CN107036522B

CN107036522B - Device and method for measuring vertical displacement of water structure of middle-span and small-span bridge

Info

Publication number: CN107036522B
Application number: CN201611085795.6A
Authority: CN
Inventors: 李胜利; 毋光明; 石鸿帅
Original assignee: Zhengzhou University
Current assignee: Zhengzhou University
Priority date: 2016-11-30
Filing date: 2016-11-30
Publication date: 2023-05-26
Anticipated expiration: 2036-11-30
Also published as: CN107036522A

Abstract

The invention discloses a device and a method for measuring the vertical displacement of a water structure of a middle-span and small-span bridge, which are suitable for the field of bridge detection, in particular to the deflection measurement of a bridge structure of a river. The invention comprises a telescopic bracket and a displacement acquisition device, wherein the telescopic bracket can be telescopic and foldable; the displacement acquisition device can effectively measure the vertical displacement of the bridge and realize the vertical displacement information of the long-distance oblique measurement structure through the cable-stayed lead; the measuring method is characterized in that the pre-measurement is realized through the extension and retraction of the telescopic bracket, the correction coefficient of the displacement meter is given, and the actually measured vertical displacement is accurately calculated according to the correction coefficient of the displacement meter. The invention is convenient for carrying engineering vehicles and on-site installation and use of measuring staff, is suitable for complex and dangerous environment measurement, and greatly improves the measuring environments of the measuring staff and measuring equipment.

Description

Device and method for measuring vertical displacement of water structure of middle-span and small-span bridge

Technical Field

The invention relates to the field of detection of middle and small span bridges, in particular to a device and a method for measuring vertical displacement of a water structure of a middle and small span bridge.

Background

With the development of society, bridges play an increasingly important role as important components of current traffic. In recent years, however, many bridge structures constructed in the past need to be fully inspected, one important item is load-bearing capacity assessment, and a direct method capable of ensuring reliable load-bearing capacity assessment results is load test. In the load test, deflection (vertical displacement) is the comprehensive reflection of the operation state of the bridge structure, and is one of the most direct and visual safety indexes of the bridge structure, but the environment and the topography under the bridge structure are often quite complex, and a displacement meter and a detector cannot work under the bridge structure. In order to measure the deflection of the bridge, a scaffold is often required to be arranged under the bridge, so that time and labor are wasted, if the river water under the bridge is too much, the stability of the scaffold is difficult to be ensured, and the safety of personnel is threatened.

Disclosure of Invention

The invention aims to provide a device and a method for measuring the vertical displacement of a water structure of a middle-span and small-span bridge, which enable a displacement meter to provide accurate and reliable displacement measurement under the condition that the displacement meter is not contacted with the bridge and is not right below a measuring position.

The specific scheme of the invention is as follows: a device for measuring the vertical displacement of a middle-span and small-span bridge water structure comprises a telescopic bracket and a displacement acquisition device; the telescopic bracket comprises a fixed column foot, a fixed column, a telescopic arm, a cross beam, pulleys and a rigid bottom plate; the fixed column feet of the telescopic support are connected with the fixed columns through bolts; the telescopic arm of the telescopic bracket is fixed through a fixing cap on the fixing column; the cross beam of the telescopic bracket is connected with the telescopic arm through a round shaft, and a 5mm gap is formed between the lower surface of the cross beam and the telescopic arm; thimble grooves are formed in the two ends of the cross beam of the telescopic bracket; the displacement acquisition device comprises a displacement meter, a correction displacement meter, a signal acquisition instrument, a heavy hammer, a magnetic gauge stand and an indium steel wire; one end of the heavy hammer is connected with the indium steel wire, and a displacement meter at the other end is propped up below the heavy hammer; the two correction displacement meters are respectively propped in the thimble grooves on the cross beam, the three magnetic meter seats are arranged on the rigid bottom plate, and the two correction displacement meters and the one displacement meter are respectively clamped; the displacement meter and the correction displacement meter are connected to the signal acquisition instrument through hydraulic cables.

Further, pulleys are arranged between the cross beams, and the axes of the pulleys are collinear with the central line of the cross beams.

Further, the outer side of the heavy hammer is provided with a steel sleeve, and two sides of the steel sleeve are fixed on the cross beam through sleeve suspenders.

Further, the displacement meter and the correction displacement meter are both resistance type displacement meters.

Further, the signal acquisition instrument is a resistance type strain gauge.

The invention provides a method for measuring the vertical displacement of a middle-span and small-span bridge water structure, which comprises the following steps:

step 1: manually loosening the fixing cap, lifting the telescopic arm upwards according to the estimated displacement of the tested structure, and then tightening the fixing cap for fixing;

step 2: acquiring the reading changes S1 and S2 of the two correction displacement meters and the reading change delta H of the displacement meters;

step 3: calculating correction coefficient of displacement meter

Wherein Δs= (s1+s2)/2, η>1；/>

Step 4: the fixing cap is loosened manually, the telescopic arm is retracted to be basically in an initial state and fixed, and system errors are reduced;

step 5: loading on site, and collecting reading change delta H of a displacement meter;

step 6: calculating the actual displacement s=η.

The invention has the beneficial effects that: under the premise of ensuring accurate and reliable measurement, manpower and material resources are saved, the difficulty of detecting displacement in bridge load test and the risk factors in the detection process are reduced, and the detection under complex topography and environmental conditions is facilitated.

Drawings

FIG. 1 is a schematic diagram of the construction of an embodiment of the present invention;

FIG. 2 is a diagram of a measurement device of the present invention;

FIG. 3 is an enlarged view of a portion of the key portion A of FIG. 2;

FIG. 4 is an enlarged view of a portion of the key portion B of FIG. 2;

FIG. 5 is an enlarged view of a portion of the critical portion C of FIG. 2;

FIG. 6 is a schematic diagram of a predicted quantity implementation;

fig. 7 is a schematic diagram of the calculation of the coefficient of calibration of the displacement meter.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

As can be seen from fig. 1 and 2, the method of the present invention is implemented by placing the measuring device at any position below the measured structure 19, and suspending the weight 12 around the pulley 5 by pulling the indium wire 13 on the measured structure 19 to the pulley 5.

The measuring device of the invention is composed of a telescopic bracket and a displacement acquisition device, wherein the telescopic bracket is composed of a rigid bottom plate 17, a fixed column base 1, a fixed column 2, a telescopic arm 3 which can be lifted, a cross beam 4, a pulley 5, a steel sleeve 6, a sleeve suspender 7 and a fixed cap 8. The inner diameter of the fixed column 2 is slightly larger than the outer diameter of the telescopic arm 3, a screw hole is formed in the fixed column 2, and the telescopic arm 3 can be conveniently fixed by rotating the fixed cap 8 so as to ensure that the telescopic arm 3 can be telescopic; the telescopic arm 3 and the cross beam 4 are connected through a round shaft 16, and the lower surface of the cross beam 4 is 5mm away from the telescopic arm, so that the telescopic arm 3 and the cross beam 4 are hinged, and the cross beam 4 is not deformed under the condition that the telescopic arm 3 stretches freely; the fixed column 2 and the fixed column base 1 are connected through a bolt 15, the fixed column base 1 can be clamped by the rotary nut, the width of the fixed column base 1 is slightly larger than that of the fixed column 2, and the telescopic bracket can be folded; thimble grooves 18 of the displacement meter are arranged at two ends of the lower part of the cross beam 4 and are used for fixing and correcting thimbles of the displacement meter 10 to prevent the thimbles from being displaced; a sleeve suspender 7 is welded near the middle part of the cross beam 4, the sleeve suspender 7 is welded on two sides of the steel sleeve 6, and the steel sleeve 6 is used for stabilizing the heavy hammer 12.

The displacement acquisition device consists of a displacement meter 9, a correction displacement meter 10, a signal acquisition instrument 11, a heavy hammer 12, an indium steel wire 13 and a magnetic gauge stand 14. The magnetic gauge stand 14 clamps the displacement meter 9 and the two correction displacement meters 10, the ejector pins of the correction displacement meters 10 at the two ends of the cross beam 4 are placed in the ejector pin grooves 18 of the cross beam shown in fig. 4, the middle displacement meter 9 is propped against the bottom surface of the heavy hammer 12, and the heavy hammer 12 is suspended in the steel sleeve 6 through the indium steel wire 13. The displacement meter 9 and the correction displacement meter 10 are connected to the signal acquisition instrument through hydraulic cables, and the connection method is a full-bridge method connection. The signal acquisition instrument 11 acquires data of each displacement meter, and transmits the data to a computer through a USB conversion line, and the data is stored by the computer.

As shown in fig. 6, a predetermined amount is required before the displacement is measured formally, and the correction coefficient of the displacement meter is obtained.

Before measurement, the vertical displacement (deflection) of the structure is estimated in advance, then the telescopic arm 3 is adjusted, and the lifting (lowering) heights S1 and S2 of the two ends of the beam 4 and the weight displacement difference Δh (approaching deflection predictive value) measured by the resistance type displacement meter 9 under the weight 12 are measured by the correction displacement meter 10, wherein Δs= (s1+s2)/2.

As can be seen from FIG. 7, when the rising distance of the middle part of the beam 4 is ΔS, the lead length of the weight 12 is increased by ΔL, and the structural displacement of the rising amount of the weight 12 is vertical displacement, the correction coefficient of the displacement meter is calculated

η>1. Wherein Δs is substantially negligible relative to the measurement point height and diagonal lead length. After the pre-measurement, the correction coefficient of the displacement meter is calculated, the telescopic arm 3 is retracted (lifted back) to an initial state, and the system error is reduced. Then, starting a field loading test, collecting the reading change delta H of the displacement meter 9, and calculating the actual structural displacement according to the correction coefficient eta, wherein the calculation formula is as follows: s=η×Δh. />

Claims

1. The utility model provides a well stride bridge water structure vertical displacement measuring device which characterized in that: comprises a telescopic bracket and a displacement acquisition device; the telescopic bracket comprises a fixed column base (1), a fixed column (2), a telescopic arm (3), a cross beam (4), a pulley (5) and a rigid bottom plate (17); the fixed column base (1) and the fixed column (2) of the telescopic support are connected through bolts (15); the telescopic arm (3) of the telescopic bracket is fixed through a fixing cap (8) on the fixing column (2); the beam (4) of the telescopic bracket is connected with the telescopic arm (3) through a round shaft (16), and a 5mm gap is formed between the lower surface of the beam (4) and the telescopic arm (3); thimble grooves (18) are formed in the two ends of the cross beam (4) of the telescopic bracket; the displacement acquisition device comprises a displacement meter (9), a correction displacement meter (10), a signal acquisition instrument (11), a heavy hammer (12), a magnetic gauge stand (14) and an indium steel wire (13); one end of the heavy hammer is connected with the indium steel wire (13), and a displacement meter (9) at the other end is propped against the lower part of the heavy hammer (12); the two correction displacement meters (10) are respectively propped in thimble grooves (18) on the cross beam (4), the three magnetic meter seats are arranged on the rigid bottom plate (17), and the two correction displacement meters (10) and the displacement meter (9) are respectively clamped; the displacement meter (9) and the correction displacement meter (10) are connected to the signal acquisition instrument through hydraulic cables.

2. The device for measuring the vertical displacement of the water structure of the medium-span bridge according to claim 1, wherein the device is characterized in that: a pulley (5) is arranged between the cross beams (4), and the axis of the pulley (5) is collinear with the central line of the cross beams (4).

3. The device for measuring the vertical displacement of the water structure of the medium-span bridge according to claim 1, wherein the device is characterized in that: the outer side of the heavy hammer (12) is provided with a steel sleeve (6), and two sides of the steel sleeve (6) are fixed on the cross beam through sleeve suspenders (7).

4. The device for measuring the vertical displacement of the water structure of the medium-span bridge according to claim 1, wherein the device is characterized in that: the displacement meter (9) and the correction displacement meter (10) are both resistance type displacement meters.

5. The device for measuring the vertical displacement of the water structure of the medium-span bridge according to claim 1, wherein the device is characterized in that: the signal acquisition instrument (11) is a resistance type strain gauge.

6. The device for measuring the vertical displacement of the water structure of the middle-span bridge, which is disclosed by claim 1, comprises the following steps:

step 1: manually loosening the fixing cap (8), lifting the telescopic arm (3) upwards according to the estimated displacement of the tested structure (19), and then tightening the fixing cap (8) for fixing;

step 2: acquiring the reading changes S1 and S2 of the two correction displacement meters (10) and the reading change delta H of the displacement meter (9);

step 3: calculating correction coefficient of displacement meter

Where Δs= (s1+s2)/2,

η>1；

step 4: the fixing cap (8) is loosened manually, the telescopic arm (3) is retracted to be basically in an initial state and fixed, and system errors are reduced;

step 5: on-site loading, and collecting reading change delta H of a displacement meter (9);

step 6: the actual displacement of the structure s=η×Δh is calculated.