Railway bridge drilling construction method

Abstract

The invention provides a railway bridge drilling construction method, and belongs to the technical field of bridge engineering. The railway bridge drilling construction method comprises the steps that construction preparation is conducted, specifically, site leveling, tamping and marking are conducted in the construction preparation; and the pile casing is buried to ensure that the pile casing is vertical and is prevented from inclining. Small-stroke trepanning is adopted, so that the hole wall of the primarily-formed hole is firm, vertical and smooth; the drill bit cleans holes for the first time, and sediments are removed; after the reinforcement cage and the guide pipe are installed, secondary hole cleaning is conducted; hole walls are prevented from being collided in the mounting and lowering process of the reinforcement cage; concrete is poured, and a guide pipe is used for pouring the concrete into the hole; and detecting and accepting. Through the steps of construction preparation, pile casing embedding, drilling, two-time hole cleaning, reinforcement cage mounting, concrete pouring, detection, acceptance inspection and the like, high-quality drilling operation is achieved, the forming quality of follow-up cast-in-place piles is improved, the overall supporting performance of a bridge is improved, and the good anti-sedimentation effect is achieved.

Description

Technical Field

[0001] The invention relates to the field of bridge engineering, and in particular to a railway bridge drilling construction method. Background Art

[0002] The construction process of bored cast-in-place piles is a complex and delicate process that needs to be carried out strictly in accordance with construction specifications and design requirements to ensure the quality of the pile body and construction safety.

[0003] The current technology of bridge bored piles requires drilling during pouring. The quality of the drilling during the construction process plays an important role in the quality of the subsequent bored pile pouring. High-quality drilling can effectively improve the bearing capacity of the bridge after pouring the piles, and also has a good control effect on settlement. Summary of the invention

[0004] In order to make up for the above shortcomings, the present invention provides a railway bridge drilling construction method, which aims to improve the general problem of drilling forming quality during the construction process.

[0005] The present invention is achieved in that:

[0006] The present invention provides a railway bridge drilling construction method, comprising:

[0007] Construction preparation, which includes leveling and compacting the site, accurately staking out the bored pile positions using the total station coordinate method, and marking around the casing;

[0008] When burying the casing, ensure that it is vertical and avoid tilting, and make adjustments according to the actual situation;

[0009] When drilling holes, use a small stroke to make the hole wall solid, vertical and smooth. During the drilling process, the stroke should be adjusted according to the soil conditions, and mud should be used to protect the wall during the drilling process.

[0010] The hole is cleaned twice. When the hole is drilled to the designed pile bottom elevation, the drill bit is raised to clean the hole for the first time to remove the sediment. After the steel cage and the guide tube are installed, the hole is cleaned for the second time.

[0011] Installation of the steel cage: Use drilling rig tower, jack or crane to align the steel cage with the center of the casing and slowly lower it to the designed elevation. Avoid collision with the hole wall during the lowering process.

[0012] Pour concrete into the hole using a conduit. During the pouring process, control the pouring speed and amount to avoid concrete segregation or bubble generation;

[0013] Inspection and acceptance: inspect and accept drilling and concrete to ensure that the construction quality meets the requirements.

[0014] In one embodiment of the present application, the construction preparation may adopt an island construction method for shallow water areas and a cofferdam construction method for deep water areas.

[0015] In one embodiment of the present application, the casing burying depth in the casing burying step is generally 2 to 4 meters.

[0016] In one embodiment of the present application, in the step of burying the casing, the casing is symmetrically filled and compacted in layers around it with clay after burying.

[0017] In one embodiment of the present application, during the drilling step, the water level in the hole is maintained at more than 500 mm above the bottom of the casing, and water is replenished in time to maintain the water head height.

[0018] In one embodiment of the present application, the second hole cleaning in the hole cleaning step uses a vacuum circulation system or a mud pump or other equipment to press the mud into the bottom of the hole, and the debris is discharged from the hole mouth.

[0019] In one embodiment of the present application, the drilling inspection in the inspection and acceptance step should inspect the completed hole, including indicators such as hole depth, hole diameter, and inclination.

[0020] In one embodiment of the present application, the concrete pile pouring inspection in the inspection and acceptance step includes indicators such as strength and density.

[0021] The beneficial effects of the present invention are as follows: the railway bridge drilling construction method obtained by the present invention through the above-mentioned design realizes high-quality drilling operations through the steps of construction preparation, burying casing, drilling, twice cleaning holes, installing steel cages, pouring concrete, testing and acceptance, and improves the subsequent cast-in-place pile forming quality, that is, improves the overall supporting performance of the bridge and has a good anti-settlement effect. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Example

[0024] The present invention provides a railway bridge drilling construction method, comprising:

[0025] Construction preparation, the construction preparation includes site leveling and compaction, accurate positioning of bored piles using total station coordinate method, and marking around casing. For shallow water areas, the construction preparation can adopt island construction method, and for deep water areas, the cofferdam method can be adopted.

[0026] The specific steps of the total station coordinate method for accurate stakeout of bored pile positions include the preparation stage: tool preparation, total station, tripod, prism, wooden piles, nails, concrete, etc. Check the performance of the total station to ensure that it is in good working condition. Set up the total station: Set up the total station at the base point, which should have accurate coordinates. Turn on the total station, turn the telescope, and turn on the laser for centering. Perform the leveling operation, only move two of the tripods up and down, level the circular level, and then adjust the tube level for fine leveling. Check whether the center point is centered. If there is a deviation, move the instrument and adjust it for fine leveling. Repeat the operation until it is centered. Set the station parameters: Enter the menu item of the total station and select the stakeout measurement mode. Enter the station settings and enter the coordinates of the station base point. Enter the coordinates of the backsight point, and after aligning the instrument crosshairs with the center of the backsight prism, press the OK key. At this time, the instrument has set the coordinates and orientation. Coordinate re-measurement: Find a known coordinate point to re-measure the coordinates to confirm whether the total station is set correctly. If the re-measurement result is not much different from the known coordinates, the next step of field measurement can be carried out. Stakeout measurement: Set up the prism at the re-measurement point, level it, and align the telescope crosshairs with the center of the prism. Select the coordinate measurement mode, enter the coordinates and compare them with the existing coordinates, and then perform the stakeout measurement after confirming that they are correct. Enter the stakeout data in the stakeout measurement, enter the coordinates of the bored pile position to be measured for measurement. After entering the coordinates, adjust them according to the angle and azimuth displayed on the instrument, and move the prism to the correct position for distance measurement. According to the distance displayed on the instrument, adjust the prism appropriately forward and backward until the error displayed on the instrument is a few millimeters or even smaller. At this time, the position of the prism is the position of the unknown point to be measured. Mark the stake position: Drive a wooden stake on the unknown point measured, and nail it with a nail to mark the stake position. Use concrete to protect the stakes around to prevent them from loosening.

[0027] The construction of the island construction method includes surveying and setting out: according to the design drawings, determine the scope and shape of the island construction, and conduct precise surveying and setting out. Material preparation: prepare the materials required for island construction, such as slag, stone, earthwork, etc. Island construction: according to the results of surveying and setting out, pile up materials near the hole position to form an artificial island. During the island construction process, it is necessary to ensure that the stability and height of the island meet the construction requirements. Equipment placement: Drilling equipment is placed on the island construction to carry out drilling operations. Subsequent processing: after the drilling operation is completed, necessary subsequent processing is carried out, such as cleaning the pile head and non-destructive detection.

[0028] The cofferdam construction method includes construction preparation: including on-site investigation, preparation of design drawings, material preparation and organization of construction teams. It is necessary to understand the geological conditions, hydrological conditions and surrounding environment of the construction area in detail to determine the location, size and construction method of the cofferdam. Cofferdam filling and reinforcement: According to the design requirements, appropriate materials and processes are used to fill the cofferdam. During the filling process, the quality of materials and the density of filling need to be strictly controlled. At the same time, the cofferdam needs to be reinforced to improve its stability and anti-scouring ability. Drainage and excavation: Drainage facilities are set up in the cofferdam to drain the accumulated water. Then the foundation pit is excavated according to the design requirements to prepare for the construction of buildings. Building construction: Buildings such as gates and dam bodies are built in the cofferdam according to the design requirements. During the construction process, the construction quality needs to be strictly controlled to ensure the stability and durability of the building. Cofferdam removal: After the building is completed, the cofferdam is removed according to the design requirements. Safety should be paid attention to during the removal process to avoid damage to permanent buildings and the surrounding environment.

[0029] The casing is buried to ensure that it is vertical and avoid tilting, and is adjusted according to actual conditions; the casing burial depth in the casing burial step is generally 2 to 4 meters. After the casing is buried, clay is used to fill and compact the casing symmetrically in layers around it.

[0030] Burying casing is an important part of bored pile construction. The following are the specific construction operations for burying casing: Select the material and specifications of casing: Material, casing is usually made of steel, because steel has high strength and toughness, which can meet the requirements of bored pile construction. In addition, there are also casings made of cast iron, plastic and other materials, but the scope of use is relatively narrow. Specifications, the specifications of casing include diameter, wall thickness and height. The diameter is usually determined according to the pile diameter, which is generally 2040cm larger than the pile diameter; the wall thickness is generally 48mm to ensure the strength and stability of the casing; the height is determined according to the construction requirements, and it should generally be higher than the ground or water surface by a certain distance. The specific construction steps for burying casing: Measurement and layout, according to the design drawings, determine the buried position and elevation of the casing, and carry out precise measurement and layout. Dig a pit for burying, dig a pit at the location of measurement and layout, and the depth and diameter of the pit should be slightly larger than the specifications of the casing. Put the casing into the pit, adjust its position and elevation, and ensure that the vertical line of the center of the casing coincides with the center line of the pile. Backfill and compaction: Backfill clay around the casing and tamp it layer by layer to ensure the stability and sealing of the casing. During the backfilling process, attention should be paid to checking whether the casing is vertical. If there is any deviation, it should be corrected in time. Inspection and acceptance: After the burial is completed, the casing should be inspected and accepted, including checking the position, elevation, verticality and sealing of the casing. Only after ensuring that the casing meets the construction requirements can the next step of drilling be carried out.

[0031] Among them, there are also precautions for burying casing, including that the plane position of the casing should be buried correctly: the deviation should not be greater than 50mm to ensure the accuracy of the pile hole position. The top elevation of the casing should be higher than the groundwater level and the highest construction water level: generally 1.5-2.0m higher to prevent water erosion and collapse. The bottom of the casing should be lower than the lowest construction water level: generally lower than 0.1-0.3m to ensure that the casing can effectively isolate surface water. Pay attention to the connection quality of the casing: the casing connection should be resistant to tension and pressure, and leak-proof to ensure the overall stability and sealing of the casing. Strengthen construction monitoring: During the process of burying the casing and drilling, the observation of the settlement and displacement of the casing should be strengthened to ensure construction safety.

[0032] Drilling, use a small stroke to make the hole wall solid, vertical and smooth. During the drilling process, the stroke should be adjusted according to the soil conditions, and mud should be used to protect the wall. During the drilling step, keep the water level in the hole higher than the bottom of the casing by more than 500mm, and add water in time to maintain the water head height.

[0033] Small-stroke drilling is a special drilling method that uses shock waves to act on the drill bit. The shock waves generated by the drill bit during the drilling process remove loose soil or rock debris from the hole, thereby realizing the detection of the depth of the borehole. The key points of construction include: selecting appropriate drill bits and shock wave parameters. According to the specific requirements and geological conditions of the drilling project, select appropriate drill bits and shock wave parameters to ensure the quality and accuracy of the drilling. Control the feed speed and rotation speed of the impact drill. When drilling, it is necessary to control the feed speed and rotation speed of the impact drill to avoid the drill bit being too fast or too slow, resulting in a decrease in the quality of the drilling. Pay attention to safety precautions. When using an impact drill for small-stroke drilling, you need to pay attention to safety precautions, such as wearing protective glasses, gloves, etc., to avoid accidents.

[0034] Precautions for drilling with a small stroke include maintaining the water level in the hole: During the drilling process, the water level in the hole should always be kept a certain distance above the groundwater level and below the top surface of the casing to prevent water erosion and collapse. Timely cleaning of drill cuttings: Drill cuttings should be cleaned in time during the drilling process to prevent the accumulation of drill cuttings from affecting the quality and progress of drilling. Strengthening construction monitoring: During the drilling process, the monitoring of parameters such as drilling depth, hole diameter, and inclination should be strengthened to ensure the quality and accuracy of drilling.

[0035] Mud wall protection is mainly achieved by injecting mud during the drilling process. The mud generates static pressure on the slot wall or hole wall, thereby forming a layer of mud skin on the slot wall or hole wall. This layer of mud skin can effectively prevent the slot wall or hole wall from collapsing and protect the hole wall. The steps of mud wall protection include preparing mud: the mud is generally composed of water, clay and additives. The mud consistency is determined according to the drilling method and the formation conditions. The mud consistency should be flexibly controlled according to the formation changes or operation requirements. The parameters such as the specific gravity, viscosity, and pH value of the mud need to be strictly controlled to ensure that the mud has a good wall protection effect. Installing casing: The casing is made of a steel plate of a certain thickness, and the inner diameter should be a certain size larger than the drill bit diameter. The setting of the casing not only plays the role of positioning and protecting the pile hole, but also plays the role of isolating water from seeping into the hole when the groundwater level is high or underwater construction. When burying the casing, it must be ensured to be accurate, firm and stable. Drilling and wall protection: Use a hole-forming machine to drill holes. During the drilling process, mud is continuously injected. The mud is injected into the hole through the drill rod or mud pipe, and the drilling debris is discharged out of the hole. The mud forms static pressure in the hole to keep the hole wall stable. Hole cleaning and inspection: After the hole reaches the designed depth, it is necessary to clean the hole to remove the sediment and silt at the bottom of the hole. After cleaning the hole, check whether the parameters such as hole position, hole diameter, hole depth, and inclination meet the design requirements.

[0036] The hole is cleaned twice. When the hole is drilled to the designed pile bottom elevation, the drill bit is raised to clean the hole for the first time to remove the sediment. After the steel cage and the guide tube are installed, the hole is cleaned for the second time. The second hole cleaning in the hole cleaning step uses a vacuum circulation system or a mud pump and other equipment to press the mud into the bottom of the hole, and the debris is discharged from the hole mouth.

[0037] The working principle of hole cleaning with vacuum circulation system is based on the negative pressure principle. During the hole cleaning process, the vacuum pump or other negative pressure equipment is connected to the hole through the drill pipe or other pipeline to generate a negative pressure environment. The mud and drilling cuttings in the hole are sucked into the pipeline under the action of negative pressure and discharged out of the hole together with the mud. In this way, the drilling cuttings and excess mud in the hole are effectively removed, providing good conditions for subsequent construction steps such as concrete pouring. The specific cleaning steps include the preparation stage: check whether the performance of the vacuum pump or other negative pressure equipment is good to ensure that the equipment can work normally. At the same time, prepare the necessary hole cleaning tools such as drill pipes and pipelines. Connect the pipeline: connect the vacuum pump or other negative pressure equipment to the drill pipe or pipeline to ensure that the connection is tight and leak-free. Start the equipment: start the vacuum pump or other negative pressure equipment to generate a negative pressure environment. Hole cleaning operation: under the action of negative pressure, the mud and drilling cuttings in the hole are sucked into the pipeline and discharged out of the hole together with the mud. During the hole cleaning process, it is necessary to constantly observe the situation in the hole to ensure a good hole cleaning effect. End of hole cleaning: When the mud and drilling cuttings in the hole are basically cleaned out, turn off the vacuum pump or other negative pressure equipment to end the hole cleaning operation.

[0038] To install the steel cage, use a drilling rig tower, a pick or a crane and other equipment to align the steel cage with the center of the casing and slowly lower it to the designed elevation. During the lowering process, avoid colliding with the hole wall. The preparation work of the steel cage includes the production of the steel cage: when the steel cage is produced, the quality of the steel bars and the steel skeleton should be ensured to meet the design requirements. The reinforcing hoops should be arranged reasonably, the main bars should be arranged evenly, and the joints of the butt welding or arc welding should be straight to avoid the conduit being stuck during construction. Lifting point arrangement: The lifting points of each section of the steel cage should be evenly arranged, usually 100cm below the top of the steel cage, with a total of 4 points evenly arranged. Weld a 25cm long and 16mm thick steel plate on two adjacent main bars, with a 60mm hole in the steel plate, as the steel cage lifting point. Protective layer pad: In order to give the main bars of the steel cage a certain protective layer, a protective layer pad needs to be set on the outside of the steel cage. The thickness of the protective layer pads is usually 75mm. A group of pads is set every 2m along the length of the steel cage. Each group of pads has 6 blocks symmetrically set along the circumferential direction of the steel cage load surface, and the pads are all set on the main reinforcement.

[0039] The installation of the steel cage includes lowering the steel cage: the steel cage is hoisted by a hoisting machine. It should be lowered slowly when lowering. If resistance is encountered, the lowering should be stopped. The cause should be found out and dealt with before continuing. It is strictly forbidden to lift and drop, collide and force lower. Butt joint and welding: For steel cages made in sections, vertical welding is required in the hole. First, lower the upper section of the steel cage to a certain distance above the top of the platform, and fix it with tools such as a hoist. Then lower the lower section of the steel cage to the top of the hole, so that the main bars of the upper and lower sections of the steel cage are aligned, and the upper and lower axes are consistent. Then weld, and the welding method is determined according to the length of the steel cage and the diameter of the main bars, such as single-sided welding or double-sided welding. Acoustic detection tube installation: The acoustic detection tube is used to detect the quality of the pile body. Its extension should be threaded, and it should be watertight when extending. At the same time, the top of the acoustic detection tube should be covered with a steel plate to prevent sand, gravel, garbage, etc. from falling into the acoustic detection tube during the extension process. Protective layer block welding: After all the joints of the steel cage are connected, the protective layer blocks need to be welded to ensure that the steel cage maintains the correct position during the concrete pouring process.

[0040] Pour concrete into the hole using a conduit. During the pouring process, control the pouring speed and amount to avoid concrete segregation or bubble generation.

[0041] During bored cast-in-place pile construction, controlling the pouring speed and pouring volume is crucial to ensure the quality of concrete and avoid concrete segregation or bubble generation.

[0042] Control the pouring speed: In the initial stage, during the initial stage of concrete pouring, pouring should be carried out at a faster speed to quickly fill the bottom of the borehole and prevent the bottom concrete from setting or mixing with impurities. In the adjustment stage, as the pouring proceeds, the pouring speed should be reasonably adjusted according to the actual situation of the concrete and the depth of the borehole. When the concrete surface approaches the bottom of the steel cage, the pouring speed should be slowed down to reduce the impact on the steel cage and prevent the steel cage from floating up. During the pouring process, a stable pouring speed should be maintained to avoid sudden acceleration or deceleration to reduce the stress changes inside the concrete. In the final stage, when the concrete pouring approaches the design elevation, the pouring speed should be gradually slowed down, and attention should be paid to observing the grouting at the orifice to ensure that the concrete fully fills the borehole.

[0043] Control the pouring volume: calculate the initial pouring volume. According to the distance between the bottom of the conduit and the bottom of the hole and the buried depth of the conduit, calculate the initial pouring volume according to the formula to ensure that the bottom of the borehole is fully filled. Monitor the buried depth of the conduit. During the pouring process, the buried depth of the conduit should be kept between 2-6m to avoid the conduit being pulled out and the pile being broken. When the length of the lowest section of the conduit in the poured concrete exceeds 2m, the conduit can be dismantled in sections at a steady speed, but the dismantling speed should not be too fast. Avoid excessive pouring. Excessive pouring should be avoided to prevent concrete from overflowing the borehole and causing waste and pollution. When the measured concrete volume has exceeded the height of the lowest section of the conduit, the lifting speed and height of the conduit need to be increased to ensure the smooth pouring of the concrete.

[0044] Avoid concrete segregation or bubbles: Concrete mixing, the concrete mixture must be uniform to prevent segregation. If a pipe is stuck, use a long rod to pound the concrete in the pipe. If it does not work, treat it as a broken pile. Appropriately move the conduit. During the pouring process, the conduit should be moved up and down appropriately to lead the formed high-pressure bubbles out of the pile body. Use retarders and add appropriate retarders to ensure that the concrete is poured underwater before the initial setting to avoid bubbles or segregation due to the initial setting. Observation and adjustment. During the pouring process, the pouring of the concrete should be continuously observed, including the quality of the concrete, the pouring speed, the buried depth of the conduit, etc., and necessary adjustments should be made according to the actual situation.

[0045] Inspection and acceptance: inspect and accept the drilling and concrete to ensure that the construction quality meets the requirements. The drilling inspection in the inspection and acceptance step should inspect the finished holes, including indicators such as hole depth, hole diameter, and inclination. The concrete pile pouring inspection in the inspection and acceptance step includes indicators such as strength and density.

[0046] This railway bridge drilling construction method achieves high-quality drilling operations through the steps of construction preparation, burying casing, drilling, twice cleaning the hole, installing steel cages, pouring concrete, testing and acceptance, etc., and improves the subsequent casting pile forming quality, that is, improves the overall supporting performance of the bridge and has a good anti-settlement effect.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A railway bridge drilling construction method, characterized in that: include Construction preparation, which includes leveling and compacting the site, accurately staking out the bored pile positions using the total station coordinate method, and marking around the casing; When burying the casing, ensure that it is vertical and avoid tilting, and make adjustments according to the actual situation; When drilling holes, use a small stroke to make the hole wall solid, vertical and smooth. During the drilling process, the stroke should be adjusted according to the soil conditions, and mud should be used to protect the wall during the drilling process. The hole is cleaned twice. When the hole is drilled to the designed pile bottom elevation, the drill bit is raised to clean the hole for the first time to remove the sediment. After the steel cage and the guide tube are installed, the hole is cleaned for the second time. Installation of the steel cage: Use drilling rig tower, jack or crane to align the steel cage with the center of the casing and slowly lower it to the designed elevation. Avoid collision with the hole wall during the lowering process. Pour concrete into the hole using a conduit. During the pouring process, control the pouring speed and amount to avoid concrete segregation or bubble generation; Inspection and acceptance: inspect and accept drilling and concrete to ensure that the construction quality meets the requirements.

2. A railway bridge drilling construction method according to claim 1, characterized in that: The construction preparation may adopt the island construction method for shallow water areas and the cofferdam construction method for deep water areas.

3. A railway bridge drilling construction method according to claim 1, characterized in that: The casing burying depth in the casing burying step is generally 2 to 4 meters.

4. A railway bridge drilling construction method according to claim 3, characterized in that: In the step of burying the casing, the casing is filled and compacted symmetrically in layers around it with clay after being buried.

5. A railway bridge drilling construction method according to claim 1, characterized in that: During the drilling step, the water level in the hole is kept at least 500 mm higher than the bottom of the casing, and water is added in time to maintain the water head height.

6. A railway bridge drilling construction method according to claim 1, characterized in that: The second hole cleaning in the hole cleaning step uses a vacuum circulation system or a mud pump and other equipment to press the mud into the bottom of the hole, and the debris is discharged from the hole mouth.

7. A railway bridge drilling construction method according to claim 1, characterized in that: The drilling inspection in the inspection and acceptance steps should be carried out on the finished holes, including indicators such as hole depth, hole diameter, inclination, etc.

8. A railway bridge drilling construction method according to claim 1, characterized in that: The concrete pile pouring test in the testing and acceptance steps includes indicators such as strength and density.