阅读说明：本技术 一种地铁站钢管桩的施工方法 (Construction method of steel pipe pile of subway station ) 是由 尹学鑫 孟涛 高晓刚 王忠钊 吴思 武美容 王振华 崔凯 贺贤群 许光耀 吕帅 于 2021-06-10 设计创作，主要内容包括：本发明公开了一种地铁站钢管桩的施工方法,包括以下步骤：S1、导洞硬化平整；S2、定桩位、开孔；S3、钢管桩取芯；S4、钻孔：取芯完成后再采用履带式钻机钻孔,钻孔过程中,检查钻机的平整度和主动钻杆的垂直度,定期检查钻头、钻杆接头,钻孔时应低速低压钻进,并通过在钻臂上设吊锤控制垂直度；S5、一次清孔；S6、测孔深、检孔；S7、安放钢管；S8、吊放注浆管；S9、检查沉查厚度；S10、混凝土灌注；S11、接桩浇筑、桩顶纵筋安装；S12、桩底后注浆。本专利解决了钻孔垂直度不符合设计规范要求、沉渣厚度控制难的问题以及钢管桩混凝土的不够密实的难题。(The invention discloses a construction method of a steel pipe pile of a subway station, which comprises the following steps: s1, hardening and flattening the pilot hole; s2, positioning the pile and opening the hole; s3, coring the steel pipe pile; s4, drilling: after coring is finished, drilling by adopting a crawler-type drilling machine, checking the flatness of the drilling machine and the verticality of a driving drill rod in the drilling process, regularly checking a drill bit and a drill rod joint, drilling at low speed and low pressure in the drilling process, and controlling the verticality by arranging a hanging hammer on a drill boom; s5, primary hole cleaning; s6, measuring the hole depth and detecting the hole; s7, placing a steel pipe; s8, hanging a grouting pipe; s9, checking and checking the thickness; s10, pouring concrete; s11, pile splicing and pouring, and pile top longitudinal bar installation; and S12, grouting the pile bottom. The problem that the straightness that hangs down of drilling is not conform to the design standard requirement, sediment thickness control is difficult and steel pipe pile concrete closely knit inadequately has been solved to this patent.)

1. A construction method of a subway station steel pipe pile is characterized by comprising the following steps:

s1, hardening and flattening the pilot hole: after the preliminary support of the pilot tunnel is finished, hardening C20 concrete with the thickness of 15cm at the bottom of the pilot tunnel to ensure that the ground is solid and flat, and building a drainage ditch, thereby facilitating the discharge of drilling slag and slurry in the drilling construction process;

s2, positioning and opening the pile: according to construction drawings and on-site lead control points, lofting the position of a steel pipe pile of an edge pile by using a total station, retesting the coordinates and the elevation of the pile position by adopting a point-changing construction method, ensuring the accuracy of the coordinates and the elevation of the pile position, and after the lofting is measured, firstly adopting tapping equipment to align the hole position, and breaking primary supports at the bottom of a pilot tunnel to perform tapping;

s3, coring the steel pipe pile: coring is carried out by adopting an XY-1A geological drilling machine, and a pile bottom rock sample is recorded so as to ensure that a pile bottom stratum meets the design requirement;

s4, drilling: after coring is finished, drilling by adopting a crawler-type drilling machine, checking the flatness of the drilling machine and the verticality of a driving drill rod in the drilling process, regularly checking a drill bit and a drill rod joint, drilling at low speed and low pressure in the drilling process, and controlling the verticality by arranging a hanging hammer on a drill boom;

s5, primary hole cleaning: after drilling to the designed hole depth, stopping footage, blowing out sediments at the bottom of the hole by adopting high-pressure air circulation, and simultaneously, in order to ensure the maximum hole cleaning, injecting clear water into the hole to ensure that the sediment thickness can meet the design and standard requirements;

s6, measuring hole depth and detecting hole: after hole cleaning is finished, checking the aperture, the hole verticality, the hole depth and the sediment thickness, and if the sediment thickness at the bottom of the pile after hole cleaning is detected to be not in accordance with the requirement, arranging hole cleaning again until the detected sediment thickness is in accordance with the requirement;

s7, placing steel pipes: when the design depth of the drilled hole meets the requirement, hoisting the steel pipe by using a winch, fixing the steel pipe at the orifice by using a pipe clamp, and hoisting the next section of pipe, wherein the length of the pipe is not less than 50cm, and the next section of pipe is connected together by using a screw thread section of pipe; when the pipe is lowered, the pipe joints in adjacent holes are staggered front and back, so that the stress of the joints on the same section is avoided;

s8, hanging and placing a grouting pipe: in order to ensure that the pile bottom of the steel pipe pile is compact, post-grouting construction needs to be carried out, grouting pipes are hung in the steel pipe pile before concrete is poured, the grouting pipes are arranged along the deep through length of the pile and are provided with 1 grouting pipe, and the grouting pipes need to extend out of the pile top by 20cm, so that later-stage grouting connection is facilitated; the pipe sections are connected by screw threads, and the pipe bottom is sealed by an adhesive tape, so that the grouting pipe is prevented from being blocked when concrete is poured;

s9, checking and checking thickness: checking the sediment thickness at the bottom of the hole, and entering the next procedure when the sediment thickness can meet the design and specification requirements; when the sediment thickness can not meet the design and specification requirements, secondary hole cleaning is carried out, and sediment at the bottom of the hole is blown out by adopting high-pressure air circulation until the sediment thickness can meet the design and specification requirements;

s10, concrete pouring: draining accumulated water at the bottom of the hole before concrete pouring, pouring sufficient concrete by using a ground pump, and vibrating when the concrete is poured to the hole opening until fresh concrete returns out from the hole opening; in order to ensure the compactness of the concrete of the steel pipe pile, retarder is doped into the concrete, the water cement ratio is strictly controlled, and the tamping is strengthened;

s11, pile splicing and pouring, and pile top longitudinal bar installation: after concrete pouring is finished, embedding 6C20 longitudinal bars in the steel pipe piles, wherein the length of the longitudinal bars is determined according to the length of the steel pipe piles anchored into the crown beam, and when the steel pipe piles are anchored into the crown beam for 550mm, the total length of the pile top longitudinal bars is 1.95 m; when the steel pipe pile is anchored into the crown beam for 1200mm, the total length of the pile top longitudinal bar is 2.60 m;

s12, post grouting at the pile bottom: the grouting operation is preferably carried out 2 days after the pile is formed and is not later than 30 days after the pile is formed; the distance between the grouting operation point and the hole forming operation point is not less than 8-10 m; the water-cement ratio of the grouting slurry is 0.5-0.6, P.O.42.5R ordinary portland cement is adopted as the cement, the grouting pressure is not lower than 1MPa, the pressure is ensured to crush the adhesive tape, the slurry is extruded out of the pipe, and the grouting flow is not more than 75L/min; stopping grouting when the grouting pressure reaches or exceeds the design requirement; when the grouting pressure is lower than the normal value for a long time or grout is blown out or surrounding pile holes are strung, intermittent grouting is changed, the intermittent time is 30-60 min, or the water-cement ratio of the grout is adjusted to be low.

2. The construction method of a steel pipe pile for a subway station according to claim 1, wherein: in step S7, the steel pipe main material is a hot-rolled seamless steel pipe a273mm with a thickness t of 12mm, and each section of steel pipe is connected by a screw, and the screw length is 80 mm. Drilling 20mm grout overflow holes below 2.2m of the pile top of the steel pipe pile at a distance of 1.0m and arranging in a quincunx shape.

3. The construction method of a steel pipe pile for a subway station according to claim 1, wherein: in step S7, the steel tube main material should meet the following requirements: the ratio of the yield strength measured value to the tensile strength measured value of the steel is not more than 0.85; secondly, the steel material should have an obvious yield step, and the elongation rate should not be less than 20%; and the steel material has good weldability and qualified impact toughness.

4. The construction method of a steel pipe pile for a subway station according to claim 1, wherein: in the step S7, when the length of the subway station steel pipe pile is 16.80m, for odd-numbered holes: the device consists of 1 bottom tube with the length of 2.0m, 7 middle tubes with the length of 2.08m and 1 top tube with the length of 0.88m, and the total length after installation is 16.80 m; for even number of wells: the device consists of 1 bottom tube 1.0m, 7 middle tubes 2.08m and 1 top tube 1.96m, and the total length after installation is 16.80 m.

5. The construction method of a steel pipe pile for a subway station according to claim 1, wherein: in the step S7, when the length of the subway station steel pipe pile is 16.15m, for odd-numbered holes: the device consists of 1 bottom tube with the length of 2.08m, 6 middle tubes with the length of 2.08m and 1 top tube with the length of 2.15m, and the total length after installation is 16.15 m; for even number of wells: the device consists of 1 bottom tube 1.08m, 7 middle tubes 2.08m and 1 top tube 1.15m, and the total length after installation is 16.15 m.

6. The construction method of a steel pipe pile for a subway station according to claim 1, wherein: in the step S7, when the length of the subway station steel pipe pile is 8.85m, for odd-numbered holes: the device consists of 1 bottom tube with the length of 2.0m, 3 middle tubes with the length of 2.08m and 1 top tube with the length of 0.93m, and the total length after installation is 8.85 m; for even number of wells: the device consists of 1 bottom tube 1.0m, 3 middle tubes 2.08m and 1 top tube 1.93m, and the total length after installation is 8.85 m.

7. The construction method of a steel pipe pile for a subway station according to claim 1, wherein: in the step S7, when the length of the subway station steel pipe pile is 8.20m, for odd-numbered holes: the device consists of 1 bottom tube with the length of 2.0m, 2 middle tubes with the length of 2.08m and 1 top tube with the length of 2.28m, and the total length after installation is 8.20 m; for even number of wells: the device consists of 1 bottom tube 1.0m, 3 middle tubes 2.08m and 1 top tube 1.28m, and the total length after installation is 8.20 m.

8. The construction method of a steel pipe pile for a subway station according to claim 1, wherein: in step S8, the slip casting pipe is a 21.3 × 2.8mm galvanized steel pipe.

9. The construction method of a steel pipe pile for a subway station according to claim 1, wherein: in step S7, the number of joints in the same section should not exceed 50% of the total number of steel pipes, and the joints of two adjacent holes are staggered by at least 1 m.

10. The construction method of a steel pipe pile for a subway station according to claim 1, wherein: in the step S4, the diameter of the drill bit is 330mm, and the specification of the drill rod is phi 89 x 1500 mm.

Technical Field

The invention relates to the technical field of subway engineering, in particular to a construction method of a steel pipe pile of a subway station.

Background

The following problems exist in the construction of the steel pipe pile of the subway station: 1. the drilling machine is not smooth, the gap of a drill rod joint is too large, the drilling verticality is easy to be caused to be not in accordance with the design specification requirement due to high drilling pressure; 2. the problems of hole collapse and difficult control of sediment thickness are easily caused due to long time for dismantling the drill rod and hoisting the steel pipe; 3. the steel pipe pile is a bearing component in the structure, and the quality of concrete relates to the safety and stability of the whole structure. Because the pilot tunnel section is less, receive the operation space restriction, the construction quality of steel-pipe pile body concrete is difficult to guarantee.

Disclosure of Invention

The invention aims to provide a construction method of a steel pipe pile of a subway station, which aims to solve one or more technical problems in the prior art and at least provide a beneficial selection or creation condition.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a construction method of a steel pipe pile of a subway station comprises the following steps:

s1, hardening and flattening the pilot hole: after the preliminary support of the pilot tunnel is finished, hardening C20 concrete with the thickness of 15cm at the bottom of the pilot tunnel to ensure that the ground is solid and flat, and building a drainage ditch, thereby facilitating the discharge of drilling slag and slurry in the drilling construction process;

s2, positioning and opening the pile: according to construction drawings and on-site lead control points, lofting the position of a steel pipe pile of an edge pile by using a total station, retesting the coordinates and the elevation of the pile position by adopting a point-changing construction method, ensuring the accuracy of the coordinates and the elevation of the pile position, and after the lofting is measured, firstly adopting tapping equipment to align the hole position, and breaking primary supports at the bottom of a pilot tunnel to perform tapping;

s3, coring the steel pipe pile: coring is carried out by adopting an XY-1A geological drilling machine, and a pile bottom rock sample is recorded so as to ensure that a pile bottom stratum meets the design requirement;

s4, drilling: after coring is finished, drilling by adopting a crawler-type drilling machine, checking the flatness of the drilling machine and the verticality of a driving drill rod in the drilling process, regularly checking a drill bit and a drill rod joint, drilling at low speed and low pressure in the drilling process, and controlling the verticality by arranging a hanging hammer on a drill boom;

s5, primary hole cleaning: after drilling to the designed hole depth, stopping footage, blowing out sediments at the bottom of the hole by adopting high-pressure air circulation, injecting clear water into the hole to ensure the maximum hole cleaning, and then extracting liquid to ensure that the sediment thickness can meet the design and specification requirements;

s6, measuring hole depth and detecting hole: after hole cleaning is finished, checking the aperture, the hole verticality, the hole depth and the sediment thickness, and if the sediment thickness at the bottom of the pile after hole cleaning is detected to be not in accordance with the requirement, arranging hole cleaning again until the detected sediment thickness is in accordance with the requirement;

s7, placing steel pipes: when the design depth of the drilled hole meets the requirement, hoisting the steel pipe by using a winch, fixing the steel pipe at the orifice by using a pipe clamp, enabling the length of the steel pipe to be exposed out of 50cm, hoisting the next section, and connecting the two sections together by using screw threads; when the pipe is lowered, the pipe joints in adjacent holes are staggered front and back, so that the stress of the joints on the same section is avoided;

s8, hanging and placing a grouting pipe: in order to ensure that the pile bottom of the steel pipe pile is compact, post-grouting construction needs to be carried out, grouting pipes are hung in the steel pipe pile before concrete is poured, the grouting pipes are arranged along the deep through length of the pile and are provided with 1 grouting pipe, and the grouting pipes need to extend out of the pile top by 20cm, so that later-stage grouting connection is facilitated; the pipe sections are connected by screw threads, and the pipe bottom is sealed by an adhesive tape, so that the grouting pipe is prevented from being blocked when concrete is poured;

s9, checking and checking thickness: checking the sediment thickness at the bottom of the hole, and entering the next procedure when the sediment thickness can meet the design and specification requirements; when the sediment thickness can not meet the design and specification requirements, secondary hole cleaning is carried out, and sediment at the bottom of the hole is blown out by adopting high-pressure air circulation until the sediment thickness can meet the design and specification requirements;

s10, concrete pouring: draining accumulated water at the bottom of the hole before concrete pouring, pouring sufficient concrete by using a ground pump, and vibrating when the concrete is poured to the hole opening until fresh concrete returns out from the hole opening; in order to ensure the compactness of the concrete of the steel pipe pile, retarder is doped into the concrete, the water cement ratio is strictly controlled, and the tamping is strengthened;

s11, pile splicing and pouring, and pile top longitudinal bar installation: after concrete pouring is finished, embedding 6C20 longitudinal bars in the steel pipe piles, wherein the length of the longitudinal bars is determined according to the length of the steel pipe piles anchored into the crown beam, and when the steel pipe piles are anchored into the crown beam for 550mm, the total length of the pile top longitudinal bars is 1.95 m; when the steel pipe pile is anchored into the crown beam for 1200mm, the total length of the pile top longitudinal bar is 2.60 m;

s12, post grouting at the pile bottom: the grouting operation is preferably carried out 2 days after the pile is formed and is not later than 30 days after the pile is formed; the distance between the grouting operation point and the hole forming operation point is not less than 8-10 m; the water-cement ratio of the grouting slurry is 0.5-0.6, P.O.42.5R ordinary portland cement is adopted as the cement, the grouting pressure is not lower than 1MPa, the pressure is ensured to crush the adhesive tape, the slurry is extruded out of the pipe, and the grouting flow is not more than 75L/min; stopping grouting when the grouting pressure reaches or exceeds the design requirement; when the grouting pressure is lower than the normal value for a long time or grout is blown out or surrounding pile holes are strung, intermittent grouting is changed, the intermittent time is 30-60 min, or the water-cement ratio of the grout is adjusted to be low.

In step S7, the steel pipe main material was a273mm hot rolled seamless steel pipe with a thickness t of 12mm, and the steel pipes were connected by threading, each having a threading length of 80 mm. Drilling 20mm grout overflow holes below 2.2m of the pile top of the steel pipe pile at a distance of 1.0m and arranging in a quincunx shape.

Further, in the step S7, the steel tube main material should meet the following requirements: the ratio of the yield strength measured value to the tensile strength measured value of the steel is not more than 0.85; secondly, the steel material should have an obvious yield step, and the elongation rate should not be less than 20%; and the steel material has good weldability and qualified impact toughness.

Further, in the step S7, when the length of the subway station steel pipe pile is 16.80m, for odd-numbered holes: the device consists of 1 bottom tube with the length of 2.0m, 7 middle tubes with the length of 2.08m and 1 top tube with the length of 0.88m, and the total length after installation is 16.80 m; for even number of wells: the device consists of 1 bottom tube 1.0m, 7 middle tubes 2.08m and 1 top tube 1.96m, and the total length after installation is 16.80 m.

Further, in the step S7, when the length of the subway station steel pipe pile is 16.15m, for odd-numbered holes: the device consists of 1 bottom tube with the length of 2.08m, 6 middle tubes with the length of 2.08m and 1 top tube with the length of 2.15m, and the total length after installation is 16.15 m; for even number of wells: the device consists of 1 bottom tube 1.08m, 7 middle tubes 2.08m and 1 top tube 1.15m, and the total length after installation is 16.15 m.

Further, in the step S7, when the length of the subway station steel pipe pile is 8.85m, for odd-numbered holes: the device consists of 1 bottom tube with the length of 2.0m, 3 middle tubes with the length of 2.08m and 1 top tube with the length of 0.93m, and the total length after installation is 8.85 m; for even number of wells: the device consists of 1 bottom tube 1.0m, 3 middle tubes 2.08m and 1 top tube 1.93m, and the total length after installation is 8.85 m.

Further, in the step S7, when the length of the subway station steel pipe pile is 8.20m, for odd-numbered holes: the device consists of 1 bottom tube with the length of 2.0m, 2 middle tubes with the length of 2.08m and 1 top tube with the length of 2.28m, and the total length after installation is 8.20 m; for even number of wells: the device consists of 1 bottom tube 1.0m, 3 middle tubes 2.08m and 1 top tube 1.28m, and the total length after installation is 8.20 m.

Further, in step S8, the slip casting pipe is a 21.3 × 2.8mm galvanized steel pipe.

Further, in step S7, the number of joints in the same section should not exceed 50% of the total number of steel pipes, and the joints of two adjacent holes are shifted by at least 1 m.

Further, in the step S4, the diameter of the drill bit is 330mm, and the specification of the drill rod is Φ 89 × 1500 mm.

The invention has the beneficial effects that:

in the drilling process (step S4), low-speed and low-pressure drilling is required during drilling, and the perpendicularity is controlled by arranging the hanging hammer on the drill boom, so that the problems that the drilling machine is not flat, the gap of a drill rod joint is too large, the drilling pressure is too high and the drilling perpendicularity is easy to meet the design specification requirement are solved;

the method adopts a mode of cleaning the holes twice, so that the problems of hole collapse and difficult control of the thickness of sediments are easily caused;

this patent is in the concrete placement process (step S10), for guaranteeing the closely knit of steel pipe pile concrete, mix the retarder in the concrete, the strict control water cement ratio to strengthen and tamp, it is less to have solved the pilot tunnel section, receives the operation space restriction, the difficult problem of the difficult assurance of construction quality of steel pipe pile body concrete.

Drawings

The invention is further described with the aid of the accompanying drawings, in which the embodiments do not constitute any limitation, and for a person skilled in the art, without inventive effort, further drawings may be obtained from the following figures:

FIG. 1 is a flow chart of the present invention.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the following detailed description of the present invention is provided with reference to the accompanying drawings and specific embodiments, and it is to be noted that the embodiments and features of the embodiments of the present application can be combined with each other without conflict.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper surface", "lower surface", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "forward", "reverse", "axial", "radial", "circumferential", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.

As shown in fig. 1, a construction method of a steel pipe pile in a subway station includes the following steps:

s1, hardening and flattening the pilot hole: after the preliminary support of the pilot tunnel is finished, hardening C20 concrete with the thickness of 15cm at the bottom of the pilot tunnel to ensure that the ground is solid and flat, and building a drainage ditch, thereby facilitating the discharge of drilling slag and slurry in the drilling construction process;

s2, positioning and opening the pile: according to construction drawings and on-site lead control points, lofting the position of a steel pipe pile of an edge pile by using a total station, retesting the coordinates and the elevation of the pile position by adopting a point-changing construction method, ensuring the accuracy of the coordinates and the elevation of the pile position, and after the lofting is measured, firstly adopting tapping equipment to align the hole position, and breaking primary supports at the bottom of a pilot tunnel to perform tapping;

s3, coring the steel pipe pile: coring is carried out by adopting an XY-1A geological drilling machine, and a pile bottom rock sample is recorded so as to ensure that a pile bottom stratum meets the design requirement;

s4, drilling: drilling by using a crawler-type drilling machine after coring is finished, wherein the diameter of a drill bit is 330mm, and the specification of a drill rod is phi 89 multiplied by 1500 mm;

s5, primary hole cleaning: after drilling to the designed hole depth, stopping footage, blowing out sediments at the bottom of the hole by adopting high-pressure air circulation, and simultaneously, in order to ensure the maximum hole cleaning, injecting clear water into the hole to ensure that the sediment thickness can meet the design and standard requirements;

s6, measuring hole depth and detecting hole: after hole cleaning is finished, checking the aperture, the hole verticality, the hole depth and the sediment thickness, and if the sediment thickness at the bottom of the pile after hole cleaning is detected to be not in accordance with the requirement, arranging hole cleaning again until the detected sediment thickness is in accordance with the requirement;

s7, placing steel pipes: when the design depth of the drilled hole meets the requirement, hoisting the steel pipe by using a winch, fixing the steel pipe at the orifice by using a pipe clamp, enabling the length of the steel pipe to be exposed out of 50cm, hoisting the next section, and connecting the two sections together by using screw threads; when the pipe is lowered, the pipe joints in adjacent holes are staggered front and back, so that the stress of the joints on the same section is avoided; the number of joints in the same section is not more than 50% of the total number of steel pipes, and the joints of the steel pipes with two adjacent holes are staggered by at least 1 m. The steel pipe main material is a273mm hot-rolled seamless steel pipe with the wall thickness t being 12mm, each section of steel pipe is connected by screw threads, and the screw thread length is 80 mm. Drilling 20mm grout overflow holes below 2.2m of the pile top of the steel pipe pile at a distance of 1.0m and arranging in a quincunx shape. The main material of the steel pipe meets the following requirements: the ratio of the yield strength measured value to the tensile strength measured value of the steel is not more than 0.85; secondly, the steel material should have an obvious yield step, and the elongation rate should not be less than 20%; and the steel material has good weldability and qualified impact toughness.

When the length of the steel pipe pile of the subway station is 16.80m, for odd holes: the device consists of 1 bottom tube with the length of 2.0m, 7 middle tubes with the length of 2.08m and 1 top tube with the length of 0.88m, and the total length after installation is 16.80 m; for even number of wells: the device consists of 1 bottom tube 1.0m, 7 middle tubes 2.08m and 1 top tube 1.96m, and the total length after installation is 16.80 m.

When the length of the steel pipe pile of the subway station is 16.15m, for odd holes: the device consists of 1 bottom tube with the length of 2.08m, 6 middle tubes with the length of 2.08m and 1 top tube with the length of 2.15m, and the total length after installation is 16.15 m; for even number of wells: the device consists of 1 bottom tube 1.08m, 7 middle tubes 2.08m and 1 top tube 1.15m, and the total length after installation is 16.15 m.

When the length of the steel pipe pile at the subway station is 8.85m, for odd holes: the device consists of 1 bottom tube with the length of 2.0m, 3 middle tubes with the length of 2.08m and 1 top tube with the length of 0.93m, and the total length after installation is 8.85 m; for even number of wells: the device consists of 1 bottom tube 1.0m, 3 middle tubes 2.08m and 1 top tube 1.93m, and the total length after installation is 8.85 m.

When subway station steel pipe pile length is 8.20m, to odd number hole: the device consists of 1 bottom tube with the length of 2.0m, 2 middle tubes with the length of 2.08m and 1 top tube with the length of 2.28m, and the total length after installation is 8.20 m; for even number of wells: the device consists of 1 bottom tube 1.0m, 3 middle tubes 2.08m and 1 top tube 1.28m, and the total length after installation is 8.20 m.

S8, hanging and placing a grouting pipe: in order to ensure that the pile bottom of the steel pipe pile is compact, post-grouting construction needs to be carried out, grouting pipes are hung in the steel pipe pile before concrete is poured, the grouting pipes are arranged along the deep through length of the pile and are provided with 1 grouting pipe, and the grouting pipes need to extend out of the pile top by 20cm, so that later-stage grouting connection is facilitated; the pipe sections are connected by screw threads, and the pipe bottom is sealed by an adhesive tape, so that the grouting pipe is prevented from being blocked when concrete is poured; the grouting pipe is a galvanized steel pipe with the diameter of 21.3 x 2.8 mm.

S9, checking and checking thickness: checking the sediment thickness at the bottom of the hole, and entering the next procedure when the sediment thickness can meet the design and specification requirements; when the sediment thickness can not meet the design and specification requirements, secondary hole cleaning is carried out, and sediment at the bottom of the hole is blown out by adopting high-pressure air circulation until the sediment thickness can meet the design and specification requirements;

s10, concrete pouring: draining accumulated water at the bottom of the hole before concrete pouring, pouring sufficient concrete by using a ground pump, and vibrating when the concrete is poured to the hole opening until fresh concrete returns out from the hole opening;

specifically, concrete placement should meet the following requirements:

(1) c35 fine stone concrete should be poured into the drill holes and the steel pipes, the concrete should be densely filled in the drill holes and the steel pipes, and the design and trial matching of strict mix proportion are carried out; the slump of the concrete can be determined according to a pouring process, and the slump is smaller than 160mm and larger than 180 mm. After concrete passes through trial preparation and tests and full basis is obtained, in order to reduce the shrinkage of the concrete, a proper amount of water reducing agent and expanding agent can be added into the concrete.

(2) The concrete in the steel pipe must be poured continuously without interruption.

(3) The pouring of the pile concrete is higher than the designed elevation, and the strength grade of the pile top concrete must meet the design requirement.

(4) The side pile construction should satisfy design requirements such as pile length, pile diameter, concrete strength grade, should not take place such as disconnected pile, concrete segregation, double-layered mud, the biggest particle size of concrete coarse aggregate must not be greater than 1/3 of the minimum clear distance between the main muscle, and pile bottom sediment is not more than 50 mm.

(5) After the concrete is poured, when the pile top longitudinal bar is placed to the designed position, whether the horizontal position and the elevation of the pile top longitudinal bar meet the design requirements or not is detected, and the pile top longitudinal bar is immediately fixed after the horizontal position and the elevation meet the design requirements.

S11, pile splicing and pouring, and pile top longitudinal bar installation: after concrete pouring is finished, embedding 6C20 longitudinal bars in the steel pipe piles, wherein the length of the longitudinal bars is determined according to the length of the steel pipe piles anchored into the crown beam, and when the steel pipe piles are anchored into the crown beam for 550mm, the total length of the pile top longitudinal bars is 1.95 m; when the steel pipe pile is anchored into the crown beam for 1200mm, the total length of the pile top longitudinal bar is 2.60 m;

s12, post grouting at the pile bottom: the grouting operation is preferably carried out 2 days after the pile is formed and is not later than 30 days after the pile is formed; the distance between the grouting operation point and the hole forming operation point is not less than 8-10 m; the water-cement ratio of the grouting slurry is 0.5-0.6, P.O.42.5R ordinary portland cement is adopted as the cement, the grouting pressure is not lower than 1MPa, the pressure is ensured to crush the adhesive tape, the slurry is extruded out of the pipe, and the grouting flow is not more than 75L/min; stopping grouting when the grouting pressure reaches or exceeds the design requirement; when the grouting pressure is lower than the normal value for a long time or grout is blown out or surrounding pile holes are strung, intermittent grouting is changed, the intermittent time is 30-60 min, or the water-cement ratio of the grout is adjusted to be low.

After the construction of the steel pipe pile of the subway station is completed, the bearing capacity needs to be checked, and the bearing capacity of a single pile is not less than the designed bearing capacity of the single pile of 750 KN. The detection method and the detection quantity simultaneously need to meet the requirements of technical Specifications for building pile foundations (JGJ94-2008) and technical Specifications for detecting building foundation piles (JGJ 106-2014).

Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.