Prefabricated hollow pipe pile for enhancing bearing capacity of coral sand field and construction method

Abstract

According to the prefabricated hollow pipe pile for enhancing the bearing capacity of the coral sand field and the construction method, a hollow pipe pile body comprises a pile A and a pile B, and the pile B is arranged at the tail end of the pile A; a prefabricated pile tip is arranged at the front end of the pile A, an embedding groove is formed in the tail of the pile A, an embedding plug is arranged at the front end of the pile B and matched with the embedding groove, a UHPC grouting sleeve is embedded in the embedding groove, anchoring steel bars are arranged in the embedding groove, the anchoring steel bars are exposed out of the embedding plug, and flange plates are arranged on the outer side walls of the embedding plug and the embedding groove. Slurry outlets are formed in the outer surfaces of the pile bodies A and B and are connected with the grouting channel; one end of the grouting channel communicates with the grout outlet, the other end of the grouting channel communicates with a grouting opening in the tail of the hollow pipe pile body, and the grouting channel on the connecting end face is connected through a pipeline connector. The problem that in the prior art, due to the fact that coral sand foundation bearing capacity is insufficient, an upper building is damaged can be solved, under the condition that the pile body strength is guaranteed, using of concrete materials is greatly reduced, the pile body manufacturing cost is reduced, and meanwhile the bearing capacity of the pile body is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of coral sand (reef) foundation construction, and in particular relates to a prefabricated hollow pipe pile for enhancing the bearing capacity of a coral sand site and a construction method. Background Art

[0002] Coral sand (calcareous sand) is a rock and soil medium with soluble carbonates such as calcium carbonate and magnesium carbonate as the main mineral components, which is formed by the biological remains of reef-building coral colonies after long-term biochemical and physicochemical reactions. Coral sand is mainly distributed in tropical islands between the Tropic of Cancer and the Tropic of Capricorn. With the development of the economy and society, the construction space extends to the ocean, and a large number of buildings need to be built on coral sand sites. However, coral sand has engineering characteristics such as high porosity, high compressibility, and easy-to-break particles, which makes buildings on coral sand sites more prone to uneven settlement, causing cracks in the buildings or even collapse. Therefore, it is crucial to improve the overall stability of the coral reef foundation.

[0003] At present, most of the coral sand and coral reef sites are treated by bored cast-in-place piles or driven steel pipe piles. However, most of these pile foundations are solid. Under the condition of the same shear strength, solid pipe piles require more concrete materials, resulting in an increase in project costs. And after the pipe piles are inserted into the coral sand stratum, they are often only fixed by the coral sand against the pipe piles, and the friction of the coral sand on the pipe piles is used to limit the displacement of the pipe piles. However, under the influence of seawater, it is very likely that the side friction resistance of the piles and the bearing capacity of the pile ends will be reduced or even disappear, resulting in a loss of bearing capacity. Therefore, the use of traditional pipe piles to reinforce the coral sand foundation has limited effect and poor stability. It is necessary to design a new type of pipe pile to solve the above problems. Summary of the invention

[0004] In view of the technical problems existing in the background technology, the present invention provides a prefabricated hollow pipe pile and a construction method for enhancing the bearing capacity of a coral sand site, which can solve the problem in the prior art that the upper structure is damaged due to insufficient bearing capacity of the coral sand foundation. While ensuring the strength of the pile body, the use of concrete materials can be greatly reduced, the cost of the pile body can be reduced, and the bearing capacity of the pile body can be improved while reducing the cost of the pile body.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A pipe pile for enhancing the bearing capacity of a coral sand field, comprising a hollow pipe pile body, the hollow pipe pile body comprising an A pile and a B pile, the B pile being arranged at the tail end of the A pile;

[0007] A prefabricated pile tip is provided at the bottom of pile A, an embedding groove is provided at the top of pile A, an embedding plug is provided at the bottom of pile B, an embedding groove is provided at the top of pile B, the embedding plug of pile B is matched with the embedding groove of pile A, and the embedding plug of pile B is matched with the embedding groove of pile B.

[0008] A UHPC grouting sleeve is embedded in the groove, anchoring steel bars are arranged inside the UHPC grouting sleeve, the anchoring steel bars are exposed in the embedded plug, and flanges are arranged between the embedded plug and the outer wall of the slot; a grouting outlet is arranged on the outer surface of the B pile body to connect to the grouting channel, and a grouting outlet is arranged on the outer surface of the A pile tip to connect to the grouting channel; one end of the grouting channel is connected to the grouting outlet, and the other end is connected to the grouting outlet at the tail of the hollow pipe pile body, and the grouting channel at the connecting end face is connected using a pipe connector.

[0009] The slurry outlets are arranged in multiple vertical rows, each row of slurry outlets includes multiple linearly arranged slurry outlets, and the multiple vertical rows of slurry outlets are arranged in a ring around the axis of the hollow pipe pile body; each vertical row of slurry outlets corresponds to a grouting channel.

[0010] The grouting channel is a U-shaped grouting channel, which is used to grout the slurry from the bottom of each vertical column of slurry outlets to the top.

[0011] The lower part of the B pile is provided with a convex embedding plug, which is matched with the embedding groove at the upper end of the A pile. Anchor steel bars are provided on the embedding plug. After the B pile and the A pile are butt-jointed, the anchor steel bars are inserted into the grouting sleeve.

[0012] The A pile and the B pile are connected by using a UHPC grouting sleeve + flange.

[0013] The grouting channels of the A pile and the B pile are connected through a pipeline connector.

[0014] There are a plurality of B piles, and two adjacent B piles are connected end to end.

[0015] The construction method of pipe piles for enhancing the bearing capacity of coral sand sites comprises the following steps:

[0016] Step 1: Arrange the pile driver in place, adjust the frame chassis of the pile driver to a horizontal level and secure it;

[0017] Step 2: According to the soil environment, if you encounter hard soil, you need to soften the soil in advance; if you do not need to soften the soil, go directly to the next step;

[0018] Step 3: Check and confirm the position of the hollow pipe pile according to the predetermined coordinate control points, drive a steel bar head into the center of the pile as a mark, paint the steel bar head to make the elevation obvious, spread lime to circle it, and check it with rectangular coordinates;

[0019] Step 4: Use the lifting hook on the pile driver to lift Pile A into the guide rod of the frame, and then align Pile A with the pile position and insert it;

[0020] Step 5: Inject UHPC ultra-high performance concrete into the grouting sleeve and vibrate and compact it in time;

[0021] Step 6: Lift Pile B just above Pile A, make sure the anchor steel bars and pipe connectors are aligned with the corresponding holes, then slowly lower it, paying attention to observe and adjust the pile posture in time;

[0022] Step 7: Use fixed connection flange between piles;

[0023] Step 8: After confirming that all pile sections have been installed, inject the expansive cement slurry into the grouting channel from the grouting port. When slurry begins to emerge from the other end of the grouting channel, it means that the slurry has been filled and grouting should be stopped.

[0024] The beneficial effects obtained by the present invention are:

[0025] 1. The pile side and pile end enlarged heads formed by pile side grouting and pile end grouting can enhance the pile side resistance and pile end resistance of the prefabricated hollow pipe pile, and improve the bearing capacity and lateral deformation resistance of the pile foundation;

[0026] 2. Use prefabricated hollow piles and fill the piles with sand and soil that can be obtained locally, which can greatly reduce the use of concrete materials and reduce costs;

[0027] 3. According to the actual site conditions of coral sand, the bearing capacity of the pile can be adjusted by controlling the amount of grouting through the bearing capacity calculation results. On the one hand, the length of the pile foundation can be reduced and the cost can be reduced;

[0028] 4. The flange plate + UHPC threaded weight grouting sleeve is used at the pile connection part, which can enhance the connection performance and joint structural toughness of the prefabricated piles, improve the ability of the pile foundation to resist horizontal shear loads, and further improve the seismic resistance of the pile foundation;

[0029] 5. After the construction of the hollow pipe pile is completed, coral sand or other construction solid waste materials can be backfilled into the hollow part in the middle of the hollow pipe pile, which can increase the bearing capacity, bending resistance and shear resistance of the hollow pipe pile itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of a whole pile of a prefabricated hollow pipe pile for enhancing the bearing capacity of a coral sand field according to the present invention;

[0031] Figure 2 Schematic diagram of the grouting channel for the pile body and pile tip of the present invention

[0032] Figure 3 A schematic diagram of the connection between pile A and pile B of the present invention;

[0033] Figure 4 This is a schematic diagram of the structure of pile A of the present invention;

[0034] Figure 5 Schematic diagram of the structure of pile B of the present invention

[0035] Figure 6 It is a schematic diagram of the arrangement of the connection end surface and the grouting channel of the present invention;

[0036] Figure 7 Schematic diagram of grouting channel connection.

[0037] In the figure: Pile A 1, Pile B 2, grout outlet 3, prefabricated pile tip 4, flange 5, pile body expansion area 6, pile end expansion area 7, embedded plug 8, plug anchor steel bar 9, embedded groove 10, UHPC ultra-high performance concrete 11, UHPC grouting sleeve 12, grouting channel 13, sleeve anchor steel bar 14, pipe connector 15. DETAILED DESCRIPTION

[0038] The present invention will be described below in conjunction with the accompanying drawings.

[0039] like Figures 1 to 7 As shown, a prefabricated hollow pipe pile for enhancing the bearing capacity of a coral sand field of the present invention is a hollow pipe pile body as a whole, which is composed of an A pile 1 and a B pile 2. A prefabricated pile tip 4 is provided at the lower part of the A pile 1, and an embedding groove 10 is provided at the upper part of the A pile 1. A grout outlet 3 is provided on the outer surface of the A pile 1, and the grout outlet 3 is connected to a grouting channel 13. The grouting channel 13 is connected to the grouting port of the hollow pipe pile.

[0040] The lower part of the B pile 2 is provided with an embedding plug 8, and the upper part of the B pile 2 is provided with an embedding groove 10 matching the embedding plug 8. The outer surface of the B pile 2 is provided with a grout outlet 3, and the grout outlet 3 is connected to a grouting channel 13.

[0041] The complete grouting channel 13 includes a straight pipe located at the B pile 2 and a U-shaped pipe located at the A pile 1, and these two parts are connected.

[0042] The UHPC grouting sleeve 12 is embedded in the embedded groove 10, and the embedded groove 10 is provided with an anchoring steel bar 14, and the embedded plug 8 exposes the anchoring steel bar 9. After the embedded plug 8 is connected to the embedded groove 10, the anchoring steel bar 9 is inserted into the UHPC grouting sleeve 12. The anchoring steel bar 9 of the embedded plug 8 and the anchoring steel bar 14 built into the UHPC grouting sleeve 12 are of the same length, and the length of the UHPC grouting sleeve 12 should meet the distance between the ends of the two steel bars after the anchoring steel bar 9 is inserted to be 50 to 100 mm. After the anchoring steel bar 9 is inserted into the UHPC grouting sleeve 12, the UHPC ultra-high performance concrete 11 is filled.

[0043] The flange 5 is provided on the outer wall of the embedded plug 8 and the embedded groove 10. The B pile 2 and the adjacent B pile 2 or the B pile 2 and the A pile 1 are fixedly connected by using a UHPC grouting sleeve + flange. After the docking is completed, the flanges on the two piles are connected by bolts to further increase the overall stability of the hollow pipe pile body.

[0044] The grouting channels 13 are connected at the connection points between the piles by using pipe connectors 15 .

[0045] When the A pile 1 is driven to the designed depth, the expansion cement slurry is injected through the grouting port, enters the pile body grouting channel 13, and flows through the grout outlet 3 to the pile body expansion area 7 and the pile end expansion area 8. After the expansion cement slurry fills these two areas, when the slurry starts to emerge from the other end of the grouting channel, it means that the slurry is full and the grouting is stopped.

[0046] The expansion cement slurry penetrates into the surrounding reef rock through the slurry outlet 3, greatly improving the integrity of the hollow pipe pile body and the reef rock, and improving the bearing capacity of the hollow pipe pile body.

[0047] Furthermore, the pile body grouting outlets 3 include multiple vertical rows, and the multiple vertical rows of grouting outlets are arranged in a ring around the axis of the hollow pipe pile body; each vertical row of grouting outlets corresponds to a grouting channel.

[0048] Furthermore, the interiors of piles A and B are both hollow pile bodies, and the middles can be backfilled with sand and soil obtained on site to increase the overall stability and shear strength of the hollow pipe pile bodies and save concrete materials.

[0049] The design purpose of the U-shaped grouting channel is that if the grouting channel is a straight-through form, it is not easy for the grouting head to grout each groove. Specifically, if the grouting head is inserted into the bottom of the straight-through grouting, the grouting will not be full when the grouting head is lifted; if the grouting head is only extended into the top of the straight-through grouting, the upper grouting will block the grouting channel and may burst prematurely. Therefore, the use of a U-shaped grouting channel can perfectly avoid the above defects.

[0050] The construction method includes the following steps:

[0051] Step 1: Arrange the pile driver in place, adjust the frame chassis of the pile driver to a horizontal level and secure it;

[0052] Step 2: Depending on the soil environment, if you encounter hard soil, you need to soften the soil first; if you do not need to soften the soil, go directly to the next step;

[0053] Step 3: Check and confirm the position of the hollow pipe pile according to the predetermined coordinate control points, drive a steel bar head into the center of the pile as a mark, paint the steel bar head to make the elevation obvious, spread lime to circle it, and check it with rectangular coordinates;

[0054] Step 4: Use the lifting hook on the pile driver to lift Pile A into the guide rod of the frame, and then insert Pile A into the pile position. If it is soft soil, the soil can be further softened, and then the soil can be extracted using suction equipment, leaving the middle rock and soil part, forming an annular groove around it, and then insert the prefabricated pile; when the upper part of Pile A is at a certain height from the ground, stop inserting;

[0055] Step 5: Inject UHPC ultra-high performance concrete into the grouting sleeve and vibrate and compact it in time;

[0056] Step 6: Lift Pile B just above Pile A, make sure the anchor steel bars and pipe connectors are aligned with the corresponding holes, then slowly lower it, paying attention to observe and adjust the pile posture in time;

[0057] Step 7: Use bolts to connect the two pile flanges;

[0058] Step 8: After confirming that all pile sections have been installed, inject the expansion cement slurry into the grouting channel from the grouting port. When slurry begins to emerge from the other end of the grouting channel, it means that the slurry has been filled and the grouting should be stopped;

[0059] After the hollow pipe pile body is assembled, sand is backfilled into the hollow part in the middle of the hollow pipe pile body to increase the bearing capacity, bending resistance and shear resistance of the hollow pipe pile body itself.

[0060] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A pipe pile for enhancing the bearing capacity of coral sand sites, characterized in that: The pipe pile is a hollow pipe pile body, and the hollow pipe pile body comprises an A pile (1) and a B pile (2); A prefabricated pile tip (4) is provided at the lower part of the A pile, an embedding groove (10) is provided at the upper part of the A pile, and a grout outlet (3) is provided at the A pile body, the grout outlet (3) is connected to a pile end grouting channel (13), and the pile end grouting channel (13) is connected to the grouting outlet; An embedding plug (8) is provided at the bottom of the B pile, a grout outlet (3) is provided on the outer surface of the B pile body, the grout outlet (3) is connected to the pile body grouting channel (13); the pile body grouting channel (13) is connected to the grouting outlet; an embedding groove (10) is provided at the top of the B pile, and the embedding plug (8) of the B pile is matched with the embedding groove (10) of the B pile; The embedding plug (8) is matched with the embedding groove (10), the embedding groove (10) is arranged at the upper end of the B pile, a UHPC grouting sleeve (12) is pre-buried in the embedding groove (10), an anchoring steel bar (14) is arranged inside the UHPC grouting sleeve (12), the embedding plug (8) exposes the anchoring steel bar (9), and after the embedding plug (8) is connected to the embedding groove (10), the anchoring steel bar (9) is inserted into the UHPC grouting sleeve (12).

2. A pipe pile for enhancing the bearing capacity of coral sand field according to claim 1, characterized in that: The A pile (1) and the B pile (2) are connected via a UHPC grouting sleeve and a flange.

3. The pipe pile for enhancing the bearing capacity of coral sand field according to claim 1, characterized in that: The pile body grouting channel (13) is a U-shaped grouting channel.

4. The pipe pile for enhancing the bearing capacity of coral sand field according to claim 1, characterized in that: The pile body grouting channels (13) are provided in plurality.

5. The pipe pile for enhancing the bearing capacity of coral sand field according to claim 1, characterized in that: A plurality of the B piles (2) are provided, and the plurality of B piles (2) are connected end to end.

6. The pipe pile for enhancing the bearing capacity of coral sand field according to claim 1, characterized in that: The pile body grouting channel (13) is located at the connection between the B piles (2) and the B piles (2) or at the connection between the B piles (2) and the A pile (1) and is connected using a pipeline connector.

7. The construction method of a pipe pile for enhancing the bearing capacity of a coral sand field as claimed in claim 1, characterized in that: The following steps are involved: (1) Install the pile driver in place, adjust the frame chassis of the pile driver to a horizontal level and secure it; (2) Depending on the soil environment, if you encounter hard soil, you need to soften the soil in advance; if you do not need to soften the soil, go directly to the next step; (3) Check and confirm the position of the hollow pipe pile according to the predetermined coordinate control points, drive a steel bar head into the center of the pile as a mark, paint the steel bar head to make the elevation obvious, spread lime to circle it, and check it with rectangular coordinates; (4) Use the lifting hook on the pile driver to lift Pile A into the guide rod of the frame, and then align Pile A with the pile position and insert it downward; when the upper part of Pile A is at a certain height from the ground, stop inserting it downward; (5) Inject UHPC ultra-high performance concrete into the grouting sleeve and vibrate and compact it in time; (6) Lift Pile B just above Pile A, ensure that the plug anchor steel bar is aligned with the grouting sleeve and the pipe connector is aligned with the pile body grouting channel and the pile end grouting channel, then slowly lower it, paying attention to observe and adjust the pile posture in time; (7) Fix the flange between the connecting piles; (8) After confirming that all pile sections have been installed, inject the expansive cement slurry into the pile body grouting channel and the pile end grouting channel from the grouting port. When slurry begins to seep out from the other end of the grouting channel, it means that the slurry has been filled and the grouting should be stopped.

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