Steel bar system conversion equipment suitable for open-cut cast-in-place arch structure and construction method

Abstract

The invention discloses steel bar system conversion equipment suitable for an open-cut cast-in-place arch structure and a construction method.The equipment comprises a cantilever gantry crane, a servo system arranged on the cantilever gantry crane and a plurality of lifting ropes controlled to stretch out and draw back through the servo system, the cantilever gantry crane is located over a foundation pit, and a walking system is arranged at the bottom of the cantilever gantry crane; the cantilever gantry crane longitudinally moves along a foundation pit, the multiple lifting ropes are arranged in the transverse direction and the longitudinal direction of the cantilever gantry crane and vertically and downwards connected to different positions of a reinforcement cage bound on the reinforcement trolley to form distributed lifting points, the lifting ropes are controlled by the servo system to apply prestress to the reinforcement cage to a preset value, and deformation of the reinforcement cage is controlled. Deformation of the reinforcement cage can be limited, streamlined operation of the open-cut cast-in-place structure is achieved, and the construction efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel engineering and municipal engineering, and more particularly to a steel bar system conversion device and construction method suitable for open-cut cast-in-situ arch structures. Background Art

[0002] Cut-and-cover cast-in-place is a common underground construction method. Its main structural construction primarily involves rebar tying and formwork concrete application, primarily using scaffolding or trolleys. Scaffolding carries a high safety risk. Trolleys come in two types: rebar trolleys and formwork trolleys. Rebar trolleys are used for tying rebar, while formwork trolleys are used for pouring concrete. After tying rebar on the rebar trolley, the rebar trolley must exit the existing rebar cage to allow the formwork trolley to enter. However, if the rebar is not supported after the trolley completes tying, gravity can cause the cage to deform downward, leading to plastic deformation or preventing the formwork trolley from entering the cage. Therefore, trolleys are often used to tie side wall rebar, and formwork trolleys are often used to tie arch rebar. Therefore, a device and construction method are needed that can limit cage deformation after the rebar trolley exits the existing cage, allowing for smooth transfer of the cage from the rebar trolley to the formwork trolley. Summary of the Invention

[0003] One purpose of the present invention is to provide a steel bar system conversion equipment and construction method suitable for open-cut cast-in-place arch structures, which can limit the deformation of the steel cage and solve the problem that after the steel bar trolley completes the tying of steel bars, the steel cage is deformed downward under the action of gravity after the steel bar trolley escapes from the current steel cage, causing plastic deformation of the steel cage or hindering the template trolley from entering the current steel cage.

[0004] In order to solve the above technical problems, the present invention provides a steel bar system conversion equipment suitable for open-cut cast-in-place arch structures, including a cantilever gantry crane, a servo system arranged on the cantilever gantry crane, and multiple lifting ropes controlled by the servo system. The cantilever gantry crane is located directly above the foundation pit and a walking system is arranged at the bottom, which moves longitudinally along the foundation pit. The multiple lifting ropes are arranged along the transverse and longitudinal directions of the cantilever gantry crane and are vertically downwardly connected to different positions of the steel cage tied on the steel bar trolley to form distributed lifting points. The servo system controls the lifting ropes to apply prestress to the steel cage to a preset value to control the deformation of the steel cage.

[0005] Preferably, the steel cage is composed of two layers of arc-shaped steel bars, each of which has standoffs at set positions, and the distributed hanging points are fixed at positions of the standoffs of the inner layer of arc-shaped steel bars.

[0006] Preferably, the distributed hanging points are symmetrically spaced along the central axis of the tunnel within the circumferential section of the tunnel, and a plurality of distributed hanging points within the circumferential section are spaced longitudinally of the tunnel.

[0007] Preferably, the lifting rope is prestressed by a through-hole jack, and the through-hole jack is controlled by a servo system. The lifting rope is also provided with a tension sensor for obtaining the tension of the lifting rope and transmitting it to the servo system.

[0008] The present invention also provides a steel bar system conversion construction method applicable to open-cut cast-in-place arch structures, comprising the following steps: Step 1: Obtain the distributed hanging point setting position, the number of distributed hanging points and the prestress of each hanging rope of the steel cage through calculation and analysis; Step 2: The steel bar trolley is positioned at the set position, and the steel bars are hoisted onto the trolley; Step 3: Tie the steel bars on the steel bar trolley and set the frame bars between the inner and outer layers of the curved steel bars; Step 4: Install the cantilever gantry crane, servo system and lifting rope at the set position on the foundation pit, and arrange the distributed lifting points according to the set lifting point positions and quantity. At the same time, the servo motor prestresses the lifting rope to the set value, and inputs the displacement value at this time into the servo system. When the displacement value changes, the servo system controls the lifting rope to the preset value to control the deformation of the steel cage; Step 5: The steel bar trolley moves out to the current steel bar cage, and the formwork trolley moves into the current steel bar cage, releasing the prestress on the hanging rope, so that the steel bar cage is attached to the formwork platform, completing the steel bar cage system conversion.

[0009] Preferably, in step 1, the calculation and analysis process is specifically as follows: Step S1, modeling the steel cage; Step S2: applying a load to the entire model and adjusting the positions and number of distributed hanging points. A deformation cloud is obtained by calculation, and the positions and number of hanging points are then adjusted to minimize deformation of the steel cage, thereby obtaining an optimal range for the positions and number of distributed hanging points. Step S3: Adjust the tension of the distributed hanging points according to the weight of the steel cage, obtain the deformation cloud map through calculation, and then fine-tune the distribution of the tension of the distributed hanging points to minimize the deformation of the steel cage and obtain the prestress of each hanging rope corresponding to the distributed hanging points.

[0010] Preferably, in step S1, only the circumferential reinforcement and the longitudinal reinforcement are modeled, and the stirrups are not modeled, and the weight of the stirrups is converted into the density of the reinforcement; the density of the reinforcement , where ρ0 is the true density of the steel bars, ρ is the calculated density, m0 is the weight of the entire steel cage, and m is the weight of the steel cage excluding stirrups; the circumferential steel bars, longitudinal steel bars, and frame bars are all modeled using beam elements. The circumferential steel bars and longitudinal steel bars are hinged, the second inner row of double-layer steel bars are hinged to the longitudinal steel bars, and the frame bars are rigidly connected to the inner and outer steel bars; the constraint of the foundation pit side wall on the steel cage is an elastic horizontal support, simulated by a nonlinear spring, and the spring stiffness k is shown in the following formula, , where l0 is the distance between the side of the steel cage and the side wall of the foundation pit; the bottom of the steel cage is fully constrained, and the vertical support is a rigid support.

[0011] Preferably, in step S2, gravity is applied to the entire model, and only the displacement in the direction of gravity is constrained at the hanging points; four hanging points are arranged in cross section, rotated at two different angles along the tunnel centerline, and arranged symmetrically; at the same time, the hanging points are arranged at intervals in the longitudinal direction, and the longitudinal spacing of the hanging points is adjusted according to the calculated deformation cloud map to minimize the deformation of the steel cage.

[0012] Preferably, in step S3, the total tension of the hanging points is set to a certain proportion of the weight of the steel cage; and the prestressing of the two rows of hanging points of the steel cage close to the tunnel centerline is set to a certain proportion of the total tension of the hanging points, and the prestressing of the other two rows of hanging points is set to the remaining proportion of the total tension; the proportional distribution of the hanging point tension is fine-tuned by the calculated deformation cloud map to minimize the deformation of the steel cage.

[0013] Preferably, the deformation of the steel cage is measured by setting multiple cross sections, and multiple deformation measuring points are set in each cross section for measurement. Multiple deformation measuring points are set at circumferential intervals along the cross section, and the deformation amount is obtained by taking the average value of multiple cross sections, and the deformation amount is set within a certain range.

[0014] The present invention has at least the following beneficial effects: (1) Compared with tying the arch top steel bars on the formwork trolley, the present invention uses the steel bar system conversion equipment to separate the steel bar tying process and the concrete pouring process, thereby realizing the streamlined operation of the open-cut cast-in-place structure and improving the construction efficiency.

[0015] (2) Compared with conventional steel bar trolleys, the present invention adopts steel bar system conversion equipment to achieve the simultaneous tying of side wall steel bars and arch top steel bars on the steel bar trolley. A tension sensor is installed on the lifting rope, and a servo system is installed at the tail end of the lifting rope to automatically compare the actual lifting rope tension, steel cage deformation and theoretical deviation. The lifting rope tension is controlled by the servo system to avoid the steel cage from being deformed after leaving the steel bar trolley, thereby ensuring the quality of the project.

[0016] (3) Compared with conventional cast-in-situ structural reinforcement construction, the present invention does not require a crane to cooperate with the lifting operation, avoids the crane occupying the lane change, and optimizes the construction organization.

[0017] Other advantages, objectives and features of the present invention will be reflected in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a flow chart of the construction process of the present invention; Figure 2 This is a structural schematic diagram of the present invention in which the steel bar trolley is moved below the template trolley; Figure 3 This is a schematic diagram of the structure of the steel bar system conversion device of the present invention for hoisting steel bars; Figure 4 This is a schematic diagram of the reinforcement arrangement structure of the present invention; Figure 5 This is a structural schematic diagram of the steel bar trolley of the present invention being released from the steel bar cage; Figure 6 This is a structural diagram of the template trolley of the present invention entering the steel cage and unlocking the distributed hanging points; Figure 7 This is a diagram showing the arrangement of deformation measurement points and support points of the present invention. DETAILED DESCRIPTION

[0019] In order to better understand the purpose, structure and function of the present invention, the present invention is further described in detail below with reference to the accompanying drawings so that those skilled in the art can implement it according to the description.

[0020] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified; in the description of the present invention, the terms "horizontal", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying 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.

[0021] like Figure 2 、 Figure 3 and Figure 5As shown, the present invention provides a steel bar system conversion equipment suitable for open-cut cast-in-situ arch structures, including a cantilever gantry crane 1, a servo system 2 arranged on the cantilever gantry crane, and multiple lifting ropes 3 controlled by the servo system for extension and retraction. The cantilever gantry crane is located directly above a foundation pit and a walking system is arranged at the bottom, which moves longitudinally along the foundation pit. The multiple lifting ropes are arranged along the transverse and longitudinal directions of the cantilever gantry crane and vertically downwardly connected to different positions of the steel cage tied on the steel bar trolley 4 to form distributed lifting points 7. The lifting ropes are controlled by the servo system to apply prestress to the steel cage to a preset value, thereby controlling the deformation of the steel cage.

[0022] The steel cage is composed of two layers of arc-shaped steel bars 5, with upright bars 6 provided at set positions. The distributed hanging points are fixed at the positions of the upright bars of the inner layer of arc-shaped steel bars.

[0023] The distributed hanging points are symmetrically arranged along the central axis of the tunnel in the circumferential section of the tunnel, and a plurality of distributed hanging points in the circumferential section are arranged at intervals in the longitudinal direction of the tunnel.

[0024] The lifting rope is prestressed by a through-hole jack, and the through-hole jack is controlled by a servo system. A tension sensor is also provided on the lifting rope for obtaining the tension of the lifting rope and transmitting it to the servo system.

[0025] The steel bar system conversion device of the present application can be moved above the foundation pit, and the device is provided with a cantilever gantry crane and distributed lifting points. When the steel cage is tied on the steel bar trolley, the steel bar system conversion device is arranged directly above the steel cage through a walking system, and the cantilever gantry crane of the steel bar system conversion device lifts the steel bars from the outside of the foundation pit to the steel bar trolley. When the steel bar trolley is tying the steel bars, the upper and lower layers of arc-shaped steel bars are provided with stand bars at designated positions. After the steel cage is tied, the distributed lifting points are fixed to the positions of the stand bars of the inner layer of arc-shaped steel bars. The distributed lifting points include a servo system for automatically controlling the lifting ropes, and the prestress of the distributed lifting points is determined by modeling calculations. After the force of the distributed lifting points is added to the specified prestress, the steel bar trolley moves out of the current steel cage, and the deformation of the steel cage is precisely controlled by the servo system. The template trolley 8 moves to the bottom of the current steel cage to support the steel cage, releases the distributed lifting points, and completes the conversion of the steel cage from the steel bar trolley to the template trolley. Compared with conventional construction, the present invention uses a steel bar system conversion device and a construction method thereof to avoid deformation caused by steel bars tied on a template trolley or steel cage being separated from the steel bar trolley and affecting subsequent construction.

[0026] The present invention uses a steel bar system conversion device to complete the conversion of the steel bar skeleton from the steel bar trolley to the template trolley. The present invention also provides a steel bar system conversion construction method suitable for open-cut cast-in-place arch structures, such as Figure 1 As shown, the following steps are included: (1) The position of the distributed hanging points of the steel cage, the number of distributed hanging points and the prestress of each hanging rope are obtained through calculation and analysis.

[0027] Step S1, modeling the steel cage; During modeling and calculation, only the circumferential and longitudinal reinforcements are modeled, and the stirrups are not modeled. The weight of the stirrups (tension bars) is converted into the density of the reinforcement. The density of the reinforcement , where ρ0 is the true density of the steel bars, ρ is the calculated density, m0 is the weight of the entire steel cage, and m is the weight of the steel cage excluding stirrups; the circumferential steel bars, longitudinal steel bars, and frame bars are all modeled using beam elements. The circumferential steel bars and longitudinal steel bars are hinged, the second inner row of double-layer steel bars are hinged to the longitudinal steel bars, and the frame bars are rigidly connected to the inner and outer steel bars; the constraint of the foundation pit side wall on the steel cage is an elastic horizontal support, simulated by a nonlinear spring, and the spring stiffness k is shown in the following formula, , where l0 is the distance between the side of the steel cage and the side wall of the foundation pit; the bottom of the steel cage is fully constrained, and the vertical support is a rigid support.

[0028] When calculating, the binding between steel bars is considered as hinged connection, and the welding between steel bars is considered as rigid connection.

[0029] Step S2: applying a load to the entire model and adjusting the positions and number of distributed hanging points. A deformation cloud is obtained by calculation, and the positions and number of hanging points are then adjusted to minimize deformation of the steel cage, thereby obtaining an optimal range for the positions and number of distributed hanging points. Gravity is applied to the entire model, and only displacement in the direction of gravity is constrained at the lifting points. Four lifting points are arranged in a cross-section, rotated along the tunnel centerline at two different angles, such as 15° and 45°, and arranged symmetrically. The lifting points are also spaced longitudinally, for example, at intervals of 2 to 3 meters. If the longitudinal length of the rebar cage is not an integer multiple of 3 meters, it is rounded up. The calculated deformation contour is used to adjust the longitudinal spacing of the lifting points to minimize cage deformation.

[0030] Step S3: Adjust the tension of the distributed hanging points according to the weight of the steel cage, obtain the deformation cloud map through calculation, and then fine-tune the distribution of the tension of the distributed hanging points to minimize the deformation of the steel cage and obtain the prestress of each hanging rope corresponding to the distributed hanging points.

[0031] The total tension of the hanging points is set to a certain proportion of the weight of the steel cage, such as 60%. The prestressing of the two rows of hanging points near the tunnel centerline is set to a certain proportion of the total tension of the hanging points, such as 70%. The prestressing of the other two rows of hanging points is set to the remaining proportion of the total tension, such as 30%. The proportional distribution of the hanging point tension is fine-tuned using the calculated deformation cloud map to minimize the deformation of the steel cage.

[0032] The deformation of the steel cage is measured by setting multiple cross sections, and multiple deformation measuring points are set in each cross section for measurement. Multiple deformation measuring points are set at circumferential intervals along the cross section. The deformation amount is obtained by taking the average value of multiple cross sections, and the deformation amount is set within a certain range.

[0033] like Figure 7 As shown, measurement points are placed at locations with significant displacement and at key connections. Three sections (edge, center, and edge) are selected. Targets are placed on the inner ring reinforcement and adjacent longitudinal reinforcement. Eleven deformation measurement points are arranged symmetrically throughout each cross section. A total station is used to measure coordinate data for each working condition and compare deformation. When measuring deformation, three cross sections are measured, and the average of these three sections is used. This can also be used to measure displacement changes in step four.

[0034] (2) If Figure 2 and Figure 3 As shown, the steel bar trolley moves to the current construction section, the steel bar system conversion device is controlled to move longitudinally, the steel bars are stored longitudinally from the transport vehicle to the edge of the foundation pit, and the cantilever gantry crane in the steel bar system conversion device is used to hoist the steel bars from outside the foundation pit to the steel bar trolley in an orderly manner.

[0035] (3) If Figure 4 As shown, the rebar is tied to the rebar trolley, and support bars are installed between the inner and outer layers of the curved rebar. To minimize deformation during hoisting of the rebar cage, five lines of support bars are arranged circumferentially at angles of 15° and 30°, with longitudinal spacing of 1.2m to 2m.

[0036] (4) If Figure 5 As shown, after the reinforcement is tied, the cantilever gantry crane, servo system and lifting rope are installed at the set position on the foundation pit, and the distributed lifting points are arranged according to the set lifting point positions and numbers, and the ends of the distributed lifting points are fixed at the positions of the lower layer of arc-shaped reinforcement stand bars, that is, the lifting ropes are fixed at the positions of the longitudinal reinforcement at the bottom of the stand bars.

[0037] (5) The distributed lifting points are pre-tensioned and controlled to the calculated value through the through-hole jacks, and the deformation value of the steel cage at the lifting point is input into the displacement servo system. When the displacement value changes, the servo system controls the lifting rope to the preset value to control the deformation of the steel cage.

[0038] (6) The steel bar trolley escapes from the steel bar cage, and the deformation of the steel bar cage is controlled by the displacement servo system.

[0039] (7) If Figure 6 As shown, the steel bar trolley is moved out to the current steel bar cage, the formwork trolley is moved to the bottom of the current steel bar cage and supports the steel bar cage, the distributed hanging points are loosened, and the pre-tension on the hanging rope is released, so that the steel bar cage is attached to the formwork platform, completing the steel bar cage system conversion.

[0040] It will be understood that the present invention is described by way of some embodiments, and those skilled in the art will appreciate that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and embodiments. They can be fully applied to various fields suitable for the present invention, and further modifications can be easily implemented by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. Suitable for steel bar system conversion equipment of open-cut cast-in-place arch structures, characterized by: It includes a cantilever gantry crane, a servo system arranged on the cantilever gantry crane, and multiple lifting ropes that are extended and retracted by the servo system. The cantilever gantry crane is located directly above the foundation pit and a walking system is arranged at the bottom. It moves longitudinally along the foundation pit. The multiple lifting ropes are arranged along the transverse and longitudinal directions of the cantilever gantry crane and are vertically downwardly connected to different positions of the steel cage tied on the steel trolley to form distributed lifting points. The lifting ropes are controlled by the servo system to apply prestress to the steel cage to a preset value, thereby controlling the deformation of the steel cage.

2. The steel bar system conversion equipment suitable for open-cut cast-in-place arch structures according to claim 1, characterized in that: The steel cage comprises two layers of arc-shaped steel bars, with stand bars arranged at set positions, and distributed hanging points fixed at the positions of the stand bars of the inner layer of arc-shaped steel bars.

3. The steel bar system conversion equipment suitable for open-cut cast-in-place arch structures according to claim 1, characterized in that: The distributed hanging points are symmetrically arranged along the central axis of the tunnel in the circumferential section of the tunnel, and a plurality of distributed hanging points in the circumferential section are arranged at intervals in the longitudinal direction of the tunnel.

4. The steel bar system conversion equipment suitable for open-cut cast-in-place arch structures according to claim 3, characterized in that: The lifting rope is prestressed by a through-hole jack, and the through-hole jack is controlled by a servo system. A tension sensor is also provided on the lifting rope for obtaining the tension of the lifting rope and transmitting it to the servo system.

5. A steel bar system conversion construction method suitable for open-cut cast-in-place arch structures, characterized in that: The steps include: Step 1: Obtain the distributed hanging point setting position, the number of distributed hanging points and the prestress of each hanging rope of the steel cage through calculation and analysis; Step 2: The steel bar trolley is positioned at the set position, and the steel bars are hoisted onto the trolley; Step 3: Tie the steel bars on the steel bar trolley and set the frame bars between the inner and outer layers of the curved steel bars; Step 4: Install the cantilever gantry crane, servo system and lifting rope at the set position on the foundation pit, and arrange the distributed lifting points according to the set lifting point positions and quantity. At the same time, the servo motor prestresses the lifting rope to the set value, and inputs the displacement value at this time into the servo system. When the displacement value changes, the servo system controls the lifting rope to the preset value to control the deformation of the steel cage; Step 5: The steel bar trolley moves out to the current steel bar cage, and the formwork trolley moves into the current steel bar cage, releasing the prestress on the hanging rope, so that the steel bar cage is attached to the formwork platform, completing the steel bar cage system conversion.

6. The steel bar system conversion construction method applicable to open-cut cast-in-situ arch structures according to claim 5, characterized in that: In step 1, the calculation and analysis process is specifically as follows: Step S1, modeling the steel cage; Step S2: applying a load to the entire model and adjusting the positions and number of distributed hanging points. A deformation cloud is obtained by calculation, and the positions and number of hanging points are then adjusted to minimize deformation of the steel cage, thereby obtaining an optimal range for the positions and number of distributed hanging points. Step S3: Adjust the tension of the distributed hanging points according to the weight of the steel cage, obtain the deformation cloud map through calculation, and then fine-tune the distribution of the tension of the distributed hanging points to minimize the deformation of the steel cage and obtain the prestress of each hanging rope corresponding to the distributed hanging points.

7. The steel bar system conversion construction method applicable to open-cut cast-in-place arch structures according to claim 6, characterized in that: In step S1, only the circumferential and longitudinal reinforcements are modeled, and the stirrups are not modeled. The weight of the stirrups is converted into the density of the reinforcement. The density of the reinforcement , where ρ0 is the true density of the steel bar, ρ is the calculated density, m o is the weight of the entire steel cage, and m is the weight of the steel cage excluding stirrups. The circumferential steel bars, longitudinal steel bars, and frame bars are all modeled using beam elements. The circumferential steel bars are hinged to the longitudinal steel bars, the second inner double-layer steel bars are hinged to the longitudinal steel bars, and the frame bars are rigidly connected to the inner and outer steel bars. The side walls of the foundation pit constrain the steel cage with elastic horizontal supports, simulated by nonlinear springs. The spring stiffness k is shown in the following formula: , where l0 is the distance between the side of the steel cage and the side wall of the foundation pit; the bottom of the steel cage is fully constrained, and the vertical support is a rigid support.

8. The steel bar system conversion construction method applicable to open-cut cast-in-situ arch structures according to claim 6, characterized in that: In step S2, gravity is applied to the entire model, and only the displacement in the direction of gravity is constrained at the hanging points; four hanging points are arranged in a cross-section, rotated at two different angles along the tunnel centerline, and arranged symmetrically; at the same time, the hanging points are arranged at intervals along the longitudinal direction, and the longitudinal spacing of the hanging points is adjusted according to the calculated deformation cloud map to minimize the deformation of the steel cage.

9. The steel bar system conversion construction method applicable to open-cut cast-in-situ arch structures according to claim 6, characterized in that: In step S3, the total tension of the hanging points is set to a certain proportion of the weight of the steel cage; and the prestressing of the two rows of hanging points of the steel cage near the tunnel centerline is set to a certain proportion of the total tension of the hanging points, and the prestressing of the other two rows of hanging points is set to the remaining proportion of the total tension; the proportional distribution of the hanging point tension is fine-tuned by the calculated deformation cloud map to minimize the deformation of the steel cage.

10. The steel bar system conversion construction method applicable to open-cut cast-in-situ arch structures according to claim 6, characterized in that: The deformation of the steel cage is measured by setting multiple cross sections, and multiple deformation measuring points are set in each cross section for measurement. Multiple deformation measuring points are set at circumferential intervals along the cross section. The deformation amount is obtained by taking the average value of multiple cross sections, and the deformation amount is set within a certain range.

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