CN107503386A - Anchor rod body holds the detection means and detection method of load - Google Patents

Abstract

The invention discloses a detection device and a detection method for the load held by the anchor rod body. The detection device includes a support stool, a jack, a dynamometer, a tool anchor and a percentage which are sequentially arranged along the axial direction of the anchor rod from bottom to top. The bottom surface of the support stool is supported on the backing plate of the waist beam of the completed anchor structure, the top surface is in contact with the bottom surface of the jack, and the support stool is fixed between the backing plate and the jack through the pre-tightening force of the jack. There is a piston at the top, and the exposed free end of the anchor rod passes through the center of the support stool, the jack, the dynamometer, and the tool anchor successively from bottom to top, and the top end protrudes from the tool anchor, and the tool anchor and the exposed anchor rod The upper part of the free end is connected with the stationary phase, the dynamometer is clamped between the piston and the tool anchor, the piston pushes the dynamometer, and the dial indicator is installed on the tool anchor. The detection device has a simple structure and can detect the load held by the bolt body. The invention also discloses a detection method for the load held by the anchor rod body.

Description

Detection device and method for detecting load held by bolt body

technical field

The invention relates to a detection device and method for a bolt, in particular to a detection device and a detection method for a load held by a bolt body.

Background technique

As a kind of tensile rod that can not only fully excavate the strength of rock and soil itself, exert its bearing capacity, but also greatly reduce the self-weight of the structure and save engineering materials, it can fully ensure construction safety and engineering stability. It can also achieve significant economic benefits and other advantages, and has been widely used in support projects in our country.

The structure of the completed anchor structure in the prior art is shown in Figure 1, including the anchor 1, the support structure 2, the waist beam 3, the backing plate 4 and the working anchor 5, and the support structure 2 is set vertically upwards, and the horizontal The surfaces are vertical, the anchor rod 1 includes the anchor rod free section 11 and the anchor rod anchoring section 12, the anchor rod 1 is arranged obliquely, the waist beam 3, the backing plate 4 and the working anchor 5 are arranged in sequence from bottom to top along the axial direction of the anchor rod 1, The anchor rod free section 11 stretches out after passing through the working anchor 5 .

A large number of engineering practices and studies have shown that the prestressed anchor rod will hold the load within a certain period of time after it is tensioned and locked, that is, the tensile force of the free section of the anchor rod will change due to various factors. Failure or even destruction, so it is very important to monitor the load held by the bolt body. Although for the prestressed anchors buried with anchor dynamometers, the holding load can be monitored at any time, but due to the high cost, most of the prestressed anchors in my country do not have dynamometers buried. The holding loads for a period of time after completion of construction are not known.

Therefore, it is very necessary to propose a detection device and method for the load held by this type of bolt body.

Contents of the invention

One of the objects of the present invention is to provide a detection device for the load held by the bolt body. The detection device has a simple structure and can detect the load held by the bolt body.

The above object of the present invention is achieved through the following technical solutions: a detection device for the load held by the anchor rod body, and the anchor rod is installed obliquely, and it is characterized in that: the detection device includes supports arranged sequentially from bottom to top along the axial direction of the anchor rod stool, jack, dynamometer, tool anchor and dial indicator, the bottom surface of the support stool is supported on the backing plate of the lumbar beam of the completed anchor structure, the top surface is in contact with the bottom surface of the jack, and the pre-tightening force of the jack will The support stool is fixed between the backing plate and the jack, the top of the jack has a piston, and the exposed free end of the anchor rod passes through the center of the support stool, the jack, the dynamometer, and the tool anchor sequentially from bottom to top, And the top end protrudes from the tool anchor, the tool anchor clamps the upper part of the exposed free end of the anchor rod, the dynamometer is clamped between the piston and the tool anchor, the piston pushes the dynamometer, and the dynamometer is used to detect the anchor For the stressed load of the rod, the dial indicator is installed on the tool anchor to measure the displacement of the anchor head of the anchor rod.

In the present invention, the tool anchor clamps the upper part of the exposed free end of the anchor rod through the clip.

In the present invention, the axis of the anchor rod is perpendicular to the pressure surface of the jack, the dynamometer, and the tool anchor.

The anchor rod in the present invention includes both a steel bar anchor rod and a steel cable anchor rod of a steel strand.

The second object of the present invention is to provide a method for detecting the load held by the bolt body.

The above object of the present invention is achieved through the following technical solutions: the method for detecting the load held by the anchor rod body by using the above detection device, is characterized in that: the detection method includes the following steps:

Step (1): Place the support stool on the backing plate of the waist beam of the completed anchor structure, and then place the jack, dynamometer and tool anchor on the support stool in sequence, and the exposed free end of the prestressed anchor rod is from bottom to top The top passes through the center of the support stool, the jack, the dynamometer, and the tool anchor in turn, and the top end protrudes from the tool anchor. The axis of the anchor is perpendicular to the compression surface of the jack, the dynamometer, and the tool anchor. Lock on the tool anchor and place the dial indicator;

Step (2): Load the entire detection device in stages through the jack (7), and simultaneously observe the displacement of the anchor head. The loading method is as follows:

The initial load is 30% of the designed locking force value p of the anchor rod. Under the initial load, the displacement of the anchor head is measured every 5 minutes. When the displacement increment of the two adjacent anchor heads is not greater than 0.01mm, it can be regarded as an anchor. The head displacement is stable, take the last reading value as the reference value of the anchor head displacement;

The graded load is 5% of the design locking force value p of the anchor rod, the purpose is to ensure that the measured holding load has a high accuracy;

During the anchor head displacement observation period, the load variation range should not exceed ±10% of the graded load;

When there is a sudden change in the displacement of the anchor head or the loosening of the working anchor (5), the test should be terminated after 2 to 4 levels of loading;

When the test load is loaded to the acceptance load, and there is no abrupt displacement of the anchor head or loosening of the working anchor (5), the test shall be terminated.

The loading speed should be 0.05~0.10p/min, and the unloading speed should be twice the loading speed.

After the application of each level of load is completed, the load is maintained for 5 minutes, and the displacement of the anchor head is measured at 0 and 5 minutes, and the average value is taken as the displacement of the anchor head under each level of load.

Draw the obtained load and the corresponding anchor head displacement into a load-displacement relationship curve;

Step (3): The determination method of the load held by the anchor rod body is as follows:

When the sudden change of displacement on the load-displacement relationship curve is obvious, the load value corresponding to the starting point of the steep rise is taken as the holding load of the bolt body.

When the load-displacement relationship curve is difficult to accurately determine the starting point of the steep rise, the previous level of load corresponding to the intersection point of the fitted straight line on both sides of the curve is taken as the holding load of the anchor rod.

Description of drawings

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is the structural representation of completed anchor rod structure in the prior art;

Fig. 2 is a reference diagram of the use state of the detection device for the load held by the anchor rod body of the present invention;

Fig. 3 is the load-displacement relationship curve obtained by the first embodiment of the detection method carried out by the detection device of the present invention. Head displacement, in millimeters (mm);

Fig. 4 is the load-displacement relationship curve obtained by the second embodiment of the detection method carried out by the detection device of the present invention. In the figure, the abscissa p represents the design locking force value of the bolt, and the unit is kilonewtons (kN), and the ordinate s represents the anchor Head displacement in millimeters (mm).

Explanation of reference signs

1 is the anchor, 11 is the free section of the anchor, 12 is the anchoring section of the anchor, 2 is the support structure, 3 is the waist beam, 4 is the backing plate, 5 is the working anchor, 6 is the support stool, 7 is the jack, 71 is a piston, 8 is a dynamometer, 9 is a tool anchor, and 10 is a dial gauge.

detailed description

The detection device for the load held by the bolt body of the present invention is shown in Figure 2. The bolt 1 is arranged obliquely, and the detection device includes a support stool 6, a jack 7, and a dynamometer arranged in sequence along the axial direction of the bolt 1 from bottom to top. 8. Tool anchor 9 and dial indicator 10.

The bottom surface of the support stool 6 is supported on the backing plate 4 of the waist beam 3 of the completed anchor rod structure, the top surface is in contact with the bottom surface of the jack 7, and the support stool 6 is fixed on the backing plate 4 and the jack through the pretightening force of the jack 7 7, the top of the jack 7 has a piston 71, and the exposed free end of the anchor rod 1 passes through the center of the support stool 6, the jack 7, the dynamometer 8, and the tool anchor 9 successively from bottom to top, and the top passes through the center of the tool anchor 9. The anchor 9 stretches out, and the axis of the anchor rod 1 is perpendicular to the pressure surface of the jack 7, the dynamometer 8, and the tool anchor 9.

The tool anchor 9 clamps the upper part of the exposed free end of the anchor rod 1, and is tightly connected with the anchor rod 1. The specific connection structure is that the tool anchor 9 clamps the upper part of the exposed free end of the anchor rod 1 through a clip, and the dynamometer 8 is clamped on the Between the piston 71 and the tool anchor 9, the piston 71 pushes the dynamometer 8, the dynamometer 8 is used to obtain the force load of the anchor 1, and the dial indicator 10 is installed on the tool anchor 9 to measure the force of the anchor 1. Anchor head displacement.

As a transformation of the present embodiment, the support stool 6 can also adopt a hollow four-sided platform tube with a small upper part and a larger lower part.

In this embodiment, the support stool 6 is a hollow cylindrical structure, the bottom surface of the support stool is supported on the steel backing plate 4 in the existing structure, the top surface contacts the bottom surface of the jack 7, and is fixed by the preload of the jack 7 Between backing plate 4 and jack 7. At the same time, in order to ensure the material strength requirements when loaded to the maximum load, it is necessary to check the compressive strength of the cylindrical section, and generally a cylindrical structure with a thicker side wall can be used.

The jack 7 is a through-the-heart jack, the bottom surface of the jack 7 is supported on the support stool 6, and the piston 71 is pressed on the dynamometer 8.

The dynamometer 8 is a hollow cylindrical structure made of high-strength alloy steel, and a plurality of string sensors are evenly arranged on the periphery of the empty pressure-bearing cylinder. When the load causes axial deformation of the steel cylinder, the deformation of the strain gauge is the same as that of the steel cylinder, and the deformation causes the stress of the vibrating wire of the strain gage to change, thereby changing the vibration frequency of the vibrating wire. The electromagnetic coil excites the vibrating wire and measures its vibration frequency. The frequency signal is transmitted to the reading device through the cable, and the strain of the steel cylinder can be measured, and the load value of the anchor dynamometer can be calculated by substituting the calibration coefficient. The pressure surface of the dynamometer should be perpendicular to the axis of the bolt.

The shape of the tool anchor 9 is the same as that of the working anchor 5 in the existing structure, and the exposed part of the prestressed anchor rod is clamped by the clip.

The present invention uses the above-mentioned detection device to detect the load held by the completed prestressed No. 1 anchor and No. 2 anchor respectively. The specific detection methods and detection results correspond to the following Embodiment 1 and Embodiment 2 respectively.

Implementation one

In this embodiment, the design locking force value p of the anchor rod is 185kN, and the design acceptance load is 440kN; the model QFZ50-6 through-hole jack is adopted, the maximum load that the jack can provide is 500kN, the diameter of the through hole is 76mm, and the outer diameter is 200mm; the dynamometer The maximum capacity is 500kN, the outer diameter is 140mm, the wall thickness is 32mm, the inner diameter is 76mm, and the height is 120mm; the outer diameter of the tool anchor is 93mm, the inner diameter of the top is 63mm, the inner diameter of the bottom is 53mm, and the height is 60mm. The support stool adopts a cylindrical structure with an outer diameter of 200mm, a wall thickness of 30mm, and an inner diameter of 140mm. The material is Q235 steel, and its design yield strength is 210MPa. The strength check is as follows:

When the supporting stool is subjected to a design acceptance load of 440kN, the compressive stress of the section is fulfil requirements.

In the formula, F is the design acceptance load; A is the cross-sectional area of the supporting stool.

The detection method for the load held by the completed prestressed No. 1 anchor rod using the above detection device, the detection method includes the following steps:

Step (1): place the support stool 6 on the backing plate 4 of the waist beam 3 of the completed anchor structure, and then place the jack 7, the dynamometer 8, the tool anchor 9, and the prestressed anchor rod on the support stool 6 in sequence. 1. The exposed free end passes through the center of the support stool 6, the jack 7, the dynamometer 8, and the tool anchor 9 from bottom to top, and the top end protrudes from the tool anchor 9. The axis of the anchor rod 1 is in line with the jack 7, The pressure-bearing surfaces of the dynamometer 8 and the tool anchor 9 are vertical, the anchor rod 1 is locked on the tool anchor 9, and the dial indicator 10 is placed;

Step (2): Load the entire detection device in stages through the jack 7, and observe the displacement of the anchor head synchronously. The loading method is as follows:

The initial load is 30% of the designed locking force value p of the anchor rod. Under the initial load, the displacement of the anchor head is measured every 5 minutes. When the displacement increment of the two adjacent anchor heads is not greater than 0.01mm, it can be regarded as an anchor. The head displacement is stable, take the last reading value as the reference value of the anchor head displacement;

The graded load is 5% of the design locking force value p of the anchor rod, the purpose is to ensure that the measured holding load has a high accuracy;

During the anchor head displacement observation period, the load variation range should not exceed 10% of the graded load;

When there is a sudden change in the displacement of the anchor head or the loosening of the working anchor 5, the test should be terminated after 2 to 4 levels of loading;

When the test load is loaded to the design acceptance load, and there is no sudden change in the displacement of the anchor head or the loosening of the working anchor 5, the test should be terminated.

The loading rate is 0.05p/min, the unloading rate is 0.1p/min,

After the application of each level of load is completed, the load is maintained for 5 minutes, and the displacement of the anchor head is measured at 0 and 5 minutes, and the average value is taken as the displacement of the anchor head under each level of load.

The parameters obtained from the measurement of No. 1 bolt are listed as follows:

Table 1: Parameters obtained from the measurement of No. 1 bolt

Draw the obtained load and the corresponding anchor head displacement into a load-displacement relationship curve, as shown in Figure 3;

Step (3): The determination method of the load held by the anchor rod body is as follows:

When the sudden change of displacement on the load-displacement relationship curve is obvious, the load value corresponding to the starting point of the steep rise is taken as the holding load of the bolt body.

When the load-displacement relationship curve is difficult to accurately determine the starting point of the steep rise, the previous level of load corresponding to the intersection point of the fitted straight line on both sides of the curve is taken as the holding load of the anchor rod.

The load-displacement relationship curve of the No. 1 anchor is shown in Fig. 3, and the displacement of the anchor head on the curve has a sudden mutation. Through the judgment method of the above step (3), it can be seen that 0.95p shown in Fig. 3 is the No. 1 anchor body. There is a load value, which is 176kN.

Implementation two

In this embodiment, the design locking force value p of the anchor rod is 185kN, and the design acceptance load is 440kN; the model QFZ50-6 through-hole jack is adopted, the maximum load that the jack can provide is 500kN, the diameter of the through hole is 76mm, and the outer diameter is 200mm; the dynamometer The maximum capacity is 500kN, the outer diameter is 140mm, the wall thickness is 32mm, the inner diameter is 76mm, and the height is 120mm; the outer diameter of the tool anchor is 93mm, the inner diameter of the top is 63mm, the inner diameter of the bottom is 53mm, and the height is 60mm. The support stool adopts a cylindrical structure with an outer diameter of 200mm, a wall thickness of 30mm, and an inner diameter of 140mm. The material is Q235 steel, and its design yield strength is 210MPa. The strength check is as follows:

When the supporting stool is subjected to a design acceptance load of 440kN, the compressive stress of the section is fulfil requirements.

In the formula, F is the design acceptance load; A is the cross-sectional area of the supporting stool.

The detection method for the load held by the completed prestressed No. 2 anchor rod using the above detection device, the detection method includes the following steps:

Step (1): place the support stool 6 on the backing plate 4 of the waist beam 3 of the completed anchor structure, and then place the jack 7, the dynamometer 8, the tool anchor 9, and the prestressed anchor rod on the support stool 6 in sequence. 1. The exposed free end passes through the center of the support stool 6, the jack 7, the dynamometer 8, and the tool anchor 9 from bottom to top, and the top end protrudes from the tool anchor 9. The axis of the anchor rod 1 is in line with the jack 7, The pressure-bearing surfaces of the dynamometer 8 and the tool anchor 9 are vertical, the anchor rod 1 is locked on the tool anchor 9, and the dial indicator 10 is placed;

Step (2): Load the entire detection device in stages through the jack 7, and observe the displacement of the anchor head synchronously. The loading method is as follows:

The initial load is 30% of the designed locking force value p of the anchor rod. Under the initial load, the displacement of the anchor head is measured every 5 minutes. When the displacement increment of the two adjacent anchor heads is not greater than 0.01mm, it can be regarded as an anchor. The head displacement is stable, take the last reading value as the reference value of the anchor head displacement;

The graded load is 5% of the design locking force value p of the anchor rod, the purpose is to ensure that the measured holding force load has a high accuracy;

During the anchor head displacement observation period, the load variation range should not exceed 10% of the graded load;

When there is a sudden change in the displacement of the anchor head or the loosening of the working anchor 5, the test should be terminated after 2 to 4 levels of loading;

When the test load is loaded to the design acceptance force load, and there is no sudden change in the displacement of the anchor head or loosening of the working anchor 5, the test should be terminated.

The loading rate is 0.05p/min, the unloading rate is 0.1p/min,

After the application of each level of load is completed, the load is maintained for 5 minutes, and the displacement of the anchor head is measured at 0 and 5 minutes, and the average value is taken as the displacement of the anchor head under each level of load.

The parameters obtained from the measurement of No. 2 bolt are listed as follows:

Table 2: Parameters obtained from the measurement of No. 2 bolt

Draw the obtained load and the corresponding anchor head displacement into a load-displacement relationship curve, as shown in Figure 4;

Step (3): The determination method of the load held by the anchor rod body is as follows:

When the sudden change of displacement on the load-displacement relationship curve is obvious, the load value corresponding to the starting point of the steep rise is taken as the holding load of the bolt body.

When the load-displacement relationship curve is difficult to accurately determine the starting point of the steep rise, the previous level of load corresponding to the intersection point of the fitted straight line on both sides of the curve is taken as the holding load of the anchor rod.

The load-displacement relationship curve of the No. 2 anchor is shown in Figure 4. It is difficult to accurately determine the sudden change point of the anchor head displacement on the curve. According to the judgment method of the above step (3), it can be known that 0.9p shown in Figure 4 is the No. 2 anchor The rod body holds a load value of 167kN.

The above-mentioned embodiments of the present invention do not limit the protection scope of the present invention. Under the premise of the above-mentioned basic technical ideas, other modifications, replacements or changes made to the above-mentioned structure of the present invention in various forms shall fall within the protection scope of the present invention.

Claims (4)

1. The detection device for the load held by the anchor rod body, the anchor rod (1) is installed obliquely, and it is characterized in that: the detection device includes support stools (6) arranged sequentially from bottom to top along the axial direction of the anchor rod (1) , jack (7), dynamometer (8), tool anchor (9) and dial gauge (10), the backing plate ( 4), the top surface is in contact with the bottom surface of the jack (7), and the support stool (6) is fixed between the backing plate (4) and the jack (7) through the pre-tightening force of the jack (7), and the jack ( 7) has a piston (71) at the top, and the exposed free end of the anchor rod (1) sequentially from the support stool (6), the jack (7), the dynamometer (8), and the tool anchor (9) from bottom to top. and the top end protrudes from the tool anchor (9), the tool anchor (9) clamps the upper part of the exposed free end of the anchor rod (1), and the dynamometer (8) is clamped between the piston (71) and the tool Between the anchors (9), the piston (71) pushes the dynamometer (8), and the dynamometer (8) is used to obtain the force load of the anchor rod (1), and the dial indicator (10 ) is installed on the tool anchor (9) to measure the anchor head displacement of the anchor rod (1). 2. The device for detecting the load held by the anchor rod body according to claim 1, characterized in that: the tool anchor (9) clamps the upper part of the exposed free end of the anchor rod (1) through a clip. 3. The detection device for the load held by the anchor rod body according to claim 1, characterized in that: the axis of the anchor rod (1) is in contact with the jack (7), the dynamometer (8), the tool anchor (9) The compression surface is vertical. 4. The method for detecting the load held by the anchor rod body by using the detection device according to any one of claims 1 to 3, characterized in that: the method comprises the following steps: Step (1): Place the support stool (6) on the backing plate (4) of the waist beam (3) of the completed anchor structure, and then place the jack (7) and the dynamometer on the support stool (6) in sequence (8) and the tool anchor (9), the exposed free end of the prestressed anchor rod (1) sequentially from the support stool (6), jack (7), dynamometer (8), tool anchor (9) from bottom to top through the center of the tool anchor (9), and the top end protrudes from the tool anchor (9), the axis of the anchor rod (1) is perpendicular to the pressure surface of the jack (7), the dynamometer (8), and the tool anchor (9), and the anchor The rod (1) is locked on the tool anchor (9), and the dial indicator (10) is placed; Step (2): Load the entire detection device in stages through the jack (7), and simultaneously observe the displacement of the anchor head. The loading method is as follows: The initial load is 30% of the designed locking force value p of the anchor rod. Under the initial load, the displacement of the anchor head is measured every 5 minutes. When the displacement increment of the two adjacent anchor heads is not greater than 0.01mm, it can be regarded as an anchor. The head displacement is stable, take the last reading value as the reference value of the anchor head displacement; The graded load is 5% of the design locking force value p of the anchor rod, the purpose is to ensure that the measured holding load has a high accuracy; During the anchor head displacement observation period, the load variation range should not exceed ±10% of the graded load; When there is a sudden change in the displacement of the anchor head or the loosening of the working anchor (5), the test should be terminated after 2 to 4 levels of loading; When the test load is loaded to the acceptance load, and there is no abrupt displacement of the anchor head or loosening of the working anchor (5), the test shall be terminated. The loading speed is 0.05～0.10p/min, and the unloading speed is twice the loading speed. After the application of each level of load is completed, the load is maintained for 5 minutes, and the displacement of the anchor head is measured at 0 and 5 minutes, and the average value is taken as the displacement of the anchor head under each level of load. Draw the obtained load and the corresponding anchor head displacement into a load-displacement relationship curve; Step (3): The determination method of the load held by the anchor rod body is as follows: When the sudden change of displacement on the load-displacement relationship curve is obvious, the load value corresponding to the starting point of the steep rise is taken as the holding load of the bolt body. When the load-displacement relationship curve is difficult to accurately determine the starting point of the steep rise, the previous level of load corresponding to the intersection point of the fitted straight line on both sides of the curve is taken as the holding load of the anchor rod.