Construction method applied to prestressed pipeline grouting and intelligent grouting system

Abstract

The invention discloses a construction method applied to prestressed pipeline grouting and an intelligent grouting system.The construction method comprises the steps that the intelligent grouting system is adopted, and a prestressed pipeline to be grouted and a grouting unit in the intelligent grouting system are connected in series through a pipeline to form a circulating grouting loop; and slurry pumped out of the slurry making unit in the intelligent grouting system circularly flows in the pipeline and the prestressed pipeline until grouting is completed. By the adoption of the construction method and the intelligent grouting system, the whole grouting process can be measured, controlled and recorded in real time, then the grouting quality is guaranteed, the construction method and the intelligent grouting system are suitable for single-hole grouting, meanwhile, the requirement for double-hole grouting is met, the grouting work efficiency is greatly improved, and the intelligent grouting system and the intelligent grouting system are worthy of application and popularization.

Description

TECHNICAL FIELD

[0001] The application relates to the prestressed pipe grouting construction method and an intelligent grouting system. BACKGROUND

[0002] The prestressed pipe is also called a corrugated pipe, and the grouting compactness of the prestressed pipe has an important influence on the durability of a bridge. In a bridge construction process, the quality of prestressed grouting construction is crucial to the safety and durability of the prestressed bridge. Therefore, the post-tensioning prestressed pipe grouting construction becomes a key process of the prestressed bridge construction.

[0003] The post-tensioning prestressed pipe grouting construction is a key process of the prestressed bridge construction, and is related to the safety and durability of the bridge structure. A large number of prestressed bridge collapse accidents are often related to the non-compact grouting and the early corrosion of the steel strand. The non-compact grouting of the prestressed pipe causes the steel strand in the pipe to be not wrapped by the cement slurry, and is prone to early corrosion. In addition, the prestressed steel strand cannot form an integral stress with the concrete structure, which reduces the bearing capacity of the structure and shortens the service life of the bridge.

[0004] At present, the traditional grouting methods mainly include two kinds: one is ordinary grouting, and the other is vacuum-assisted grouting. The ordinary grouting adopts a single-cylinder piston pump to press the slurry into the pipe from the grouting inlet, and the thick slurry can flow out from the outlet. Compared with the ordinary grouting, the vacuum-assisted grouting increases a vacuum pump at the outlet to extract the vacuum, so that the pipe can reach a certain negative pressure to solve the problem that the air cannot be completely exhausted in the ordinary grouting. However, the vacuum-assisted grouting has the following problems: if the anchor is not tightly sealed, air will leak into the pipe when the vacuum machine is used to extract the vacuum, which is difficult to meet the use requirements; and when the height difference between the two ends of the pipe is large, the effect of the vacuum grouting is not as good as that of the ordinary grouting process.

[0005] Since the main function of the prestressed duct grouting is to protect the prestressed steel strand, prevent corrosion, form adhesion, reduce the burden of the anchor, and ensure the prestressed tendon and the concrete to work together, it is necessary to ensure that the grouting is full and compact during the construction process. If the prestressed pipe grouting is not compact, the steel strand in the pipe is not wrapped by the cement slurry, which is prone to early corrosion. In addition, the prestressed steel strand cannot form an integral stress with the concrete structure, which reduces the bearing capacity of the structure and greatly shortens the service life of the bridge. SUMMARY

[0006] The technical problem solved by the present application is to ensure the prestressed pipe grouting compactness by completely removing the air in the pipe during the grouting process, thereby providing a convenient grouting method.

[0007] To solve the above technical problems, the technical solution adopted by the present application is as follows: a construction method applied to prestressed pipe grouting, which adopts an intelligent grouting system, connects the prestressed pipe to be grouted and a grout preparation unit in the intelligent grouting system through a pipeline to form a circulating grouting loop, and makes the grout pumped out of the grout preparation unit in the intelligent grouting system flow in the pipeline and the prestressed pipe until the grouting is completed. S1. Construction preparation, when pouring concrete, a hard plastic pipe is pre-penetrated into the pipe to prevent the corrugated pipe from deforming and being damaged, and the diameter of the hard plastic pipe is required to be less than 1 cm of the diameter of the pipe; after the tensioning construction is completed, the exposed steel strand should be cut off, the exposed steel strand after cutting should be less than or equal to 30 mm, then the non-shrinkage cement mortar is used to seal the head, the one-time grout stop valve is installed, the serial connection pipe is used to connect the grouting hole, and the whole grouting system is ensured to be normally used to prepare for the prestressed pipe grouting; the hole should be grouted as soon as possible, and the grouting is generally completed within 48 hours; before grouting, water should be prevented from entering the pipe, and when it is necessary to wash the pipe before grouting, compressed air without oil should be used to blow out all the water in the hole after the pipe is washed; S2. Anchorage sealing, the gap between the anchorage device and the clamping piece is sealed with fast-hardening cement to ensure that the steel strand is exposed outside the anchor head; S3. Pipeline installation, the grouting pump inlet is connected with the grout storage barrel through a rubber pipe, and the grouting pump outlet is connected with the grouting pump inlet intelligent measurement and control instrument through a high-pressure pipe; S4. Grout preparation, the weighed water is poured into the grout preparation barrel, then the cement and the grouting agent are poured while stirring, then the remaining water is added to flush the surrounding cement in the grout preparation barrel, and the stirring is continued for 3-5 minutes to make the grout fully and uniformly; then the stirred grout is filtered through a filter screen with a diameter of not greater than 3 mm and then enters the grout storage barrel, and the grout preparation machine impeller is kept rotating; S5. Grout circulation, when the actual water-binder ratio tested by the water-binder ratio sensor in the intelligent grouting system meets the specified requirements, the grouting pump is started to start grouting, and after the thick grout flows out of the return pipe, it is poured into the grout storage barrel to continue stirring the return grout in the grout storage barrel; and the air in the pipe is continuously circulated to be exhausted; S6. Parameter control, after the pulp in the pipeline circulation 3-5 min, the pulp, back to the pulp flow and pressure to stabilize, at this time the control program automatically test record pipeline both ends pressure loss value ΔP, the pressure loss value ΔP meet the requirements of the requirements; S7. Automatic pressure regulation, with the pulp outlet pressure is not less than 0.5 MPa as the lock pressure basis, when the pulp inlet and outlet pressure exceeds 1.5 MPa, the system will start the safety protection, automatic pressure relief; S8. Automatic closing, when the automatic pressure regulation is completed, at the same time, the inlet and outlet pressure meet the set requirements, then control the electro-hydraulic valve in the inlet and outlet pulp measuring and control instrument to close in turn, at the same time, the overflow valve is opened, so that the pulp is diverted to flow back to the slurry tank; In addition, the inlet and outlet manual control switch at both ends need to be closed; S9. Pressure grouting record, when the pressure grouting is completed, the pressure grouting record table is automatically generated and the pressure grouting process record is saved; S10. Cleaning tools, when the pressure grouting is completed, after closing the inlet and outlet manual control switch at both ends, the pipeline can be disconnected for the next hole to continue pressure grouting or flush the pipeline, the grouting machine and the grouting pump. When the pressure grouting is not carried out for a long time, before pressure grouting again, the pipeline and the grouting pump should be checked carefully.

[0008] Further, the application discloses a construction method applied to prestressed pipeline pressure grouting, in the step S3 pipeline installation process, for single-hole grouting, the operation mode is that pressure grouting nozzles are installed on the anchor pad at both ends of a hole to be pressure grouted, and a manual switch control valve is installed on the pressure grouting nozzle; the inlet grouting pipe and the back grouting pipe of the intelligent pressure grouting system are connected with the pressure grouting nozzles at the inlet grouting end and the back grouting end through high-pressure pipes.

[0009] Further, the application discloses a construction method applied to prestressed pipeline pressure grouting, in the step S3 pipeline installation process, for double-hole grouting, the operation mode is that pressure grouting nozzles are installed on the anchor pads of two holes to be pressure grouted; the inlet grouting pipe and the back grouting pipe of the intelligent pressure grouting system are connected to the lower and higher holes at the inlet grouting end respectively, and the two holes at the back grouting end are connected through a short high-pressure pipe.

[0010] Further, the application discloses a construction method applied to prestressed pipeline pressure grouting, in the step S4 slurry preparation process, the water-binder ratio of the prepared slurry is detected, and the slurry is pumped out only when the water-binder ratio meets the requirements; otherwise, the amount of raw materials is adjusted, and the slurry is stirred again; the water-binder ratio is required to be 0.26-0.28.

[0011] Further, the application discloses a construction method applied to prestressed pipeline pressure grouting, in the step S6 parameter control, the pressure loss value ΔP is pre-set to be 0.50±0.10 MPa.

[0012] Further, in the step S8 automatic closing process, when the outlet pressure is 0.5 MPa and the inlet pressure is not more than 1.0 MPa, the control valve in the inlet and outlet measuring and controlling instrument is closed in sequence, that is, the outlet stop valve is closed first, and then the inlet electromagnetic valve is closed, at this time, the inlet pipeline is in a closed state, and the overflow pipeline is in an open state.

[0013] Further, in the step S9 pressure grouting recording process, the pressure grouting recording table includes the water-binder ratio, the filling degree, the grouting pressure and the grouting flow rate parameters, and generates the water-binder ratio-time curve, the flow rate-time curve, the inlet and outlet pressure-time curve, and the pipeline pressure loss-time curve, and when the pressure grouting of a beam body is completed, the pressure grouting recording table of the beam body is generated.

[0014] The application further provides an intelligent pressure grouting system using the construction method, which comprises a grouting unit and a computer. The water-binder ratio testing instrument is connected with the low-speed grout storage barrel, the low-speed grout storage barrel is connected with the mortar pump through the grout suction pipe, the prestressed pipeline is embedded in the beam body to be constructed, and the pressure grouting nozzles are respectively arranged at the inlet and outlet ends of the prestressed pipeline, the mortar pump is connected with the pressure grouting nozzle at the inlet end of the prestressed pipeline through the inlet pipe, the pressure grouting nozzle at the outlet end of the prestressed pipeline is connected with the low-speed grout storage barrel through the return pipe, the inlet measuring and controlling instrument is arranged on the inlet pipe, and the return measuring and controlling instrument is arranged on the return pipe, and the pressure sensors and the control valves are arranged in the inlet measuring and controlling instrument and the return measuring and controlling instrument, wherein the control valves comprise the inlet electromagnetic valve in the inlet measuring and controlling instrument and the outlet stop valve in the return measuring and controlling instrument. The high-speed grout making machine pours the slurry into the low-speed grout storage barrel through the opened bottom valve after the grout making is completed. An overflow valve is further arranged in the inlet pipe, and the low-speed grout storage barrel is connected with the overflow valve through the overflow pipe. The computer is installed with control software, and the computer is used for receiving the pressure sensor measurement data in the water-binder ratio testing instrument, the inlet measuring and controlling instrument and the return measuring and controlling instrument, and simultaneously controlling the opening and closing of the mortar pump, the inlet electromagnetic valve, the outlet stop valve and the overflow valve.

[0015] Furthermore, in the intelligent grouting system described in this invention, manual control switches are respectively installed at the front end of the grouting nozzles between the prestressed duct and the grout inlet pipe, and between the prestressed duct and the return grout pipe.

[0016] The construction method and intelligent grouting system for prestressed duct grouting described in this invention offer several advantages over existing technologies. Firstly, the intelligent grouting system utilizes a circulating grouting method, leveraging the continuity and fluidity of the grout to effectively remove residual air from the duct, thus improving grouting quality. Secondly, the continuous circulation of the grout within the duct and controlled flow rate ensure complete removal of air and other particulate impurities. Thirdly, the system automatically generates and saves grouting records for each hole during the grouting process, guaranteeing stability and reliability and further enhancing grouting quality. Therefore, the construction method and intelligent grouting system described in this invention enable real-time monitoring and recording of the entire grouting operation, ensuring grouting quality. This method is suitable for both single-hole and double-hole grouting, significantly improving grouting efficiency and making it worthy of widespread application. Attached Figure Description

[0017] The present invention will now be described in further detail with reference to the accompanying drawings.

[0018] Figure 1 This is a schematic diagram of the process flow of the construction method described in this invention; Figure 2 This is a schematic block diagram of the intelligent grouting system described in this invention. Detailed Implementation

[0019] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0020] It should be noted that the term "comprising" or any other variation is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Example 1

[0021] like Figure 2 As shown, this embodiment provides an intelligent grouting system for a construction method of prestressed duct grouting. The intelligent grouting system includes a grouting unit and a computer. The grouting unit includes a grout pump, a high-speed grout mixer, a low-speed grout storage tank, a water-cement ratio tester, a grout suction pipe, a grout inlet control instrument, a grout return control instrument, an inlet pipe, a return pipe, an overflow pipe, and a prestressed duct. The water-cement ratio tester is connected to the low-speed slurry storage tank, which is connected to the grout pump via a slurry suction pipe. The prestressed duct is embedded in the beam to be constructed, and grouting nozzles are installed at the slurry inlet and return ends of the prestressed duct. The grout pump is connected to the grouting nozzle at the slurry inlet end of the prestressed duct via a slurry inlet pipe, and the grouting nozzle at the slurry outlet end of the prestressed duct is connected to the low-speed slurry storage tank via a slurry return pipe. The slurry inlet control instrument is installed on the slurry inlet pipe, and the slurry return control instrument is installed on the slurry return pipe. Pressure sensors and control valves are configured in both the slurry inlet control instrument and the slurry return control instrument. The control valves include a solenoid valve at the slurry inlet in the slurry inlet control instrument and a shut-off valve at the slurry outlet in the slurry return control instrument. After pulping is completed, the high-speed pulping machine opens the bottom valve to allow the pulp to be retained into the low-speed storage tank. An overflow valve is also installed in the slurry inlet pipe, and the low-speed slurry storage tank is connected to the overflow valve through the overflow pipe; The computer is equipped with control software. The computer is used to receive measurement data from the pressure sensors in the water-cement ratio tester, the slurry inlet control instrument, and the slurry return control instrument, and simultaneously control the opening and closing of the slurry pump, the slurry inlet solenoid valve, the slurry outlet shut-off valve, and the overflow valve through signals.

[0022] Furthermore, in the intelligent grouting system provided in this embodiment, manual control switches are respectively installed at the front end of the grouting nozzles between the prestressed duct and the grout inlet pipe, and between the prestressed duct and the return grout pipe. Example 2

[0023] like Figure 1 As shown, this embodiment provides a construction method for applying the intelligent grouting system described in Embodiment 1 to prestressed duct grouting. Taking a beam as an example, the method employs a large-circulation intelligent grouting process, using a large-circulation loop. Multiple parameters are monitored and controlled during the grouting process. The method connects the prestressed duct to be grouted to the slurry preparation unit in the intelligent grouting system via pipelines, forming a circulating grouting loop. The slurry pumped from the slurry preparation unit circulates in the pipelines and the prestressed duct until grouting is complete. The construction method includes steps such as construction preparation, anchor sealing, pipeline installation, slurry mixing, slurry circulation, parameter control, automatic pressure adjustment, automatic shutdown, grouting recording, and equipment cleaning. The specific steps are as follows: S1. Construction Preparation When using post-tensioned prestressed structures, rigid plastic pipes should be pre-inserted inside the pipes during concrete pouring to prevent deformation and damage to the corrugated pipes. The diameter of the rigid plastic pipes should preferably be 1cm smaller than the pipe diameter.

[0024] After tensioning is completed, exposed steel strands should be cut off (the exposed steel strands should be ≤30mm after cutting), and then the anchors should be sealed with cement grout. During each construction step before grouting, water should be prevented from entering the pipes. If it is necessary to flush the pipes before grouting, all accumulated water in the ducts should be blown out using oil-free compressed air after flushing. Simultaneously, the equipment involved in the grouting unit of the intelligent grouting system needs to be cleaned regularly. The equipment should be free of residue and water after cleaning, and its normal operation should be checked before grouting.

[0025] S2. Anchoring The gap between the anchor and the wedge is sealed with quick-setting cement, ensuring that the steel strand is exposed outside the anchor head.

[0026] S3. Pipeline connection The grouting pump's inlet is connected to the grout storage tank via a 50 mm nominal diameter hose; the grouting pump's outlet is connected to the inlet intelligent monitoring and control instrument via a 25 mm nominal diameter high-pressure hose. For single-hole grouting, the operation involves installing grouting nozzles on the anchor plates at both ends of the hole to be grouted, with manual control valves on them. The inlet and return pipes of the intelligent grouting system are connected to the inlet and return grouting nozzles respectively via high-pressure hoses. For double-hole grouting, grouting nozzles are installed on the anchor plates of both holes to be grouted. The inlet and return pipes of the intelligent grouting system are connected to the lower and higher inlet holes respectively, while the two return holes are connected via a shorter high-pressure hose.

[0027] S4. Mixing the slurry First, pour the weighed water into the slurry mixing tank (reserve a small amount). Then, while stirring, pour in the cement and grouting agent, add the remaining water to rinse the surrounding cement, and stir for another 3-5 minutes to ensure thorough homogenization. Next, pass the mixed slurry through a filter screen with a diameter no greater than 3mm into the storage tank, ensuring the impeller of the slurry mixer remains rotating continuously. During the slurry mixing process, the water-cement ratio needs to be checked. Only if the ratio meets the requirements should the slurry be pumped out; otherwise, adjust the raw material dosage and re-stir. The required water-cement ratio is 0.26-0.28.

[0028] S5. Slurry circulation After the actual water-cement ratio obtained by the water-cement ratio sensor meets the specified requirements, the grouting pump is started to begin grouting. After the thick grout flows out of the return grout pipe, it is put into the storage tank, so that the return grout continues to be stirred in the storage tank, and the air in the pipeline is purged through continuous circulation.

[0029] S6. Parameter Measurement and Control After the slurry circulates in the pipeline for 3 to 5 minutes, its inlet and outlet flow rates and pressure will tend to stabilize. At this time, the control program automatically tests and records the pressure loss value ΔP at both ends of the pipeline. The pressure loss value ΔP is preset to a pressure range of 0.50 ± 0.10 MPa.

[0030] S7. Automatic voltage regulation The pressure at the slurry outlet is not less than 0.5MPa (the pressure can be appropriately reduced for long and curved pipes; refer to the pressure drop machine parameters for specific values). If the pressure at the inlet or outlet exceeds 1.5MPa, the system will activate safety protection and automatically release pressure.

[0031] S8. Automatic shutdown After automatic pressure regulation ends, both the inlet and outlet pressures meet the set requirements, i.e., the outlet pressure is approximately 0.5 MPa and the inlet pressure does not exceed 1.0 MPa (under normal circumstances). The electro-hydraulic valves inside the inlet and outlet slurry control instruments close sequentially (the outlet shut-off valve closes first, followed by the inlet solenoid valve), while the overflow valve opens, redirecting the slurry flow directly back to the storage tank. Simultaneously, the manual control switches at both the inlet and outlet are closed. At this point, the inlet pipeline is closed, while the overflow pipeline is open.

[0032] In practical applications, longitudinal prestressed steel strands are grouted once. If the grouting quality cannot be guaranteed, grouting holes should be left in sections. Vertical prestressed grouting adopts a circulating grouting process, that is, U-shaped connecting pipes are used at the bottom to connect adjacent grouting holes so that the grouting holes and grout outlet holes are located on the bridge deck. In order to ensure the grouting quality, multiple grouting replenishments should be carried out.

[0033] S9. Grouting Record After grouting of a borehole is completed, a grouting record sheet for that borehole will be generated, along with records of the grouting process, such as water-cement ratio, filling degree, grouting pressure, and grouting flow rate. Water-cement ratio-time curves, flow rate-time curves, inlet / outlet grout pressure-time curves, and pipeline pressure loss-time curves will also be generated. A grouting record sheet for a beam can be generated after grouting is completed.

[0034] S10. Equipment Cleaning After closing the manual control switches for the inlet and outlet grout ports, the pipeline can be disconnected and connected to the next hole to continue grouting (multiple sets of grouting nozzles should be provided) or the pipeline, grout mixer, and grouting pump can be flushed. If grouting has not been performed for a long time, the pipeline and grouting pump should be carefully checked for blockages before grouting is resumed.

[0035] In practical applications of the construction method provided by this invention, if insufficient grouting occurs, preventative and supplementary grouting measures are required. These measures aim to achieve the design requirements through supplementary grouting. Specific preventative measures are as follows: 1. The main reasons for incomplete grouting in prestressed ducts are as follows: The causes of grout leakage include: 1) cross-holes in the upper and lower or left and right ducts; 2) inadequate sealing and anchoring leading to grout leakage; 3) inability to maintain constant pressure during grouting pressurization; 4) the calculated total amount of grout injected into the ducts being less than the total grouting requirement for the ducts; 5) grout not escaping from the vent holes at the top of the wave-shaped curved ducts, especially vertical wave-shaped curved ducts; and 6) grout leakage due to hidden internal defects in the beam body such as honeycomb, troughs, and cracks.

[0036] The above reasons can cause quality hazards such as incomplete or loose grouting, and some of these hazards are not easily detected at the time. Once these quality hazards are caused, failure to detect and properly handle them in time is like planting a time bomb, which will directly affect the service life of the beam.

[0037] 2. Analysis of the causes of loose orifices First, from a design perspective, there are three main situations: First, the designed ducts have narrow gaps after the prestressing tendons are inserted, making it difficult to inject cement grout. Second, the designed duct curves are long, with low curvature and many inflection points. Third, the specified hole-forming materials are inadequate, resulting in a high coefficient of friction within the ducts.

[0038] Secondly, from the perspective of construction technology, there are mainly the following situations: First, poor hole-forming quality during construction, with uneven diameter or misaligned corrugated pipe ducts, neck shrinkage, and prestressing tendons barely able to be inserted, but cement grout cannot pass through. Second, inappropriate selection of hole-forming materials, resulting in rough, collapsed, peeling, wavy, and wrinkled corrugated pipe duct walls. Third, cross-holes, internal leakage, inadequate sealing and anchoring, and inability to maintain pressure and load. Fourth, improper placement of vent holes, leading to poor venting and the formation of air stagnation cavities in certain vertical curve sections, preventing grout entry and causing premature voids. Fifth, in prestressed bundle binding, excessively dense or loose binding wires cause obstruction and accumulation of binding wires outside the ducts during threading, forming mesh plugs that allow water and air to pass through but not grout during grouting. Sixth, improper grout preparation, such as uncontrolled consistency or poor filtration, resulting in blockages caused by hard lumps and impurities. Seventh, an improper water-cement ratio; an excessively high water-cement ratio not only reduces strength but also increases water penetration, as water occupies space and, after evaporation or absorption, forms voids.

[0039] 3. Preventive measures Based on the causes analyzed above, targeted and appropriate solutions should be implemented. In addition, key factors affecting grouting quality should be strictly controlled, and construction techniques should be improved. The preventative measures mainly include the following aspects: First, the gaps between the prestressing tendons outside the anchorage should be filled with epoxy resin grout or cotton cement grout to prevent grout leakage and loss of grouting pressure. Vent holes should be left when sealing the anchorage.

[0040] Secondly, the ducts should be flushed with pressurized water before grouting to remove powder, slag, and debris, ensuring unobstructed flow. After flushing, use an air compressor to blow away any accumulated water, but keep the ducts moist to ensure good bonding between the cement grout and the duct walls. If water seepage or leakage is observed during flushing, the leaks should be plugged immediately. If cross-cutting is found and difficult to handle, the number of cross-cutting ducts should be determined, and several ducts should be grouted simultaneously. Alternatively, after grouting one duct, immediately flush the adjacent ducts thoroughly with high-pressure water.

[0041] Third, grouting should be slow and uniform. Generally, each duct should be grouted once at each end.

[0042] Fourth, the optimal mix ratio: The mix ratio of the grouting material is crucial to the quality of grouting. A well-designed mix ratio is a prerequisite for controlling the quality of grouting in the ducts. A preferred mix ratio of grouting materials can ensure sufficient strength and effectively control the bleeding rate and related expansion coefficients. Proper control of all indicators of the grouting material is essential.

[0043] Fifth, ensure grouting pressure: appropriately increase the grouting pressure holding pressure; grouting should be done using a piston grouting machine, and the grouting pressure should be based on ensuring that the grout material in the hole is dense. The initial pressure should be small and gradually increased. The maximum pressure is generally 0.5 to 0.8 MPa. When the grouting pipeline is long or when grouting is done in one go, the pressure should be increased appropriately. After each hole is grouted to the maximum pressure, there should be a certain stabilization time (not less than 5 minutes). Grouting should reach the point where the other end of the hole is full and grout is discharged, and the vent hole should discharge cement grout with the same consistency as specified before the grout discharge valve can be closed.

[0044] 4. Grouting measures If the prestressed ducts are found to be loose, the following grouting measures should be taken.

[0045] First, select appropriate grouting ports and venting ports. For the four overlapping channels, when channel N1 or N4 is not tight, that is, when the bottom or top channel is not tight, make a hole on the bottom or top surface of the beam; when channel N2 or N3 is not tight, that is, when the middle channel is not tight, make a hole on the side of the beam. The opening position is where the grouting is not tight after inspection.

[0046] The second method is mechanical drilling, which involves using an electric drill to drill holes at the predetermined positions at both ends of the channel. When drilling, the following precautions should be taken: First, avoid disturbing the surrounding concrete; second, control the drilling depth, ideally drilling to the position of the corrugated tube, and then enlarging the hole after reaching this position; third, take special care to prevent the drilling machine from damaging the reinforcing bars and steel strands.

[0047] Third, install the exhaust pipe and grouting port pipe, and pre-embed them in the opening position with cement grout of the same strength.

[0048] Fourth, after the grouting material reaches the design strength, the duct is injected with grout to meet the design requirements.

[0049] Therefore, the construction method and intelligent grouting system for prestressed duct grouting described in this invention, utilizing the intelligent grouting system and the circulating grouting method, leverages the continuity and sufficient fluidity of the grout to effectively remove residual air from the duct, thereby improving grouting quality. Simultaneously, the continuous circulation of the grout within the duct and the controlled flow rate ensure complete removal of air and other particulate impurities. Furthermore, the system automatically generates and saves grouting record sheets for each hole during the grouting process, guaranteeing the stability and reliability of the entire grouting process and further improving grouting quality.

[0050] In summary, the construction method and intelligent grouting system described in this invention can monitor and record the entire grouting process in real time, thereby ensuring grouting quality. It is suitable not only for single-hole grouting but also for double-hole grouting, greatly improving the efficiency of grouting work and is worthy of widespread application.

[0051] Other aspects of this invention that are not detailed herein are all conventional techniques known to those skilled in the art.

[0052] The scope of protection of this invention is not limited to the technical solutions disclosed in the specific embodiments. The above description is only a preferred embodiment of this invention and does not limit this invention. Any minor modifications, equivalent substitutions and improvements made based on the technical solutions of this invention should be included within the scope of protection of the technical solutions of this invention.

Claims

1. A construction method for grouting prestressed ducts, characterized in that: The construction method employs an intelligent grouting system, which connects the prestressed pipe to be grouted to the slurry preparation unit in the intelligent grouting system through pipelines to form a circulating grouting loop. This allows the slurry pumped from the slurry preparation unit in the intelligent grouting system to circulate in the pipelines and prestressed pipes until grouting is completed.

2. The construction method for grouting prestressed ducts according to claim 1, characterized in that: The construction method includes the following steps: construction preparation, anchor sealing, pipeline installation, grout mixing, grout circulation, parameter control, automatic pressure adjustment, automatic shutdown, grouting record keeping, and equipment cleaning. The specific steps are as follows: S1. Construction preparation: When pouring concrete, pre-insert rigid plastic pipes into the pipes to prevent deformation and damage to the corrugated pipes. The diameter of the rigid plastic pipes should be 1cm smaller than the pipe diameter. After tensioning, the exposed steel strands should be cut off. After cutting with a cutting machine, the exposed steel strands should be ≤30mm. Then, use non-shrink cement mortar to seal the ends, install a one-time grout stop valve, and connect the grouting ducts with series pipes to ensure that the entire pressure system can be used normally, preparing for the grouting of the prestressed pipes. The ducts should be grouted as early as possible, generally within 48 hours. Before grouting, prevent water from entering the pipes. If it is necessary to flush the pipes before grouting, use oil-free compressed air to blow out all the water in the ducts after flushing. S2. Anchor sealing: Use quick-setting cement to seal the gap between the anchor and the wedge to ensure that the steel strand is exposed outside the anchor head; S3. Piping installation: The grouting pump inlet is connected to the grout storage tank via a rubber hose, while the grouting pump outlet is connected to the inlet intelligent monitoring and control instrument via a high-pressure pipe. S4. Mix the slurry. Pour the weighed water into the slurry mixing tank, then pour in the cement and grouting agent while stirring. Then add the remaining water to rinse the cement around the inside of the slurry mixing tank, and stir for 3-5 minutes to make it fully uniform. After that, pass the mixed slurry through a filter screen with a diameter of no more than 3mm into the slurry storage tank, and keep the impeller of the slurry mixer rotating. S5. Grout circulation: When the actual water-cement ratio measured by the water-cement ratio sensor in the intelligent grouting system meets the specified requirements, the grouting pump is started to begin grouting. After the thick grout flows out of the return grout pipe, it is put into the grout storage tank, so that the return grout continues to be stirred in the grout storage tank; and the air in the pipeline is purged through continuous circulation. S6. Parameter control: After the slurry circulates in the pipeline for 3 to 5 minutes, the slurry inlet and outlet flow rates and pressure tend to stabilize. At this time, the control program automatically tests and records the pressure loss value ΔP at both ends of the pipeline. The pressure loss value ΔP is required to meet the specified requirements. S7. Automatic pressure regulation, with the pressure at the slurry outlet not less than 0.5MPa as the locking basis. When the pressure at the inlet or outlet exceeds 1.5MPa, the system will activate safety protection and automatically release pressure. S8. Automatic shutdown: After the automatic pressure regulation ends, and the inlet and outlet pressures both meet the set requirements, the electro-hydraulic valves in the slurry inlet and outlet control instruments will close in succession, while the overflow valve will open, allowing the slurry to flow back directly to the slurry storage tank. In addition, the manual control switches at both ends of the slurry inlet and outlet ports need to be closed. S9. Grouting Record: After grouting is completed, a grouting record table for that hole is automatically generated and the grouting process record is saved. S10. Clean the equipment. After grouting is completed, close the manual control switches at both ends of the inlet and outlet of the grout. Then, the pipeline can be disassembled and connected to the next hole to continue grouting or to flush the pipeline, grouting machine and grouting pump. If grouting has not been carried out for a long time, the pipeline and grouting pump should be carefully checked for unobstructed flow before grouting again.

3. The construction method for grouting prestressed ducts according to claim 2, characterized in that: During the pipeline installation process in step S3, for single-hole grouting, the operation method is as follows: grouting nozzles are installed on the anchor plates at both ends of the hole to be grouted, and manual switch control valves are installed on them. The grout inlet pipe and grout return pipe in the intelligent grouting system are connected to the grouting nozzles at the grout inlet end and the grout return end respectively with high-pressure pipes.

4. The construction method for grouting prestressed ducts according to claim 2, characterized in that: During the pipeline installation process in step S3, for dual-hole grouting, the operation method is as follows: grouting nozzles need to be installed on both anchor plates of the two holes to be grouted. The grout inlet pipe and return pipe of the intelligent grouting system are connected to the lower and higher holes of the grout inlet end, respectively. At the same time, the two holes of the return end are connected with a short high-pressure pipe.

5. A construction method for grouting prestressed ducts according to claim 2, characterized in that: During the slurry mixing process in step S4, the water-cement ratio of the slurry is tested. Only if the requirement is met can the slurry be pumped out. Otherwise, the amount of raw materials is adjusted and the slurry is remixed. The required water-cement ratio is 0.26 to 0.

28.

6. The construction method for grouting prestressed ducts according to claim 2, characterized in that: In the parameter control step S6, the pressure loss value ΔP is preset to a pressure range of 0.50 ± 0.10 MPa.

7. A construction method for grouting prestressed ducts according to claim 2, characterized in that: During the automatic shutdown process in step S8, when the outlet pressure is 0.5MPa and the inlet pressure does not exceed 1.0MPa, the control valves in the inlet and outlet measuring and control instrument are closed in the following order: first, the outlet shut-off valve is closed, and then the inlet solenoid valve is closed. At this time, the inlet pipeline is closed, while the overflow pipeline is open.

8. A construction method for grouting prestressed ducts according to claim 2, characterized in that: During the grouting recording process in step S9, the grouting record table includes parameters such as water-cement ratio, filling degree, grouting pressure, and grouting flow rate, and generates water-cement ratio-time curves, flow rate-time curves, inlet and outlet grout pressure-time curves, and pipeline pressure loss-time curves. When the grouting of a beam is completed, the grouting record table for that beam is generated.

9. An intelligent grouting system applied to the construction method according to any one of claims 1 to 8, characterized in that: The intelligent grouting system includes a grouting unit and a computer. The grouting unit includes a grout pump, a high-speed grouting machine, a low-speed grout storage tank, a water-cement ratio tester, a grout suction pipe, a grout inlet control instrument, a grout return control instrument, a grout inlet pipe, a grout return pipe, an overflow pipe, and a prestressed pipe. The water-cement ratio tester is connected to the low-speed slurry storage tank, which is connected to the grout pump via a slurry suction pipe. The prestressed duct is embedded in the beam to be constructed, and grouting nozzles are installed at the slurry inlet and return ends of the prestressed duct. The grout pump is connected to the grouting nozzle at the slurry inlet end of the prestressed duct via a slurry inlet pipe, and the grouting nozzle at the slurry outlet end of the prestressed duct is connected to the low-speed slurry storage tank via a slurry return pipe. The slurry inlet control instrument is installed on the slurry inlet pipe, and the slurry return control instrument is installed on the slurry return pipe. Pressure sensors and control valves are configured in both the slurry inlet control instrument and the slurry return control instrument. The control valves include a solenoid valve at the slurry inlet in the slurry inlet control instrument and a shut-off valve at the slurry outlet in the slurry return control instrument. After pulping is completed, the high-speed pulping machine opens the bottom valve to allow the pulp to be retained into the low-speed storage tank. An overflow valve is also installed in the slurry inlet pipe, and the low-speed slurry storage tank is connected to the overflow valve through the overflow pipe; The computer is equipped with control software. The computer is used to receive measurement data from the pressure sensors in the water-cement ratio tester, the slurry inlet control instrument, and the slurry return control instrument, and simultaneously control the opening and closing of the slurry pump, the slurry inlet solenoid valve, the slurry outlet shut-off valve, and the overflow valve through signals.

10. The intelligent grouting system according to claim 9, characterized in that: Manual control switches are installed at the front end of the grouting nozzles between the prestressed duct and the grout inlet pipe, and between the prestressed duct and the return grout pipe.

Images