Pile foundation construction method under complex geological conditions

Abstract

The invention provides a pile foundation construction method under a complex geological condition, and aims to provide a pile foundation construction method which is convenient to demould under the complex geological condition, does not need pre-demoulding, is demoulded after the concrete strength reaches the standard, and is used for grouting a cavity generated by pulling through an embedded air pipe during pulling, so that the construction efficiency is improved. According to the technical scheme, the pile foundation construction method under the complex geological condition comprises the following steps that S1, a long pile casing is put down, S2, standard joints are manufactured, S3, the standard joints are connected, S4, pouring pieces are put down, S5, concrete is poured, S6, the long pile casing is pulled out, S7, primary grouting is conducted, S8, pulling out is conducted again, S9, grouting is conducted again, and S8-S9 are repeated till the long pile casing is completely pulled out to the ground.

Description

Technical Field

[0001] The invention relates to building construction, in particular to a pile foundation construction method under complex geological conditions. Background Art

[0002] Pile foundation construction refers to the construction process of the foundation of a building, which is mainly used to improve the stability and bearing capacity of the building, especially in cases where the geological conditions are poor. The pile foundation consists of piles and pile caps. The pile foundation construction methods include hammering, vibration, pressing and water jetting.

[0003] Pile foundation construction generally involves sinking prefabricated reinforced concrete pipe piles into the soil layer by hammering or vibration. However, mud will be generated on site when the piles are sunk. At the same time, the verticality cannot be visually checked during the sinking process. In addition, mud guards are not suitable for special geological conditions where it is difficult to form holes, such as silt and sand layers and thick gravel backfill layers. The prior art generally uses a long casing pile foundation construction method to solve this problem.

[0004] The long casing pile foundation construction method is to use lifting equipment to hang the long casing at the pile drilling site, sink the long casing into the drill hole by hammering or vibration, and then drill into the long casing through a diameter barrel drill bit to clear out the debris in the long casing, then send the steel cage into the long casing, and then pour concrete. Since it will be difficult to demold after the concrete is poured, the long casing is pre-pulled out before the concrete is formed, and then additional concrete is poured. After the strength is formed, it is pulled out for the second time to complete the concrete pile pouring.

[0005] However, in the existing long casing pile foundation construction, it will be difficult to demould the long casing after the concrete strength reaches the standard, so pre-demolding is required when the strength has not fully reached the standard. Although the pile foundation has a certain structural strength during pre-demolding, the steel cage may deflect or cracks may appear in the pile foundation during demoulding, which may affect the strength of the pile foundation. At the same time, after pulling out, a cavity will be generated between the hole wall and the pile foundation, which will cause the risk of pile foundation displacement. Summary of the invention

[0006] In order to solve the problem in the background technology that a cavity is generated between the hole wall and the pile foundation after pulling out, thereby causing the risk of the pile foundation being offset, the present invention proposes a pile foundation construction method under complex geological conditions.

[0007] The technical solution of the present invention comprises the following steps: S1 Long casing lowering: long casing is made on site and placed after the pile is drilled; S2 standard section production: the steel cage, casing and air pipe are produced in sections, avoidance holes are opened on the casing, and sealing plugs are installed in the avoidance holes; The steel cage is arranged in the casing, the steel cage sleeve is fixedly connected to the inside of the casing, an air pipe is arranged in the steel cage, and the air pipe is fixedly connected to the avoidance hole; S3 standard section connection: connect multiple standard sections into one integral casting, and connect the air pipes in adjacent standard sections; S4 Casting lowering: Casting is lowered into the pile hole section by section, and the casing is adapted to the inner wall shape of the long casing; S5 concrete pouring: concrete is delivered into the long casing through the concrete delivery device; S6: Pull out the long casing: pull out the long casing part, and a cavity is formed between the wall of the pile hole and the casing; S7 initial grouting: grouting in the air pipe, the casing located at the cavity is not blocked by the long casing, the seal in the avoidance hole at the cavity is squeezed out under pressure, the air pipe is connected with the cavity, the slurry flows in through the air pipe and fills the cavity from the bottom; S8: Pull out the long casing again, and a cavity will be formed between the pile hole wall and the casing again; S9 grouting again: grouting the air pipe, setting a plug in the hole in the cavity to block the pressure and squeeze out, and the slurry fills the cavity; Repeat S8-S9 until the long casing is completely pulled out to the ground.

[0008] Preferably, the standard section in S2 includes a steel cage standard section and a sleeve standard section, a connecting hole is provided on the sleeve standard section, a connecting rod is fixedly connected to the steel cage standard section, and one end of the connecting rod away from the steel cage standard section is fixedly connected to the connecting hole; The standard section of the casing is provided with avoidance holes arranged in an array at upper and lower intervals, and the avoidance holes are transparent front to back, and sealing plugs are provided in the avoidance holes.

[0009] Preferably, the lower end of the casing standard section in S3 is provided with an insertion end, the upper end of the casing standard section is provided with a socket end for inserting the insertion end, and the insertion end of the casing standard section is plugged into the socket end of the casing standard section adjacent below.

[0010] Preferably, the standard steel cage section in S3 is detachably connected to the adjacent standard steel cage section via a connector.

[0011] Preferably, the connecting part includes a connecting sleeve, a connecting rod and a locking pin. The upper end of the standard section of the steel cage is provided with a plurality of connecting sleeves, and the lower end of the standard section of the steel cage is provided with a plurality of connecting rods. The upper part of the connecting rod is inserted into the interior of the connecting sleeve at corresponding upper and lower positions. The connecting sleeve is provided with a locking opening that is transparent to the left and right, and the connecting rod is provided with a socket that is transparent to the left and right. The socket and the locking opening correspond to each other on the left and right and form a through hole that is transparent to the left and right, and a locking pin is inserted in the through hole.

[0012] Preferably, the long casing in S1 includes a plurality of long casing standard sections, the plurality of long casing standard sections are arranged in an array along the up and down direction, and a plurality of bayonet holes are provided at both upper and lower ends of the long casing standard sections; The positions of the bayonet openings on two adjacent long casing standard sections correspond to each other vertically, and a clamping block is arranged between the two adjacent bayonet openings, and the clamping block is an I-shaped structure extending vertically.

[0013] Preferably, both upper and lower ends of the outer surface of the long casing standard section are provided with an annular protrusion structure extending outward, and the annular protrusion structure on the long casing standard section is provided with a bayonet, and the bayonet is transparent from top to bottom; The clamping block includes a connecting part and two clamping plates. The connecting part extends in the up and down directions. The upper and lower ends of the connecting part are fixedly connected with clamping plates. The connecting part is adapted to the shape of the bayonet. The width of the clamping plate is greater than the width of the connecting part. The lower surface of the clamping plate contacts the annular protrusion structure on the standard section of the long casing.

[0014] Preferably, the clamping plate is provided with a protrusion extending in the direction of the standard section of the long casing; An inclined surface is arranged on the annular protruding structure on the standard section of the long casing, and an inclined surface matching the annular protruding structure is arranged on the protruding portion on the plate.

[0015] Preferably, sealing gaskets are fixedly connected to the upper surface and the lower surface of the long casing standard section.

[0016] Preferably, a hook is provided on the upper surface of the clamping block, and a clamping plate located on the upper side of the clamping block is fixedly connected with the hook.

[0017] Advantages of the present invention: 1. By installing a sleeve outside the steel cage, the demoulding can be carried out after the concrete strength reaches the standard, thus avoiding the risk of traditional pre-pulling that may cause the steel cage to deviate or the foundation pile to break.

[0018] When the long casing is pulled out, grouting is performed at the cavity position through the air pipe, so that grouting is performed while the casing is pulled out. In this way, the long casing is pulled out section by section, thereby avoiding the formation of cavities between the borehole wall and the pile foundation during the pulling out, thereby avoiding the risk of pile foundation displacement caused by the cavity.

[0019] Before the steel cage is lowered, the standard section of the casing and the air pipe are assembled with the standard section of the steel cage, so as to facilitate the connection of the casing and the air pipe with the steel cage.

[0020] No bolts are required when splicing long casing standard sections, and they can be quickly spliced ​​through snap-on connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 This is a schematic diagram of the standard section structure of a long casing; Figure 2 This is a schematic diagram of the cross-sectional structure of a standard section of a long casing; Figure 3 for Figure 2 A schematic diagram of the enlarged structure at point A; Figure 4 for Figure 3 Schematic diagram of the card block structure; Figure 5 This is a schematic diagram of the standard section structure of the steel cage; Figure 6 This is a schematic diagram of the top view of the standard section of the steel cage; Figure 7 for Figure 1 Schematic diagram of the connector structure; Figure 8 It is a schematic diagram of the sleeve structure.

[0023] In the figure, 1 is a standard section of a long casing, 101 is a sealing gasket, 102 is a boss, 2 is a standard section of a casing, 201 is a connecting hole, 3 is a bayonet, 4 is a block, 401 is a connecting part, 402 is a clamping plate, 403 is a hook, 5 is a standard section of a steel cage, 6 is a connecting piece, 601 is a connecting sleeve, 602 is a connecting rod, and 603 is a locking pin. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Example 1: This example aims to propose a pile foundation construction method under complex geological conditions.

[0026] according to Figures 5 to 8 As shown, the following steps are included: S1 Long casing lowering: Long casing is made on site according to the designed pile length based on the on-site ground and building structure design drawings, and then the site is leveled. Then the pile position is laid out according to the actual drawings, and clear marks are made. The lines between the pile positions are checked, and then the guide hole is drilled by a rotary drilling rig. The rotary drilling rig stops drilling piles before drilling through the miscellaneous fill and entering the silt and silt sand layers, and the pile driver is removed. The crawler crane hoists the long casing to the pile position, and the crawler crane is used to assist the vibratory hammer to drive the long casing into the soil layer. After the long casing is driven into the soil layer, the rotary drilling rig uses a cylindrical drill bit with the pile design diameter to drill a second hole in the long casing and lift the slag out of the hole.

[0027] Standard section production: the length of the steel cage and casing is set according to the designed pile length, the steel cage is divided into a plurality of steel cage standard sections 5, the casing is divided into a plurality of casing standard sections 2, a connecting hole 201 is provided on the casing standard section 2, avoidance holes arranged in an upper and lower interval array are provided on the casing standard section 2, and the avoidance holes are transparent from front to back, and a sealing plug is provided in the avoidance hole.

[0028] The standard section 5 of the steel cage is arranged in the standard section 2 of the casing. The standard section 5 of the steel cage is connected to the standard section 2 of the casing through a connecting rod. In this embodiment, the connecting rod can be selected as a steel bar. The steel bar extends from the connecting hole 201, and then the steel bar is welded to the standard section 5 of the steel cage by welding equipment, and then the steel bar part outside the standard section 2 of the casing is cut off.

[0029] An air pipe is fixedly connected to the avoidance hole. In this embodiment, the air pipe can be fixed by bundling or hot melting. In this embodiment, a T-type hose can be used for the air pipe. The air pipe is tied to the standard section 5 of the steel cage by iron wire, and the air pipe extends in the up and down directions.

[0030] Standard section connection: connect multiple standard sections into an integral casting, and the standard section 5 of the steel cage is detachably connected to the adjacent standard section 5 of the steel cage through a connecting piece 6. The connecting piece 6 includes a connecting sleeve 601, a connecting rod 602 and a locking pin 603. The upper end of the standard section of the steel cage is provided with multiple connecting sleeves 601, and the lower end of the standard section of the steel cage is provided with multiple connecting rods 602. The crane lifts the standard section, and then places the second standard section below the lifted standard section. The upper part of the connecting rod 602 on the standard section of the steel cage in the lower standard section is inserted into the interior of the connecting sleeve 601 on the lifted standard section. A locking port that is transparent on the left and right is opened on the connecting sleeve 601, and a socket that is transparent on the left and right is opened on the connecting rod 602. The socket corresponds to the locking port on the corresponding connecting sleeve 601 on the left and right and forms a through hole that is transparent on the left and right. The construction personnel use a tool to drive the locking pin 603 into the through hole, thereby inserting the locking pin 603 into the through hole.

[0031] When the standard section 5 of the steel cage is connected, an insertion end is provided at the lower end of the standard section 2 of the casing, and a socket end is provided at the upper end of the standard section 2 of the casing. The insertion end is an annular protruding structure extending downward, and the socket end is an annular slot adapted to the shape of the annular protruding structure. The insertion end of the standard section 2 of the casing is plugged into the socket end of the adjacent standard section 2 of the casing below, and the insertion end of the standard section 2 of the casing and the socket of the standard section 2 of the casing are hot-melted by hot-melt equipment.

[0032] The connecting ends of the air pipes between two adjacent standard sections are fixedly connected, and the fixed connection method in this embodiment can be selected from hot melting or bundling.

[0033] Lowering of castings: The connected castings are lifted to the pile drilling hole by crawler crane, and the castings are lowered into the pile drilling hole section by section. The casing is adapted to the inner wall shape of the long casing, and the acoustic detection tube is fixed in the castings when they are lowered section by section. After the castings are lowered, the steel cage is temporarily fixed to the long casing by fixing ribs. The temporary fixing method is to weld the fixing ribs to the steel cage and the long casing at the same time to prevent the steel cage from floating after the concrete is poured.

[0034] Concrete pouring: The concrete pouring conduit is hoisted to the pile position by a crane, so that the concrete conduit is installed centrally inside the standard section, and the air pipe on the top standard section leaks out, and then concrete is poured into the casting through the concrete conduit.

[0035] Pulling out long casing: After the strength of concrete foundation piles reaches the standard, the long casing is partially pulled out by a casing pulling machine. The long casing is partially displaced upward. During the displacement, a partial cavity is generated between the borehole wall and the cast part due to the pulling out of the long casing.

[0036] Initial grouting: Cement slurry is injected into the air pipe through a grouting machine. Since the casing part located at the cavity is not blocked by the long casing on the outside, after the air pipe is filled with slurry, the sealing plug in the avoidance hole on the casing part at the cavity is squeezed out by the cement slurry. After the sealing plug is lost, the air pipe is connected with the cavity, and the slurry flows into the air pipe and fills the cavity from the bottom.

[0037] Pulling out again: The long casing is pulled out again, and a cavity is formed again between the hole wall and the casing at the pile position.

[0038] Grouting again: continue to grout the trachea, the lower cavity and the lower part of the trachea are filled with slurry, so that the slurry generates pressure on the sealing plug in the hole at the newly generated cavity, so that the sealing plug is squeezed out, and the slurry fills the newly generated cavity. When the slurry completely fills the cavity, the trachea is also filled with slurry. The slurry can be selected from cement slurry in this embodiment.

[0039] The cavity is gradually filled through multiple pulling out and grouting until the long casing is completely pulled out to the ground.

[0040] The length of the steel cage can be designed according to the designed pile length. At the same time, the air pipe and sleeve standard section 2 are installed on the steel cage standard section 5 when making the standard section. After the concrete is poured, the long casing is not in direct contact with the concrete. It is only necessary to demould the long casing and the sleeve, so as to facilitate the demoulding of the long casing. In order to avoid the difficulty of demoulding the long casing after the concrete strength reaches the standard, the prior art generally needs to demould when the concrete does not reach the standard. However, this construction method can wait until the concrete strength reaches the standard before demoulding, so as to avoid the displacement of the steel cage and the generation of cracks in the concrete when the concrete that does not reach the strength standard is demoulded. At the same time, when pulling out, the cavity generated by pulling out is grouted through the air pipe pre-buried in the steel cage, so as to avoid the risk of displacement of the foundation pile due to the cavity generated by pulling out.

[0041] Embodiment 2: According to Figures 1 to 4 As shown, the long casing in S1 includes a plurality of long casing standard sections 1, which are arranged in an array along the up-down direction. The upper and lower ends of the outer surface of the long casing standard section 1 are provided with an annular protrusion structure extending outward. The annular protrusion structure on the long casing standard section 1 is provided with a bayonet 3, and the bayonet 3 is transparent from top to bottom. The bayonet positions on two adjacent long casing standard sections 1 correspond to each other up and down, and a clamping block 4 is clamped between two adjacent bayonet openings.

[0042] The clamping block 4 includes a connecting portion 401 and two clamping plates 402. The connecting portion 401 extends in the up-down direction. The upper and lower ends of the connecting portion 401 are fixedly connected with clamping plates 402. The connecting portion 401 is adapted to the shape of the bayonet 3. The width of the clamping plate 402 is greater than the width of the connecting portion 401. The lower surface of the clamping plate 402 contacts the annular protrusion structure on the long casing standard section 1.

[0043] The clamping plate 402 is provided with a protrusion extending toward the long casing standard section 1 , the annular protrusion structure on the long casing standard section 1 is provided with an inclined surface, and the protrusion on the plate 402 is provided with an inclined surface matching the annular protrusion structure.

[0044] Sealing gaskets 101 are fixedly connected to the upper and lower surfaces of the long casing standard section 1 .

[0045] A hook 403 is provided on the upper surface of the clamping block 4, and the hook 403 is fixedly connected to a clamping plate 402 located on the upper side of the clamping block 4. The remaining structures and construction methods are the same as those of the first embodiment.

[0046] Working principle: Place one of the long casing standard sections 1 on top of the other long casing standard section 1, so that the positions of the bayonet holes on the two long casing standard sections 1 correspond and are aligned up and down, and then the staff aligns the card block 4 with the card slot formed by the two adjacent card slots, and then drives the card block 4 into the card slot by a knocking tool. In the process of driving the card block 4 into the card slot, the gap between the two adjacent long casing standard sections 1 is reduced, and the sealing gasket 101 is compressed. After multiple card blocks 4 are driven into the card slot, the two adjacent long casing standard sections 1 are spliced.

[0047] Repeat the above method to connect all the long casing standard sections 1 into one.

[0048] Therefore, a suitable number of long casing standard sections 1 can be selected according to the pile length, and no bolts or connecting flanges are required during connection, and the connection can be quickly made by means of snap-on connection.

[0049] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is limited by the appended claims rather than the above description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. Pile foundation construction method under complex geological conditions, characterized by: The following steps are involved: S1 Long casing lowering: long casing is made on site and placed after the pile is drilled; S2 standard section production: the steel cage, casing and air pipe are produced in sections, avoidance holes are opened on the casing, and sealing plugs are installed in the avoidance holes; The steel cage is arranged in the casing, the steel cage sleeve is fixedly connected to the inside of the casing, an air pipe is arranged in the steel cage, and the air pipe is fixedly connected to the avoidance hole; S3 standard section connection: connect multiple standard sections into one integral casting, and connect the air pipes in adjacent standard sections; S4 Casting lowering: Casting is lowered into the pile hole section by section, and the casing is adapted to the inner wall shape of the long casing; S5 concrete pouring: concrete is delivered into the long casing through the concrete delivery device; S6: Pull out the long casing: pull out the long casing part, and a cavity is formed between the wall of the pile hole and the casing; S7 initial grouting: grouting in the air pipe, the casing located at the cavity is not blocked by the long casing, the seal in the avoidance hole at the cavity is squeezed out under pressure, the air pipe is connected with the cavity, the slurry flows in through the air pipe and fills the cavity from the bottom; S8: Pull out the long casing again, and a cavity will be formed between the pile hole wall and the casing again; S9: Grouting again: Grouting the air pipe, a plug is set in the avoidance hole at the cavity to block the pressure and squeeze out, and the slurry fills the cavity; Repeat S8-S9 until the long casing is completely pulled out to the ground.

2. The pile foundation construction method under complex geological conditions according to claim 1, characterized in that: The standard section in S2 comprises a steel cage standard section (5) and a casing standard section (2), a connecting hole (201) is provided on the casing standard section (2), a connecting rod is fixedly connected to the steel cage standard section (5), and one end of the connecting rod away from the steel cage standard section (5) is fixedly connected to the connecting hole (201); The casing standard section (2) is provided with avoidance holes arranged in an array at intervals up and down, and the avoidance holes are transparent from front to back, and a sealing plug is provided in the avoidance hole.

3. The pile foundation construction method under complex geological conditions according to claim 2, characterized in that: The lower end of the casing standard section (2) in S3 is provided with an insertion end, and the upper end of the casing standard section (2) is provided with a socket end for inserting the insertion end. The insertion end of the casing standard section (2) is plugged into the socket end of the casing standard section (2) adjacent to the lower side.

4. The pile foundation construction method under complex geological conditions according to claim 2 or 3, characterized in that: The standard steel cage section (5) in S3 is detachably connected to an adjacent standard steel cage section (5) via a connecting piece (6).

5. The pile foundation construction method under complex geological conditions according to claim 4, characterized in that: The connecting member (6) comprises a connecting sleeve (601), a connecting rod (602) and a locking pin (603); the upper end of the standard section of the steel cage (5) is provided with a plurality of connecting sleeves (601); the lower end of the standard section of the steel cage (5) is provided with a plurality of connecting rods (602); the upper portion of the connecting rod (602) is inserted into the interior of the connecting sleeve (601) at corresponding upper and lower positions; the connecting sleeve (601) is provided with a locking opening which is transparent to the left and right; the connecting rod (602) is provided with a socket which is transparent to the left and right; the socket and the locking opening are in corresponding positions to the left and right and form a through hole which is transparent to the left and right; the locking pin (603) is inserted into the through hole.

6. The pile foundation construction method under complex geological conditions according to claim 1 or 2, characterized in that: The long casing in S1 comprises a plurality of long casing standard sections (1), the plurality of long casing standard sections (1) are arranged in an array along the up and down direction, and a plurality of bayonet holes (3) are provided at both upper and lower ends of the long casing standard sections (1); The positions of the bayonet openings on two adjacent long casing standard sections (1) correspond to each other vertically, and a clamping block (4) is provided between the two adjacent bayonet openings, and the clamping block (4) is an I-shaped structure extending vertically.

7. The pile foundation construction method under complex geological conditions according to claim 6, characterized in that: The outer surface of the long casing standard section (1) is provided with an annular protrusion structure extending outward at both upper and lower ends, and the annular protrusion structure on the long casing standard section (1) is provided with a bayonet (3), and the bayonet (3) is transparent from top to bottom; The clamping block (4) comprises a connecting portion (401) and two clamping plates (402), wherein the connecting portion (401) extends in the up-down direction, the upper and lower ends of the connecting portion (401) are fixedly connected to the clamping plates (402), the connecting portion (401) is adapted in shape to the clamping port (3), the width of the clamping plates (402) is greater than the width of the connecting portion (401), and the lower surface of the clamping plates (402) is in contact with the annular protruding structure on the long casing standard section (1).

8. The pile foundation construction method under complex geological conditions according to claim 7, characterized in that: The clamping plate (402) is provided with a protrusion extending in the direction of the long casing standard section (1); The annular protruding structure on the long casing standard section (1) is provided with an inclined surface, and the protruding portion on the plate (402) is provided with an inclined surface matching the annular protruding structure.

9. The pile foundation construction method under complex geological conditions according to claim 6, characterized in that: The upper surface and the lower surface of the long casing standard section (1) are both fixedly connected with sealing gaskets (101).

10. The pile foundation construction method under complex geological conditions according to claim 6, characterized in that: A hook (403) is provided on the upper surface of the clamping block (4), and the clamping plate (402) located on the upper side of the clamping block (4) is fixedly connected to the hook (403).

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