Prestressed beam body cutting construction technology based on BIM

Abstract

The invention discloses a BIM (Building Information Modeling)-based prestressed beam body cutting construction process which comprises the following process steps: firstly, collecting a bridge completion drawing and prestressed system data, establishing a BIM model and marking the position of a steel beam; then through model analysis, small beam sections are divided, a cutting surface is planned, and a safety distance is quantified; then, non-core components such as side wings and panels are pre-disassembled, and a supporting system, a rail type rope saw cutting machine and an infrared camera are deployed; setting a large-aperture cutting operation hole and precise water cooling parameters during equipment debugging; and finally, the cutting machine is remotely controlled, infrared images and the BIM model are superposed, steel bars and steel bundles are recognized through material heat conduction differences, and risks are intervened and avoided in real time. And when the end part of the beam body is cut, a plurality of cutting machines are synchronously arranged for cooperative operation, so that balanced stress of the beam body is guaranteed. According to the technology, cutting digitization, visualization and unmanned operation are achieved, construction safety and efficiency are improved, and a reliable technical scheme is provided for prestressed beam body dismantling.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bridge structure demolition construction methods, and particularly relates to a prestressed beam cutting construction process based on BIM. BACKGROUND

[0002] Traditional bridge demolition methods include blasting demolition and mechanical hoisting, the former of which greatly disturbs the surrounding environment, and the latter of which is difficult to precisely control the stress of large components, and neither of which is suitable for complex prestressed beam bodies. In recent years, prestressed beam bodies are increasingly used in bridge systems, and how to safely and effectively demolish the prestressed beam bodies in the bridge to be demolished is an extremely important concern in bridge demolition engineering.

[0003] Traditional prestressed beam body demolition processes need to first adopt special equipment to prestress the prestressed steel strands at the structural anchoring end of the bridge prestressed steel strands for the full-length prestressed beam body, so as to prestress the prestressed steel strands and change the prestressed beam body into an ordinary reinforced concrete beam body, and then perform subsequent breaking, decomposition and removal. For the beam body with short prestressed steel strands, the two ends of the prestressed steel strands are anchored inside the two ends of a single beam segment or inside the same joint bridge, and if the prestressed steel strands of each beam segment are prestressed, the process is complex, the cost is high, and local damage to the beam body will also be caused, which is difficult to implement. For this situation, the existing process adopts a method of cutting the whole bridge into multiple small beam bodies with complete internal prestress to demolish the bridge, specifically: first, confirm and mark the position of the prestressed steel strands of the beam body in combination with the drawings, set up a support system for the support system of the beam body by avoiding cutting the position of the steel strands, and transfer the gravity and prestress system of the beam body to the temporary support or jacking system, and then cut the beam body into small beam bodies; finally, the complete small beam bodies are transported away from the site by transportation equipment, and the subsequent breaking, decomposition and removal of the beam body are performed.

[0004] The traditional cutting scheme has multiple technical bottlenecks: first, the positioning of the prestressed steel strand and the cutting process mainly rely on drawings and manual experience, lack of digital visualization support, and are difficult to cope with the problem of steel strand position deviation caused by construction deviation; second, the temporary support system is mostly a fixed structure, which cannot dynamically adjust the support intensity according to the load of the beam body, and is prone to risks such as beam body sinking and deviation during the cutting process; third, the cutting process lacks real-time monitoring means and cannot timely identify the steel strand approach signal, and relies on close-range operation of personnel, with prominent safety hazards. Once the position of the prestressed force in the beam body is evaluated incorrectly, or the cutting process fails to effectively monitor the cutting surface, it is easy to cut into the prestressed steel strand. At this time, the energy stored in the prestressed system will be released instantaneously, which may cause the whole concrete beam body to be damaged, increase the construction difficulty, or even cause serious construction safety hazards, or even bring fatal danger to the on-site personnel. In addition, the traditional process has low cutting efficiency and cannot realize multi-device collaborative operation, and synchronous cutting of non-core components and the main body may cause process interference, further prolonging the construction period. Therefore, if the position of the prestressed steel strand in the prestressed beam body can be more intuitively and accurately located as a cutting surface guide, a dynamically stable support system can be constructed, and the cutting process can be effectively monitored to realize remote and unmanned prestressed beam body cutting, the risks brought by the cutting of the prestressed beam body can be effectively prevented and avoided, and the safety and efficiency of the prestressed beam body dismantling construction process can be further ensured. SUMMARY

[0005] The purpose of the present application is to solve the problems existing in the prior art and provide a prestressed beam cutting construction process based on BIM.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme: a prestressed beam cutting construction process based on BIM, comprising the following steps: Step S1: data collection and BIM modeling: obtaining the engineering drawings of the structure where the prestressed beam to be dismantled is located, extracting the prestressed system data, constructing the BIM model of the structure and marking the position of the prestressed steel strand in the beam body; Step S2: model analysis and cutting surface planning: analyzing the distribution law of the prestressed steel strand based on the BIM model, combining the integrity of the prestressed system to divide the beam cutting unit, and planning the cutting area between the units; Step S3: construction preparation and pretreatment: arranging hoisting equipment and rope saw cutting machines, cutting and dismantling the non-load-bearing accessory structure of the beam body and transferring it to the outside of the field by the hoisting equipment; Step S4: Support system, automation operation and monitoring device deployment: temporary support device is arranged under the cutting area, track is arranged on the surface of the beam body, and a rope saw cutting machine with a remote control module is arranged, and an infrared camera for collecting images of the cutting surface in real time is arranged; Step S5: Device debugging and water cooling parameter setting: a cutting operation hole is arranged in the cutting area, and a cutting part is arranged, a water cooling system is arranged to align the cutting area, the water flow speed is adjusted to ensure the function of the infrared camera, and the device is started to check the operation state; Step S6: Remote cutting and real-time monitoring: after the construction personnel leave, the cutting unit of the beam body divided in step S2 is started to cut through the remote control module; the image data collected by the infrared camera is fused with the BIM model to dynamically monitor the cutting process, if the reinforcement is detected, the alarm is triggered, and the cutting parameters or path are adjusted combined with the alarm and monitoring results; Step S7: Cutting unit finishing and device transition: after the cutting is completed, the device is stopped through the remote control module, the cutting part is removed by the operation personnel, and the device is transferred to the area corresponding to the next cutting unit; the beam unit is separated through the temporary support device and is transferred to the specified area.

[0007] Preferably, the bridge where the prestressed beam body is located comprises a beam body and a column pier, the beam body comprises a side wing, a panel, a bottom plate and a web containing prestressed steel strands; the prestressed system data in step S1 comprises the size of the beam body, the size of the column pier, the beam body reinforcement distribution, the position of the prestressed steel strands and the concrete grade, and the position of the prestressed steel strands in the beam body is highlighted and marked when the BIM modeling is performed.

[0008] Preferably, the beam body cutting unit is divided in combination with the integrity of the prestressed system in step S2, specifically, the beam body is divided into several small beam segments according to the principle that each prestressed steel strand is an independent and complete prestressed system; the cutting area planning needs to avoid the prestressed steel strand anchoring area and the bent-up section, and meet the safety distance requirement from the prestressed anchoring end; based on the planned cutting surface, the rope saw cutting process can be simulated through the BIM model, the stereoscopic view and the sectional view of the cutting surface are intercepted, and a file containing the cutting position number is generated.

[0009] Preferably, the safety distance is specifically: for the bonded prestressed steel strand, the safety distance is not less than 30 cm; for the unbonded prestressed steel strand, the safety distance is greater than the maximum possible retraction length Ls of the steel strand at the fracture point, wherein Ls=(Δσ×L) / E, Δσ is the effective stress of the steel strand, unit: MPa, L is the length from the anchoring end to the cutting point, unit: m, and E is the elastic modulus of the steel strand, unit: MPa.

[0010] Preferably, the non-load-bearing appendage structure of the beam body in step S3 includes side wings, and the side wings are cut respectively along the parallel bridge span direction and the vertical bridge span direction when cutting and removing, and the cutting operation holes are drilled at the connection positions of the side wings and the main body of the beam body when cutting, and the rope saw cutting machine is erected to cut the side wings into small pieces that meet the load of the hoisting equipment and then hoisted away; step S3 also includes a pre-cutting step for the beam body panel and the bottom plate, specifically, cutting operation holes are drilled at both ends of the cutting range of the panel and the bottom plate, the rope saw cutting machine is erected and cut along the vertical bridge span direction, so that the panel and the bottom plate are first separated from the column pier, and the pre-cutting does not affect the normal work of the internal prestress system of the beam body web.

[0011] Preferably, the number of tracks in step S4 corresponds to the number of beam body webs, the tracks are laid at positions perpendicular to the cutting area and aligned with the midpoint of the cutting area on the bridge deck, and each track is disconnected and spliced at the cutting position of the beam body; the remote control module can realize the functions of track movement, start-stop control, feed speed adjustment and position locking of the rope saw cutting machine; the infrared camera is installed at the bottom of the beam body non-cutting surface part, the lens is arranged towards the cutting surface, can collect cutting surface temperature data in real time and transmit to the operation room, can capture temperature changes exceeding 1℃, and simultaneously performs linear calculation on the temperature data change process.

[0012] Preferably, the temporary support device in step S4 includes a module vehicle carrying a jacking system and a temporary support bracket erected at the column pier position, after the module vehicle drives into the cutting area below, the jacking system lifts and aligns with the support part of the beam body, for the unloading and removal of the beam body after cutting.

[0013] Preferably, in the equipment debugging stage (step S5), the cutting operation hole adopts a large aperture structure to meet the flexible adjustment requirements of the position of the rope saw during subsequent cutting surface adjustment, the water flow rate of the water cooling system is quantitatively determined based on the heat balance principle, a reasonable value range is set in combination with the working power and energy conversion characteristics of the rope saw cutting machine, to ensure that the water flow rate matches the cutting heat load, and at the same time, the water cooling system aims to ensure the recording effect of the infrared monitoring equipment and avoid overheating failure of the cutting equipment, and controls the temperature of the cutting surface after cooling within a preset interval.

[0014] Preferably, in step S6, the cutting state recognition is realized by fusing the image data collected by the infrared camera with the BIM model, specifically, the cross section of the BIM model with a matching angle is superimposed with the infrared image, the differences in thermal conductivity characteristics of concrete and steel strands are utilized, and the temperature field distribution and characteristic stripe conditions of the superimposed image are combined to distinguish ordinary reinforcement and prestressed steel strands; when the prestressed steel strand signal is recognized, the corresponding avoidance adjustment operation is performed, and when cutting the end part of the same beam body, multiple rope saw cutting machines equipped with independent control and monitoring units can be simultaneously arranged, and through collaborative work, the synchronous cutting of each web of the beam body is ensured to avoid uneven local stress.

[0015] The application has the following beneficial effects: 1. By integrating beam size, reinforcement distribution, concrete grade and other multi-dimensional data through BIM technology, a visual model is established and the steel beam is highlighted and marked, which not only intuitively displays the internal structure of the beam and the position of the steel beam, but also simulates the cutting process and intercepts the cutting surface view in the model to form a precise operation guidance document. Compared with the traditional positioning method of combining drawings with experience, the digital characteristics of the model can realize virtual deduction before construction, reduce rework caused by data deviation, and reduce the technical threshold of construction personnel, thereby significantly improving the positioning efficiency of safe cutting position.

[0016] 2. The track guides the precision operation of the rope saw cutting machine on site, cooperates with the infrared camera to build a real-time monitoring link, uses the thermal conductivity difference between concrete and steel beam to identify the structural change of the cutting surface, superimposes and compares the temperature field image and the BIM model, realizes the remote prediction and intervention of the cutting process. This combination mode of track precision guidance, infrared real-time monitoring and remote control completely realizes unmanned operation of the cutting site; at the same time, a closed-loop mechanism of abnormal identification, shutdown adjustment and rework is formed, which greatly reduces the risk of steel beam mis-cutting.

[0017] 3. The water flow velocity of the water cooling system is quantitatively calculated through the heat balance equation to ensure that the temperature of the cutting surface after cooling meets the recording requirements of the infrared camera, and to avoid the failure of the rope saw due to overheating, thereby realizing the organic unity of cooling effect, equipment protection and monitoring accuracy, and meeting the dual requirements of green construction and efficient operation. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a BIM-based prestressed beam cutting construction process schematic diagram; Figure 2 It is a BIM-based prestressed beam cutting construction process construction site layout diagram; Figure 3 It is a BIM-based prestressed beam cutting construction process side wing cutting operation schematic diagram; Figure 4 It is a BIM-based prestressed beam cutting construction process panel and bottom plate cutting operation schematic diagram; Figure 5 It is a BIM-based prestressed beam cutting construction process web cutting operation schematic diagram; In the drawings: 1, beam; 11, side wing; 12, panel; 13, bottom plate; 14, web; 15, prestressed steel beam; 2, column pier; 3, small crane; 4, cutting operation hole; 5, rope saw cutting machine; 6, support; 7, track; 8, infrared camera; DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.

[0020] With reference to Figures 1-5 The specific embodiment of the present application is a method for integrally disassembling and transporting a bridge beam by using a module vehicle in combination with a jacking system. The bridge includes a beam 1 and a column pier 2. The beam 1 includes a side wing 11, a face plate 12, a bottom plate 13, and a web plate 14 containing prestressed steel strands 15. The specific implementation steps of the present application are as follows: Step S1: Data collection and BIM modeling: Collect the as-built drawings of the pre-demolished bridge on site, establish the BIM model of each span of the bridge according to the relevant data of the prestressed system in the as-built drawings, and highlight the color and label the position of the prestressed steel strands 15 in the beam 1. By integrating multi-dimensional engineering data to construct a digital model, the scattered technical parameters are converted into an intuitive visual carrier. This process can accurately locate the steel strand position which is difficult to identify in traditional construction, not only completely solves the industry pain point of “invisible” prestressed steel strands 15, but also provides a unified digital reference for subsequent construction, effectively reduces the rework caused by data deviation, and significantly improves the planning efficiency and accuracy in the early stage of construction.

[0021] In step S1, the relevant data includes the size of the beam 1, the size of the column pier 2, the reinforcement distribution of the beam 1, the position of the prestressed steel strands 15, the concrete grade, etc. The completeness of these data directly determines the accuracy of the BIM model. Complete data support enables the model to truly restore the structural characteristics of the bridge, providing a reliable basis for subsequent cutting surface planning, equipment selection, etc., avoiding construction risks caused by data loss, and ensuring the scientificity and safety of the process implementation.

[0022] Step S2: Model analysis and cutting surface planning: According to the BIM model made in step S1, view and analyze the distribution of the prestressed steel strands 15 in the beam 1, divide the beam 1 into several small beam segments according to each prestressed steel strand 15 as a single complete prestressed system, and select cutting surfaces between the small beam segments. Dividing units based on the integrity of the prestressed system can maximize the stability of the steel strand stress, and on this basis, the cutting surface can be selected to avoid the anchoring area and the bent section, which can effectively prevent the structure from being damaged due to stress mutation of the steel strand during cutting, and ensure the stability of the bridge main body during construction. The cutting surfaces can be numbered, and the cutting surfaces should avoid the prestressed steel strand 15 anchoring area and the bent section.

[0023] For the case where the concrete segment size is large and there is no prestressed steel strand 15 between the beam segments, the selected cutting surface can further consider a safety distance from the prestressed anchoring end. The safety boundary of the unbounded steel strand is calculated by the quantitative formula Ls = (Δσ x L) / E, and combined with the fixed standard of the bonded steel strand, a differentiated safety control system is formed. This precise quantitative method breaks the experience dependence of traditional construction, making the safety distance setting more scientific and greatly reducing the risk of steel strand rupture, structure cracking, etc. For the bonded prestressed steel strand 15, the safety distance is not less than 30 cm; for the unbonded prestressed steel strand 15, the safety distance is greater than the maximum possible retraction length Ls of the steel strand at the rupture point, where Ls = (Δσ x L) / E, Δσ is the effective stress of the steel strand, unit: MPa, L is the length from the anchoring end to the cutting point, unit: m, E is the elastic modulus of the steel strand, unit: MPa.

[0024] Based on the selected cutting surface, the wire saw cutting process is simulated, and the perspective view and sectional view of the cutting surface are directly cut from the BIM model, and a file containing the cutting position number is generated. Using the visualization function of the model, the construction process is deduced in advance, the abstract cutting scheme is converted into a concrete technical file, which is convenient for site personnel to accurately perform the work, reduces human understanding deviation, at the same time provides a clear carrier for construction briefing, improves the efficiency of process connection.

[0025] Through the image display of the BIM model, the internal structure of the beam body 1 and the position of the prestressed steel strand 15 and the anchoring position can be more intuitively displayed, so as to better locate the safe cutting position and solve the problem of "invisible" steel strand in the prestressed beam body 1. This visualization presentation reduces the technical threshold of construction personnel, enabling site workers to quickly master the key construction points and reduce safety accidents caused by incorrect position judgment, providing double protection for construction safety.

[0026] Step S3: construction preparation and pretreatment: set up hoisting equipment (small crane 3 in this embodiment) on the bridge, and erect the wire saw cutting machine 5, cut the side wings 11 along the parallel bridge span direction and the vertical bridge span direction respectively, and remove the side wings 11 from the site by the hoisting equipment. For the non-load-bearing side wing 11 structure, adopt the way of block cutting and accurate hoisting to ensure the efficiency of removal and control the construction load, avoid impact on the main structure of the beam body 1, and the block processing makes hoisting more convenient and reduces the operation difficulty of large equipment. In specific operation, the hoisting equipment hook hangs the side wing 11 structure through the traction rope, drills a cutting operation hole 4 at the connection position of the side wing 11 and the main body of the beam body 1, erects the wire saw cutting machine 5 and puts the wire saw into the cutting operation hole 4, and cuts the side wing 11 into small pieces that meet the load of the hoisting equipment, and then completes the hoisting and removal.

[0027] The side wing 11 does not contain a prestressed system, is an additional part of the beam body 1, and has municipal guardrails and other accessories installed thereon. Removing this part helps to reduce the weight of the beam body 1, reduces the main load by stripping non-core components, improves the stability of the subsequent cutting and hoisting process, optimizes the construction site space, creates favorable conditions for the core process, and ensures the balance of the center of gravity of the main part of the web plate 14.

[0028] Further, in step S3, for the structure in which the prestressed steel strand 15 only exists in the web plate 14, the face plate 12 and the bottom plate 13 of the beam body 1 can also be pre-cut: cutting operation holes 4 are drilled at both ends of the cutting range of the face plate 12 and the bottom plate 13, a rope saw cutting machine 5 is erected and cut along the vertical bridge direction, so that the face plate 12 and the bottom plate 13 are first separated from the column pier 2. For the face plate 12 and the bottom plate 13 that are less related to the core stress, the separation is completed under the premise of not touching the prestressed system, which can not only avoid hindering the subsequent web plate 14 cutting, but also disperse the construction task, shorten the overall construction period, and at the same time guarantee the rationality of the structure stress in the construction process. This pre-cutting does not affect the normal work of the prestressed system inside the web plate 14, and can reduce the intervention of the prestressed system on the subsequent web plate 14 formal cutting process.

[0029] Step S4: Support system, automated operation and monitoring equipment deployment: drive the module vehicle equipped with the jacking system under the cutting surface position described in step S2, lift and align the support part of the beam body 1 through the jacking system, and at the same time, erect the bracket 6 of the temporary support at the position of the column pier 2 to form a temporary support system. The double support mode of “module vehicle + bracket” can dynamically adjust the support strength according to the load of the beam body 1, guide the cutting machine to run more accurately with the number of tracks 7 matched with the number of web plates 14, not only can effectively disperse the weight of the beam body 1 to prevent sinking or deviation in the cutting process, but also can improve the operation accuracy of the cutting machine, ensure the flatness of the cutting surface, and lay a foundation for subsequent splicing or processing. The tracks 7 are erected on the upper surface of the beam body 1 along the parallel bridge direction, the number of tracks 7 corresponds to the number of web plates 14, each track 7 is laid at a position perpendicular to the cutting surface and is disconnected and spliced at the cutting position of the beam body 1; the rope saw cutting machine 5 is slidably installed on the track 7, and a remote control module is configured, which can realize the functions of track 7 movement, start-stop control, feed speed adjustment and position locking of the rope saw cutting machine 5. A plurality of infrared cameras 8 are fixedly installed at the bottom of the beam body 1, the lenses are arranged to face the cutting surface, and are used to real-time record the cutting surface image and transmit it to the operation room, so as to build a real-time monitoring link through remote equipment, so that the operator can be away from the high-risk operation area, which not only ensures the safety of personnel, but also can timely find cutting abnormalities and intervene, and improves the controllability of construction.

[0030] In this embodiment, the infrared camera 8 is selected to capture temperature changes of more than 1℃, and the wire saw is made of diamond material to ensure cutting efficiency and monitoring accuracy. Through the track 7, remote control module and infrared camera 8 in step S4, remote control and real-time monitoring of the wire saw cutting process can be realized. This “mechanized operation + remote control” mode breaks the spatial limitations of traditional construction, greatly reduces the safety risks of on-site operators, improves construction efficiency and accuracy, and provides technical support for standardized construction.

[0031] Step S5: Equipment debugging and water cooling parameter setting: Drill cutting operation holes 4 with a diameter greater than 10 cm at both ends of the cutting surface selected in step S2 on the beam body 1 to facilitate subsequent flexible adjustment of the wire saw position during cutting surface adjustment; put the wire saw into the cutting operation hole 4, and set up a cooling water pipe on the beam body 1 and align it with the cutting surface to form a water cooling system. The reserved large-diameter cutting operation hole provides redundant space for construction adjustment, and the water cooling system designed based on the heat balance equation can accurately control the cutting temperature and equipment state, not only reducing the construction risks caused by positioning deviation, but also avoiding damage to the wire saw due to overheating, prolonging the service life of the equipment, and ensuring that the monitoring effect of the infrared camera 8 is not affected by temperature interference.

[0032] The water flow rate of the water cooling system is determined by the heat balance equation, which satisfies Qw=Qr / (ΔTw×Cp×ρ), where Qr is the cutting heat load, unit: kW, ΔTw is the temperature difference between the inlet and outlet of the cooling water, unit: ℃, Cp is the specific heat capacity of water, unit: kJ / (kg·℃), ρ is the density of water, unit: kg / m³, Qr=W×thermal conversion efficiency (W is the motor power of the wire saw cutting machine 5, and the thermal conversion efficiency is 80%). Combined with industry experience, the cooling water flow rate needs to be more than 25L / min, so the actual water flow rate is between 25L / min and the calculated value Qw. The construction scene temperature in this embodiment is about 30℃, the non-cutting surface concrete temperature is maintained at 30-40℃, and the motor power of the wire saw cutting machine 5 is selected as 30kW. According to the calculation, Qr=24kW; in order to ensure the cooling effect and monitoring accuracy, the outlet water temperature of the cooling water is set to not more than 45℃, so ΔTw is 15℃, Cp is 4.186kJ / (kg·℃), and ρ is 1000kg / m³. Finally, Qw=38.2L / min is calculated, and the cooling water flow rate is 25L / min-38.2L / min. This precise and quantitative flow control method balances the cooling effect and energy consumption, avoids the impact of insufficient cooling on construction quality, prevents water resource waste, and realizes the unity of green construction and efficient operation.

[0033] The water cooling system needs to ensure that the cutting surface is cooled to a temperature above 40°C to ensure the recording effect of the infrared camera 8 and avoid overheating of the rope saw. After the above layout is completed, the equipment is started in advance, and the rope saw cutting machine 5, remote control module and infrared camera 8 are checked to see if they are working normally. The comprehensive pre-adjustment process can troubleshoot equipment failures in advance, reduce downtime for maintenance during construction, ensure smooth process connection, and improve overall construction efficiency.

[0034] Step S6: Remote cutting and real-time monitoring: After the equipment is debugged, the site personnel are evacuated, and the operator is in place in the operation room. The rope saw cutting machine 5 is locked in the current position by the remote control module, and the rope saw cutting machine 5 is started to begin cutting work, and the infrared image and BIM model superposition are monitored simultaneously, and the cutting process is intervened in real time. This operating mode realizes the physical isolation of the operator and the work site, and uses image superposition technology to feedback the cutting state in real time, fundamentally avoiding personnel exposure to high-risk environments such as high altitude and dust, and ensuring job safety; at the same time, the real-time intervention mechanism can quickly handle emergencies and effectively reduce construction errors.

[0035] During the cutting operation, the continuous friction between the rope saw and the concrete is the core principle of cutting, and this process generates high temperatures. The infrared camera 8 can accurately record the temperature changes of the cutting surface and form a temperature field image, and technicians can verify whether the temperature change process conforms to the linear temperature rise rule through data processing. It is worth noting that the heat generated by the rope saw cutting mainly comes from the conversion of motor power, and these high temperatures will be conducted to the steel bars inside the concrete, which have higher thermal conductivity, causing the surrounding concrete of the steel bars to "preheat" in advance. This feature provides a key basis for structure identification.

[0036] Based on this principle, the difference in thermal conductivity between concrete and steel beam - the pre-stressed steel beam 15 heats up faster and is more sensitive to heat than concrete - can be used to combine infrared monitoring with BIM models to form a precise structure identification system. This non-contact monitoring method not only does not interfere with normal cutting operations, but also accurately locates the position of the steel beam and the steel bar, avoiding structural risks caused by mis-cutting, significantly improving the safety and reliability of construction. The specific observation and operation process is as follows: Step S61: Select a BIM model cross-section at the same angle as the infrared image for superposition, and establish a precise digital reference benchmark for subsequent temperature field analysis.

[0037] Step S62: After completing the image superposition, focus on analyzing the distribution characteristics of the temperature field in the superimposed image. The core judgment index is whether there are long bright stripes. Different temperature field performances correspond to completely different operating states and processing methods: If the temperature field image is uniform and presents a continuous bright band area, and the temperature data change process conforms to the linear law, it indicates that the wire saw only acts on the concrete, and there is no risk of cutting the prestressed steel strand 15. At this time, the operator only needs to adjust the wire saw feed speed through the remote control module to continuously cut according to the predetermined route. This way of quickly judging the operation state through the characteristics of the temperature field does not need to stop for detection, can maintain the continuity of construction and improve the operation efficiency, and can ensure that the cutting is always carried out in a safe area. From the law of heat conduction, in this case, heat will be concentrated at the cutting seam and gradually spread to the concrete on both sides. Influenced by the internal gravel aggregate of the concrete, a point-like heat image may appear, which further confirms that the wire saw does not contact the steel bar and the prestressed steel strand 15, and the construction can continue according to the plan.

[0038] If the temperature field image appears distorted, long bright stripes appear near the cutting surface, and the brightness of the stripes increases as the cutting distance decreases, while the temperature change process deviates from the linear law, it means that there is a steel bar or prestressed steel strand 15 near the cutting surface. In this case, the cutting speed needs to be slowed down immediately, and the precise matching stripe position is marked in combination with the BIM model to clearly distinguish between ordinary steel bars and prestressed steel strands 15. After finding the abnormality, timely speed reduction and investigation, accurate identification of the structure type through model matching can effectively avoid damaging the prestressed steel strand 15 or damaging the steel bar due to blind cutting, prevent structural collapse, and ensure construction safety and engineering quality. The direction indicated by the long bright stripe is the actual layout position of the ordinary steel bar or the prestressed steel strand 15.

[0039] Step S63: According to the above analysis results, the corresponding operation is performed on the wire saw cutting machine 5 through the remote control module to form a closed loop control: if it is determined that the long bright stripe corresponds to the prestressed steel strand 15, the wire saw cutting machine 5 needs to be stopped first, and after the wire saw is loosened, the cutting machine position is adjusted through the remote control module to move the wire saw to a safe position that avoids the prestressed steel strand 15 and the surrounding steel bar in the cutting operation hole 4, and then the equipment is restarted. If the position adjustment still cannot avoid the steel strand, all equipment on site needs to be stopped, and the cutting area planning needs to be re-performed from step S2 to drill a new cutting operation hole 4, and then the equipment adjustment and water cooling parameter setting are completed according to the requirements of step S5, and then the cutting process is restarted. This closed loop control mechanism of "finding problems-accurate adjustment-reworking" can minimize the loss caused by construction mistakes, ensure that each step of cutting meets the safety standards, and ensure the stability of the engineering quality.

[0040] For the end cutting operation of the same beam body 1, in order to improve efficiency and ensure structural safety, multiple rope saw cutting machines 5 can be arranged simultaneously according to the number of cutting areas. Each cutting machine needs to be equipped with an independent remote control module and a dedicated monitoring personnel, and through coordinated scheduling, synchronous cutting operation is realized to ensure that each web 14 of the beam body 1 is synchronously cut off. This multi-device collaborative operation mode ensures the synchronicity of the operation through dedicated management and control, which not only greatly shortens the cutting time and improves the construction efficiency, but also fundamentally avoids the construction risks such as deformation and structural damage of the beam body 1 caused by uneven local stress, and ensures the structural integrity.

[0041] Through the implementation of the above remote control cutting process, the dual core values are realized: on the one hand, the whole process of the beam body 1 cutting process is ensured to be monitored, the cutting surface state can be timely predicted and adjusted, and the risk of concrete collapse caused by cutting to the prestressed steel 15 or mistakenly damaging the steel bar is effectively avoided; on the other hand, unmanned operation of the cutting site is completely realized, even in the extreme case of prestressed steel 15 being mistakenly cut to cause concrete collapse, personnel casualties can be completely avoided, and the construction safety is greatly improved.

[0042] Step S7: cutting unit finishing and equipment transfer: after cutting is completed, the rope saw cutting machine 5 is stopped by the remote control module, the worker enters the construction site to remove the rope saw, and moves the rope saw cutting machine 5 along the track 7 to the vicinity of the next cutting surface, repeats the equipment debugging and water cooling parameter setting of step S5 and the subsequent steps. For the beam body 1 unit that has been cut, it is unloaded from the column pier 2 by the jacking system in place on the beam bottom and the module car, and is moved to the construction site outside for further processing. The standardized subsequent processing process realizes efficient connection of equipment transfer and beam body 1 removal, which not only reduces the waiting time between processes and improves construction continuity, but also protects the beam body 1 unit and the surrounding structure through smooth removal, avoids collision damage, optimizes the construction site environment, and facilitates subsequent process development.

[0043] Through the complete construction steps of steps S1 to S7, the process successfully solves the multiple technical problems existing in the cutting construction of the traditional prestressed beam body 1: first, with the help of BIM modeling and visual marking, the core pain point of "invisible and difficult positioning" of the prestressed steel beam 15 is completely solved, which provides accurate data support for cutting operation; second, by scientifically dividing the cutting unit and quantifying the safety distance standard, the risk of structural collapse caused by instability of the prestressed system and steel beam fracture in the cutting process is effectively avoided; third, the safety hidden danger of close-range operation, low cutting precision and poor efficiency in traditional construction is overcome. At the same time, the process brings significant beneficial effects: the fusion application of BIM technology, infrared monitoring and remote control realizes the digitization, visualization and unmanned of the cutting process, greatly improves the construction safety; the standardized process flow and multi-device collaborative operation mode effectively shorten the construction period and reduce human error; the pre-demolition of non-core components and the construction of precise support system guarantee the structural integrity of the beam body 1 and reduce construction loss, providing an efficient, safe and reliable technical solution for the cutting construction of the prestressed beam body 1.

[0044] Finally, it should be noted that: the above is only the preferred embodiment of the present application and does not limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced, any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A BIM-based prestressed beam cutting construction process, characterized in that, Includes the following steps: Step S1: Data collection and BIM modeling: Obtain engineering drawings of the structure containing the prestressed beam to be demolished, extract the prestressing system data, construct the BIM model of the structure and mark the position of the prestressed steel strands in the beam; Step S2: Model Analysis and Cutting Surface Planning: Based on the BIM model, analyze the distribution pattern of prestressed steel strands, divide the beam into cutting units in combination with the integrity of the prestressed system, and plan the cutting area between units; Step S3: Construction preparation and pretreatment: Deploy lifting equipment and wire saw cutting machine, cut and dismantle non-load-bearing auxiliary structures of the beam and transfer them off-site by lifting equipment; Step S4: Deployment of support system, automated operation and monitoring equipment: Set up temporary support devices below the cutting area, install a track on the beam surface and assemble a wire saw cutting machine with a remote control module, and install an infrared camera for real-time acquisition of images of the cut surface. Step S5: Equipment debugging and water cooling parameter setting: Pre-set the cutting operation holes in the cutting area and assemble the cutting components. Set up the water cooling system aligned with the cutting area and adjust the water flow speed to ensure the function of the infrared camera; start the equipment and check the operating status. Step S6: Remote Cutting and Real-time Monitoring: After the construction personnel have left, the cutting of the beam cutting unit divided in Step S2 is started through the remote control module; the image data collected by the infrared camera is fused with the BIM model to dynamically monitor the cutting process. If steel bars are detected, an alarm is triggered, and the cutting parameters or path are adjusted based on the alarm and monitoring results. Step S7: Cutting unit completion and equipment transfer: After cutting is completed, the equipment is shut down via remote control module, the operators dismantle the cutting components and transfer the equipment to the corresponding area of ​​the next cutting unit; the beam unit is separated and transferred to the designated area using temporary support devices.

2. The BIM-based prestressed beam cutting construction process according to claim 1, characterized in that, The bridge containing the prestressed beam includes the beam and the pier. The beam includes the side wings, the panel, the bottom plate, and the web containing the prestressed steel strands. The prestressed system data in step S1 includes the beam dimensions, the pier dimensions, the reinforcement layout of the beam, the location of the prestressed steel strands, and the concrete grade. When modeling with BIM, the location of the prestressed steel strands in the beam is highlighted with color.

3. The BIM-based prestressed beam cutting construction process according to claim 1, characterized in that, In step S2, the beam cutting unit is divided based on the integrity of the prestressed system. Specifically, the beam is divided into several small beam segments according to the principle that each prestressed steel strand is an independent and complete prestressed system. The cutting area planning needs to avoid the prestressed steel strand anchorage area and the bent-up section, and meet the safety distance requirements with the prestressed anchorage end. Based on the planned cutting surface, the wire saw cutting process can be simulated through the BIM model, and the three-dimensional view and sectional view of the cutting surface can be extracted and integrated to generate a file containing the cutting position number.

4. The BIM-based prestressed beam cutting construction process according to claim 3, characterized in that, The specific safety distance is as follows: for bonded prestressed steel strands, the safety distance is not less than 30cm; for unbonded prestressed steel strands, the safety distance is greater than the maximum possible retraction length Ls of the steel strand at the fracture point, where Ls=(Δσ×L) / E, Δσ is the effective stress of the steel strand in MPa, L is the length from the anchoring end to the cutting point in m, and E is the elastic modulus of the steel strand in MPa.

5. The BIM-based prestressed beam cutting construction process according to claim 1, characterized in that, The non-load-bearing auxiliary structure of the beam in step S3 includes side wings. During the cutting and dismantling, the side wings are cut along the direction parallel to the bridge span and perpendicular to the bridge span respectively. During the cutting, cutting holes are first drilled at the connection position between the side wings and the main body of the beam. After setting up the wire saw cutting machine, it is cut into small pieces that meet the load of the lifting equipment before being lifted away. Step S3 also includes a pre-cutting step for the beam panel and bottom plate. Specifically, cutting holes are drilled at both ends of the cutting range of the panel and bottom plate. The wire saw cutting machine is set up and cut along the direction perpendicular to the bridge span, so that the panel and bottom plate are separated from the column pier first. The pre-cutting does not affect the normal operation of the prestressed system inside the web of the beam.

6. The BIM-based prestressed beam cutting construction process according to claim 1, characterized in that, The number of tracks mentioned in step S4 corresponds to the number of web plates of the beam. The tracks are laid at a position perpendicular to the cutting area and aligned with the bridge deck corresponding to the center of the cutting area. Each track is disconnected and spliced ​​at the beam cutting point. The remote control module can realize the track movement, start and stop control, feed speed adjustment and position locking functions of the wire saw cutting machine; the infrared camera is installed at the bottom of the beam on the non-cutting surface, with the lens facing the cutting surface, which can collect the cutting surface temperature data in real time and transmit it to the operating room. It can capture temperature changes of more than 1°C and perform linear verification on the temperature data change process.

7. The BIM-based prestressed beam cutting construction process according to claim 1, characterized in that, The temporary support device mentioned in step S4 includes a modular vehicle equipped with a lifting system and a temporary support bracket erected at the column pier position. After the modular vehicle drives into the area below the cutting zone, the lifting system lifts and aligns with the beam support position for unloading and moving the beam after cutting.

8. The BIM-based prestressed beam cutting construction process according to claim 1, characterized in that, In step S5, the cutting hole adopts a large-diameter structure to meet the flexible adjustment requirements of the wire saw position when adjusting the cutting surface. The water flow rate of the water cooling system is quantitatively determined based on the principle of thermal balance. A reasonable value range is set in combination with the working power and energy conversion characteristics of the wire saw cutter to ensure that the water flow rate matches the cutting heat load. At the same time, the water cooling system aims to ensure the recording effect of the infrared monitoring equipment and avoid overheating failure of the cutting equipment, and controls the temperature of the cut surface after cooling within a preset range.

9. The BIM-based prestressed beam cutting construction process according to claim 1, characterized in that, In step S6, the cutting status is identified by fusing the image data collected by the infrared camera with the BIM model. Specifically, the BIM model section with a matching angle is selected and superimposed with the infrared image. The difference in thermal conductivity between concrete and steel strands is used to distinguish between ordinary steel bars and prestressed steel strands by combining the temperature field distribution and characteristic stripe pattern of the superimposed image. When the prestressed steel strand signal is identified, the corresponding avoidance adjustment operation is performed. When cutting the end of the same beam section, multiple wire saw cutting machines equipped with independent control and monitoring units can be deployed simultaneously to ensure that each web of the beam is cut off synchronously through collaborative operation to avoid uneven local stress.

Images