A method for analyzing overall stability of bridges

Abstract

The invention discloses a method for analyzing the overall stability of a bridge, and the specific steps are as follows: S1: installing a displacement sensor and a temperature sensor on a bridge pier, the displacement sensor and the temperature sensor are symmetrically arranged with the midpoint of the bridge as the symmetrical point, and the temperature sensor and the displacement sensor are installed at the same position; S2: making the bridge unloaded, measuring the data of the change of bridge deformation with temperature, and establishing a model of the change law of deformation with temperature; S3: measuring the initial position of the displacement sensor in the load stage, and then calculating the load deformation that eliminates the influence of temperature according to the relationship between displacement and temperature; S4: calculating the load imbalance deviation using the load deformation, and judging the overall stability of the bridge according to the imbalance deviation; in step S2, the monitoring time of the displacement change with temperature under the load-free condition is not less than 1 day, and the sampling frequency is not less than 1 Hz; in step S2, the relationship between displacement and temperature is calculated using the least square method, which solves the technical problem of complex bridge stability judgment.

Description

Technical Field

[0001] The invention relates to the technical field of building bridge stability measurement, in particular to a bridge overall stability analysis method. Background Art

[0002] The stability and safety of the bridge state is directly related to the safety of people's lives and property. It is very important to conduct stability analysis on the bridge. Therefore, how to solve the above-mentioned problems has become a difficult problem that needs to be solved urgently. Summary of the invention

[0003] The purpose of the present invention is to provide an analytical method which is simple to install and easy to operate, and which can obtain the deformation of the pier caused by the load, calculate the load imbalance deviation, and judge the overall stability of the bridge by installing displacement sensors and temperature sensors at symmetrical positions on the pier.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a method for analyzing the overall stability of a bridge, and the specific implementation steps are as follows: S1: installing displacement sensors and temperature sensors on the piers of the bridge, and the displacement sensors and temperature sensors are symmetrically arranged with the midpoint along the bridge direction as the symmetrical point, and the temperature sensor and the displacement sensor are installed at the same position; S2: making the bridge unloaded, measuring the data of the change of bridge deformation with temperature, and establishing a model of the change law of deformation with temperature; S3: measuring the initial position of the displacement sensor in the load stage, and then calculating the load deformation that eliminates the influence of temperature based on the relationship between displacement and temperature; S4: using the load deformation to calculate the load imbalance deviation, and judging the overall stability of the bridge based on the imbalance deviation.

[0005] Preferably, in step S2, the monitoring time of displacement variation with temperature under no load condition is not less than 1 day, and the sampling frequency is not less than 1 Hz.

[0006] Preferably, the displacement-temperature relationship in step S2 is calculated using the least squares method.

[0007] Preferably, the displacement sensor and the temperature sensor in step S1 are fixed by bolt connection.

[0008] Preferably, the displacement sensor and the temperature sensor in step S1 both monitor data through optical fiber materials.

[0009] Compared with the prior art, the present invention has the following beneficial effects:

[0010] (1) The present invention installs displacement monitoring sensors and temperature sensors on the piers of the bridge, and obtains the statistical relationship between displacement and temperature using the least square method based on the measurement results of temperature and displacement under no-load conditions. Then, the displacement measured under load conditions is corrected for temperature effects to obtain dynamic displacement, and on this basis, the load imbalance deviation is obtained. The overall stability of the bridge is judged based on the load imbalance deviation, thus solving the difficulty of analyzing the overall stability of the bridge. (2) The method is simple to implement and operate. By using the displacement sensors and temperature sensors installed at symmetrical positions on the piers, the deformation of the piers caused by the load is obtained, and the load imbalance deviation is calculated to judge the overall stability of the bridge.

[0011] (3) Traditional bridge health monitoring mainly uses strain measurement technology of electrical sensors. This method is susceptible to electromagnetic interference, has complex wiring, and has low timeliness. In addition, the instantaneous results measured cannot accurately and continuously predict the working status of the bridge. Compared with traditional electrical detection technology, optical fiber sensors have the advantages of long service life, good stability, low power consumption, long transmission distance, and strong resistance to external interference. Therefore, for the monitoring scenario in this article, optical fiber sensors are selected to monitor the target object.

[0012] (4) The installation methods of fiber optic sensors include gluing, welding, embedding or bolting. The installation method will affect the speed and cost of installation, as well as the monitoring effect. For concrete or metal structures, bolt connection is the preferred installation method. Bolt connection not only has low installation requirements, but also facilitates the removal of the sensor. Only the nut needs to be unscrewed without removing the stud bolt, which can prevent the connection from being damaged by the threaded holes on the connector. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The figure is a schematic diagram of analyzing an embodiment of the present invention.

[0014] In the figure: 1. temporary consolidation column on the left; 2. temporary consolidation column on the right; 3. displacement sensor on the temporary consolidation column on the left; 4. temperature sensor on the temporary consolidation column on the left; 5. displacement sensor on the temporary consolidation column on the right; 6. temperature sensor on the temporary consolidation column on the right; 7. digital signal acquisition instrument; 8. computer. DETAILED DESCRIPTION

[0015] In the following description, a large number of specific details are given in order to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features known in the art are not described. In order to enable those skilled in the art to better understand the present application scheme, the technical scheme in the embodiment of the present application will be clearly and completely described below in conjunction with the drawings in the embodiment of the present application. Obviously, the described embodiment is only an embodiment of a part of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians of the art without making creative work should belong to the scope of protection of this application.

[0016] In addition, the terms "installed", "set", "provided with", "connected", "connected", and "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0017] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0018] Embodiment 1:

[0019] The present invention provides a method for analyzing the overall stability of a bridge. Figure 1 As shown, in the method, a displacement sensor 3 on the left temporary consolidation column and a displacement sensor 5 on the right temporary consolidation column are installed at symmetrical positions at the same height of the left temporary consolidation column 1 and the right temporary consolidation column 2 to measure the axial displacement of the temporary consolidation column; a temperature sensor 4 on the left temporary consolidation column and a temperature sensor 6 on the right temporary consolidation column are installed at the positions of the displacement sensor 3 on the left temporary consolidation column and the displacement sensor 5 on the right temporary consolidation column; a load is applied to the bridge to cause the left temporary consolidation column 1 and the right temporary consolidation column 2 to deform, and the deformation of the temporary consolidation column is measured by the displacement sensor 3 on the left temporary consolidation column and the displacement sensor 5 on the right temporary consolidation column respectively; the displacement sensor 3 on the left temporary consolidation column, the temperature sensor 4 on the left temporary consolidation column, the displacement sensor 5 on the right temporary consolidation column, and the temperature sensor 6 on the right temporary consolidation column are connected to a computer 8 through a digital signal acquisition instrument 7.

[0020] In the present invention, the temperature correction method involved is as follows:

[0021] Under no-load conditions, displacement and temperature are measured simultaneously. The displacement value measured by the displacement sensor is called the initial displacement. The displacement X measured by the displacement sensor 3 on the temporary consolidation column on the left is 0 (1) , corresponding to the temperature measured by the temperature sensor 4 on the left temporary consolidation column is T (1) , the displacement measured by displacement sensor 5 on the right temporary consolidation column is X 0 (2) , the temperature measured by the temperature sensor on the right temporary consolidation column is T (2) .

[0022] Under the condition of no load, the initial displacement and corresponding temperature data are measured for more than one day without load, and then the linear least square method is used to establish the statistical relationship between the initial displacement and temperature;

[0023]

[0024] For the initial displacement and temperature measured at a certain time, the load displacement caused by the applied load

[0025]

[0026] The displacement calculated by formula (2) is the load displacement of each displacement sensor caused by the load after temperature correction.

[0027] In the present invention, the derivation process of calculating the unbalance deviation according to the load displacement is as follows:

[0028] The weight of the left pier is W 1 , the weight of the right pier is W 2 ; The initial displacements of the left and right piers are X 0 (1) and X 0 (2) , and the corresponding temperature is T (1) and T (2) Then, the load displacement X is obtained by formula (2): (1) and X (2) .

[0029] Assume that the axial forces of the left temporary consolidation column and the right temporary consolidation column caused by the left pier and the right pier are F 1 and F 2 The distance between the left temporary consolidation column and the right temporary consolidation column is b, and the distance from the weight application point of the construction beam section to the temporary consolidation column is l.

[0030] From the moment balance at point A, we can get:

[0031] F 2 xb=W2 x(1+b)-W 1 xl; (3)

[0032] From the moment balance at point B, we can get:

[0033] F 1 xb=W 1 x(1+b)-W 2 x1; (4)

[0034] Subtracting formula (3) from formula (4) yields:

[0035] F 1 -F 2 =(W 1 -W 2 )(21 / b+1);(5)

[0036] Formula (4) plus formula (3) yields:

[0037] F 1 +F 2 =W 1 +W 2 ; (6)

[0038] From the relationship between axial force and displacement, we can know that:

[0039] F 1 =EAx (1) (7)

[0040] F 2 =EAx (2) (8)

[0041] Where E is the elastic modulus of the temporary consolidation column, and A is the cross-sectional area of ​​the consolidation column. Substituting equations (7) and (8) into (5) and (6), and simplifying them, we obtain:

[0042]

[0043] Where W e is the load unbalance deviation, X e is the unbalanced displacement ratio.

[0044] Since the displacement and temperature are sampled continuously during the construction process, X in formula (11) (1) and X (2) . It is obtained by subtracting the initial displacements of each beam segment before and after construction after temperature correction.

[0045] Formula (9) shows that the load imbalance deviation of the construction beam section can be quantitatively calculated using the displacement of the temporary consolidation column. After obtaining the load imbalance deviation, the stability can be judged according to the first paragraph of Article 16.5.4 on page 141 of the Technical Specifications for Highway Bridge and Culvert Construction.

[0046] The above embodiments are only preferred embodiments of the present invention and are not limitations of the technical solutions of the present invention. Any technical solution that can be implemented on the basis of the above embodiments without creative work should be deemed to fall within the scope of protection of the patent of the present invention.

[0047] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A bridge overall stability analysis method, characterized by: The specific steps are as follows: S1: Install displacement sensors and temperature sensors on the piers of the bridge. The displacement sensors and temperature sensors are symmetrically arranged with the midpoint of the bridge as the symmetrical point, and the temperature sensor and displacement sensor are installed at the same position; S2: Make the bridge unloaded, measure the data of the change of bridge deformation with temperature, and establish a model of the change law of deformation with temperature; S3: Measure the initial position of the displacement sensor in the load stage, and then calculate the load deformation that eliminates the influence of temperature based on the relationship between displacement and temperature; S4: Use the load deformation to calculate the load imbalance deviation, and judge the overall stability of the bridge based on the imbalance deviation; The expression for judging the overall stability of the bridge is: Among them, W e is the load unbalance deviation, X e is the unbalanced displacement ratio, b is the distance between the left temporary consolidation column and the right temporary consolidation column, l is the distance from the construction beam weight action point to the temporary consolidation column, W1 and W2 are the weight of any pier on the left or right side, respectively, and X (1) and X (2) are the load displacement of any pier on the left or right side, respectively.

2. A bridge overall stability analysis method according to claim 1, characterized in that: The monitoring time of the displacement variation with temperature under no-load condition in step S2 is not less than 1 day, and the sampling frequency is not less than 1 Hz.

3. A bridge overall stability analysis method according to claim 1, characterized in that: The relationship between displacement and temperature in step S2 is calculated using the least squares method.

4. A bridge overall stability analysis method according to claim 1, characterized in that: The displacement sensor and the temperature sensor in step S1 are fixed by bolt connection.

5. A bridge overall stability analysis method according to claim 1, characterized in that: The displacement sensor and the temperature sensor in step S1 both monitor data through optical fiber materials.

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