular hole is provided in the center. The anchor rod or anchor cable can pass through the hole, and the metal foam plate has a normal bearing capacity not less than the maximum axial force of the anchor rod or anchor cable. As the load on the metal foam plate increases, it is gradually flattened, There is a monotonically increasing relationship between the load on the foam metal plate and the resulting displacement; the upper backing plate and the lower backing plate are both flat plate structures, and the center is provided with a hole in the steel plate, and the anchor rod or the anchor cable can pass through the hole Through, its strength is much greater than that of the foam metal plate; the distance measuring instrument is used to measure the distance between the upper and lower backing plates.

The application method of the present invention is:

1. carry out compression test to described metal foam plate; Carry out compression test to it in normal direction by press machine, obtain its stress-strain relationship curve;

②Install the anchor rod or anchor cable; use conventional methods to fix the inner anchor section of the anchor rod behind the anchor hole, make the anchor rod or anchor cable pass through the hole reserved in the composite plate, and then tighten the nuts to press the composite plate tightly live;

③ After the anchor rod or anchor cable starts to be stressed, the axial force of the anchor rod reacts on the composite plate through the nut, and the foam metal plate is deformed under the pressure; the vertical distance between the upper backing plate and the lower backing plate is measured by a distance measuring instrument , and then according to the original distance between the two, the relative displacement caused by compression can be obtained, and then the normal strain can be obtained;

④ According to the stress-strain relationship curve measured in step ①, and the normal strain measured in step ③, the stress of the foam metal plate can be obtained by conversion, and then the load on it can be obtained, which is equal to the anchor rod or anchor cable. Axial force.

The basic principle of the present invention is: according to the compression characteristics of the foamed metal material, using the definite relationship between the load and the deformation, the measurement of the load is converted into the measurement of the displacement, and then the axial force of the anchor rod or anchor cable is obtained.

The beneficial effects of the invention are: the device and its application method make the measurement of the axial force of the bolt simple and easy, greatly reduce the measurement cost, and have great significance for the dynamic feedback support design on the engineering site.

Description of drawings

Below in conjunction with accompanying drawing and specific embodiment the present invention will be further described:

Fig. 1 is the schematic diagram of the principles of the bolt stress testing device and application method thereof of the present invention;

Fig. 2 is a kind of stress-strain curve of the stress testing device for the anchor rod.

Detailed ways

In conjunction with accompanying drawing 1, a kind of bolt stress testing device is characterized in that mainly comprising: foam metal plate 1, upper backing plate 2, lower backing plate 3 and distance measuring instrument, foam metal plate 1 is positioned at upper backing plate 2 and lower backing plate Between the backing plates 3, the three are bonded together by an adhesive to form a composite plate, and the centers of the three are located on the same axis; the foam metal plate 1 is made of foam metal material, and the whole is a flat plate structure with a square shape Or circular, with a circular hole in its center, the anchor rod or anchor cable 4 can pass through the hole, the foam metal plate has a normal bearing capacity not less than the maximum axial force of the anchor rod or anchor cable, with the foam The load on the metal plate increases, and it is gradually flattened, and there is a monotonically increasing relationship between the load on the metal foam plate and the displacement generated; the upper backing plate 2 and the lower backing plate 3 are flat plate structures, and The steel plate with a hole in the center, the anchor rod or anchor cable can pass through the hole, and its strength is much greater than that of the foam metal plate; the distance measuring instrument is used to measure the distance between the upper and lower backing plates.

The application method of the present invention is:

1. carry out compression test to described metal foam plate; Carry out compression test to it in normal direction by press machine, obtain its stress-strain relationship curve, as shown in Figure 2;

②Install the anchor rod or anchor cable 4; fix the inner anchor section of the anchor rod behind the anchor hole by conventional methods, make the anchor rod or anchor cable pass through the hole reserved in the composite plate, and then tighten the nut 5 to tighten the composite plate hold tight;

③ After the anchor rod or anchor cable starts to be stressed, the axial force F of the anchor rod reacts on the composite plate through the nut, and the foam metal plate is deformed under the pressure; the vertical distance between the upper backing plate and the lower backing plate is measured by a distance measuring instrument. The distance L, and then according to the original distance between the two, the relative displacement caused by the compression can be obtained, and then the normal strain can be obtained;

④ According to the stress-strain relationship curve measured in step ①, and the normal strain measured in step ③, the stress of the foam metal plate can be obtained by conversion, and then the load on it can be obtained, which is equal to the anchor rod or anchor cable. Axial force.

The above-described embodiments are only one of the more preferred specific implementation modes of the present invention, and the usual changes and replacements performed by those skilled in the art within the scope of the technical solutions of the present invention shall be included in the protection scope of the present invention.

Claims (1)

1. A bolt force testing device is characterized in that it mainly comprises: a foam metal plate, an upper backing plate, a lower backing plate and a distance measuring instrument, the foam metal plate is positioned between the upper backing plate and the lower backing plate, and the three pass through The adhesive is bonded together to form a combined board, and the centers of the three are located on the same axis; the foam metal board is made of foam metal material, and the whole is a flat plate structure, which is square or circular in shape, with a circular A hole through which the anchor rod or anchor cable can pass. The foam metal plate has a normal bearing capacity not less than the maximum axial force of the anchor rod or anchor cable. As the load on the foam metal plate increases, it is gradually compressed. Flat, there is a monotonically increasing relationship between the load on the foam metal plate and the resulting displacement; the upper backing plate and the lower backing plate are both flat plate structures, and the steel plates with holes in the center, anchor rods or anchor cables can Passing through the hole, its strength is much greater than that of the foam metal plate; the distance measuring instrument is used to measure the distance between the upper and lower backing plates.