Permanent steel pipe column concrete structure front insertion construction method

Abstract

The invention discloses a permanent steel pipe column concrete structure front insertion method construction method which comprises the following steps: S1, changing a steel pipe column with a closed bottom in the original design into a bottom opening form, improving a pile foundation concrete mark to be consistent with the strength of concrete in the steel pipe column, and then performing customized processing of the steel pipe column and manufacturing processing of a reinforcement cage; s2, during construction, after pile foundation hole forming, hole cleaning and hole checking are completed, a reinforcement cage is lowered and installed; s3, lowering and mounting the steel pipe column; s4, concrete is directly poured from the interior of the steel pipe column during pouring; s5, before initial setting of pile foundation concrete, the outer side of the steel pipe column is filled with sand to the position 1 m below the designed elevation, and water is injected densely; and S6, the tool pipe is dismantled, backfilling protection is conducted on the pile top, and finally pile body detection is conducted. According to the scheme, a front insertion method is adopted for construction, the pile foundation concrete mark is improved to be consistent with the strength of concrete in the steel pipe column, the construction precision can be better controlled, the pile forming quality is guaranteed, the construction period is shortened, and cost is saved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of building construction, and in particular to a permanent steel pipe column concrete structure front insertion method construction method. BACKGROUND

[0002] With the acceleration of social progress, the form of building structure is increasingly diversified, and high-rise buildings, heavy structures and underground reverse construction projects are emerging. In these projects, the structure form of concrete foundation or bored pile foundation combined with permanent steel pipe column is widely used. However, in the actual construction process, the traditional construction method has many problems and needs to be improved.

[0003] The traditional construction method usually adopts the post-insertion method, that is, the pile foundation concrete is poured first, and the steel pipe column is inserted before the concrete solidifies. This method has many disadvantages. First, the concrete buoyancy is too large, which causes the steel pipe column to float up, making it difficult to accurately control the pile position and verticality. Second, the construction period is long, and the concrete setting time is difficult to control, further increasing the construction difficulty and cost. In addition, the test detection is difficult, and the overall benefit is low.

[0004] Taking a certain engineering project as an example, the foundation form of the project is designed to use pile foundation or independent foundation, and the basement part is designed to use bored pile and steel pipe column as permanent structure. According to the traditional construction method, the steel pipe column is designed to be anchored in the pile foundation with a length of 5.1 meters, and the foundation part concrete needs to be poured with slow-setting concrete. However, this process faces many problems, such as excessive concrete buoyancy, long construction period, and concrete setting caused by concrete setting, which makes the steel pipe column float up, the pile position and verticality difficult to adjust, the construction difficulty large, the precision control poor, the period long and the cost high.

[0005] In summary, the prior art has obvious shortcomings in construction precision, construction period and cost control, and it is difficult to meet the high precision, high efficiency and low cost requirements of modern building construction. Therefore, there is an urgent need for a new construction method to overcome the shortcomings of the prior art, improve construction quality and efficiency, and reduce construction cost. SUMMARY

[0006] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, one object of the present application is to provide a permanent steel pipe column concrete structure front insertion method construction method.

[0007] The technical solution of the present application is as follows: a permanent steel pipe column concrete structure front insertion method construction method, characterized in that it comprises the following steps:

[0008] S1, before construction, communicate with the design unit to change the original design of the bottom closed steel pipe column to the bottom opening form, and improve the pile foundation concrete grade to be consistent with the concrete strength in the steel pipe column, and then carry out the customization and processing of the steel pipe column and the production and processing of the steel reinforcement cage;

[0009] S2, during construction, after the pile foundation is formed, cleaned and inspected, the steel reinforcement cage is first installed;

[0010] S3, then the steel pipe column is installed, and in this process, the pile column installation machine is used to fix the steel pipe column, adjust the pile position and verticality;

[0011] S4, when pouring, directly pour concrete from the inside of the steel pipe column, first pour the pile foundation concrete outside the steel pipe column, and then pour the concrete inside the steel pipe column;

[0012] S5, before the initial setting of the pile foundation concrete, fill sand to 1m below the design elevation outside the steel pipe column, and inject water to compact;

[0013] S6, remove the tool pipe and backfill the pile top for protection, and finally detect the pile body.

[0014] Further, in step S1, the pile foundation concrete grade is improved to S350, and the concrete grade in the steel pipe column is S350.

[0015] Further, in step S3, the pile column installation machine includes an operating platform that can move ±5S3m in XY direction, two closing plates for fixing the steel pipe column, and four hydraulic oil legs for supporting and adjusting the verticality.

[0016] Further, the steel pipe column installation adopts tool pipe assisted positioning, and the length of the tool pipe is calculated and determined according to the height of the hydraulic oil leg and the ground elevation.

[0017] Further, the verticality adjustment of the steel pipe column includes the following contents:

[0018] When lowering, two total stations are set in XY direction to monitor in real time;

[0019] After each section is lowered, the horizontal level of the flange plate is measured by a level;

[0020] After installation is completed, an ultrasonic detector is used for review, and the verticality error is ≤1‰ and ≤15mm.

[0021] Further, the pile position control adopts cross wire positioning, and the pile position error of the steel pipe column is adjusted to ±5mm.

[0022] Further, in step S4, the concrete pouring adopts a diameter φ300mm conduit, and the first pouring concrete volume is ≥5.9m 3 , and the conduit bottom is 300-500mm from the hole bottom.

[0023] Further, the pipe is buried to a depth of 26 m during pouring, and the pile foundation concrete is poured to a height of 0.5 m above the top of the pile.

[0024] Further, in step S5, the top of the steel pipe column is covered to prevent sand from entering during sand filling, and water is injected to compact the sand after sand filling.

[0025] Further, in step S6, pile body detection includes the following contents:

[0026] Ultrasonic transmission method is used to detect the integrity of the pile body;

[0027] By embedding a load box in the pile body, a self-balancing method is used to test the single pile compressive bearing capacity.

[0028] Compared with the prior art, the beneficial effects of the present application are as follows:

[0029] The present application adopts the method of changing the steel pipe column into an open lower end for front insertion construction, and increases the pile foundation concrete grade to the same strength as the concrete in the steel pipe column, thereby ensuring that the design concrete strength meets the requirements, avoiding a series of problems caused by the large buoyancy after inserting the closed steel pipe column, better controlling the construction precision, ensuring the pile quality, shortening the construction period, and saving labor and mechanical costs.

[0030] Additional aspects and advantages of the present application will be partially given in the following description, partially will become obvious from the following description, or will be understood by practicing the present application. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and the drawings are only examples and are not strictly drawn according to scale. For ordinary skilled in the art, other drawings can be obtained from these drawings without creative labor.

[0032] Figure 1 is a permanent steel pipe column concrete structure front insertion construction flow chart of the present application;

[0033] Figure 2 is a schematic diagram of setting a triangular support of the reinforcing cage of the present application;

[0034] Figure 3 is a positioning schematic diagram of the present application by cross wire method;

[0035] Figure 4 is a physical diagram of the intelligent detection system of the rotary drilling rig of the present application;

[0036] Figure 5 is a bored pile foundation hole-forming construction schematic diagram of the present application;

[0037] Figure 6 is a steel reinforcement cage hoisting schematic diagram of the present application;

[0038] Figure 7 is a steel pipe column hoisting schematic diagram of the present application;

[0039] Figure 8 is a steel pipe column top flange plate horizontal correction schematic diagram of the present application;

[0040] Figure 9 is a steel pipe column lowering schematic diagram of the present application;

[0041] Figure 10 is a total station steel pipe column pile position rechecking schematic diagram of the present application;

[0042] Figure 11 is an ultrasonic detector steel pipe column verticality rechecking schematic diagram of the present application;

[0043] Figure 12 is a pile foundation concrete pouring schematic diagram of the present application;

[0044] Figure 13 is a test block reservation and slump test schematic diagram of the present application;

[0045] Figure 14 is a steel pipe column outer sand filling schematic diagram of the present application;

[0046] Figure 15 is a steel pipe column inner concrete pouring schematic diagram of the present application;

[0047] Figure 16 is a pile hole backfilling protection schematic diagram of the present application;

[0048] Figure 17 is a self-balancing method static load test detection schematic diagram of the present application. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0050] As shown in the permanent steel pipe column concrete structure front insertion method of construction shown in the figure, comprising the following steps: Figures 1-17

[0051] ​S1, before construction, communicate with the design unit to change the original design of the bottom closed steel pipe column to the bottom opening form, and improve the pile foundation concrete grade to be consistent with the strength of the steel pipe column, and then carry out the customization and processing of the steel pipe column and the production and processing of the steel reinforcement cage.

[0052] Specifically, before construction, the design unit needs to review the steel pipe column construction process and determine the design form of the steel pipe column. Usually, such concrete foundation or bored pile foundation is constructed with steel pipe column structure by post-insertion method, and the steel pipe column is in the form of bottom sealing. The pre-insertion method needs to change the design to open the bottom of the steel pipe column, and the concrete is poured from the inside of the steel pipe column. After confirming the construction process, contact the manufacturer for steel pipe column processing.

[0053] The processing of steel pipe column should select qualified manufacturers, and provide qualified steel, welding detection report and quality qualification certificate. At the same time, according to the needs of the project, contact the laboratory in advance to prepare the pile body integrity test and single pile vertical ultimate bearing capacity test related equipment.

[0054] According to the actual situation on site, after the steel reinforcement cage is formed, self-inspection, hidden inspection and handover inspection are carried out according to the requirements of the specification, including steel reinforcement (appearance, variety, model, specification), welding (length, width, thickness, bite, surface flatness, etc.), mechanical connection (sleeve specification, thread length, exposed number of thread, etc.), steel reinforcement cage allowable deviation (main reinforcement spacing, stiffening reinforcement spacing, steel reinforcement cage diameter and length, etc.), and good records. The steel reinforcement cage that has passed the inspection should be placed flat on the flat ground according to the specification number, to prevent deformation. The stacking height should not be more than two layers.

[0055] S2, during construction, after the pile foundation is formed, cleaned and inspected, the steel reinforcement cage is first installed.

[0056] Specifically, during the hole forming construction process, the integrity, reliability and accuracy of the measuring instruments and equipment should be checked before measurement and positioning, the instrument identification certificate issued by the legal measurement unit should be reviewed and reported to the supervision unit for review.

[0057] Review the guide line points, triangular network points, level base points and related measurement data delivered by the owner. If the marks are not clear, the points are not stable or damaged, and the accuracy does not meet the construction requirements, the points should be reinforced and restored in time. After the points are stable, the measurement is re-conducted, and the measurement results are reported for approval before being used for construction. The construction control network is used to set up the reference wooden pile, and the supervision unit is reported for re-measurement. After the re-measurement is qualified, the next process construction can be carried out.

[0058] The existing ground elevation is measured and reviewed, and the technical parameters of the pile casing, pile top, pile bottom and hole depth are calculated, and the site construction measurement is introduced.

[0059] After the center point of pile position is determined by measurement and lofting, the center point will be destroyed when the casing is buried. According to the requirements, four protection piles must be set. The protection piles are used to check the accuracy of the casing and ensure that the deviation of the pile position meets the requirements and the accuracy of the subsequent drilling rig positioning and the lowering of the reinforcement cage. According to the simple geometric principle of two-point straight line and the general provisions of protection pile burial, the cross intersection equidistant quantitative control method is used to bury the protection pile.

[0060] According to the pile position mark, excavate the casing hole. The diameter of the casing is 20 cm larger than the design hole diameter. Since the top elevation of the steel pipe column is lower than the ground elevation, the height of the casing should not be less than the difference between the two elevations to ensure that the area from the top of the steel pipe column to the ground is fully protected by the casing. After the casing is placed, the pile position is precisely placed again in the casing hole, the plumb is checked, the position and perpendicularity of the casing are corrected and fixed, the space between the casing and the pit wall is filled with cohesive soil, the durability, accuracy and stability of the casing position are ensured, and the deviation of the center position of the casing should not be greater than 50 mm. The casing should use steel casing that can withstand the lateral pressure generated by the additional load on the ground. According to the site conditions, the casing should be higher than the ground by 20 cm to prevent surface water flow. In some projects, if the pile is located in an existing hardened pavement area and the surrounding conditions are good, the casing elevation can be set flush with the ground to facilitate mechanical positioning. After the casing is buried, the surrounding area should be backfilled and compacted with cohesive soil.

[0061] The main functions of mud during drilling are to remove slag, protect the wall, prevent hole wall collapse, and cool the drill bit. The performance of mud directly affects the drilling speed and hole quality, so mud performance indicators should be tested frequently during construction and recorded. Chemical mud is used for hole formation and wall protection. The mud specific gravity parameters are shown in the table below. The mud specific gravity should be adjusted in a timely manner according to different geological conditions and site feedback.

[0062] The scheme uses chemical mud for hole formation and wall protection. The mud specific gravity parameters are shown in the table below. The mud specific gravity should be adjusted in a timely manner according to different geological conditions and site feedback.

[0063] Mud Specific Gravity Parameters

[0064]

[0065] The design pile diameter of the pile foundation in this scheme is 1.80 m. The Sany 255 rotary drilling rig is used for hole formation. The rig is equipped with a complete set of verticality, rotation, and drill depth automatic calibration intelligent system. The verticality of the drill pipe is monitored by the total station and the depth of the hole is monitored by the plumb line. High-precision and high-quality hole formation can be achieved.

[0066] When the drilling reaches the design depth and requirements, the supervision engineer should be notified for acceptance and confirmation before the hole is terminated. When there is a discrepancy with the geological exploration data, the next step should be agreed upon by all parties before it can be carried out.

[0067] After drilling, an ultrasonic detector should be used to check the hole depth, diameter, position, and shape. The final inspection parameter table for pile foundation drilling is shown below. The supervisor should conduct an acceptance inspection. Once the design requirements are met and the supervisor engineer signs off, the next construction step can be carried out.

[0068] Pile foundation drilling final hole detection parameter table

[0069] Serial Item Quality Standard 1 Pile Position Not more than 50mm 2 Pile Perpendicularity Not more than 0.5% H (Pile Length) 3 Sediment Thickness Sediment thickness should not be more than 50mm 4 Pile Diameter - 50mm 5 Hole Depth Not less than design depth

[0070] After the borehole meets the requirements, the first hole cleaning is carried out. Its main purpose is to pump out and replace the mud in the original drill hole, reduce the relative density, viscosity, sand content and other indicators of the mud, remove sediment, reduce the thickness of the bottom of the hole, and prevent excessive sedimentation at the bottom of the pile from reducing the bearing capacity of the pile. The thickness of the bottom of the hole after cleaning shall not exceed 50mm.

[0071] Special lifting equipment is used during the transportation, storage and transportation of the steel cage. The lifting points and support points must meet the design requirements. Lifting should be done gently to prevent collisions. This solution uses a 50t truck crane to lift the steel cage in sections. During installation, the center of the steel cage must coincide with the center of the pile.

[0072] In order to ensure that the steel cage does not deform when hoisted, the method of long lifting rope with small angle is used to reduce the horizontal force. The large hook lifts the cage head and the small hook lifts the cage body. The cage head is slowly lifted to make the steel cage upright. Note that the cage head hook should be set symmetrically to ensure that the steel cage can be straight and without deviation in the vertical state.

[0073] S3. Then the steel pipe column is lowered and installed. During this process, the steel pipe column is fixed, and the pile position and verticality are adjusted using a pile column installation machine.

[0074] Specifically, this solution uses a pile installation machine to secure and adjust the steel pipe columns. Once the pile foundation reinforcement cage is lowered, the pile installation machine can be put into place. The equipment features crawler tracks and four hydraulic legs that support the installation of the steel pipe columns and adjust their verticality. The equipment's operating platform features two closable pressure plates for securing the steel pipe columns. The platform can also adjust its horizontal position in both the X and Y directions, with an adjustment range of approximately ±5cm. This equipment allows for adjustment of the verticality of the steel pipe columns and the pile position after they have been lowered, while ensuring that construction tolerances meet requirements and guaranteeing construction quality.

[0075] Because the original design placed the top of the steel pipe column higher than the existing ground level, a custom-made tool column was designed to connect to the column cap to assist in lowering and positioning the column. The overall hoisting method for the steel pipe column is the same as for conventional steel cage hoisting. For hoisting instructions, refer to the section on hoisting steel cages above. Care should be taken to reserve hoisting points in advance during fabrication, including at the column head and shaft, to prevent damage to the anti-corrosion paint finish on the steel pipe column due to wire rope binding.

[0076] The key of steel pipe column construction quality control is the control of pile position, elevation and perpendicularity. Different measures are taken to correct, adjust and control the above three points.

[0077] The elevation control is relatively conventional. After the installation of steel pipe column is completed, the total station instrument is used to check the elevation control point. The allowable range of elevation error is 0-20mm. The top elevation of steel pipe column is consistent in this scheme, and the ground elevation changes little. Before construction, the appropriate length of tool pipe should be calculated and determined in combination with the hydraulic oil leg height of pile column installation machine. When the elevation deviates, the elevation can be corrected by adjusting the hydraulic oil leg height.

[0078] The pile position is lofted before construction using the total station instrument. The cross silk method is used to mark the pile position. The subsequent hole forming, equipment positioning, steel reinforcement cage and steel pipe column lowering are all centered according to the cross silk. After the installation of steel pipe column is completed, the center position of steel pipe column is confirmed. The total station instrument is used to check the pile position with prism. The pile position error of steel pipe column is ±5mm. When the error exceeds the limit, the pile position error can be adjusted to be qualified by adjusting the equipment construction platform.

[0079] During the lowering process of steel pipe column, two total station instruments should be set up in XY two directions to scan up and down, and the verticality of lowering is monitored synchronously. If there is deviation, the lifting posture should be adjusted in time. The level is used to measure the level of flange plate in XY two directions after each section of steel pipe column is lowered. After the steel pipe column is completely placed, the ultrasonic detector is used to lower into the steel pipe column to check the perpendicularity of steel pipe column. The allowable range of perpendicularity error of steel pipe column is 1‰, and it is not more than 15mm. When the error exceeds the allowable range, the perpendicularity can be corrected by adjusting the hydraulic oil leg alone. After the perpendicularity is adjusted, the elevation and pile position of steel pipe column should be re-measured.

[0080] S4, directly pouring concrete from the inside of the steel pipe column, first pouring the pile foundation concrete outside the steel pipe column, and then pouring the concrete inside the steel pipe column.

[0081] Specifically, the guide pipe for pouring concrete in this scheme is selected with a diameter of φ300mm. The lowermost end of the guide pipe is 4m long, the standard length of each section is 2-3m, and a short pipe of 1-1.5m is provided to adjust the length. Special connecting pieces are used between each section of guide pipe, and rubber gaskets are added to the connecting parts for sealing. The guide pipe is lowered into the pile foundation hole together with the steel pipe column. The hoisting process should be slow to avoid collision with the side wall of the steel pipe column, which may cause deviation of the perpendicularity. The distance between the bottom end of the guide pipe and the hole bottom should be 300-500mm.

[0082] The concrete strength of the pile foundation design in this scheme is C35. In order to realize the inner pouring of the lower opening of the steel pipe column, the actual label on site is improved to C50 to ensure that the design requirements are met. Before pouring the concrete, a steel wire hanging water stopper should be set at the position near the mud surface in the guide pipe. The water stopper uses a hopper to support a prefabricated steel plate plug. After the reinforcement cage is lowered and placed and the second hole is cleaned, the concrete should be poured in time, and the time should not exceed 2h. If the time exceeds, the thickness of the sediment layer at the bottom of the hole should be re-measured, and if it does not meet the requirements, it should be re-cleaned.

[0083] The pipe bottom is 300-500mm from the hole bottom, the first pouring of concrete buries the pipe depth of more than 800mm, forming a concrete and mud interface to separate the mud and concrete. Considering the groundwater (mud) pressure causing the concrete to remain in the guide pipe, the first pouring of concrete is at least 5.9 cubic meters. A 6 cubic meter hopper is used for pouring on site, and the first pouring of concrete must fill the hopper while keeping the concrete in the hopper sufficient. After opening the water stopper to release the concrete, the concrete should be continuously discharged, and the guide pipe should not leak air during the process.

[0084] During the pouring process, the rising height of the concrete surface should be measured frequently. With the rising of the concrete, the guide pipe should be lifted and dismantled in time, and the depth of the guide pipe into the concrete should be controlled to be 2-6m, and the bottom end of the guide pipe should not be lifted out of the concrete surface. The guide pipe should not collide with the reinforcement cage during lifting.

[0085] When pouring to the vicinity of the design height of the concrete, the pouring speed should be reduced. The concrete in the hole should be continuously poured, and the longest interruption time should not exceed 30 minutes. The pouring height of the concrete is 0.5m above the top of the pile, which can also avoid the influence of sand filling on the design pile length range of the concrete.

[0086] Before pouring the concrete, the slump and workability tests of the commercial concrete should be carried out, and the inspection records should be well kept, and the site supervision should be notified to stand by during the slump and workability test process; check whether the concrete is segregated during transportation, if segregation occurs, it should be re-mixed; record the transportation time, and prevent the use of more than the initial setting time, and the concrete that does not meet the requirements should not be used. During the period, the construction site should be well protected to prevent large machinery from scratching the pile installation machine and causing the pile position to change.

[0087] S5, before the initial setting of the pile foundation concrete, the sand outside the steel pipe column is filled to 1m below the design elevation, and water is injected to compact it;

[0088] S6, remove the tool pipe and backfill the protection of the top of the pile, and finally detect the pile body.

[0089] Specifically, the pile foundation can be filled with sand outside the steel pipe column before the initial setting of the overfilling concrete, and the filling height is preferably 1 m below the designed top elevation of the steel pipe column. The top of the steel pipe column should be covered with a steel plate during the sand filling to prevent the backfilled sand from falling into the steel pipe column. After the sand filling is completed, a suitable amount of water should be injected outside the steel pipe column to make it compact. Then the pile column installation machine can be moved, and the concrete pouring in the steel pipe column can begin.

[0090] The concrete pouring in the steel pipe column adopts the high-position throwing self-compacting method, and the design concrete type in the steel pipe column is C50. Special attention should be paid to the concrete compactness at the flange part of the permanent steel pipe column during pouring. When pouring to the flange part, the guide pipe should be pulled up and down to make the concrete fully fill the gap at the bottom of the flange. After a period of observation, if the concrete self-compacts and sinks, additional pouring should be performed to the top of the column. After pouring is completed, the tool pipe is removed, and the pile top is backfilled for protection after the initial setting of the concrete.

[0091] In this scheme, the pile foundation adopts the ultrasonic transmission method for pile integrity test detection, and the self-balancing method for single pile compressive bearing capacity test detection. The static load test can only be performed after the pile integrity test is qualified. The slow sustained load method is adopted for loading, and the loading amount measurement, unloading amount measurement, stability standard, and compressive termination loading conditions are performed according to the "Technical Specification for Self-Balancing Static Load Test of Building Pile" JGJ / T403-2017.

[0092] The slow sustained load method is adopted. Within the first hour after each level of loading (unloading), the displacement should be measured at 5, 10, 15, 30, 45, and 60 minutes, and then measured every 30 minutes. After reaching relative stability, the next level of loading (unloading) can be applied. After unloading to zero, at least 2 hours of observation should be performed, and the measurement time interval is the same as loading. The electronic displacement sensor is connected to the computer, which directly controls the measurement and displays the Q-S, S-lgt, and S-lgQ curves on the computer screen.

[0093] In summary, this scheme focuses on the problems that may occur when constructing a steel pipe column concrete structure, such as the steel pipe column floating due to excessive concrete buoyancy, long construction period, and difficulty in adjusting the pile position and verticality. The overall construction period is long, the test detection is difficult, and the overall benefit is low. By changing the design in advance, the steel pipe column is changed to an open bottom method for pre-insertion construction, and the concrete grade of the pile foundation is increased to the same strength as the concrete in the steel pipe column. This not only ensures that the design concrete strength meets the requirements but also avoids the above problems caused by the large buoyancy of the closed steel pipe column after insertion. It better controls the construction precision, ensures the pile quality, and shortens the construction period.

[0094] During construction, the elevation, pile position and perpendicularity of the steel pipe column are rechecked and corrected by using a level, a total station and an ultrasonic detector, and are adjusted by using a pile column installation machine buckle plate and a hydraulic support leg, so that the construction quality meets the requirements. After the age of the pile foundation meets the requirements, a self-balancing method single pile compression bearing capacity test is performed by using a specially designed load box pre-embedded in advance. The whole process scientifically and reasonably ensures the feasibility, reliability, repeatability and generalizability of the construction operation.

[0095] Therefore, compared with the prior art, the scheme adopts the open lower end of the steel pipe column to perform the front insertion method construction, avoids the problem that the precision control is difficult due to the large buoyancy after the closed steel pipe column is inserted, effectively reduces the construction difficulty, ensures the construction quality, saves the construction period, and saves the labor and mechanical costs.

[0096] For example, in the air traffic control capacity improvement infrastructure construction project in the northeast region (Harbin), the main construction contents are a newly-built control main and auxiliary building and an underground garage, two to three floors above ground and one floor underground; a power energy house, one floor above ground; a night shift house and a logistics support house project, four floors above ground. The total construction area of the project is about 29894.15 square meters, of which the above-ground construction area is 24896.61 square meters, and the underground construction area is about 4997.54 square meters. The foundation form is intended to adopt a pile foundation or an independent foundation, wherein the part of the basement is designed to adopt a cast-in-situ bored pile plus a steel pipe column form permanent structure, the steel pipe column is designed to be anchored in the pile foundation with a length of 5.1 m, and the conventional construction foundation part concrete needs to be poured by using a slow-setting concrete, and the steel pipe column is inserted before the concrete solidifies. This process faces the problems of the steel pipe column floating up, the pile position and the perpendicularity being difficult to adjust due to the reasons of the large concrete buoyancy, the long construction period leading to the concrete solidification, and the like. The construction difficulty is large, the precision control is poor, the period is long, and the cost is high.

[0097] After the permanent steel pipe column concrete structure front insertion method construction method is used, the construction period of the cast-in-situ bored pile foundation plus the permanent steel pipe column single pile can be shortened by 2 days, a total of 4 roots save the construction period by 8 days, and the labor and mechanical costs are saved by about (22000+8000) * 8 = 240000 yuan. A total of about 240,000 yuan is saved. Therefore, the scheme has good reference significance for similar steel pipe column concrete structure engineering construction, can effectively reduce the construction difficulty, easily control the precision, and shorten the construction period.

[0098] Although some embodiments of the present application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and purposes of the present application, and all fall within the protection scope of the claims of the present application.

Claims

1. A permanent steel pipe column concrete structure front insertion construction method, characterized in that: The following steps are involved: S1. Before construction, communicate with the design company to change the original closed-bottom steel pipe column to an open-bottom one, and increase the concrete grade of the pile foundation to the same strength as the concrete inside the steel pipe column. Then, customize the steel pipe column and fabricate the steel cage. S2. During construction, after the pile foundation hole is drilled, cleaned and inspected, the steel cage is lowered and installed first; S3, then the steel pipe column is lowered and installed, during which the steel pipe column is fixed, and the pile position and verticality are adjusted using a pile installation machine; S4. When pouring, pour concrete directly from the inside of the steel pipe column. First pour the pile foundation concrete outside the steel pipe column, and then pour the concrete inside the steel pipe column. S5. Before the initial setting of the pile foundation concrete, fill the outer side of the steel pipe column with sand to 1m below the design elevation and inject water to compact it; S6. Remove the tool pipe and backfill the pile top for protection, and finally conduct pile body inspection.

2. The method for constructing a permanent steel pipe column concrete structure by forward insertion according to claim 1 is characterized in that: In step S1, the concrete grade of the pile foundation is increased to S350, and the concrete grade in the steel pipe column is S350.

3. The method for constructing a permanent steel pipe column concrete structure by forward insertion according to claim 1, characterized in that: In step S3, the pile installation machine includes an operating platform capable of moving in two directions of ±5S3m in XY direction, two closable pressing plates for fixing steel pipe columns, and four hydraulic oil legs for supporting and adjusting verticality.

4. The method for constructing a permanent steel pipe column concrete structure by forward insertion according to claim 3 is characterized in that: The steel pipe column is installed using a tool tube to assist in positioning, and the length of the tool tube is calculated and determined based on the height of the hydraulic oil leg and the ground elevation.

5. The method for constructing a permanent steel pipe column concrete structure by forward insertion according to claim 1, characterized in that: The vertical adjustment of steel pipe columns includes the following: During lowering, two total stations are set up in the XY directions for real-time monitoring; After each section is lowered, use a level to measure the levelness of the flange; After the installation is completed, use an ultrasonic detector to check and the verticality error shall be ≤1‰ and ≤15mm.

6. The method for constructing a permanent steel pipe column concrete structure by forward insertion according to claim 1, characterized in that: The pile position control adopts the cross-wire method, and the steel pipe column pile position error is adjusted to ±5mm.

7. The method for constructing a permanent steel pipe column concrete structure by forward insertion according to claim 1, characterized in that: In step S4, the concrete pouring is carried out using a conduit with a diameter of φ300mm, and the first concrete pouring volume is ≥5.9m 3 , the bottom of the conduit is 300-500mm away from the bottom of the hole.

8. The method for constructing a permanent steel pipe column concrete structure by forward insertion according to claim 7 is characterized in that: During pouring, the buried depth of the conduit is controlled at 26m, and the pile foundation concrete is over-poured to 0.5m above the pile top elevation.

9. The method for constructing a permanent steel pipe column concrete structure by forward insertion according to claim 1, characterized in that: In step S5, the top of the steel pipe column needs to be covered to prevent sand from entering during sand filling, and water is injected to compact the sand after sand filling.

10. The method for constructing a permanent steel pipe column concrete structure by forward insertion according to claim 1, characterized in that: In step S6, the pile body detection includes the following contents: Ultrasonic transmission method is used to test the integrity of the pile body; By pre-embedding a load box in the pile body, the self-balancing method is used to conduct a single pile compressive bearing capacity test.

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