A beam jacking control method based on stiffness-lifting threshold mapping

Abstract

The present invention discloses a beam jacking control method based on stiffness-lifting threshold mapping, which includes: during the beam jacking process, monitoring the reaction forces and lifting amounts of each support point at the bottom of the beam, and determining the lifting threshold of each support point and the corresponding beam jacking threshold after each support point is jacked to the designed lifting amount through the stiffness coefficients and reaction forces of each support point; judging whether the actual lifting amounts of each support point meet the requirements according to the beam jacking threshold, and adjusting the lifting amounts of the support points that do not meet the requirements until the actual lifting amounts of each support point all meet the requirements; and simultaneously controlling the reaction forces of each support point during the jacking process and the lifting amount adjustment process to meet the design requirements. The present invention establishes the lifting threshold of the beam support points by using the structural stiffness of the beam, clarifies a reasonable range of lifting amounts, and combines the control of the reaction forces of each support point, thereby improving the lifting adjustment accuracy and adjustment efficiency of the beam during the jacking construction.

Description

Technical Field

[0001] The present invention relates to the technical field of jacking construction of beam bodies. More specifically, the present invention relates to a beam body jacking control method based on stiffness-lifting threshold mapping. Background Art

[0002] With the continuous development of the transportation network, newly built bridges may cross deep valleys, rivers, highways, railways, etc. Also, due to the narrow construction site, it is difficult to transport large machinery to the site. For such projects, in order to reduce the impact on the existing traffic, the jacking construction method is often adopted. First, the beam body is lifted as a whole, then the jacking translation oil cylinder is pushed forward for a stroke, and then the beam body is lowered as a whole and placed on the temporary bearing beam. The jacking translation oil cylinder then retracts to the end to complete the jacking of one stroke. During the jacking process of a long-span steel beam, the overall stiffness of the long-span steel beam is small, and the deformation during the jacking process is large and uneven. The traditional jacking method does not consider the error control problem of the jacking amount under the condition of flexible deformation, and mostly estimates based on the experience of the bridge type structure, resulting in no basis for the control of the jacking process of the flexible steel beam. The jacking heights of multiple support points are inconsistent. If the accuracy requirements of the experience are followed, frequent adjustments are required, and the construction efficiency is low. At the same time, when the jacking forces at each point are uneven, it is easy to cause the beam body structure to be damaged due to excessive jacking force at some jacking points. Therefore, there is an urgent need for a reasonable control method to meet the requirements of efficient and accurate jacking of the beam body. Summary of the Invention

[0003] An object of the present invention is to solve at least the above problems and provide at least the advantages described later.

[0004] To achieve these objects and other advantages of the present invention, there is provided a beam body jacking control method based on stiffness-lifting threshold mapping, including: monitoring the reaction forces and jacking amounts of each support point at the bottom of the beam body during the jacking process of the beam body, determining the jacking threshold and the corresponding beam body jacking threshold after each support point jacks up to the designed jacking amount through the stiffness coefficients and reaction forces of each support point; judging whether the actual jacking amounts of each support point meet the requirements according to the beam body jacking threshold, and adjusting the jacking amounts of the support points that do not meet the requirements until the actual jacking amounts of each support point meet the requirements; and simultaneously controlling the reaction forces of each support point during the jacking process and the jacking amount adjustment process to meet the design requirements.

[0005] Preferably, the stiffness coefficients of each support point at the bottom of the beam body are obtained by establishing a finite element model of the beam body; the jacking threshold of each support point is the ratio of the reaction force of each support point to its stiffness coefficient.

[0006] Preferably, the support points with equal stiffness coefficients are grouped into one group, and the average value of the jacking thresholds of each support point in the same group is the beam body jacking threshold corresponding to this group of support points.

[0007] Preferably, determining whether the actual jacking amount of each support point meets the requirements specifically includes the following steps:

[0008] S1. Determine whether the jacking threshold of each support point is within the set jacking threshold range. If it is within the set jacking threshold range, proceed to step S2; otherwise, adjust the jacking amount of the corresponding support point.

[0009] S2. Calculate the difference between the jacking amount of each support point and the designed jacking amount. If the difference is not greater than the jacking threshold of the beam body, the actual jacking amount of the corresponding support point meets the requirements; otherwise, adjust the jacking amount of the corresponding support point.

[0010] Preferably, the set jacking threshold range is δd s ±3σ, where δd s is the jacking threshold of the beam body corresponding to each support point, and σ is the standard deviation of the jacking thresholds of each support point in the same group.

[0011] Preferably, during the jacking of the beam body, the reaction forces of each support point are controlled to meet the design requirements by the following formula:

[0012]

[0013] In the above formula, F ij and F mn are both the reaction forces of any one support point on the beam body; δF is the difference between the reaction forces of any two set support points; α is the jacking coefficient. When the subsequent jacking construction is a horizontal push, α = 1; when the subsequent jacking construction is not a horizontal push, 0 < α < 1.

[0014] Preferably, at least two rows of support points are arranged at intervals at the bottom of the beam body. Each row of support points includes multiple support points arranged at intervals along the longitudinal direction of the beam body. A jacking device is arranged on each support point, and each jacking device synchronously jacks the beam body upward to the designed jacking amount.

[0015] The present invention has at least the following beneficial effects:

[0016] The beam body jacking control method based on the stiffness-jacking threshold mapping provided by the present invention adopts a position-load dual control strategy. The position control establishes the jacking threshold for the jacking of each support point through the structural stiffness, clarifies a reasonable jacking amount range, and the load control controls the reaction forces of each support point to meet the design requirements, which can effectively avoid excessive local stress on the beam body caused by unbalanced loads at the support points and reduce the risk of beam body failure. Compared with the traditional empirical method adjustment, the adjustment process is clearer, the adjustment efficiency is higher under the condition of ensuring the adjustment accuracy, and the repeated trial-and-error adjustment of the traditional method is avoided, solving the problem of difficult jacking control of long-span flexible steel beams.

[0017] Other advantages, objects, and features of the present invention will be partly reflected by the following description, and partly will be understood by those skilled in the art through the research and practice of the present invention. Description of the Drawings

[0018] Figure 1 It is a flowchart of the beam jacking control method based on stiffness-lifting threshold mapping according to the present invention;

[0019] Figure 2 It is a schematic structural diagram of the flexible deformation after the beam is jacked up according to the present invention; Detailed Embodiments

[0020] The following further describes the present invention in detail with reference to the drawings, so that those skilled in the art can implement it according to the text of the specification.

[0021] It should be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified; in the description of the present invention, the terms "lateral", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0022] As Figure 1 and Figure 2 shown, the present invention provides a beam jacking control method based on stiffness-lifting threshold mapping, including: monitoring the reaction force and lifting amount of each support point at the bottom of the beam during the beam jacking process, determining the lifting threshold of each support point and the corresponding beam jacking threshold after each support point is jacked up to the designed lifting amount through the stiffness coefficient and reaction force of each support point; judging whether the actual lifting amount of each support point meets the requirements according to the beam jacking threshold, and adjusting the lifting amount of the support points that do not meet the requirements until the actual lifting amounts of all support points meet the requirements; and simultaneously controlling the reaction force of each support point during the jacking process and the lifting amount adjustment process to meet the design requirements.

[0023] In this technical solution, the flexible deformation generated by the beam body during the jacking process causes an error value between the actual jacking amount and the designed jacking amount during the jacking process. In order to accurately control the error of the beam body jacking amount, the present invention adopts a position-load dual control strategy. For position control, the jacking threshold of each support point is established through the structural stiffness, and this jacking threshold is the maximum error value of the current jacking amount. The beam body jacking threshold is further obtained through the jacking thresholds of each support point, serving as a benchmark for evaluating whether the actual jacking amount of the support point meets the requirements. When the jacking amounts of all support points meet the requirements, it indicates that the jacking deformation amount of the current beam body is within the elastic deformation range of the structure; otherwise, the jacking amount of the corresponding support point needs to be adjusted. After each adjustment of the jacking amount, the jacking thresholds of each support point and the beam body jacking threshold need to be recalculated based on the adjusted reaction force until the actual jacking amounts of all support points meet the requirements, so as to achieve precise control of the beam body jacking process and clarify a reasonable jacking amount range; for load control, during the jacking process and the process of adjusting the jacking amount, the initial jacking rate of each support point is the same, and the reaction force value gradually increases during the jacking process; and adjusting the jacking amount of the support point under the position control strategy will also affect its reaction force. During the above process, by monitoring the reaction forces of each support point, if the reaction force of a certain support point does not meet the requirements, it is adjusted by adjusting its jacking rate to avoid excessive local stress on the beam body caused by the unbalanced load of the support point and resulting in damage.

[0024] In another technical solution, the stiffness coefficients of each support point at the bottom of the beam body are obtained by establishing a finite element model of the beam body; the jacking threshold of each support point is the ratio of the reaction force of each support point to its stiffness coefficient. The reaction forces and actual jacking amounts of each support point are monitored and obtained through pressure sensors and rangefinders respectively. After establishing the finite element model of the beam body, continuous support points are taken at the possible support positions on the jacking path of the beam body for finite element analysis to obtain the stiffness coefficients of each support point. The jacking threshold δd of each support point ij is calculated according to the following formula:

[0025] (1)

[0026] In formula (1), k ij is the stiffness coefficient of each support point, i = 1, 2…M; j = 1, 2…N; F ij is the reaction force of each support point, i = 1, 2…M; j = 1, 2…N. As shown in Figure 2 , for the four support points of the beam body, the reaction forces of each support point are F 11 , F 12 , F 21 , F 22 , and the jacking thresholds are δd 11 , δd 12 , δd 21, δd 22 .

[0027] In another technical solution, the support points with the same beam structure properties at corresponding positions are grouped into one group, and the average value of the jacking thresholds of each support point in the same group is the beam jacking threshold corresponding to this group of support points. For the case where the structural properties of consecutive points on the beam are the same, the stiffness of each support point is the same, so the beam jacking thresholds of each support point are the same, and they are all the average value of the jacking thresholds of each support point. When the structural properties at the corresponding positions of each support point on the beam are different, such as the presence of stiffeners resulting in a relatively large stiffness at the corresponding positions, it is necessary to group each support point to accurately set the beam jacking threshold.

[0028] Furthermore, determining whether the actual jacking amount of each support point meets the requirements specifically includes the following steps:

[0029] S1. Determine whether the jacking threshold of each support point is within the set jacking threshold range. If it is within the set jacking threshold range, then proceed to step S2; otherwise, adjust the jacking amount of the corresponding support point.

[0030] In step S1, the set jacking threshold range is δd s ±3σ, where δd s is the beam jacking threshold corresponding to each support point, and σ is the standard deviation of the jacking thresholds δd ij of each support point in the same group. For each support point, when its jacking threshold δd ij is within the set jacking threshold range, its jacking threshold is considered valid, that is, δd ij satisfies ; otherwise, it is necessary to readjust the jacking amount of this support point.

[0031] S2. Calculate the difference between the jacking amount of each support point and the designed jacking amount. If this difference is not greater than the beam jacking threshold, then the actual jacking amount of the corresponding support point meets the requirements; that is , then the actual jacking amount of the corresponding support point meets the requirements; otherwise, adjust the jacking amount of the corresponding support point. In another technical solution, during the beam jacking process, the reaction force of each support point is controlled to meet the design requirements by the following formula:

[0032] (2)

[0033] In formula (2), F ij , F mnThey are all the reaction forces of any support point on the beam body; δF is the difference in the reaction forces of any two set support points; α is the jacking coefficient. When the subsequent jacking construction is a horizontal push, α = 1; when the subsequent jacking construction is not a horizontal push, 0 < α < 1. During the horizontal push process, the reaction forces of each support point need to be kept equal. If they are not equal, the local stress at some points will be too large, which is likely to cause local damage to the beam body. For the non-horizontal push process with a slope of the beam body, the reaction forces of each support point are controlled to meet the requirements through the jacking coefficient α.

[0034] In another technical solution, at least two rows of support points are arranged at intervals on the bottom of the beam body. Each row of support points includes a plurality of support points arranged at intervals along the longitudinal direction of the beam body. A jacking device is arranged on each support point, and each jacking device jacks up the beam body to the designed jacking amount synchronously and at the same rate. During actual construction, the jacking device can be selected as a hydraulic cylinder, and the flow rate of each hydraulic cylinder is controlled by a hydraulic synchronous control system to make the jacking speed of each support point consistent.

[0035] Although the embodiments of the present invention have been disclosed as above, it is not limited to only the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the illustrated and described examples here.

Claims

1. A beam lifting control method based on stiffness-lifting threshold mapping, characterized in that: include: During the beam lifting process, the support reaction force and lifting amount of each support point at the bottom of the beam are monitored, and the lifting threshold after each support point is lifted to the designed lifting amount and the corresponding beam lifting threshold are determined through the stiffness coefficient and support reaction force of each support point; According to the beam body lifting threshold, it is judged whether the actual lifting amount of each support point meets the requirements, and the lifting amount of the support points that do not meet the requirements is adjusted until the actual lifting amount of each support point meets the requirements; and at the same time, the lifting process and the support reaction force of each support point during the lifting amount adjustment process are controlled to meet the design requirements; The stiffness coefficient of each support point at the bottom of the beam is obtained by establishing a finite element model of the beam; the lifting threshold of each support point is the ratio of the support reaction force of each support point to its stiffness coefficient; The support points with equal stiffness coefficients are grouped together, and the average of the lifting thresholds of the support points in the same group is the beam lifting threshold corresponding to the support points in the group.

2. The beam lifting control method based on stiffness-lifting threshold mapping according to claim 1, characterized in that: Determining whether the actual lifting amount of each support point meets the requirements specifically includes the following steps: S1, judging whether the lifting threshold of each supporting point is within the set lifting threshold range, if it is within the set lifting threshold range, entering step S2, otherwise adjusting the lifting amount of the corresponding supporting point; S2. Calculate the difference between the lifting amount of each support point and the designed lifting amount. If the difference is not greater than the lifting threshold of the beam body, the actual lifting amount of the corresponding support point meets the requirement; otherwise, adjust the lifting amount of the corresponding support point.

3. The beam lifting control method based on stiffness-lifting threshold mapping according to claim 2 is characterized in that: The lifting threshold range is set to δd s ±3σ, where δd s is the beam lifting threshold corresponding to each support point, and σ is the standard deviation of the lifting threshold of each support point in the same group.

4. The beam lifting control method based on stiffness-lifting threshold mapping according to claim 1, characterized in that: During the beam lifting process, the reaction force of each support point is controlled by the following formula to meet the design requirements: In the above formula, F ij 、F mn are the support reaction forces of any supporting point on the beam body; δF is the difference between the support reaction forces of any two supporting points; α is the jacking coefficient. When the subsequent jacking construction is horizontal pushing, α=1; when the subsequent jacking construction is non-horizontal pushing, 0<α<1.

5. The beam lifting control method based on stiffness-lifting threshold mapping according to claim 1, characterized in that: At least two rows of support points are arranged at intervals at the bottom of the beam body, each row of support points includes a plurality of support points arranged at intervals along the longitudinal direction of the beam body, each support point is provided with a jacking device, and each jacking device synchronously jacks the beam body upward to a designed jacking amount.

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