Cast-in-situ bored pile construction method
Through measures such as precise pile positioning using a total station, standardized site leveling and casing burial, vertical drilling control, mud circulation and continuous grouting, the problems of pile position deviation, hole mouth collapse and concrete quality in bored pile construction were solved, achieving improvements in construction accuracy and quality.
Patent Information
- Application Number
- CN202511209908.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-27
- Publication Date
- 2025-10-21
AI Technical Summary
In the existing bored pile construction, there are problems such as pile position layout being easily affected by human operation or environmental factors, resulting in deviation, improper site treatment causing drilling rig tilt and settlement, and improper casing burial, which can easily lead to hole collapse or mud leakage.
The process involved precise pile positioning using a total station, standardized site leveling and platform construction, and the use of 10mm thick A3 steel plates to roll steel casings. This was combined with crosshair positioning and compaction with impurity-free clay to ensure casing sealing. After the drilling rig was in place, the center of the steel wire rope was aligned with the pile center. During drilling, the rig was operated with vertical, light pressure and slow rotation. The process also incorporated mud circulation and sedimentation box testing. The reinforcing cage was fabricated and hoisted in sections, the guide pipe was lubricated, and concrete was continuously poured. Strict control was maintained over the mud specific gravity and concrete slump.
It improves the pile positioning accuracy, enhances the stability of the construction site, prevents hole collapse and mud leakage, ensures the stability of pile hole formation, improves the quality of steel cage and concrete pouring density, reduces slag sediment in inclined holes and mud inclusion in broken piles, and improves the reliability and quality of construction.
Smart Images
Figure CN120819093A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of bridge foundation engineering construction, in particular to a bored cast-in-place pile construction method. Background Art
[0002] Bored cast-in-place piles are a common foundation engineering construction technology and are widely used in engineering fields such as bridges, buildings, and water conservancy projects. They form pile holes through mechanical drilling, then lower the steel cage and pour concrete to eventually form a load-bearing structure. They have the characteristics of strong adaptability, high bearing capacity, and relatively small impact on the surrounding environment. In the existing technology, bored cast-in-place pile construction usually includes pile position layout, site preparation, casing burial, drilling rig placement, drilling, hole cleaning, steel cage installation and concrete pouring.
[0003] However, the existing construction methods have many problems in actual operation: the pile position layout relies on traditional measuring tools, which are easily affected by human operation or environmental factors, resulting in large pile position deviations; the site treatment is simple and rough, especially on steep slopes or soft soil sections, which can easily cause the drilling rig to tilt and settle, affecting the drilling accuracy; the casing is not buried in a standardized manner, and the gap is not filled properly, which can easily cause the hole mouth to collapse or mud leakage. Therefore, a bored cast-in-place pile construction method is proposed. Summary of the Invention
[0004] In view of the deficiencies in the prior art, the present invention provides a bored cast-in-place pile construction method to solve the problems raised in the above background technology.
[0005] To achieve the above object, the present invention provides the following technical solution: a bored cast-in-place pile construction method, comprising the following steps: Step 1: Construction Preparation: Use a total station to place piles according to the baseline control network and the design coordinates of the piers to improve the accuracy of pile positioning and reduce pile position deviations caused by human and environmental factors. Level and clear the dry land, replace the soft soil with rammed earth, and build a temporary road. Use racks or sleepers to build platforms on steep slopes to enhance the bearing capacity and stability of the construction site and prevent the drilling rig from sinking or tilting during construction. Equip with excavators, loaders, cranes, drill slag transporters, steel casings (three per drilling rig), submersible pumps, and mud pumps to ensure that all construction links are fully equipped to meet the construction needs of different working conditions. Step 2: Casing installation: Use 10mm thick A3 steel plate to roll the steel casing, with a diameter 20-40cm larger than the pile diameter, a burial depth of 2-4m, and a top plate 0.3m above the ground. Use cross-line positioning, with a center deviation of ≤50mm and an inclination of ≤1%. Fill the gap with impurity-free clay to enhance the sealing between the casing and the surrounding soil, effectively prevent hole collapse and mud leakage, and ensure the stability of the pile hole. Step 3: Position the drilling rig: Align the center of the lifting and lowering wire ropes with the center of the pile, and ensure that the base is flat and stable to ensure accurate center positioning during drilling and reduce hole position deviation caused by rig offset. After the site is compacted, lay sleepers horizontally, and lay waste rails or steel on the sleepers as a platform to further improve the bearing strength and flatness of the drilling rig operating platform, providing support for the stable operation of the drilling rig. The size must meet the requirements for equipment placement and transportation. Step 4: Drilling: Align the drill bit center with the pile center, and drill the drill rod vertically with light pressure and slow rotation to ensure the verticality of the drilling direction and reduce the probability of inclined holes. Check the verticality every 2-3 meters, and record the hole position, hole mouth elevation, drilling time, drilling speed, cumulative depth and geological conditions. This will facilitate real-time monitoring of drilling quality, timely detection and adjustment of drilling deviations, and provide accurate geological and hole position parameter basis for subsequent construction. Step 5: Hole Inspection and Cleaning: After reaching the designed depth and being inspected by the supervisor, the hole is cleaned to ensure that the pile hole depth meets the design requirements, reduce the impact of bottom sediment on the bearing capacity of the pile body, control the mud density to 1.03-1.10, the consistency to 17-20s, the sand content to ≤2%, and the sediment thickness to meet the requirements; after lowering the steel cage and guide tube, measure the sediment. If it exceeds 5cm, clean the hole a second time, use a steel bar borehole inspection device to detect the hole diameter, hole shape and inclination, accurately control the sediment thickness and pile hole forming quality, and avoid affecting the pile body's bearing performance due to excessive sediment or irregular hole shape; Step 6: Fabrication and hoisting of the steel cage: Fabricate in sections, connect the main bars of the same section with straight threaded sleeves to improve the strength and stability of the steel bar connection and ensure the overall structural performance of the steel cage; weld triangular supports to the long frame, hoist and adjust the vertical lowering at two points, and weld the sections to prevent deformation of the steel cage during the hoisting process, ensuring its verticality and position accuracy in the pile hole; tie the main bars to the acoustic detection tube every 2m, seal the joints, check with water injection, make sure the top is flush with the casing, and support it on the sleepers after positioning according to the hole elevation to ensure the sealing and position accuracy of the acoustic detection tube, providing a reliable channel for subsequent pile quality inspection; Step 7: Pour underwater concrete: Connect the conduit to a 3m³ hopper, lubricate the conduit and place water-repellent balls to enhance the conduit's lubricity and sealing, and prevent blockage or leakage during concrete pouring. Calculate the first batch of concrete according to the formula (4.72 cubic meters for a 1.5m pile diameter), with a burial depth of ≥1.0m. Continuously pour concrete to a controlled burial depth of 2-6m. Replace or calibrate the measuring rope every five times, and over-pour by 0.6m to ensure the integrity and density of the concrete and avoid broken piles due to pouring interruptions. Pull the conduit vertically and in the center, with a removal time of ≤15 minutes. If final pouring becomes difficult, dilute mud should be excavated and settled. Pull the concrete slowly to prevent the conduit from colliding with the steel cage or damaging the pile structure, thus ensuring the quality of concrete pouring. The width of the access road shall be no less than 3m, the slope shall be no more than 1:10, and it shall be paved with gravel with a thickness of no less than 20cm to ensure smooth passage of construction vehicles; Comprehensive and meticulous construction preparations ensure that site conditions meet construction requirements. Various types of equipment are equipped to provide guarantees for subsequent processes. Casings are accurately buried to ensure accurate and stable hole positions. Drilling rigs are positioned in accordance with regulations to facilitate verticality control. Drilling operation parameters are recorded in detail to facilitate timely adjustments. Hole inspection and cleaning are rigorous to ensure hole quality. Rebar cages are meticulously manufactured and hoisted to ensure their strength and verticality. The steps for pouring underwater concrete are clear to ensure pile quality, thereby improving the reliability and quality of bored pile construction as a whole.
[0006] Preferably, in the casing burying step, the verticality of the steel casing is checked with a level before burying, and during the burying process, four observation points are symmetrically set around the casing, and the verticality and plane position deviation of the casing are monitored in real time using a total station. Once the deviation is found to be beyond the allowable range, it is adjusted immediately; the burial depth is adjusted according to the soil layer distribution in the geological survey report, with 4m for soft soil layers and 2m for hard soil layers. At the same time, a 10cm thick gravel cushion layer is laid at the bottom of the casing to enhance the stability of the bottom of the casing; During the casing installation process, if the total station detects that the verticality or plane position deviation exceeds the allowable range, immediately use an excavator or jack to fine-tune the casing position, and use a level to check the verticality to ensure that it meets the requirements of ≤1% inclination and ≤50mm center deviation; This casing burial method uses a spirit level and a total station for coordinated monitoring to achieve real-time and precise control of verticality and plane position, avoiding burial deviations. The layered burial depth design and gravel cushion layer enhance bottom stability, effectively cope with the differences in soft and hard strata, improve the casing's ability to resist deformation, and provide reliable support for subsequent drilling operations.
[0007] Preferably, in the step of positioning the drilling rig, the sleepers are pine wood with a cross-sectional size of 20 cm × 20 cm, and are laid horizontally with a spacing of 50 cm. The scrap rails or steel sections are of model I20a and are fixed to the sleepers with spikes. After the fixation is completed, the drilling rig platform is fully measured using a level to control the platform flatness error within ±5 mm. After the drilling rig is in place, all components of the drilling rig are fully inspected, including the wear of the wire rope and the firmness of the drill bit, to ensure that the drilling rig is in good working condition. If I20a steel cannot be obtained due to environmental constraints, it can be replaced with H-shaped steel or steel plate welded structure with equivalent load-bearing capacity to ensure platform stability. When fixing spikes is changed to bolt connections, spring washers should be installed to prevent loosening. If the level is not accurate enough, use a total station to verify the height difference of the four corners of the platform. This drilling rig positioning method ensures the stability of the platform structure by standardizing the specifications and spacing of sleepers, and clarifying the types and fixing methods of scrap rails; a spirit level is used to strictly control the flatness of the platform to avoid hole position deviation caused by tilting of the drilling rig; a comprehensive inspection of drilling rig components can promptly detect hidden dangers such as wire rope wear or loose drill bits, ensuring the safety and accuracy of drilling operations and extending the service life of the equipment.
[0008] Preferably, in the drilling operation step, the drilling record also includes mud density, drilling pressure and rotation speed parameters. When encountering a sand layer or gravel layer, the drilling speed is reduced to 0.5-1m / h, and the verticality inspection frequency is increased to once every 1m of footage. At the same time, during the drilling process, the mud mix ratio is adjusted in time according to different geological conditions, such as appropriately increasing the content of bentonite in the sand layer to improve the wall protection performance of the mud. In addition, various indicators of the mud are tested every 2 hours to ensure that the mud performance meets the requirements. When encountering soft soil layers, add appropriate amount of cellulose to enhance mud viscosity; when encountering rock layers, add dispersant to improve mud fluidity to ensure wall protection and slag removal effects; This drilling operation procedure records parameters such as mud density and drilling pressure, and dynamically adjusts the drilling speed and mud ratio in combination with geological changes, which not only ensures the verticality of the borehole and the stability of the wall protection, but also optimizes the mud performance. Regular testing of mud indicators can correct deviations in a timely manner to avoid hole collapse or poor slag discharge, improve the quality of the hole and construction efficiency, and reduce safety hazards. This refined control makes the construction more adaptable to complex geological conditions and ensures the reliability and durability of bored piles.
[0009] Preferably, in the hole inspection and cleaning step, the secondary hole cleaning adopts the mud circulation method, and the sediment thickness after hole cleaning is verified by using a sedimentation box and a standard measuring hammer method, so that the sediment thickness is ≤5cm; during the secondary hole cleaning process, the flow rate and pressure of the mud pump are adjusted to circulate the mud in the hole and remove the sediment at the bottom of the hole; at the same time, when testing the sedimentation box, the sedimentation box is placed at different positions at the bottom of the hole for multiple tests, and the average value is taken as the final data of the sediment thickness to improve the accuracy of the test; The mud in the hole is pumped out by a mud pump, purified in a sedimentation tank and then re-injected into the hole, forming a continuous cycle and effectively removing the sediment at the bottom of the hole; The use of mud circulation method for secondary hole cleaning, combined with the dual method of sedimentation box and standard hammer to verify the thickness of the sediment, can significantly improve the hole cleaning effect and ensure that the sediment thickness meets the standard; this method effectively removes the sediment at the bottom of the hole through continuous circulation of mud, and the dual-method verification improves the accuracy of detection, providing reliable protection for subsequent construction.
[0010] Preferably, in the steps of manufacturing and hoisting the steel cage, the exposed thread length of the main reinforcement connected by the straight thread sleeve is 2 to 3 threads, the bending angle at the joint is ≤3°, and the number of joints in the same cross-section is ≤50% of the number of main reinforcements; when manufacturing the steel cage, torque testing is performed on each straight thread sleeve joint to ensure that the connection strength meets the requirements; during the hoisting process of the steel cage, two cranes are used to operate simultaneously to keep the steel cage stable and avoid distortion of the steel cage; and during the lowering process of the steel cage, the verticality of the steel cage is measured every 5m, and any deviation is adjusted in time; When connecting the straight thread sleeve to the main reinforcement, use a special torque wrench to tighten it to ensure that the torque of each joint meets the required value of the specification. At the same time, use an angle ruler to check the bending angle of the joint, and use a steel bar counter to count the number of joints with the same section to prevent exceeding the standard. The hoisting process for the steel cage production strictly limits the connection parameters of the straight thread sleeve (exposed thread length, bending angle, and number of joints), and cooperates with torque testing to ensure connection reliability; dual cranes are used to work together to maintain hoisting stability and reduce deformation risks; verticality is regularly measured and corrected in real time during the process to ensure pile quality; these measures form a quality closed loop from the three aspects of connection strength, hoisting safety, and spatial positioning, providing a stable carrier for subsequent concrete pouring, and ultimately improving the structural durability of bored piles.
[0011] Preferably, the method further includes the step of installing an acoustic detection pipe, wherein the acoustic detection pipe adopts a seamless steel pipe with a diameter of 57 mm and a wall thickness of 3 mm, the joint is connected by threaded connection and sealed with raw tape, and the water level drop rate after water injection inspection is ≤5 cm / h to be qualified; before the acoustic detection pipe is installed, each acoustic detection pipe is visually inspected to ensure that there are no defects such as cracks and holes; during the installation process, the position required by the drawing is strictly arranged to ensure the straightness of the acoustic detection pipe; and after each section of the acoustic detection pipe is installed, an air compressor is used to perform a pressure test on the acoustic detection pipe to further check its sealing; During the installation of the acoustic detection pipe, if the pressure test finds that the sealing is insufficient, you can re-wrap the raw tape and tighten the threaded connection, and then press again until it is qualified. At the same time, if it is found that the straightness of the acoustic detection pipe does not meet the requirements during the installation process, it can be corrected by fine-tuning the installation position or adding a support device; The installation steps of the acoustic detection pipe ensure the reliability and durability of the acoustic detection pipe by specifying the pipe specifications, connection methods and sealing inspection methods in detail; the appearance inspection and straightness control ensure the accuracy of the inspection, and the pressure test further verifies the sealing performance, effectively avoiding the leakage problem that may occur during the concrete pouring process.
[0012] Preferably, in the step of pouring underwater concrete, the buried depth of the conduit is controlled at 2 to 4 meters, and the height of the concrete surface is measured before each removal of the conduit to ensure that the buried depth after removal is not less than 2 meters and not more than 6 meters; during the pouring process, a scale mark is set on the conduit to facilitate operators to accurately grasp the buried depth of the conduit; at the same time, two concrete delivery pumps are equipped, one for use and one for backup, to ensure the continuity of concrete pouring; and the slump of the concrete is tested every 30 minutes to ensure that the workability of the concrete meets the pouring requirements; The outer wall of the conduit can be marked with obvious scales at certain intervals (such as 0.5m) using paint, etc., to facilitate operators to accurately grasp the burial depth; This underwater concrete pouring procedure has many benefits. By controlling the buried depth of the conduit and measuring the height of the concrete surface, the quality of concrete pouring can be guaranteed. Setting scale marks on the conduit facilitates operation. Equipping two concrete pumps can ensure the continuity of pouring and avoid interruptions. Regularly testing the slump can ensure the workability of the concrete, facilitate pouring and molding, and improve the quality of the pile.
[0013] Preferably, the water-avoiding ball is made of natural rubber, inflated at a pressure of 0.2-0.3 MPa, and placed in the conduit 50 cm from the bottom end. When the first batch of concrete is poured, the water-avoiding ball falls out of the conduit as the concrete falls. Before using the water-avoiding ball, the air tightness of the water-avoiding ball is strictly checked to ensure that there is no air leakage. When pouring the first batch of concrete, pay close attention to the falling of the water-avoiding ball to ensure that it is smoothly out of the conduit. During the pouring process, if the water-avoiding ball shows signs of blocking the conduit, the pouring is stopped immediately and appropriate measures are taken to deal with it. What to do when the water-avoiding ball blocks the conduit: If signs of blockage are found, immediately clear it with a long pole or start a spare conduit. At the same time, check the mud properties and adjust the mix ratio to ensure fluidity and avoid concrete segregation. The water-avoiding ball's operational design ensures sealing and pressure resistance through its natural rubber material and precise inflation pressure control; its placement 50 cm from the bottom of the conduit effectively blocks mud, preventing concrete from direct contact with water and causing segregation; strict airtightness inspections and falling monitoring can promptly troubleshoot and prevent conduit blockages from affecting pouring continuity; spare conduits and mud adjustment mechanisms further ensure construction stability, achieving overall reliable bottom sealing and quality control for underwater concrete pouring.
[0014] Preferably, the method further comprises a pile top elevation control step, wherein the over-filled 0.6m concrete is mechanically cut off after the strength reaches 80%, and the deviation of the cutting surface from the designed pile top elevation is ≤5mm; before cutting, the pile top elevation is accurately measured using a level to determine the cutting position; during the cutting process, a dedicated concrete cutting device is used to ensure the flatness and verticality of the cutting surface; and after cutting is completed, the pile top is cleaned to remove residual concrete debris to ensure that the pile top quality meets the requirements; If mechanical cutting cannot achieve the deviation requirement of ≤5mm, manual fine trimming should be used instead, and level and ruler should be used for calibration to ensure the accuracy of the cutting surface; The pile top elevation control step ensures the accuracy of the pile top elevation and the flatness and verticality of the cut surface through a combination of precise measurement, mechanical cutting and manual cleaning. This process not only improves construction quality, but also avoids structural safety hazards caused by elevation deviation or uneven cutting surface, laying a solid foundation for subsequent construction.
[0015] In summary, compared with the prior art, the present invention provides a bored cast-in-place pile construction method with the following beneficial effects: This invention uses a total station to accurately place piles, standardize site leveling and platform construction, thereby improving pile positioning accuracy and enhancing construction site stability. It has the benefits of reducing pile position deviation and avoiding drilling rig settlement and tilt, and solves the problem of insufficient construction accuracy caused by traditional layout and site preparation. By filling the gaps in the casing with clay, checking the verticality of the borehole, cleaning and testing the hole in layers, connecting the steel cage with straight threads and lifting it at two points, lubricating the conduit and continuously pouring the concrete, the stability of the pile hole, the quality of the steel cage and the density of the concrete pouring are improved. This has the advantages of preventing the collapse of the hole mouth, reducing the slag in the inclined hole, ensuring the strength and accurate position of the steel bar connection, and avoiding broken piles and mud. It solves the problem of many quality defects of the pile body in traditional construction. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a step diagram of the bored cast-in-place pile construction method of the invention.
[0017] Figure 2 This is a schematic diagram of the first concrete pouring of the invention.
[0018] Figure 3 This is a construction process diagram of the bored cast-in-place pile of the invention. DETAILED DESCRIPTION
[0019] The present invention provides a technical solution, a bored pile construction method, please refer to Figure 1 、 Figure 2 and Figure 3 , including the following steps: Step 1: Construction Preparation: Use a total station to place piles according to the baseline control network and the design coordinates of the piers; level and clear the dry land, replace the soft soil with rammed earth, and build a temporary road. For steep slopes, use racks or sleepers to build a platform; equip with excavators, loaders, cranes, drill slag transporters, steel casings (three per drilling rig), submersible pumps, and mud pumps; Step 2: Casing installation: Use 10mm thick A3 steel plate to roll the steel casing, with a diameter 20-40cm larger than the pile diameter, a burial depth of 2-4m, and a top plate 0.3m above the ground. Position it using the cross-line, with a center deviation of ≤50mm and an inclination of ≤1%. Fill the gaps with clay without impurities. Step 3: Position the drilling rig: Align the center of the lifting and lowering wire ropes with the center of the pile, and ensure the base is flat and stable. After the site is compacted, lay sleepers horizontally, and lay scrap rails or steel sections on the sleepers as a platform. The size should meet the requirements for placing and transporting the equipment. Step 4: Drilling: Align the drill bit center with the pile center, and drill vertically with the drill rod gently pressed and rotated slowly; check verticality every 2-3 meters, and record the hole position, hole mouth elevation, drilling time, drilling speed, cumulative depth, and geological conditions; Step 5: Hole Inspection and Cleaning: After reaching the designed depth and being inspected by the supervisor, the hole is cleaned, and the mud density is controlled at 1.03-1.10, the consistency is 17-20s, the sand content is ≤2%, and the sediment thickness meets the requirements; after lowering the steel cage and the guide tube, the sediment is measured. If it exceeds 5cm, the hole is cleaned again, and the hole diameter, hole shape and inclination are checked with a steel bar borehole detector; Step 6: Fabrication and hoisting of the steel cage: Fabricate in sections, connect the main bars of the same section with straight threaded sleeves; weld triangular supports to the long frame, hoist at two points and adjust it to be vertical and lowered, and weld the sections; tie the main bars every 2m with the acoustic testing pipe, seal the joints, check with water injection, make sure the top is flush with the casing, and support it on the sleepers after positioning it according to the hole elevation; Step 7: Pour underwater concrete: Connect the conduit to a 3m³ hopper, lubricate the pipe and place water-repellent balls. Calculate the first batch of concrete according to the formula (4.72 cubic meters for a 1.5m pile diameter), with a burial depth of ≥1.0m. Continuously pour to a controlled burial depth of 2-6m. Replace or calibrate the measuring rope every five times, with an over-pouring depth of 0.6m. Pull the pipe vertically and centered, with a removal time of ≤15 minutes. If final pouring proves difficult, dilute the slurry and allow it to settle. Pull slowly to prevent a mud core. The access road should be no less than 3m wide, with a slope no greater than 1:10, and paved with gravel no less than 20cm thick to ensure smooth passage for construction vehicles. If access to the access road is blocked, steel plates can be added or the route can be adjusted. If the geology is complex during casing burial, additional positioning steel bars can be installed to ensure stability. If the platform is uneven after the drilling rig is in place, thin steel plates can be used to level it. When drilling into a hard layer, a roller drill bit can be used and the drilling pressure increased. Comprehensive and meticulous construction preparations ensure that site conditions meet construction requirements. Various types of equipment are equipped to provide guarantees for subsequent processes. Casings are accurately buried to ensure accurate and stable hole positions. Drilling rigs are positioned in accordance with regulations to facilitate verticality control. Drilling operation parameters are recorded in detail to facilitate timely adjustments. Hole inspection and cleaning are rigorous to ensure hole quality. Rebar cages are meticulously manufactured and hoisted to ensure their strength and verticality. The steps for pouring underwater concrete are clear to ensure pile quality, thereby improving the reliability and quality of bored pile construction as a whole.
[0020] See also Figure 1 、 Figure 2and Figure 3 In the casing burial process, the verticality of the steel casing is checked with a level ruler before burying. During the burial process, four observation points are symmetrically set around the casing, and the verticality and plane position deviation of the casing are monitored in real time using a total station. Once the deviation is found to be beyond the allowable range, it is adjusted immediately. The burial depth is adjusted according to the soil layer distribution in the geological survey report, with 4m for soft soil layers and 2m for hard soil layers. At the same time, a 10cm thick gravel cushion is laid at the bottom of the casing to enhance the stability of the bottom of the casing. During the casing installation process, if the total station detects that the verticality or plane position deviation exceeds the allowable range, immediately use an excavator or jack to fine-tune the casing position, and use a level to check the verticality to ensure that it meets the requirements of ≤1% inclination and ≤50mm center deviation; This casing burial method uses a spirit level and a total station for coordinated monitoring to achieve real-time and precise control of verticality and plane position, avoiding burial deviations. The layered burial depth design and gravel cushion layer enhance bottom stability, effectively cope with the differences in soft and hard strata, improve the casing's ability to resist deformation, and provide reliable support for subsequent drilling operations.
[0021] See also Figure 1 、 Figure 2 and Figure 3 During the drilling rig placement process, sleepers are made of pine wood with a cross-sectional size of 20cm×20cm, laid horizontally at intervals of 50cm. Used scrap rails or steel sections of type I20a are fixed to the sleepers with spikes. After the fixation is completed, a level is used to fully measure the drilling rig platform to control the platform flatness error within ±5mm. After the drilling rig is in place, all components of the drilling rig are thoroughly inspected, including the wear of the wire rope and the firmness of the drill bit, to ensure that the drilling rig is in good working condition. If I20a steel cannot be obtained due to environmental constraints, it can be replaced with H-shaped steel or steel plate welded structure with equivalent load-bearing capacity to ensure platform stability. When fixing spikes is changed to bolt connections, spring washers should be installed to prevent loosening. If the level is not accurate enough, use a total station to verify the height difference of the four corners of the platform. This drilling rig positioning method ensures the stability of the platform structure by standardizing the specifications and spacing of sleepers, and clarifying the types and fixing methods of scrap rails; a spirit level is used to strictly control the flatness of the platform to avoid hole position deviation caused by tilting of the drilling rig; a comprehensive inspection of drilling rig components can promptly detect hidden dangers such as wire rope wear or loose drill bits, ensuring the safety and accuracy of drilling operations and extending the service life of the equipment.
[0022] See also Figure 1 、 Figure 2 and Figure 3During the drilling operation, the drilling record also includes mud density, drilling pressure and rotation speed parameters. When encountering sand or gravel layers, the drilling speed is reduced to 0.5-1m / h, and the verticality inspection frequency is increased to once every 1m of footage. At the same time, during the drilling process, the mud mix ratio is adjusted in time according to different geological conditions, such as appropriately increasing the content of bentonite in the sand layer to improve the mud's wall protection performance. In addition, various mud indicators are tested every 2 hours to ensure that the mud performance meets the requirements. When encountering soft soil layers, add appropriate amount of cellulose to enhance mud viscosity; when encountering rock layers, add dispersant to improve mud fluidity to ensure wall protection and slag removal effects; This drilling operation procedure records parameters such as mud density and drilling pressure, and dynamically adjusts the drilling speed and mud ratio in combination with geological changes, which not only ensures the verticality of the borehole and the stability of the wall protection, but also optimizes the mud performance. Regular testing of mud indicators can correct deviations in a timely manner to avoid hole collapse or poor slag discharge, improve the quality of the hole and construction efficiency, and reduce safety hazards. This refined control makes the construction more adaptable to complex geological conditions and ensures the reliability and durability of bored piles.
[0023] See also Figure 1 、 Figure 2 and Figure 3 During the hole inspection and cleaning process, the secondary hole cleaning adopts the mud circulation method. After the hole is cleaned, the sediment thickness is verified by using a sedimentation box and a standard hammer method to ensure that the sediment thickness is ≤5cm. During the secondary hole cleaning process, the flow rate and pressure of the mud pump are adjusted to circulate the mud in the hole and remove the sediment at the bottom of the hole. At the same time, during the sedimentation box test, the sedimentation box is placed at different positions at the bottom of the hole for multiple tests, and the average value is taken as the final sediment thickness data to improve the accuracy of the test. The mud in the hole is pumped out by a mud pump, purified in a sedimentation tank and then re-injected into the hole, forming a continuous cycle and effectively removing the sediment at the bottom of the hole; The use of mud circulation method for secondary hole cleaning, combined with the dual method of sedimentation box and standard hammer to verify the thickness of the sediment, can significantly improve the hole cleaning effect and ensure that the sediment thickness meets the standard; this method effectively removes the sediment at the bottom of the hole through continuous circulation of mud, and the dual-method verification improves the accuracy of detection, providing reliable protection for subsequent construction.
[0024] See also Figure 1 、 Figure 2 and Figure 3During the production and hoisting steps of the steel cage, the exposed thread length of the main reinforcement connected by the straight thread sleeve is 2 to 3 teeth, the bending angle at the joint is ≤3°, and the number of joints in the same section is ≤50% of the number of main reinforcements; when making the steel cage, torque testing is performed on each straight thread sleeve joint to ensure that the connection strength meets the requirements; during the lifting process of the steel cage, two cranes are used to operate simultaneously to keep the steel cage stable and avoid distortion; and during the lowering process of the steel cage, the verticality of the steel cage is measured every 5m, and any deviation is adjusted in time; When connecting the straight thread sleeve to the main reinforcement, use a special torque wrench to tighten it to ensure that the torque of each joint meets the required value of the specification. At the same time, use an angle ruler to check the bending angle of the joint, and use a steel bar counter to count the number of joints with the same section to prevent exceeding the standard. The hoisting process for the steel cage production strictly limits the connection parameters of the straight thread sleeve (exposed thread length, bending angle, and number of joints), and cooperates with torque testing to ensure connection reliability; dual cranes are used to work together to maintain hoisting stability and reduce deformation risks; verticality is regularly measured and corrected in real time during the process to ensure pile quality; these measures form a quality closed loop from the three aspects of connection strength, hoisting safety, and spatial positioning, providing a stable carrier for subsequent concrete pouring, and ultimately improving the structural durability of bored piles.
[0025] See also Figure 1 、 Figure 2 and Figure 3 , also includes the installation steps of the acoustic detection pipe. During the installation steps, the acoustic detection pipe adopts a seamless steel pipe with a diameter of 57mm and a wall thickness of 3mm. The joints are connected with threaded threads and sealed with raw tape. After the water injection inspection, the water level drop rate is ≤5cm / h to be qualified. Before the installation of the acoustic detection pipe, each acoustic detection pipe is visually inspected to ensure that there are no defects such as cracks and holes. During the installation process, the position required by the drawings is strictly followed to ensure the straightness of the acoustic detection pipe. After each section of the acoustic detection pipe is installed, an air compressor is used to perform a pressure test on the acoustic detection pipe to further check its sealing. During the installation of the acoustic detection pipe, if the pressure test finds that the sealing is insufficient, you can re-wrap the raw tape and tighten the threaded connection, and then press again until it is qualified. At the same time, if it is found that the straightness of the acoustic detection pipe does not meet the requirements during the installation process, it can be corrected by fine-tuning the installation position or adding a support device; The installation steps of the acoustic detection pipe ensure the reliability and durability of the acoustic detection pipe by specifying the pipe specifications, connection methods and sealing inspection methods in detail; the appearance inspection and straightness control ensure the accuracy of the inspection, and the pressure test further verifies the sealing performance, effectively avoiding the leakage problem that may occur during the concrete pouring process.
[0026] See also Figure 1 、 Figure 2 and Figure 3During the underwater concrete pouring process, the buried depth of the conduit is controlled at 2-4m. The height of the concrete surface is measured before each removal of the conduit to ensure that the buried depth after removal is not less than 2m and not more than 6m. During the pouring process, scale marks are set on the conduit to facilitate operators to accurately grasp the buried depth of the conduit. At the same time, two concrete pumps are equipped, one for use and one for backup, to ensure the continuity of concrete pouring. The slump of the concrete is tested every 30 minutes to ensure that the workability of the concrete meets the pouring requirements. The outer wall of the conduit can be marked with obvious scales at certain intervals (such as 0.5m) using paint, etc., to facilitate operators to accurately grasp the burial depth; This underwater concrete pouring procedure has many benefits. By controlling the buried depth of the conduit and measuring the height of the concrete surface, the quality of concrete pouring can be guaranteed. Setting scale marks on the conduit facilitates operation. Equipping two concrete pumps can ensure the continuity of pouring and avoid interruptions. Regularly testing the slump can ensure the workability of the concrete, facilitate pouring and molding, and improve the quality of the pile.
[0027] See also Figure 1 、 Figure 2 and Figure 3 The water-avoiding ball is made of natural rubber and has an inflation pressure of 0.2~0.3MPa. It is placed 50cm from the bottom end of the conduit. When the first batch of concrete is poured, it will fall out of the conduit as the concrete falls. Before using the water-avoiding ball, strictly check the air tightness of the water-avoiding ball to ensure that there is no leakage. When pouring the first batch of concrete, pay close attention to the falling of the water-avoiding ball to ensure that it is smoothly out of the conduit. During the pouring process, if there is any sign of the water-avoiding ball blocking the conduit, stop pouring immediately and take appropriate measures to deal with it. What to do when the water-avoiding ball blocks the conduit: If signs of blockage are found, immediately clear it with a long pole or start a spare conduit. At the same time, check the mud properties and adjust the mix ratio to ensure fluidity and avoid concrete segregation. The water-avoiding ball's operational design ensures sealing and pressure resistance through its natural rubber material and precise inflation pressure control; its placement 50 cm from the bottom of the conduit effectively blocks mud, preventing concrete from direct contact with water and causing segregation; strict airtightness inspections and falling monitoring can promptly troubleshoot and prevent conduit blockages from affecting pouring continuity; spare conduits and mud adjustment mechanisms further ensure construction stability, achieving overall reliable bottom sealing and quality control for underwater concrete pouring.
[0028] See also Figure 1 、 Figure 2 and Figure 3, also includes the pile top elevation control step. In the pile top elevation control step, the 0.6m of over-filled concrete is mechanically cut away after the strength reaches 80%, and the deviation of the cutting surface from the designed pile top elevation is ≤5mm. Before cutting, the pile top elevation is accurately measured with a level to determine the cutting position. During the cutting process, dedicated concrete cutting equipment is used to ensure the flatness and verticality of the cutting surface. After cutting, the pile top is cleaned to remove any remaining concrete debris to ensure that the pile top quality meets the requirements. If mechanical cutting cannot achieve the deviation requirement of ≤5mm, manual fine trimming should be used instead, and level and ruler should be used for calibration to ensure the accuracy of the cutting surface; The pile top elevation control step ensures the accuracy of the pile top elevation and the flatness and verticality of the cut surface through a combination of precise measurement, mechanical cutting and manual cleaning. This process not only improves construction quality, but also avoids structural safety hazards caused by elevation deviation or uneven cutting surface, laying a solid foundation for subsequent construction.
Claims
1. A bored pile construction method, characterized in that: The steps include: Step 1: Construction Preparation: Use a total station to place piles according to the baseline control network and the design coordinates of the piers; level and clear the dry land, replace the soft soil with rammed earth, and build a temporary road. Build a platform with racks or sleepers on steep slopes; equip with excavators, loaders, cranes, drilling slag transporters, steel casings, submersible pumps, and mud pumps; Step 2: Burying the casing: Use steel plates to roll the steel casing, and fill the gaps with clay without impurities; Step 3: Position the drilling rig: Align the center of the lifting and lowering wire ropes with the center of the pile, and ensure the base is flat and stable. After the site is compacted, lay sleepers horizontally, and lay waste rails or steel sections on the sleepers as a platform. Step 4: Drilling: Align the drill bit center with the pile center and drill vertically. Check verticality by footage, and record the hole position, hole elevation, drilling time, drilling speed, cumulative depth, and geological conditions. Step 5: Hole Inspection and Cleaning: After reaching the designed depth, clean the hole after inspection; measure the slag after lowering the steel cage and guide tube, and use a steel hole inspection device to check the hole diameter, hole shape and inclination; Step 6: Fabrication and hoisting of the steel cage: Fabricate in sections, connect the main bars of the same section with straight threaded sleeves; weld triangular supports to the long frame, hoist at two points and adjust it to be vertical and lowered, and weld the sections; tie the main bars with the sonic testing pipe, seal the joints, check with water injection, make sure the top is flush with the casing, and support it on the sleepers after positioning it according to the hole elevation; Step 7: Pour underwater concrete: Connect the conduit to the hopper, lubricate the pipeline and place a water-proof ball; pour continuously; pull out the pipe and center it vertically.
2. A bored pile construction method according to claim 1, characterized in that: In the casing burying step, the verticality of the steel casing is checked with a spirit level before burying, and during the burying process, four observation points are symmetrically set around the casing, and a total station is used to monitor the verticality and plane position deviation of the casing in real time; the burial depth is adjusted according to the soil layer distribution in the geological survey report, 4m for soft soil layer and 2m for hard soil layer, and at the same time, a 10cm thick gravel cushion layer is laid at the bottom of the casing.
3. A bored pile construction method according to claim 1, characterized in that: During the drilling rig placement step, the sleepers are laid horizontally and fixed with spikes; after the fixation is completed, the drilling rig platform is fully measured using a level to control the platform flatness error within ±5mm; and after the drilling rig is in place, all components of the drilling rig are fully inspected, including the wear of the wire rope and the firmness of the drill bit.
4. A bored pile construction method according to claim 1, characterized in that: During the drilling operation, the drilling record also includes mud density, drilling pressure and rotation speed parameters. When encountering sand or gravel layers, the drilling speed is reduced to 0.5-1m / h, and the verticality inspection frequency is increased to once every 1m of footage. At the same time, during the drilling process, the mud mix ratio is adjusted in time according to different geological conditions; and various mud indicators are tested every 2 hours.
5. A bored pile construction method according to claim 1, characterized in that: In the hole inspection and cleaning steps, the secondary hole cleaning adopts the mud circulation method, and the sediment thickness after cleaning is verified by the double method of sedimentation box and standard hammer, so that the sediment thickness is ≤5cm; in the secondary hole cleaning process, the flow and pressure of the mud pump are adjusted to make the mud circulate in the hole and bring out the sediment at the bottom of the hole; at the same time, when testing the sedimentation box, the sedimentation box is placed at different positions at the bottom of the hole for multiple tests, and the average value is taken as the final data of the sediment thickness.
6. A bored pile construction method according to claim 1, characterized in that: In the steps of manufacturing and hoisting the steel cage, the exposed thread length of the main reinforcement connected by the straight thread sleeve is 2 to 3 teeth, the bending angle at the joint is ≤3°, and the number of joints in the same cross-section is ≤50% of the number of main reinforcements; when manufacturing the steel cage, torque testing is performed on each straight thread sleeve joint; during the lifting process of the steel cage, two cranes are used to operate simultaneously; and during the lowering process of the steel cage, the verticality of the steel cage is measured every 5 meters, and any deviation is adjusted in time.
7. A bored pile construction method according to claim 1, characterized in that: It also includes the steps of installing the acoustic detection pipe. In the acoustic detection pipe installation steps, the acoustic detection pipe is made of seamless steel pipe, the joints are connected by threaded connection and sealed with raw tape, and the water level drop speed after water injection inspection is ≤5cm / h to be qualified; before the acoustic detection pipe is installed, each acoustic detection pipe is visually inspected; during the installation process, it is arranged strictly in accordance with the position required by the drawings; and after each section of the acoustic detection pipe is installed, an air compressor is used to perform a pressure test on the acoustic detection pipe to further check its sealing.
8. The bored pile construction method according to claim 1, characterized in that: During the underwater concrete pouring step, the buried depth of the conduit is controlled at 2 to 4 meters, and the height of the concrete surface is measured before each removal of the conduit, so that the buried depth after removal is not less than 2 meters and not more than 6 meters. At the same time, two concrete pumps are equipped, one for use and one for backup. The slump of the concrete is tested every 30 minutes to ensure that the workability of the concrete meets the pouring requirements.
9. A bored pile construction method according to claim 1, characterized in that: The water-avoiding ball is made of natural rubber and has an inflation pressure of 0.2~0.3MPa. It is placed in the conduit 50cm away from the bottom end and will fall out of the conduit as the first batch of concrete is poured. Before using the water-avoiding ball, the air tightness of the water-avoiding ball is strictly checked to prevent air leakage. When pouring the first batch of concrete, pay close attention to the falling of the water-avoiding ball to ensure that it can smoothly leave the conduit. During the pouring process, if there are signs that the water-avoiding ball is blocking the conduit, stop pouring and take appropriate measures to deal with it.
10. The bored pile construction method according to claim 1, characterized in that: The method also includes a pile top elevation control step, in which the over-filled 0.6m concrete is removed by mechanical cutting after its strength reaches 80%, and the deviation of the cutting surface from the designed pile top elevation is ≤5mm; before cutting, a level is used to accurately measure the pile top elevation and determine the cutting position; during the cutting process, special concrete cutting equipment is used to ensure the flatness and verticality of the cutting surface; and after the cutting is completed, the pile top is cleaned to remove residual concrete debris.