CN117721789A - Post-tensioned prestressing large-pulling-resistant pile for cement deep-stirring implanted pipe pile - Google Patents

Abstract

The invention relates to a post-tensioned prestressing large pulling resistance pile of a cement deep stirring implanted pipe pile, which is characterized in that a cement strong stirring pile machine is adopted to stir to form a cylindrical cement soil pile body 1 with the designed depth L and the diameter D, then a precast reinforced concrete pipe pile 2 is implanted in sections, and steel stranded wires 3 are arranged in each section of pipe pile; when the underground structure bearing platform 21 is poured, the pile head embedded anchor bars 11 of the prefabricated reinforced concrete pipe pile 2 are anchored into the bearing platform, meanwhile, the steel backing plate 15 and the anchoring piece 9 of the steel stranded wire 3 are embedded, and gaps 17 are reserved at the positions of the steel backing plate 15 and the anchoring piece 9; after the steel stranded wires 3 are prestressed and locked, concrete 12 is poured into the tubular pile cavity, cement slurry pressure grouting is carried out on the whole tubular pile cavity from the bottom to the top through a pre-buried grouting pipe 13, and the construction of the post-tensioned prestressed high-pulling-resistance pile with cement deep stirring implanted into the tubular pile is completed; the novel anti-floating pile has the advantages of high bearing capacity, simple and convenient construction, low cost, small influence on environment, simple construction operation and the like.

Description

Post-tensioned prestressing large-pulling-resistant pile for cement deep-stirring implanted pipe pile

Technical Field

The invention relates to a novel uplift pile method, namely a cement deep stirring post-implanted tubular pile tensile prestress high uplift pile, which is suitable for underground engineering.

Background

In recent years, underground engineering accidents such as floating of a basement structure and cracking of the basement structure are frequently caused by incorrect anti-floating design or construction. At present, the anti-pulling pile of the basement mostly adopts the traditional bored pile, and because of the requirement of durability, the anti-pulling pile must be subjected to crack checking under the action of water buoyancy, the consumption of reinforcing steel bars is often 2-4 times that of the anti-pulling pile, the construction cost is high, the construction work efficiency is low, and slurry is generated to pollute the environment. The prefabricated reinforced concrete pipe pile is also used as an anti-floating pile, but the problems of low pulling resistance, pile sinking soil compaction, difficult pile pressing in construction, low pile joint reliability and the like exist.

With the development and utilization of urban underground space, foundation embedding is deeper and deeper, two-layer basements are adopted in residential projects, and three-layer or more basements are adopted in commercial projects. The anti-floating problem of underground engineering is increasingly outstanding, and the investment in anti-floating is greatly increased, so that the development of a novel anti-floating pile for anti-floating design is imperative, the engineering cost is reduced, and the work efficiency is improved.

Disclosure of Invention

The invention relates to a new technology of anti-floating pile construction, namely a cement deep stirring post-implanted tubular pile tensile prestress high-pulling-resistance pile, which is more suitable for large-depth underground engineering. The anti-floating pile adopts a single-shaft telescopic stirring drill rod, cement slurry is injected while stirring, a prefabricated reinforced concrete tubular pile with an internal strip steel hinge line or a high-strength steel rod is implanted to form a composite anti-floating pile, and after the bottom plate of the underground structure is poured, the steel hinge line or the high-strength steel rod is stretched to apply prestress to the pile body to finish the construction of the post-tensioned prestressing large-pulling pile after cement deep stirring and implantation of the tubular pile (figure I).

The beneficial effects of the invention are as follows: the prestressed composite anti-floating pile (the tensile prestressed large anti-pulling pile after cement is deeply stirred into the pipe pile) has the advantages of high bearing capacity, simple and convenient construction, low manufacturing cost, small influence on environment, simple construction operation and the like; the significance of developing and popularizing the prestress composite anti-floating pile is great.

Drawings

FIG. 1 is a cross-sectional view of a tensile prestressed high-pulling-resistance pile after cement stirring and implantation into the pile;

FIG. 2.1 is a cross-sectional view of a pile bottom;

fig. 2.2 is a plan view of a steel pile head;

fig. 2.3 is a side view of a steel pile head;

fig. 2.4.1 is a plan view of a single hole anchor;

fig. 2.4.2 is a plan view of a dual hole anchor;

fig. 2.4.3 is a plan view of a triple hole anchor;

fig. 2.4.4 is a plan view of a four hole anchor;

fig. 2.4.5 is a plan view of a five hole anchor;

fig. 2.4.6 is a plan view two of a five hole anchor;

fig. 2.4.7 is a plan view of a six hole anchor;

fig. 2.4.8 is a plan view of a seven-hole anchor;

fig. 3.1 is a cross-sectional view of a steel strand anchor stub bar connection;

fig. 3.2 is a plan view of a steel strand anchor stub bar connection;

FIG. 3.3 is a cross-sectional view of a steel strand anchor sleeve connection;

FIG. 3.4 is a plan view of a steel strand anchor sleeve connection;

FIG. 3.5 is a cross-sectional view of a box connection with a protruding edge of a steel strand anchor;

FIG. 3.6 is a plan view of a box connection with a protruding edge of a steel strand anchor;

FIG. 4.1 is a vertical cross-section of a steel strand connector;

FIG. 4.2 is a perspective view of a steel strand connector;

FIG. 4.3 is a transverse cross-sectional view of a steel strand connector;

FIG. 4.4 is an external view of a steel strand connector;

FIG. 5 is a cross-sectional view of a pile head of a composite anti-floating pile;

FIG. 6 is a schematic view of pile head position adjustment;

FIG. 7.1 is a schematic diagram showing the spiral placement of steel strands in a pipe pile;

FIG. 7.2 is a schematic diagram showing the spiral placement of steel strands in a pipe pile;

in the figure: 1-cement pile body, 2-precast reinforced concrete pipe pile (comprising three parts of a, b and c), 3-steel stranded wires, 4-steel pile heads, 5-steel stranded wire connectors (comprising 9 and 10), 6-pipe pile connectors, 7-steel sealing covers, 8-round steel plates, 9-anchoring parts, 10-single steel stranded wire connectors, 11-embedded anchor bars, 12-concrete in a cavity, 13-grouting pipes, 14-grouting pipes, 15-steel backing plates, 16-isolation sleeves, 17-reserved gaps, 18-reinforced short steel bars, 19-sleeves, 20-sleeves with protruding edges, 21-bearing platforms, 22-lifting hooks, a-lowest-section pipe piles, b-middle-section pipe piles and c-uppermost-section pipe piles.

Detailed Description

The invention can be implemented in the following steps and ways.

1. The newly developed cement strong stirring pile machine is adopted, the diameter of the stirring drill rod blade is 800-1200 mm, the power of the rotary power head can enable the soil cutting torque to be larger than 80kN.m, the rotating speed is larger than 40 r/min, and the descending and lifting stirring speeds of the drill rod are controlled to be 0.5-2 m/min. The main frame of the stirring pile machine is generally 25-40 m in height, the stirring depth of a conventional drill rod is limited, and when the composite anti-floating pile is deeper, a telescopic drill rod can be adopted, so that the drilling and stirring depth of the drill rod can reach more than 50m, and the design requirement of large anti-pulling force is met. According to the requirement of 20% -30% of cement mixing ratio, the grouting pressure of drilling and stirring cement is 0.5-2.5 MPa. The cement-soil pile body 1 is formed by grouting and lifting stirring at the same time through a drill rod according to construction parameters of design requirements, the diameter D of the cylindrical cement-soil pile body 1 is determined by the diameter of a blade of the stirring drill rod, the effective depth L of the composite anti-floating pile is designed, and the depth L0 (foundation burial depth) of an upper empty stirring section is designed, and is shown in fig. 1.

2. And (3) stirring through a drill rod to form a cement soil pile body 1 with the designed depth L and the diameter D, and then implanting a prefabricated reinforced concrete pipe pile 2 (with the outer diameter D and the cavity inner diameter D1) for construction. The prefabricated reinforced concrete pipe pile is formed by implanting and connecting the prefabricated parts in sections due to the length limitation (generally not more than 15 m), and each section of pipe pile is manufactured into a pile cap and a connection 6 according to the conventional anti-floating pile requirement. And steel stranded wires 3 are arranged in each section of pipe pile, and the number and the size of the steel stranded wires are determined by anti-floating design. The brand new post-tensioned prestressed composite anti-floating pile is formed in this way, the composite anti-floating pile is provided with frictional resistance by a cylindrical cement soil pile body 1 with the effective depth L and the diameter D and containing a prefabricated pipe pile 2, the steel wires 3 in the pile and the reinforcement bars of the prefabricated reinforced concrete pipe pile 2 bear pulling force together, and the steel wires 3 in the tensioned pile apply prestress to the anti-floating pile, as shown in figure 1.

3. The implanted precast reinforced concrete pipe pile 2 is formed by connecting a lowermost section pipe pile a, a middle section pipe pile b and an uppermost section pipe pile c; the bottom end of the lowest section pipe pile a is provided with a special steel pile head 4, and the steel stranded wires 3 are arranged in the pipe pile and are connected with the pipe pile in an anchoring way. The upper part of the steel strand 3 is connected with a steel strand connector 5 which is temporarily fixed at the upper end of the pipe pile; the upper and lower parts of d steel strands 3 in the middle section of pipe pile b are connected with steel strand connectors 5 which are temporarily fixed at the upper and lower ends of the section of pipe pile; the lower part of the steel strand 3 in the uppermost pipe pile c is connected with a steel strand connector 5 fixed at the lower end of the pipe pile, and the upper end is used for simply fixing the steel strand 3 with the hook on the bottom surface of a temporary steel sealing cover 7 paved on the pile top after an extension section (the thickness of a pile top bearing platform is determined by design and is generally 500-1000 mm) is reserved according to the design requirement of the steel strand 3. The temporary steel sealing cover 7 is paved on the top of the uppermost tubular pile c and also plays a role in preventing cement soil slurry from entering the cavity of the tubular pile, as shown in fig. 1.

4. The bottom end of the implanted lowest section pipe pile a is provided with a specially-made steel pile head 4, and the steel pile head 4 consists of a round steel plate 8 and a conventional universal anchoring piece 9. The diameter d2 of the round steel plate 8 is 10mm smaller than the outer diameter d of the lowest section pipe pile a, and the thickness t is determined by meeting the requirement of the shearing strength under the action of the pulling resistance of the steel stranded wires 3. The number and diameter of the holes drilled in the round steel plate 8 correspond to the anchor 9 used. The specifications of the anchoring elements 9 adapted to anchor different numbers of prestressed steel strands are single-hole or multi-hole (fig. 2.4.1-2.4.8). The anchoring piece 9 and the round steel plate 8 are fixed into a whole by fillet welding, see fig. 2.1-2.3.

5. The connection of the implanted lowest section pipe pile a and the middle section pipe pile b and the connection of the middle section pipe pile b and the uppermost section pipe pile c comprise the connection 5 of steel stranded wires in the pipe pile and the connection 6 of the pipe pile. The method for connecting the steel strands in the pipe pile 5 comprises two steps:

one is that the anchors 9 are directly connected. When the tensile resistance to be provided is relatively small and the number of steel strands is small, the upper and lower anchoring members 9 can be directly welded and connected by the short steel bars 18, and the diameter and the number of the short steel bars 18 are designed (fig. 3.1 and 3.2). When the required tensile strength is relatively large, i.e. the number of steel strands is large, the sleeve 19 is used for welding (fig. 3.3, fig. 3.4). When the required tensile force is large, namely the number of steel strands is large, the upper sleeve 20 and the lower sleeve 20 with the protruding edges are welded and connected, and the welded short steel bars 18 are added for reinforcement if necessary (fig. 3.5 and 3.6). The anchoring piece 9 of the steel strand in the pipe pile is hung on the hollow inner wall of the pipe pile at the upper end of the pipe pile, and the anchoring piece 9 and the steel strand are pulled out of the pile top (the length of the steel strand is reserved to be 300-500 mm higher than the pile top) after the lower section pile is planted, and the anchoring piece 9 is connected with the steel strand anchoring piece 9 of the upper section pile.

And secondly, the single steel strand connector 10 is connected. The single steel strand connector 10 is composed of two specially processed steel semi-cylinders, and the two cylinders are fixed and welded by electric welding after the upper and lower steel strands and the fixed wedge-shaped clamp are embedded and fastened by a central bolt. The upper end of the steel strand in the pipe pile is hung on the hollow inner wall of the pipe pile, the upper end of the steel strand is pulled out of the pile top (the length of the steel strand is reserved to be 300-500 mm higher than the pile top) after the lower section pile is planted, and the steel strand is connected with the steel strand of the upper section pile one by a connector 10 (fig. 4.1-4.4).

6. The connection 6 of the upper and lower section pipe piles is carried out after the steel stranded wires in the pipe pile cavity are connected. The connection 6 of the upper and lower pipe piles is completely connected by adopting various modes of the existing anti-floating pipe piles. The anti-pulling reinforcement of the whole composite anti-floating pile consists of anti-pulling reinforcements arranged on the pipe piles and steel strands in the pipe piles, the pipe piles are more in the uppermost section of pipe piles c after the whole composite anti-floating pile is connected, the middle section of pipe piles b can be gradually reduced, the lowermost section of pipe piles a are fewer, and the pile is specifically determined by design, so that the pile accords with the rule that the cross section anti-pulling stress of the whole composite anti-floating pile gradually reduces along with the depth, and the construction cost is saved.

7. After the implantation of each section of tubular pile of the composite anti-floating pile is completed and the pile head is excavated, the pile head sealing cover 7 is removed and the steel stranded wires 3 are pulled out. The pile head is subjected to operations of pre-burying anchor bars 11 and cavity concrete pouring 12 (figure 5) according to the conventional anti-floating pile method. At this time, the steel strand 3 pulled out of the pile head cavity should be first sleeved with the isolating sleeve 16 (typically a PVC plastic pipe) so that the steel strand 3 is separated from the cavity poured concrete 12, and thus the prestress applied by tensioning the steel strand 3 can not be affected by the resistance of the concrete 12. Grouting pipes 13 (typically PVC plastic pipes) and a bleed pipe 14 (fig. 5) which only need to pass through the concrete 12, which lead to the bottom of the pile, are also pre-buried before the concrete 12 is poured.

8. After the pipe pile head is processed, pouring of the basement foundation pile cap 21 can be performed. The pile head embedded anchor bars 11 are anchored in the pile head when the pile head 16 is poured, and meanwhile, the steel backing plates 15 and the anchoring pieces 9 penetrating through the steel stranded wires 3 are embedded (fig. 5). The drill holes on the steel backing plate 15 are consistent in size and number with the anchors 9 (consistent with the steel strands 3). During the concrete pouring of the bearing platform 21, gaps 17 are reserved at the positions of the steel backing plate 15 and the anchoring parts 9.

9. After the steel stranded wires 3 are prestressed and locked, cement slurry pressure grouting is carried out on the whole tubular pile cavity from the bottom of the pipe through the pre-buried grouting pipe 13. The pressure grouting is carried out until the pre-buried slurry discharging air pipe 14 is out of slurry. The reserved gap 17 is filled with high-strength micro-expansive concrete after the above operation is completed (fig. 5). Thus, the implementation of the whole cement deep stirring post-implantation pile tensile prestress large pulling resistance pile is completed.

10. The second implementation method of the invention is as follows: the steel pile head 4 is arranged at the top of the lowest section pipe pile a and the bottom of the middle section pipe pile b, so that the whole length of the steel stranded wire can be reduced, the manufacturing cost is saved, and the work efficiency is simplified. Specifically, after the lowermost section of pipe pile a is implanted, the steel stranded wires 3 are anchored at the steel pile head 4 and welded at the bottom of the middle section of pipe pile b, then the middle section of pipe pile b is connected with the lowermost section of pipe pile a, and if necessary, the short steel bars 18 are welded for reinforcement (fig. 6).

11. The third implementation method of the invention is as follows: the reinforcement and the inner diameter of the pipe pile of the prefabricated reinforced concrete pipe pile are enlarged (thin-wall or larger-diameter pipe pile is adopted), so that the diameter and the number of the configured steel strands 3 are reduced under the condition that the total pulling-resistant bearing capacity of the composite floating pile is unchanged, the steel strands 3 do not need to be connected in a subdivision mode, the whole steel strands 3 (the length from the steel pile head 4 to a foundation bearing platform) connected with the steel pile head 4 are directly and spirally arranged in the cavity of the lowermost section pipe pile a, after the section pipe pile is implanted, the steel strands 3 are pulled by the lifting hooks 22 on the steel strands 3 through the lifting hooks in the upper section pipe pile connected with the section pipe pile, the pile is further pressed after the upper section pipe pile and the lower section pipe pile are connected, the lifting hooks pull out the steel strands 3 from the pile top, and the steel strands 3 are connected section by section and implanted into the pile (if the middle section pipe pile b has a plurality of sections) until the uppermost section pipe pile c is implanted, and the pile planting is completed. The steel pile head 4 can be located at the bottom of the lowest section pipe pile or at the bottom of the middle section pipe pile (fig. 7.1, fig. 7.2).

Claims (10)

1. A cement is stirred deeply and is planted pile post-tensioned prestressing and is greatly resisted the pulling force stake, characterized by: after a cylindrical cement pile body 1 with the designed depth L and the diameter D is formed by stirring by adopting a cement strong stirring pile machine, precast reinforced concrete pipe piles 2 are planted in sections, and steel stranded wires 3 are arranged in each section of pipe piles; when the underground structure bearing platform 21 is poured, the pile head embedded anchor bars 11 of the prefabricated reinforced concrete pipe pile 2 are anchored into the bearing platform 21, meanwhile, the steel backing plate 15 and the anchoring piece 9 of the steel stranded wire 3 are embedded, and gaps 17 are reserved at the positions of the steel backing plate 15 and the anchoring piece 9; after the steel stranded wires 3 are prestressed and locked, concrete 12 is poured into the tubular pile cavity, cement slurry pressure grouting is carried out on the whole tubular pile cavity from the bottom to the top through the pre-buried grouting pipe 13, and the construction of the post-tensioned prestressed high-pulling-resistance pile with cement deep stirring implanted into the tubular pile is completed.

2. According to claim 1, a cement deep-stirring post-implantation pile is a tensile prestressed large-pulling-resistance pile, which is characterized in that: the prefabricated reinforced concrete pipe pile 2 is formed by connecting a lowermost section pipe pile a, a middle section pipe pile b and an uppermost section pipe pile c; the bottom end of the lowest section pipe pile a is provided with a special steel pile head 4, and a steel stranded wire 3 arranged in the pipe pile is connected with the steel stranded wire in an anchoring manner; equal amount of steel strands 3 are arranged in each section of pipe pile, and each section of pipe pile end is connected with a connector 5 fixed at the section of pipe pile end; the reserved extension section of the top steel strand 3 of the uppermost tubular pile c is fixed with a hook on the bottom surface of a temporary steel sealing cover 7 paved on the pile top.

3. According to claim 2, a cement deep-stirring post-implantation pile is a tensile prestressed large-pulling-resistance pile, which is characterized in that: the steel pile head 4 consists of a round steel plate 8 and an anchoring piece 9; the diameter d2 of the round steel plate 8 is 10mm smaller than the outer diameter d of the lowest section pipe pile a, and the thickness t is determined by meeting the requirement of the shearing strength under the action of the pulling resistance of the steel stranded wires 3; the number and the diameter of the drilled holes on the round steel plate 8 are consistent with those of the adopted anchoring pieces 9, and the round steel plate and the anchoring pieces 9 are fixed into a whole by fillet welding.

4. According to claim 1, a cement deep-stirring post-implantation pile is a tensile prestressed large-pulling-resistance pile, which is characterized in that: the connection of the steel strands 3 in each pipe pile can adopt two different connection modes according to the difference of the tensile force, firstly, the connection is carried out by adopting a sleeve, and secondly, the connection is carried out by adopting a single steel strand connector 10 of a split steel semi-cylinder.

5. According to claim 1, a cement deep-stirring post-implantation pile is a tensile prestressed large-pulling-resistance pile, which is characterized in that: the prefabricated reinforced concrete pipe pile 2 is formed by connecting a lowermost section pipe pile a, a middle section pipe pile b and an uppermost section pipe pile c, and according to the design bearing capacity requirement, the uppermost section pipe pile c is provided with more reinforcing bars, and the reinforcing bar quantity of the middle section pipe pile b and the lowermost section pipe pile a is gradually reduced.

6. According to claim 1, a cement deep-stirring post-implantation pile is a tensile prestressed large-pulling-resistance pile, which is characterized in that: after the prefabricated reinforced concrete pipe pile 2 is implanted in sections and connected to finish the excavation of a pile head, the pile head is subjected to the operations of embedding anchor bars 11 and pouring concrete 12 into a cavity; the steel strand 3 pulled out of the pile head cavity is sleeved with an isolating sleeve 16, and a grouting pipe 13 which is communicated to the pile bottom and a grouting air pipe 14 which only needs to pass through the concrete 12 are pre-buried.

7. According to claim 1, a cement deep-stirring post-implantation pile is a tensile prestressed large-pulling-resistance pile, which is characterized in that: the pile head embedded anchor bars 11 are anchored in the underground structure bearing platform 21 during pouring, and meanwhile, the steel backing plate 15 and the anchoring pieces 9 are embedded; the steel backing plate 15 has holes of the same size and number as the anchors 9, and the holes are fixed by spot welding to form a pre-stressed pedestal.

8. According to claim 1, a cement deep-stirring post-implantation pile is a tensile prestressed large-pulling-resistance pile, which is characterized in that: and after the prestress is applied to the steel stranded wires 3 and the steel stranded wires are locked, the precast reinforced concrete pipe pile 2 performs cement slurry pressure grouting on the whole pipe pile cavity from the bottom through the pre-buried grouting pipe 13 until the slurry leakage pipe 14 is in slurry leakage.

9. According to claim 2, a cement deep-stirring post-implantation pile is a tensile prestressed large-pulling-resistance pile, which is characterized in that: the steel pile head 4 can be arranged at the top of the lowest section pipe pile a and the bottom of the middle section pipe pile b, so that the whole length of the steel stranded wires can be reduced, the manufacturing cost is saved, and the work efficiency is simplified.

10. According to claim 1, a cement deep-stirring post-implantation pile is a tensile prestressed large-pulling-resistance pile, which is characterized in that: the prefabricated reinforced concrete pipe pile 2 can enlarge the inner diameter of the anti-pulling reinforcement and the cavity of the prefabricated reinforced concrete pipe pile 2 during design, reduce the diameter and the number of the configured steel strands 3, ensure that the steel strands are not required to be connected in a subdivision mode, directly and completely place the whole steel strands 3 after being connected with the steel pile head 4 in the cavity of the lower pipe pile in a spiral mode, pull the steel strands 3 out of the pile top by using a lifting hook before connecting each upper section pipe pile, and so on until the uppermost section pipe pile c is planted, pull the steel strands 3 out of the pile top to complete pile planting.