Rapid pier construction method based on UHPC (Ultra High Performance Concrete) non-dismantling formwork

Abstract

The invention belongs to the field of bridge engineering and building construction, and discloses a rapid pier construction method based on a UHPC (Ultra High Performance Concrete) non-dismantling formwork, which is mainly used for solving the problems of long construction period, low efficiency, poor quality, high cost, difficulty in precision control, insufficient joint sealing performance, dependence on manual positioning precision, complex connection process and the like in the prior art. According to the method, the prefabricated UHPC non-dismantling formwork segments are adopted, the BIM model and the three-dimensional laser radar system are combined to achieve accurate hoisting and in-place of the UHPC non-dismantling formwork segments, automatic bolt connection is conducted through the bolt fastening robot, and the construction efficiency of the UHPC non-dismantling formwork segments is remarkably improved; precise positioning and connection between UHPC non-dismantling formwork segments are completed through intelligent construction, the perpendicularity and appearance quality of a pier column and the reliability and integrity of segment connection can be guaranteed, and the construction quality is remarkably improved; the UHPC non-dismantling formwork does not need to be dismantled, the formwork material and labor cost can be reduced, and meanwhile the construction period is shortened, and the indirect cost of equipment leasing, personnel management and the like is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of bridge engineering and construction, and particularly relates to a bridge pier rapid construction method based on UHPC formwork. BACKGROUND

[0002] As the throat project of the traffic line, the construction quality and efficiency of the bridge directly affect the road network traffic capacity. According to the statistics of the Ministry of Transport, by the end of 2022, China's highway bridges have reached 961,000 (including 7,417 super-large bridges), and railway bridges have reached 92,000 (high-speed rail bridges have reached 19,000 kilometers), ranking first in the world. Concrete bridges occupy a dominant position due to their low steel consumption, low comprehensive cost and low maintenance cost, but their inherent defects restrict the sustainability of the project. In the traditional bridge pier construction, wood formwork or steel formwork is usually used for the overall pouring and forming of concrete. Although the wood formwork has relatively low cost, it has limited turnover times and is prone to deformation and damage, resulting in poor appearance quality of the pier. A large amount of manual labor is required for the installation and removal of the formwork, which reduces the construction efficiency and prolongs the construction period. Although the steel formwork has good rigidity and turnover performance, it is heavy and has high transportation and installation costs, and may cause damage to the surface of the pier during removal. In addition, the construction period of a single pier using wood formwork or steel formwork is as long as 15-20 days, which is in conflict with the demand for rapid construction of modern traffic engineering.

[0003] In addition, the traditional formwork construction is prone to problems such as leakage at the joint of the formwork, affecting the integrity and durability of the pier, and the ultimate tensile strength of the formed concrete is only 1 / 10-1 / 20 of the compressive strength, which is prone to shrinkage cracks, leading to chloride ion penetration and steel corrosion, affecting the service life of the structure. At the same time, the removal process of the formwork not only increases the construction cost, but also may affect the quality and safety of the pier due to improper removal. With the continuous development of bridge construction, the requirements for the efficiency, quality and environmental protection of bridge construction are becoming higher and higher, and the traditional formwork construction method has been difficult to meet the needs of modern bridge engineering.

[0004] Some existing formwork-free technologies have improved the above problems to some extent, but still have some shortcomings. For example, the connection method of some formwork-free technologies is not reliable, the traditional bolt connection torque dispersion is >15%, the joint water leakage rate is >5%, and it is prone to looseness during construction or use. The positioning accuracy of the formwork segments is not high, which affects the perpendicularity and appearance quality of the pier, and may have a great impact on the stress performance of the structure. The automation level in the construction process is low, and still relies on a large amount of manual operation, which limits the improvement of construction efficiency. Therefore, it is of great practical significance to develop a more efficient, reliable and precise formwork-free pier rapid construction method. SUMMARY

[0005] The application aims to provide a bridge pier rapid construction method based on UHPC formwork, aiming to solve the problems of long construction period, low efficiency, poor quality, high cost, difficult precision control in the traditional formwork construction method, and insufficient joint sealing, manual positioning precision, and complex connection process in the existing formwork construction method.

[0006] To achieve the above-mentioned purpose, the application provides the following technical scheme: A bridge pier rapid construction method based on UHPC formwork, characterized in that it comprises the following steps: S1: Preparation of UHPC formwork segments, combining the core design parameters and technical standards of UHPC formwork segments, designing the formwork based on the BIM model, and then producing the UHPC formwork segments according to the design requirements of the BIM model; the inner wall of the UHPC formwork segment is pre-buried with an inner flange, and a plurality of bolt connection holes are uniformly arranged on the inner flange; the outer wall of the UHPC formwork segment is uniformly pre-buried with a lifting steel ring; S2: Construction of pier column foundation slab, according to the design requirements, using conventional construction technology to sequentially perform steel bar binding, slab mold installation and concrete pouring of the pier column foundation slab; during the concrete pouring process, the pre-buried parts for subsequent positioning and connection are accurately pre-buried according to the design position; S3: Binding of pier column steel reinforcement cage, on the completed pier column foundation slab, the binding of the pier column steel reinforcement cage is performed according to the design requirements; S4: Transportation of UHPC formwork segments, transporting the prepared UHPC formwork segments to the construction site; S5: Smearing epoxy resin glue, uniformly smearing epoxy resin glue on the splicing surface of the UHPC formwork segments to be spliced; S6: Hoisting and positioning of UHPC formwork segments, using a three-dimensional laser radar system to scan the pre-buried parts on the pier column foundation slab to obtain accurate position information; matching the position information obtained by scanning with the BIM model, and guiding the hoisting equipment to hoist the UHPC formwork segments to the accurate design position through the lifting steel ring according to the matching result; S7: Connection of UHPC formwork segments, temporarily building an axial crawling track in the internal space of the UHPC formwork segments, using a bolt fastening robot to move along the crawling track to the inner flange, and using its own mechanical arm to automatically install the bolts on the inner flange; S8: Pouring and curing of the core concrete of the pier column, after the segment connection of the UHPC formwork is completed and checked, the pouring work of the core concrete of the pier column is carried out; self-compacting concrete is poured into the UHPC formwork segment, and after pouring is completed, the core concrete of the pier column is cured according to the specified curing conditions until the design strength is reached; S9: Repeat the above steps S5 to S8 to complete the construction of the entire pier section by section.

[0007] As a further supplementary scheme of the above technical scheme, the UHPC formwork segment is formed by a formwork steel reinforcement framework and UHPC pouring, the formwork steel reinforcement framework includes a plurality of annularly arranged longitudinal reinforcements and a plurality of stirrups for fixing all the longitudinal reinforcements, and the plurality of stirrups are uniformly arranged along the length direction of the longitudinal reinforcements.

[0008] As a further supplementary scheme of the above technical scheme, the step S1 includes: S101: Preparing a mold for pouring the UHPC formwork segment, a mold of a corresponding size is made according to the design specifications of the UHPC formwork segment, to ensure the dimensional accuracy and surface flatness of the mold; spraying release agent on the pouring surface of the mold; S102: Preparing a formwork steel reinforcement framework, a plurality of longitudinal reinforcements and a plurality of stirrups are bound or welded together according to design requirements; S103: Placing the formwork steel reinforcement framework in the mold and fixing it at the center position of the mold by a positioning fixture; S104: Pouring the prepared UHPC concrete into the mold, before the initial setting of the concrete, the inner flange and the lifting steel ring are pre-buried, and the position is ensured to be accurate; after the UHPC concrete is solidified, curing is carried out, and the curing time and conditions are determined according to the performance requirements of UHPC.

[0009] As a further supplementary scheme of the above technical scheme, in step S3, the pier steel reinforcement framework is a steel reinforcement cage for internal core concrete pouring, the processed steel is arranged and bound according to design requirements, the connection of the steel is welded or mechanically connected to ensure firm connection; during the binding process, the positioning rib of the steel is arranged to ensure that the perpendicularity and spacing of the steel reinforcement framework meet the requirements, and the binding is carried out before the UHPC formwork is hoisted and spliced in place.

[0010] As a further supplementary scheme of the above technical scheme, in step S5, before the epoxy resin adhesive is applied, the splicing surface of the UHPC formwork segment to be spliced is cleaned to remove impurities on the surface; then a special application tool is used to uniformly apply the epoxy resin adhesive on the splicing surface, and the application thickness is controlled at 2mm-3mm; after the application is completed, the UHPC formwork segment is hoisted and spliced.

[0011] As a further supplementary scheme of the above technical solution, the step S6 comprises: S601: Start the three-dimensional laser radar system to scan the embedded part of the pier column foundation slab, obtain its accurate position information, and output point cloud data (XYZ coordinates). The three-dimensional laser radar system is a KONICA MINOLTA SLAM-K120 handheld three-dimensional laser scanner, with a scanning frequency of ≥10HZ and an accuracy of ±1mm; S602: Transmit the scanning information to the computer control system, match the BIM model with the point cloud data through the iterative closest point (ICP) algorithm, calculate and output the deviation between the actual coordinates and the calculated coordinates after data registration and analysis, and the deviation requirement is ≤2mm; finally, according to the BIM model and the deviation data, the hoisting path is planned, and the hoisting trajectory instruction is output; S603: Slowly hoist the UHPC formwork segment with the hoisting equipment, accurately hoist the UHPC formwork segment to the designed position under the guidance of the computer control system; during the hoisting process, the total station / visual sensor is used to track the lifting device in real time, and real-time positioning and adjustment are carried out, and dynamic compensation is carried out combined with interference factors such as gravity deformation and wind load, so as to achieve accurate positioning, and the positioning error is ≤2mm; S604: Start the three-dimensional laser radar system again to scan and re-measure, generate the completed model, and perform data verification and storage, update the construction quality information in the BIM database; at the same time, generate the acceptance report containing the positioning error data information of the UHPC formwork segment.

[0012] As a further supplementary scheme of the above technical solution, in step S7, the bolt fastening robot is equipped with a visual positioning system and a torque sensor, the bolt connection hole position on the inner flange is recognized through the visual positioning system, and the mechanical arm is driven to accurately insert the bolt into the bolt connection hole; the bolt fastening robot controls the mechanical arm to tighten the torque through the torque sensor, so that the bolt reaches the specified tightening force, and ensures that the tightening torque control accuracy is ±5%.

[0013] As a further supplementary scheme of the above technical solution, in step S8, the self-compacting concrete is delivered into the UHPC formwork by high-pressure pumping, and the self-compacting concrete is slowly poured from one side of the UHPC formwork, and the concrete flows and fills the internal space of the formwork; during the pouring process, the flow condition and filling effect of the concrete are observed, and auxiliary vibration is carried out according to the actual pouring condition; after the pouring is completed, the concrete surface is leveled.

[0014] As a further supplementary scheme of the above technical scheme, the step of establishing the BIM model comprises: determining the core design parameters and technical standards of the UHPC formwork segment, constructing a three-dimensional geometric model of the UHPC formwork segment by using Revit software, and assisting in processing complex component connection details by using CATIA software; drawing the main contour of the UHPC formwork segment according to the design specifications, establishing an internal structure model in combination with the formwork reinforcement framework, and ensuring that the annular distribution of the reinforcement framework, the spacing of the longitudinal reinforcement and the stirrup meet the design requirements; accurately embedding the inner mouth flange and the lifting steel ring in the model, and marking the material, size parameters and spatial coordinates thereof; on the basis of the three-dimensional geometric model, associating construction progress information, material information and quality control information, binding the model with subsequent construction steps, and providing data support for construction simulation and path planning; finally, the UHPC formwork segment can be manufactured according to the design requirements of the BIM model; the BIM model comprises three-dimensional geometric information, construction progress information, material information and quality control information of the pier.

[0015] As a further supplementary scheme of the above technical scheme, the construction quality is monitored in real time during the entire construction process, and the monitoring content comprises the positioning accuracy of the UHPC formwork segment, the tightening torque of the bolt, the pouring quality of the pier core concrete and the maintenance condition.

[0016] Compared with the prior art, the beneficial effects of the present application are: 1. Construction efficiency is improved: the UHPC formwork segment is prefabricated, which reduces the time and workload of pouring formwork installation and removal on the construction site; the present application combines the BIM model and the three-dimensional laser radar system to realize the precise lifting and positioning of the UHPC formwork segment, and realizes the bolt connection between the UHPC formwork segments by using the bolt tightening robot, which significantly improves the assembly speed of the UHPC formwork segment, so that the single segment construction period can be shortened to ≤4 hours, and the whole pier construction period is reduced by more than 40% compared with the traditional process.

[0017] 2. Construction quality is guaranteed: the UHPC material used in the present application has high strength, high durability and good impermeability, and can effectively improve the overall quality and durability of the pier column as a formwork; the present application realizes the precise positioning and connection between the UHPC formwork segments by intelligent construction, ensures the perpendicularity and appearance quality of the pier column, and uses the automatic construction of the bolt tightening robot to ensure the torque accuracy of the bolt connection, thereby improving the reliability and integrity of the segment connection.

[0018] 3. Construction cost is reduced: the UHPC formwork in the application does not need to be removed, reducing the turnover and loss of the formwork, reducing the cost of formwork materials and labor; at the same time, the shortening of the construction period also reduces the indirect costs such as equipment rental and personnel management, and the labor cost can be reduced by about 30% after measurement.

[0019] Green and environmentally friendly: the UHPC formwork in the application reduces the generation of construction waste, meets the requirements of green construction, in addition, the use of self-compacting concrete reduces the noise and energy consumption in the vibrating process, reduces the impact of construction on the environment, and the construction energy consumption can be reduced by 25%. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the present application, and constitute a part of the specification, together with the embodiments of the present application, to explain the present application, and do not constitute a limitation on the present application, in the drawings: Figure 1 is the construction step flow chart of the present application; Figure 2 is the BIM and three-dimensional laser radar system collaborative positioning flow chart of the present application; Figure 3 is the UHPC formwork segment structure schematic diagram of the present application; Figure 4 is the formwork segment connection diagram of the present application; Figure 5 is the bolt fastening robot automatic bolt connection construction scene diagram of the present application.

[0021] Wherein, 1-UHPC formwork segment, 2-inner mouth flange, 3-connection bolt, 4-bolt connection hole, 5-epoxy resin glue, 6-mechanical arm, 7-torque sensor, 8-vision positioning system, 9-bolt fastening robot, 10-vision camera, 11-crawling track. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0023] The application provides a bridge pier rapid construction method based on UHPC formwork free of disassembly.

[0024] The whole-cycle construction process of the application comprises: I. Construction preparation stage Technical preparation: organize construction personnel to be familiar with construction drawings and relevant specifications, and conduct technical briefing; use BIM technology to establish a three-dimensional model of the bridge pier, simulate and analyze the construction process, and determine the optimal construction scheme and construction parameters.

[0025] Material preparation: according to the design requirements, high-quality UHPC raw materials are purchased, UHPC is prepared and test block is made according to the mixing ratio, and whether the performance indicators meet the requirements is checked. At the same time, epoxy resin glue, bolts, self-compacting concrete and other materials are prepared and quality inspection is conducted.

[0026] Equipment preparation: appropriate hoisting equipment, three-dimensional laser radar system, bolt fastening robot and other construction equipment are prepared and debugged and tested to ensure that the equipment performance is good and the operation is normal.

[0027] Site preparation: the construction site is leveled and cleaned, the material stacking area, equipment parking area and construction operation area are set up, and the construction site is ensured to meet the construction requirements.

[0028] II. Construction implementation stage This stage is the core innovation point of the application, as shown in Figures 1 to 5 The specific implementation steps comprise: S1: Preparation of UHPC formwork free of disassembly section, design based on BIM model, determine the parameters of UHPC formwork free of disassembly section, in a professional prefabrication factory, according to the design requirements of BIM model, prepare UHPC formwork free of disassembly section; the inner wall of the UHPC formwork free of disassembly section is pre-buried with an inner port flange, a plurality of bolt connection holes are uniformly arranged on the inner port flange; the outer wall of the UHPC formwork free of disassembly section is uniformly pre-buried with a hoisting steel ring.

[0029] In this step, the size, shape, mechanical property requirements and construction process of the pier are fully considered, and a BIM model is constructed using Revit and CATIA according to the design drawings of the pier, geological data, construction parameters and other information. The BIM model contains three-dimensional geometric information, construction progress information, material information and quality control information of the pier. The parameters of the UHPC formwork segment and the coordinate points of the embedded parts are accurately determined.

[0030] Specifically, the establishment of the BIM model includes: first, determining the core design parameters and technical standards of the UHPC formwork segment. The core design parameters are derived from the geometric parameters of the pier designed under different construction conditions, and the technical standards are derived from the pier construction technical standards in the industry, which will not be described here. Revit software is used to construct a three-dimensional geometric model of the UHPC formwork segment, and CATIA software is used to assist in processing complex component connection details, such as integrated design of the formwork based on the inner flange connection structure. The main outline of the UHPC formwork segment is drawn according to the design specifications, and the internal structure model is established in combination with the formwork reinforcement skeleton to ensure that the annular distribution of the reinforcement skeleton, the spacing of the longitudinal reinforcement and the stirrup meet the design requirements. The inner flange and the outer wall lifting steel ring are accurately embedded in the model, and their material, size parameters and spatial coordinates are labeled. Based on the three-dimensional geometric model, construction progress information, material information and quality control information are associated. The above model is bound with subsequent construction steps, such as presetting the connection node of the lifting steel ring and the lifting equipment in the model, matching the operation path parameters of the inner flange and the bolt fastening robot, providing data support for construction simulation and path planning. Finally, the UHPC formwork segment is manufactured according to the design requirements of the BIM model Structurally, the UHPC formwork segment is formed by the formwork reinforcement skeleton and UHPC pouring. The formwork reinforcement skeleton includes a plurality of annularly arranged longitudinal reinforcement and a plurality of stirrups for fixing all longitudinal reinforcement. The plurality of stirrups are uniformly arranged along the length direction of the longitudinal reinforcement.

[0031] The preparation process of the UHPC formwork segment includes: S101: preparing a mold for pouring the UHPC formwork segment. The mold of the corresponding size is made according to the design specifications of the UHPC formwork segment to ensure the dimensional accuracy and surface flatness of the mold. A release agent is sprayed on the pouring surface of the mold; S102: preparing a formwork reinforcement skeleton, which is bound or welded according to the design requirements; S103: placing the formwork reinforcement skeleton in the mold and fixing it at the center position of the mold by positioning fixtures; S104: Pour the prepared UHPC concrete into the mold, and use the vibration process to ensure the compactness of the concrete. Before the initial setting of the concrete, embed the inner port flange plate and lifting steel ring, and ensure their accurate positions. After the UHPC concrete solidifies, perform curing, and the curing time and conditions are determined according to the performance requirements of UHPC.

[0032] S2: Construction of the pier column foundation slab. According to the design requirements, use conventional construction techniques to successively perform reinforcement binding, slab mold installation, and concrete pouring. During the concrete pouring process, accurately embed the embedded parts for subsequent positioning and connection at the designed positions. The embedded parts are used for positioning and connection between the pier column foundation slab and the lowermost UHPC formwork segment.

[0033] The pier column foundation slab construction in this step uses conventional technical means. In general, first, process and bind the reinforcement to ensure that the connection method and spacing of the reinforcement meet the design requirements. Then, install the slab mold to ensure the size and perpendicularity of the mold. Before pouring the concrete, check the positions and fixation of the embedded parts again. Use the layered pouring method to pour the concrete, and vibrate and compact it to ensure the quality of the slab. After pouring is completed, perform covering curing, and the curing time is not less than the specified number of days.

[0034] S3: Binding of the pier column reinforcement cage. On the completed pier column foundation slab, perform the binding work of the core concrete reinforcement cage of the pier column according to the design requirements. The reinforcement cage for pouring the internal core concrete needs to be bound before the UHPC formwork segment is lifted and spliced, otherwise it will be difficult to arrange in place, causing difficulties for the next construction.

[0035] In this step, the processed reinforcement is arranged and bound according to the design requirements. The connection of the reinforcement uses welding or mechanical connection to ensure firm connection. During the binding process, the positioning bars of the reinforcement are set to ensure that the perpendicularity and spacing of the reinforcement cage meet the requirements.

[0036] S4: Transportation of the UHPC formwork segment. Transport the prepared UHPC formwork segment to the construction site.

[0037] In this step, select appropriate transportation vehicles to transport the prepared UHPC formwork segment to the construction site. During transportation, fix and protect the formwork segment to prevent collisions and deformation. The transportation vehicles should choose routes with good road conditions to ensure transportation safety.

[0038] S5: Apply epoxy resin glue. Uniformly apply epoxy resin glue on the splicing surface of the UHPC formwork segment to be spliced.

[0039] In this step, before applying the epoxy resin adhesive, clean the splicing surfaces of the UHPC template segments to be spliced, removing dust, oil, and other impurities. Then, use a dedicated application tool to evenly apply the epoxy resin adhesive to the splicing surfaces, controlling the thickness to 2mm-3mm. After application, hoist and splice the UHPC template segments as soon as possible to avoid prolonged exposure of the epoxy resin adhesive to the air, which could affect its bonding performance.

[0040] S6: The hoisting and positioning of UHPC formwork segments without dismantling is carried out by using a 3D LiDAR system to scan the embedded parts on the pier foundation platform to obtain precise location information. The scanned location information is then matched with the BIM model, and the hoisting equipment is guided to hoist the UHPC formwork segments to the accurate design position using hoisting steel rings based on the matching results. During the hoisting process, a dedicated person is assigned to direct and monitor the operation to ensure hoisting safety.

[0041] The specific implementation process for this step includes: S601: Start the three-dimensional lidar system. The three-dimensional lidar system uses a Kolida SLAM-K120 handheld three-dimensional laser scanner to scan the embedded parts of the pier foundation cap, obtain their precise position information, and output point cloud data (XYZ coordinates). The scanning frequency of the three-dimensional lidar system is ≥10HZ and the accuracy is ±1mm. S602: Transmits the scanned information to the computer control system, matches the BIM model and point cloud data through the iterative nearest point ICP algorithm, and calculates and outputs the deviation between the actual coordinates and the calculated coordinates after data registration and analysis. The deviation requirement is ≤2mm. Finally, the hoisting path is planned based on the BIM model and the deviation data, and the hoisting trajectory command is output. S603: The UHPC formwork segments are slowly lifted using hoisting equipment. Under the guidance of the computer control system, the UHPC formwork segments are accurately hoisted to the design position. During the hoisting process, a total station / visual sensor is used to track the hoisting equipment in real time, and to position and adjust it in real time. Dynamic compensation is also performed in combination with interference factors such as gravity deformation and wind load to achieve accurate positioning with a positioning error of ≤2mm. S604: Restart the 3D LiDAR system to perform scanning and re-measurement, generate the as-built model, verify and store the data, update the construction quality information in the BIM database, and generate an acceptance report containing data such as the positioning error of the UHPC non-removable formwork segment.

[0042] S7: Connection of UHPC non-removable template segments: A temporary axial crawling track is built in the internal space of the UHPC non-removable template segment. A bolt tightening robot moves along the crawling track to the inner flange and uses its own robotic arm to automatically install the bolts on the inner flange.

[0043] In this step, the bolt tightening robot uses existing equipment on the market, as can be found in the invention patent with application number "202210613074.7" and patent name "A Bolt Tightening Robot for Angle Steel Tower". This bolt tightening robot is equipped with a vision positioning system and a torque sensor. The bolt tightening robot uses the vision positioning system to identify the position of the bolt connection hole on the inner flange and drives the robotic arm to accurately insert the bolt into the bolt connection hole. The bolt tightening robot uses the torque sensor to control the tightening torque of the robotic arm to make the bolt reach the specified tightening force and ensure that the tightening torque control accuracy is ±5%.

[0044] The specific implementation process for this step includes: S701: Temporarily set up a crawling track and install the bolt-tightening robot onto the crawling track; S702: Start the bolt tightening robot and make it crawl along the crawling track to the bolt hole position of the inner flange; S703: The bolt fastening robot identifies the bolt hole position through a visual positioning system and accurately inserts the bolt into the bolt hole; S704: The bolt tightening robot uses a torque sensor to control the tightening torque of the robotic arm, so that the bolt reaches the specified tightening force, and the tightening torque control accuracy is ±5%; S705: Install all bolts in a specific order to ensure a secure connection between the UHPC non-removable template sections.

[0045] S8: Pouring and curing of the core concrete of the pier column. After the UHPC formwork-free segment connection is completed and inspected and qualified, the core concrete of the pier column is poured. Self-compacting concrete is poured into the UHPC formwork-free segment. After the pouring is completed, the core concrete of the pier column is cured according to the specified curing conditions until it reaches the design strength.

[0046] In this step, self-compacting concrete is delivered into the UHPC formwork using a high-pressure pump. The self-compacting concrete is slowly poured from one side of the UHPC formwork, allowing it to flow and fill the internal space of the formwork on its own. During the pouring process, the flow and filling effect of the concrete are observed, and auxiliary vibration is performed according to the actual pouring conditions. After pouring, the concrete surface is leveled, and finally cured according to the specified curing conditions, such as covering with moisture-retaining materials and watering regularly. The curing time is determined according to the type of concrete and design requirements.

[0047] S9: Construction of the next pier segment. After the core concrete of the current pier segment reaches a certain strength, repeat steps S5 to S8 above to construct the next pier segment, thus completing the construction of the entire pier segment by segment. During the construction process, pay attention to the connection quality and verticality control between adjacent segments to ensure the construction quality and appearance of the entire pier.

[0048] III. Construction Quality Control and Acceptance Stage Quality Control: A strict quality control system is established throughout the construction process to monitor the quality of each construction stage. The fabrication quality of the UHPC formwork-free segments is inspected, including dimensional accuracy, strength, and appearance quality. Real-time monitoring and control are implemented for the positioning accuracy of the UHPC formwork segments, the application quality of the epoxy resin adhesive, the tightening torque of the bolts, the pouring quality of the core concrete of the pier columns, and the curing condition, ensuring that all indicators meet design and specification requirements.

[0049] Acceptance: After construction is completed, acceptance will be carried out in accordance with relevant standards and specifications. The dimensions, verticality, appearance quality, and concrete strength of the bridge piers will be tested. The connection and sealing of the UHPC formwork segments will be checked. Only when all acceptance indicators meet the requirements can the bridge pier construction be deemed qualified.

[0050] Through the above full-cycle construction process, the rapid construction method for bridge piers based on UHPC without the need for formwork can be effectively implemented, achieving the goals of improving construction efficiency, ensuring construction quality, reducing construction costs, and being environmentally friendly. In practical applications, construction parameters and processes can be appropriately adjusted and optimized according to specific project conditions.

[0051] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0052] Example 1: Construction of Conventional Highway Bridge Piers Project Overview: A newly constructed highway overpass has piers with a design height of 18m and a diameter of 1.5m. The geological conditions are hard clay. The beam span combination is (3×30)m prestressed concrete continuous box girder. The seismic fortification intensity is VIII (0.3g). The design flood frequency is 1 / 100. The environmental conditions are: annual average temperature of 16.8℃ and annual precipitation of 1200mm. The strata distribution is: 0-5m silty clay, 5-15m hard clay, and below 15m strongly weathered sandstone. The foundation bearing capacity is σ0=350kPa. The groundwater level is 8.5m deep.

[0053] The construction of the aforementioned bridge includes the following steps: First, construction preparation and site treatment were carried out: a vibratory roller was used to compact the construction access road in layers; a three-level measurement and control network was established; a steel bar processing shed was built and equipped with a CNC bending machine and an automated bolt construction robot.

[0054] Preparation of UHPC formwork segments: Six 3m high UHPC formwork segments were designed using BIM, with a wall thickness of 10cm, an inner flange thickness of 20mm, and bolt hole spacing of 200mm. The inner flange was made of high-strength steel with a yield strength of not less than 345MPa, and was integral with the cast-in-place formwork, with pre-drilled bolt holes. Lifting steel rings were installed on the outer wall of the UHPC formwork segments. After preparation, each UHPC formwork segment was subjected to ultrasonic testing, and its dimensions and verticality were checked. The steel bars used to make the UHPC formwork segments were sampled for tensile / bending tests in each batch, with a 100% pass rate. Before the self-compacting concrete was poured, its spread, T500 time, and air content were tested.

[0055] Construction of the pier foundation cap: The reinforcement binding of the pier foundation cap is carried out according to design requirements and conventional construction techniques. Simultaneously, eight sets of positioning embedded parts are pre-embedded. The coordinates of the embedded parts are determined through collaborative positioning using BIM and a 3D LiDAR system. A laser line projector is used to project crosshairs at corresponding positions on the top surface of the cap. The embedded parts are fixed with positioning channel steel, with bolt hole deviation ≤0.5mm. After installation, a 3D LiDAR system is used for re-measurement, with a scanning accuracy of ±1mm and XYZ axis deviation controlled within ±0.8mm. The cap mold uses standardized steel molds, which are calibrated with a laser level during assembly. The mold joints are sealed with double-sided adhesive strips.

[0056] Binding of the pier column reinforcement cage: After the pier column foundation cap has reached the design strength, the pier column reinforcement cage is bound. The processed steel bars are arranged and bound according to the requirements of the design drawings. The steel bars are connected by welding. After the connection is completed, the reliability of the steel bar connection is checked. During the binding process, positioning bars are set for the steel bars, and the verticality and spacing of the reinforcement cage are checked.

[0057] Transportation of UHPC formwork segments: Flatbed trailers are used to transport the prepared UHPC formwork segments to the construction site. During transportation, the UHPC formwork segments are fixed and protected to prevent collisions and deformation. The transport vehicles choose routes with good road conditions to ensure transportation safety.

[0058] Apply epoxy resin adhesive: Apply epoxy resin adhesive evenly to the splicing surfaces of the UHPC template segments to be assembled. Before applying the epoxy resin adhesive, clean the splicing surfaces of the UHPC template segments to be assembled, removing dust, oil, and other impurities. Then, use a dedicated application tool to evenly apply the epoxy resin adhesive to the splicing surfaces, controlling the thickness to 2mm-3mm, and allow the curing time to not exceed two hours. After application, hoist and assemble the UHPC template segments as soon as possible to avoid prolonged exposure of the epoxy resin adhesive to air, which could affect its bonding performance.

[0059] Hoisting and positioning of UHPC formwork segments: The 3D LiDAR system (Kolida SLAM-K120 handheld 3D laser scanner) is activated to scan the embedded parts of the pier foundation cap to obtain their precise location information; the scanned information is transmitted to the computer control system for matching and analysis with the BIM model to determine the hoisting position and angle of the UHPC formwork segments; a 200t truck crane is used to slowly lift the UHPC formwork segments, which are equipped with a hydraulic leveling device. Under the guidance of the computer control system, the UHPC formwork segments are accurately hoisted to the design position with an error controlled within 2mm; before the formwork is installed, a 3mm thick rubber strip is pasted on the top surface of the pier foundation cap to prevent grout leakage.

[0060] Connection of UHPC non-disassembly template segments: First, a robot crawling track is built inside the template. The bolt tightening robot is started and crawls along the set track to the bolt connection hole position of the inner flange. The bolt tightening robot identifies the bolt connection hole through a vision positioning system and controls the robotic arm to accurately insert the bolt into the bolt connection hole. Then, the torque sensor is used to control the tightening torque of the robotic arm to make the bolt reach the specified tightening force. The tightening torque control accuracy is ±5%.

[0061] The core concrete of the pier column is poured as follows: the slump expansion of the self-compacting concrete used for pouring is 700mm, the pouring temperature is controlled between 15-25℃, the temperature deviation upon entering the formwork is ≤±2℃, the pouring speed is 0.5m / h, the layer thickness is ≤500mm, the T500 time is 3s, and the concrete is cured for 7 days to reach the design strength; a tremie pipe is used for assisted pouring, and the free fall height is ≤2m; a high-frequency vibrator is used for compaction during the pouring process, and a three-dimensional laser radar system is used to monitor the deformation of the formwork every 1m of pouring height.

[0062] Curing of the core concrete of the pier: An intelligent curing system is adopted, with a fiber optic temperature sensor built into the concrete to automatically record the temperature every 2 hours; steam curing is divided into three stages: heating up → constant temperature → cooling down; the surface is covered with nano-insulation material and moisturized for ≥14 days.

[0063] Construction of the next segment will begin once the core concrete of the pier reaches the design strength.

[0064] The technical advantage of this embodiment is that: 1. Construction period optimization: UHPC non-removable formwork segments are prefabricated in the factory, improving production speed and efficiency; automated bolt connection is achieved through bolt tightening robots, which is quick and convenient; the intelligent curing system accelerates the growth of concrete strength, reducing the time required for concrete to reach the design strength.

[0065] 2. Cost savings: UHPC reusable formwork segments can be reused more frequently, reducing formwork costs; robots replace manual labor for high-altitude operations and segment connection work, reducing labor costs; shorter construction periods save on project management fees; UHPC has strong impermeability, with a chloride ion diffusion coefficient ≤3×10⁻⁶. -12 It has a flow rate of m² / s, good corrosion resistance, and saves on daily maintenance costs.

[0066] 3. Quality Improvement: The structural precision is improved, with extremely high accuracy in the hoisting and splicing of each segment and good verticality of the piers; the material performance is improved, with higher compressive strength of UHPC and higher bonding strength of epoxy resin adhesive, and proper curing allows the internal core concrete to also achieve high strength.

[0067] 4. Construction safety: High-altitude operations and complex connection work are replaced by bolt tightening robots, reducing the probability of risks to workers; at the same time, real-time monitoring through a three-dimensional lidar system avoids collision accidents.

[0068] 5. Green and environmentally friendly: UHPC modular panels replace steel formwork, reducing steel consumption; precise quantity control through intelligent curing system saves water resources; factory prefabrication reduces on-site operations and dust emissions; self-compacting concrete requires fewer vibrations, reducing noise pollution.

[0069] Example 2: Bridge pier construction under complex geological conditions Project Overview: A municipal bridge spans a soft soil foundation, with piers 18m high and 2.0m in diameter, requiring rapid construction to minimize the impact of settlement.

[0070] This embodiment makes the following technical optimizations compared to Embodiment 1: 1. Template design: The wall thickness of the UHPC template segment is increased to 15cm, and the built-in prestressed steel strands enhance the resistance to deformation.

[0071] 2. Positioning technology: A dynamic laser monitoring system is used during the construction of the foundation to compensate for the settlement and displacement of soft soil in real time.

[0072] 3. Bonding process: The addition of nano-silica powder to the epoxy resin adhesive increases the bonding strength to 7MPa and the impermeability grade to P12.

[0073] The construction of the aforementioned bridge includes the following steps: First, soft soil foundation pretreatment is carried out, and deep mixing piles are used for deep reinforcement to form a composite foundation; plastic drainage boards are installed and vacuum preloading is carried out until the soil consolidation degree and settlement rate meet the requirements; layered settlement markers, pore water pressure gauges and inclinometers are installed; and an automated monitoring system is established.

[0074] Preparation of UHPC formwork without dismantling: Six 3m high UHPC formwork segments with a wall thickness of 15cm and built-in prestressed steel strands with a tensile stress of 1570MPa are designed using BIM, effectively improving the formwork's resistance to deformation. The inner flange is 20mm thick, and the bolt hole spacing is 200mm. The flange is made of high-strength steel with a yield strength of not less than 345MPa, and it is integrated with the cast-in-place formwork. After the formwork is prepared, ultrasonic testing is performed on each UHPC formwork segment, and its dimensions and verticality are checked.

[0075] Construction of the pier foundation cap: The reinforcement binding of the pier foundation cap is carried out according to design requirements and conventional construction techniques. Mechanical connections are used for the reinforcement. After binding, the reliability of the reinforcement connections is tested to ensure reliability. During the reinforcement binding process, positioning bars are set to ensure the verticality and spacing of the reinforcement cage meet requirements. After the reinforcement binding of the pier foundation cap is completed, eight sets of positioning embedded parts are pre-embedded. The embedded parts are welded to the cap reinforcement to form a whole. The coordinates of the embedded parts are determined through collaborative positioning using BIM and a 3D LiDAR system. A laser line projector is used to project crosshair control lines at the corresponding positions on the top surface of the cap. The embedded parts are fixed with positioning channel steel. The bolt hole position deviation meets the accuracy requirements. After installation, a 3D LiDAR system is used for re-measurement. The 3D LiDAR scanning accuracy is ±1mm, and the XYZ axis deviation is controlled within ±0.8mm. Simultaneously, the 3D LiDAR system monitors settlement in real time. When excessive cumulative settlement is detected, hydraulic jacks are activated to fine-tune the position of the embedded parts.

[0076] Binding of the pier column reinforcement cage: After the pier column foundation cap has reached the design strength, the pier column reinforcement cage is bound. The processed steel bars are arranged and bound according to the requirements of the design drawings. The steel bars are connected by mechanical connection. After the connection is completed, the reliability of the steel bar connection is checked. During the binding process, positioning bars are set for the steel bars, and the verticality and spacing of the reinforcement cage are checked.

[0077] The UHPC formwork segments are transported to the construction site using flatbed trailers. During transportation, the UHPC formwork segments are secured and protected to prevent collisions and deformation. The transport vehicles should choose routes with good road conditions to ensure transportation safety.

[0078] Apply epoxy resin adhesive: Apply epoxy resin adhesive evenly to the splicing surfaces of the UHPC template segments to be assembled. Before applying the epoxy resin adhesive, clean the splicing surfaces of the UHPC template segments to be assembled, removing dust, oil, and other impurities. Use double O-rings and nano-silica epoxy resin adhesive to bond the segments together. Apply the nano-silica epoxy resin adhesive evenly to the splicing surfaces using mechanical spraying, controlling the thickness to 2mm-3mm, and allow the curing time to not exceed two hours. After application, hoist and assemble the UHPC template segments as soon as possible to avoid prolonged exposure of the epoxy resin adhesive to air, which could affect its bonding performance.

[0079] Hoisting and positioning of UHPC formwork segments without dismantling: The 3D LiDAR system (Kolida SLAM-K120 handheld 3D laser scanner) is activated to scan the embedded parts of the pier foundation cap to obtain their precise location information; the scanned information is transmitted to the computer control system for matching and analysis with the BIM model to determine the hoisting position and angle of the UHPC formwork segments without dismantling; a hydraulic synchronous lifting system is used for hoisting and positioning of the formwork, which consists of 8 hydraulic jacks working in tandem with a displacement deviation of ≤1mm; four sets of temporary supports are set for positioning the first formwork segment, and the bearing capacity of each set must meet the requirements, while ensuring that the verticality accuracy of the formwork meets the requirements.

[0080] Connection of UHPC non-disassembly template segments: First, a robot crawling track is built inside the template. The bolt tightening robot is started and crawls along the set track to the bolt connection hole position of the inner flange. The bolt tightening robot identifies the bolt connection hole position through a vision positioning system and controls the robotic arm to accurately insert the bolt into the bolt connection hole. M24 high-strength bolts are used. Then, the torque sensor is used to control the tightening torque of the robotic arm to make the bolt reach the specified tightening force. The tightening torque control accuracy is ±5%.

[0081] Pouring of core concrete for pier columns: Polypropylene fibers are added to the self-compacting concrete, and its initial setting time is controlled at 5±0.5h, and its final setting time is ≤8h; the slump spread of the self-compacting concrete is controlled at 650-750mm, and the spread time T500 is 2-5s; the pouring process adopts the high-throw, vibration-free process, and the concrete is poured in layers; before pouring each segment, CO2 cooling technology is used to reduce the concrete temperature; during the pouring process, the flow and filling effect of the concrete are observed in real time, and appropriate auxiliary vibration can be carried out when necessary.

[0082] Curing of the core concrete of the pier: The concrete has an internal circulating water pipe with the water temperature controlled at 20±1℃. The surface is covered with nano-insulation material, and the curing cycle is extended to 14 days. The concrete surface is also leveled.

[0083] Construction of the next segment will begin once the core concrete of the pier reaches the design strength.

[0084] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rapid construction method for bridge piers based on UHPC-based formwork without the need for dismantling, characterized in that, Includes the following steps: S1: Preparation of UHPC removable formwork segments: Combining the core design parameters and technical standards of UHPC removable formwork segments, the formwork is designed based on the BIM model, and then the UHPC removable formwork segments are manufactured according to the design requirements of the BIM model; the inner wall of the UHPC removable formwork segment has an inner flange pre-embedded, and several bolt connection holes are evenly opened on the inner flange; the outer wall of the UHPC removable formwork segment has lifting steel rings evenly pre-embedded. S2: Construction of the pier foundation cap: According to the design requirements, conventional construction techniques are used to carry out the reinforcement binding, cap formwork installation and concrete pouring of the pier foundation cap in sequence; during the concrete pouring process, embedded parts for subsequent positioning and connection are accurately pre-embedded according to the design position. S3: Binding of the steel reinforcement cage for the pier column. On the completed pier column foundation platform, the steel reinforcement cage for the pier column is bound according to the design requirements. S4: Transportation of UHPC formwork segments without dismantling: Transporting the prepared UHPC formwork segments without dismantling to the construction site; S5: Apply epoxy resin adhesive evenly to the splicing surface of the UHPC no-removal template segment to be spliced. S6: The hoisting and positioning of UHPC formwork segments without dismantling: The three-dimensional lidar system is used to scan the embedded parts on the pier foundation platform to obtain accurate position information; the scanned position information is matched with the BIM model, and the hoisting equipment is guided to hoist the UHPC formwork segments without dismantling to the accurate design position through the hoisting steel ring according to the matching results. S7: Connection of UHPC non-removable template segments: A temporary axial crawling track is built in the internal space of the UHPC non-removable template segment. A bolt fastening robot moves along the crawling track to the inner flange and uses its own robotic arm to automatically install the bolts on the inner flange. S8: Pouring and curing of the core concrete of the pier column. After the UHPC formwork-free segment connection is completed and inspected and qualified, the core concrete of the pier column is poured. Self-compacting concrete is poured into the UHPC formwork-free segment. After the pouring is completed, the core concrete of the pier column is cured according to the specified curing conditions until it reaches the design strength. S9: Repeat steps S5 to S8 above to complete the construction of the entire bridge pier segment by segment.

2. The rapid construction method for bridge piers according to claim 1, characterized in that, The UHPC non-removable formwork segment is formed by casting the UHPC with the formwork steel reinforcement skeleton. The formwork steel reinforcement skeleton includes several longitudinal bars arranged in a ring and several stirrups for fixing all longitudinal bars. The stirrups are evenly arranged along the length of the longitudinal bars.

3. The rapid construction method for bridge piers according to claim 2, characterized in that, Step S1 includes: S101: Prepare a mold for casting UHPC template-free segments. Make a mold of the appropriate size according to the design specifications of the UHPC template-free segments, ensuring the dimensional accuracy and surface flatness of the mold; spray a release agent on the casting surface of the mold. S102: Prepare the formwork reinforcement cage, and tie or weld several longitudinal bars and several stirrups together according to the design requirements; S103: Place the template steel reinforcement cage in the mold and fix it at the center of the mold using a positioning clamp; S104: Pour the prepared UHPC concrete into the mold. Before the concrete sets, pre-embed the inner flange and lifting steel ring and ensure their accurate position. After the UHPC concrete has cured, perform curing. The curing time and conditions are determined according to the performance requirements of UHPC.

4. The rapid construction method for bridge piers according to claim 1, characterized in that, In step S3, the pier column steel reinforcement cage is a steel cage used for internal core concrete pouring. The processed steel bars are arranged and tied according to the design requirements. The steel bars are connected by welding or mechanical connection to ensure a firm connection. During the tying process, positioning bars are set for the steel bars to ensure that the verticality and spacing of the steel reinforcement cage meet the requirements. The tying is carried out before the UHPC formwork is hoisted and spliced ​​into place.

5. The rapid construction method for bridge piers according to claim 1, characterized in that, In step S5, before applying epoxy resin adhesive, the splicing surfaces of the UHPC template segments to be spliced ​​are cleaned to remove impurities. Then, a special application tool is used to evenly apply epoxy resin adhesive to the splicing surfaces, with the application thickness controlled at 2mm-3mm. After application, the UHPC template segments are hoisted and spliced.

6. The rapid construction method for bridge piers according to claim 1, characterized in that, Step S6 includes: S601: Start the three-dimensional lidar system to scan the embedded parts of the pier foundation platform, obtain their precise position information, and output point cloud data (XYZ coordinates). The three-dimensional lidar system is a Kolida SLAM-K120 handheld three-dimensional laser scanner with a scanning frequency ≥10HZ and an accuracy of ±1mm. S602: Transmits the scanned information to the computer control system, matches the BIM model and point cloud data through the iterative nearest point ICP algorithm, and calculates and outputs the deviation between the actual coordinates and the calculated coordinates after data registration and analysis. The deviation requirement is ≤2mm. Finally, the hoisting path is planned based on the BIM model and the deviation data, and the hoisting trajectory command is output. S603: The UHPC formwork segments are slowly lifted using hoisting equipment. Under the guidance of the computer control system, the UHPC formwork segments are accurately hoisted to the design position. During the hoisting process, a total station / visual sensor is used to track the hoisting equipment in real time, and to position and adjust it in real time. Dynamic compensation is also performed in combination with interference factors such as gravity deformation and wind load to achieve accurate positioning with a positioning error of ≤2mm. S604: Restart the 3D LiDAR system to perform scanning and re-measurement, generate the as-built model, verify and store the data, update the construction quality information in the BIM database, and generate an acceptance report containing data such as the positioning error of the UHPC non-removable formwork segment.

7. The rapid construction method for bridge piers according to claim 1, characterized in that, In step S7, the bolt tightening robot is equipped with a vision positioning system and a torque sensor. The vision positioning system identifies the position of the bolt connection hole on the inner flange and drives the robotic arm to accurately insert the bolt into the bolt connection hole. The bolt tightening robot controls the tightening torque of the robotic arm through a torque sensor, so that the bolt reaches the specified tightening force and the tightening torque control accuracy is ±5%.

8. The rapid construction method for bridge piers according to claim 1, characterized in that, In step S8, self-compacting concrete is delivered into the UHPC formwork using a high-pressure pump. The self-compacting concrete is slowly poured from one side of the UHPC formwork, allowing it to flow and fill the internal space of the formwork on its own. During the pouring process, the flow and filling effect of the concrete are observed, and auxiliary vibration is performed according to the actual pouring conditions. After the pouring is completed, the concrete surface is leveled.

9. The rapid construction method for bridge piers according to claim 1, characterized in that, The steps for establishing the BIM model include: determining the core design parameters and technical standards of the UHPC formworkless segment; constructing a three-dimensional geometric model of the UHPC formworkless segment using Revit software; and using CATIA software to assist in handling complex component connection details. The main outline of the UHPC formworkless segment is drawn according to the design specifications, and an internal structural model is established in conjunction with the formwork reinforcement skeleton to ensure that the circular distribution of the reinforcement skeleton and the spacing between longitudinal bars and stirrups meet the design requirements. The inner flange and lifting steel ring are precisely pre-embedded in the model, and their material, size parameters, and spatial coordinates are marked. Based on the three-dimensional geometric model, construction progress information, material information, and quality control information are associated, binding the model with subsequent construction steps to provide data support for construction simulation and path planning. Finally, the UHPC formworkless segment can be manufactured according to the design requirements of the BIM model. The BIM model includes the three-dimensional geometric information of the piers, construction progress information, material information, and quality control information.

10. The rapid construction method for bridge piers according to claim 1, characterized in that, Throughout the construction process, the construction quality is monitored in real time. The monitoring includes the positioning accuracy of the UHPC formwork segments, the tightening torque of the bolts, the pouring quality of the core concrete of the pier columns, and the curing status.

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