CN110616708A - Novel variable cross-section cast-in-place pile and construction method thereof - Google Patents

Abstract

The invention belongs to the technical field of cast-in-situ pile construction, and specifically provides a novel variable-section cast-in-place pile and its construction method. The invention forms a ring-shaped outer expansion hole at the side wall of the cast-in-place pile foundation pit by partially expanding the diameter of the foundation pit, and the position of the ring-shaped outer expansion hole And the quantity can be flexibly arranged according to the actual engineering situation. The reaming reinforcement cage connected with the vertical pile reinforcement cage is set in the circular reaming hole through the outrigger device, so as to form a high compressive and pull-out bearing capacity by pouring. Variable cross-section grouting foundation pile. The cast-in-place pile with variable cross-section of the invention is easy to construct, better solves the problem of insufficient compressive and pull-out bearing capacity of the pile, and has strong engineering practicability.

Description

A new variable cross-section cast-in-situ pile and its construction method

technical field

The invention belongs to the technical field of cast-in-situ pile construction, and in particular relates to a novel variable-section cast-in-situ pile and a construction method thereof.

Background technique

Ordinary cast-in-place piles have average compressive and pull-out resistance. Compared with piles with constant cross-section, variable-section cast-in-place piles have greatly improved bearing capacity and reduced settlement. However, the current variable cross-section cast-in-place piles are relatively difficult in concrete construction, and the construction cost is also high.

For this series of defects, the variable cross-section cast-in-situ pile of the present invention can be set at different positions of the pile body according to the required bearing capacity of the pile foundation, and the size, position and quantity of the variable cross-section can be flexibly set. The device is simple and easy to operate and the manufacturing process is simple, easy to process and bind, low in cost, easy to implement, strong in versatility, makes up for the defects of equal-section piles and variable-section piles at present, and has good application prospects.

Contents of the invention

The purpose of the present invention is to provide a novel variable cross-section cast-in-place pile and its construction method, to at least solve the problems of weakened compressive and pull-out bearing capacity of current equal cross-section piles when in use, difficulty in construction and high cost of current variable cross-section piles.

In order to achieve the above object, the present invention provides the following technical solutions:

A new variable cross-section cast-in-place pile, the cast-in-situ pile is located in a foundation pit, the cast-in-situ pile includes a vertical pile body and a laterally extended reaming reinforcement cage, and the outwardly extending reaming reinforcement cage is arranged in a ring-shaped outer reaming hole, The foundation pit expands radially outward at the elevation where the extended reaming steel cage is located to form an annular reaming hole;

The extended reaming reinforcement cage includes an inner reaming reinforcement cage and an outer reaming reinforcement cage, the outer reaming reinforcement cage has the same diameter as the vertical pile body and is arranged in the foundation pit. Layers of reaming reinforcement cages are connected to the vertical reinforcement cages in the vertical pile body, guide rails are arranged on the outer reaming reinforcement cages, and the inner reaming reinforcement cages protrude into the annular outer reaming holes along the guide rails.

For the new variable cross-section cast-in-situ pile as described above, preferably, the outer reaming reinforcement cage includes guiding main reinforcement, vertical connecting reinforcement and horizontal connecting reinforcement, and the guiding main reinforcement is cross-connected with the horizontal connecting reinforcement to form a lateral outer A layer of reinforcement mesh; the guide main reinforcement and the vertical connecting reinforcement are cross-connected to form a vertical outer layer of reinforcement mesh, and two of the horizontal outer layer of reinforcement mesh are surrounded by two of the vertical outer layer of reinforcement mesh Cylindrical outer reaming reinforcement cage.

As described above, the novel variable cross-section cast-in-place pile, preferably, the outer reaming reinforcement cage is connected to the vertical reinforcement cage by binding or welding.

For the new variable cross-section cast-in-place pile as described above, preferably, the inner reaming reinforcement cage includes an inner reinforcement mesh and connecting transverse bars, and a plurality of inner reinforcement meshes are arranged at intervals, and a plurality of inner reinforcement meshes pass through The connecting transverse bars are connected together to form the inner reaming reinforcement cage;

The inner reinforcement mesh includes guiding horizontal bars and connecting vertical bars, and a plurality of guiding horizontal bars are cross-connected with the connecting vertical bars to form a grid-like inner layer reinforcing mesh. The guiding horizontal bars and the connecting vertical bars on the top of the inner layer reinforcing mesh The guide horizontal bars at the bottom are arranged in parallel, and the connecting vertical bars are arranged between the top and bottom guide bars of the inner reinforcement mesh;

The guide cross bars on the top and bottom of the inner reaming reinforcement cage are arranged in the guide rail;

Still preferably, the guide rail is a guide rail with a rectangular groove.

For the new variable cross-section cast-in-situ pile as described above, preferably, the outer reaming reinforcement cage is a cuboid frame structure, and the two inner reaming reinforcement cages are respectively arranged at both ends of the outer reaming reinforcement cage , extending from the inside of the outer reaming reinforcement cage to the annular outer reaming hole; preferably, there are two outer reaming reinforcement cages, and the two outer reaming reinforcement cages are arranged crosswise , the two outer reaming reinforcement cages are arranged along the radial direction of the vertical pile body.

For the new type variable cross-section cast-in-situ pile as described above, preferably, the horizontal outer layer steel mesh is a fan ring structure, and two adjacent inner layer steel meshes are connected by a plurality of connecting horizontal bars, and the connecting horizontal bars It is a telescopic structure, the connecting transverse ribs include A sliding ribs, B sliding ribs and sliding sleeves, the fixed ends of the A sliding ribs and the B sliding ribs are respectively connected to the inner steel mesh, the A sliding ribs and the B sliding ribs The free ends of the B sliding ribs respectively penetrate into the sliding sleeve from both ends of the sliding sleeve, and the A sliding ribs and the B sliding ribs slide freely along the sliding sleeve to realize the connection The elongation and shortening of the transverse rib;

More preferably, the connecting horizontal reinforcement is arranged at the junction of the guiding horizontal reinforcement and the connecting vertical reinforcement in two adjacent inner layer reinforcement meshes.

In the novel variable cross-section cast-in-place pile as described above, preferably, the inner reaming reinforcement cage partially overlaps with the outer reaming reinforcement cage after stretching out to the annular outer reaming hole.

For the new variable cross-section cast-in-place pile as described above, preferably, the extended reaming reinforcement cage also includes a reinforcement cage displacement tie rod, and the reinforcement cage displacement pull rod includes a main rod and an auxiliary rod, and the main rod is arranged on the reinforcement cage. The cage displacement rod protection tube slides freely along the steel cage displacement rod protection tube, the two ends of the main rod protrude from the reinforcement cage displacement rod protection tube, and the bottom end of the main rod is located in the annular outer expansion hole At the elevation of , one end of the auxiliary rod is hinged to the bottom end of the main rod, and the other end is hinged to the inner reaming reinforcement cage.

As mentioned above, the construction method of the novel variable cross-section cast-in-place pile, preferably, the construction method comprises the following steps:

Step S1, drilling and setting the annular outer reaming hole, carrying out reaming and forming annular outer reaming at the connection elevation of the outer reaming reinforcement cage and the vertical reinforcement cage;

Step S2, put the vertical reinforcement cage in the vertical pile body down in the foundation pit, and stretch out the reaming reinforcement cage into the annular outer reaming hole in step S1;

In step S3, the vertical reinforcement cage in the vertical pile body of the variable cross-section cast-in-place pile and the outwardly extending reaming reinforcement cage are poured in an integrated manner to obtain the variable-section cast-in-situ pile.

Compared with the closest prior art, the technical solution provided by the present invention has the following excellent effects:

The new variable cross-section cast-in-place pile and its construction method provided by the present invention enlarge the hole diameter of the side wall of the foundation pit at the elevation where the extended reaming reinforcement cage is located to form a ring-shaped outer reaming hole, and the reaming reinforcement cage and the vertical pile body of the variable-section cast-in-place pile, etc. Diameter reinforcement cages are bound or welded, and the connection position and quantity are flexibly arranged according to the actual situation of the project. The extended reaming reinforcement cage includes an outer reaming reinforcement cage and an inner reaming reinforcement cage. The layer reaming reinforcement cage slides out into the annular outer reaming hole. The reinforcement cage displacement rod is set to connect with the inner reaming reinforcement cage, so as to realize the remote control of the sliding of the inner reinforcement cage (controlling the inner reinforcement cage in the deep pile hole from the ground). The reinforcement cage displacement rod has a simple structure and lower cost Low. After the concrete pouring is completed, the extended reaming reinforcement cage and the concrete connection of the equal-diameter reinforcement cage of the vertical pile body of the variable-section cast-in-situ pile become a whole, which greatly enhances the bearing capacity of the foundation pile against compression and pullout. The outer reaming reinforcement cage and the inner reaming reinforcement cage are used as the external reaming reinforcement cage, which is simple and easy to install, easy to process and bind, the overall structure is simple, and the construction cost is low. Bind or weld the outer reaming reinforcement cage and the variable-section cast-in-place pile vertical pile body equal-diameter reinforcement cage together, so that the pile hole and the circular outer expansion hole structure of the variable-section cast-in-place pile vertical pile body equal-diameter reinforcement cage The pouring is integrated, which significantly improves the compressive pullout capacity of ordinary equal-section piles and the bearing capacity of cast-in-situ piles. Compared with the current variable-section piles, the variable-section position, quantity and section size of the piles can be flexibly according to the actual situation of the project. The setting is simple and easy to make, which makes up for the defects of ordinary equal-section piles, and also obviously improves the application level of the current variable-section piles, so it has a good application prospect in engineering applications.

Description of drawings

The accompanying drawings constituting a part of this application are used to provide a further understanding of the present invention, and the schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention.

in:

Fig. 1 is the structural representation of cast-in-place pile when the annular outer reaming hole of the embodiment of the present invention is positioned at the top of the pile body and the inner layer reaming reinforcement cage does not stretch out to the annular outer reaming hole;

Fig. 2 is positioned at pile body top and inner layer reaming reinforcement cage stretches out to the structural representation of cast-in-place pile after annular outer reaming for the annular outer reaming hole of the embodiment of the present invention;

Fig. 3 is the structural representation of cast-in-place pile when the annular outer reaming hole of the embodiment of the present invention is positioned at the bottom of the pile body and the inner layer reaming reinforcement cage does not stretch out to the annular outer reaming hole;

Fig. 4 is positioned at the bottom of the pile body and the internal reaming reinforcement cage stretches out to the structural representation of cast-in-place pile after the annular outer reaming hole of the embodiment of the present invention;

Fig. 5 is the A-A view of Fig. 1 in the embodiment 1 of the present invention;

Fig. 6 is the A-A view of Fig. 2 in Embodiment 1 of the present invention;

Fig. 7 is the A-A view of Fig. 1 in Embodiment 2 of the present invention;

Fig. 8 is the A-A view of Fig. 2 in Embodiment 2 of the present invention;

Fig. 9 is a schematic diagram of the structure of the inner reaming reinforcement cage in the embodiment of the present invention when the reinforcement cage is not stretched out;

Fig. 10 is a schematic diagram of the structure of the inner reaming reinforcement cage in the embodiment of the present invention when it is stretched out;

Figure 11 is a schematic diagram of the positional relationship between the outer reaming reinforcement cage and the inner reaming reinforcement cage in Figure 6

Fig. 12 is a schematic diagram of the guide rail structure in the embodiment of the present invention;

Fig. 13 is a schematic diagram of the structure in the state where the inner reaming reinforcement cage is not stretched out in Example 2 of the present invention;

Fig. 14 is a schematic diagram of the structure in the state where the inner reaming reinforcement cage is stretched out in Embodiment 2 of the present invention.

In the figure: 1. Vertical reinforcement cage; 4. Extended reaming reinforcement cage; 16. Reinforcement cage displacement rod; 17. Reinforcement cage displacement rod protection tube; 21. Annular outer expansion hole; 22. Guide rail; 23. Outer layer Reaming reinforcement cage; 24. Inner reaming reinforcement cage; 25. Concrete grouting pipe; 26. Grouting system; 27. Vertical connection reinforcement; 28. Sliding sleeve; 29. Guide main reinforcement; 30. Horizontal connection reinforcement; 31 , connecting horizontal bars; 32, guiding horizontal bars; 33, connecting vertical bars; 34, main bars; 35, auxiliary bars.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and examples. It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

In the description of the present invention, the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", " The orientation or positional relationship indicated by "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and does not require that the present invention must be constructed and operated in a specific orientation, so it cannot be understood as Limitations on the Invention. The terms "connected" and "connected" used in the present invention should be understood in a broad sense. For example, they can be fixedly connected or detachably connected; they can be directly connected or indirectly connected through intermediate components. A skilled person can understand the specific meanings of the above terms according to specific situations.

Example 1

According to specific embodiments of the present invention, as shown in Figures 1 to 6 and Figures 9 to 12, the present invention provides a new variable cross-section cast-in-situ pile and its construction method. Figure 1 shows that the annular external expansion hole 21 is located in the vertical The structural representation of the cast-in-place pile when the top of the pile body and the inner reaming reinforcement cage 24 do not stretch out to the annular outer reaming hole 21;

Fig. 2 is positioned at the vertical pile body top and inner layer reaming reinforcement cage 24 stretches out to the structural representation of cast-in-place pile after annular outer reaming 21 for annular outer reaming 21. The cast-in-situ pile of the present invention is located in the foundation pit, and a vertical reinforcement cage 1 having the same diameter as the vertical pile body is arranged in the foundation pit. , the extended reaming reinforcement cage 4 is arranged in the annular reaming hole 21, and the reaming reinforcement cage 4 can be connected with the vertical reinforcement cage 1 in the vertical pile body of the variable cross-section cast-in-situ pile by binding or welding, and the circular reaming The position of the hole 21 can be located at any position of the vertical pile body, and the specific position, quantity and cross-sectional size can be flexibly set according to the actual situation of the project. Annular external expansion hole 21, as shown in Figures 1 to 4. Simultaneously, grouting system 26 is arranged on the ground, is connected with concrete grouting pipe 25 on the grouting system 26, and concrete grouting pipe 25 runs through vertical pile body, is used for pouring concrete in vertical pile body.

Grouting system 26 is used for grouting in the foundation pit at the place of the vertical reinforcement cage 1 in the vertical pile body of the variable cross-section cast-in-place pile and the annular outer reaming hole 21 at the place of the extended reaming reinforcement cage 4.

One end of the extended reaming reinforcement cage 4 protrudes from the upper and lower elevations of the connection between the outer layer reaming reinforcement cage 4 and the vertical reinforcement cage 1 in the vertical pile body of the variable-section cast-in-place pile, and extends into the annular outer reaming hole 21. After pouring concrete , the reinforced concrete of the vertical pile body of the variable cross-section cast-in-place pile is connected with the concrete of the extended reaming steel bar 4 in the annular outer expansion hole 21 to form a ring-shaped convex structure. The annular protruding structure can be firmly clamped in the annular outer expansion hole 21, thereby increasing the pullout bearing capacity and compressive bearing capacity of the foundation pile in subsequent use.

Further, the extended reaming reinforcement cage 4 includes an inner reaming reinforcement cage 24, the outer reaming reinforcement cage 23 is provided with a guide rail 22, the inner reaming reinforcement cage 24 runs along the guide rail 22, and the inner reaming reinforcement cage One end of 24 stretches out the outer layer reaming reinforcement cage 23 to in the annular outer reaming hole 21. The inner layer reaming reinforcement cage 24 is set to go deep into the annular outer reaming hole 21, after the subsequent pouring of concrete, it can be ensured that the vertical pile body reinforced concrete of the variable cross-section cast-in-place pile and the externally extending reaming reinforcing bar 4 concrete in the annular outer reaming hole 21 can be easily Good combination together greatly improves the pull-out bearing capacity of the variable cross-section cast-in-situ pile, and the inner layer reaming reinforcement cage 24 is set to be free to expand and contract relative to the outer reaming reinforcement cage 23, which overcomes the internal expansion of the annular outer reaming hole 21. It is difficult to directly arrange the defects of steel bars.

Further, the extended reaming reinforcement cage 4 also includes an outer reaming reinforcement cage 23, and the outer reaming reinforcement cage 23 includes a guiding main reinforcement 29, a vertical connecting reinforcement 27 and a transverse connecting reinforcement 30, and the guiding main reinforcement 29 and the horizontal connecting reinforcement 30 cross-connected to form a horizontal outer steel mesh; the guiding main reinforcement 29 and the vertical connecting reinforcement 27 are cross-connected to form a vertical outer layer reinforced mesh, and two horizontal outer layer reinforced meshes are enclosed by two vertical outer layer reinforced meshes Form the cylindrical outer layer reaming reinforcement cage 23. Guide rail 22 is arranged in the outer layer reaming reinforcement cage 23, and the outer layer reaming reinforcement cage 23 is bound or welded with the vertical reinforcement cage in the vertical pile body of variable cross-section pouring pile. Further, the inner layer reaming reinforcement cage 24 includes an inner layer reinforcement mesh and connecting transverse bars 31, a plurality of inner layer reinforcing meshes are arranged at intervals, and a plurality of inner layer reinforcing meshes are connected together by connecting transverse bars 31 to form an inner layer reaming Steel cage 24.

The inner layer of steel mesh includes guiding horizontal bars 32 and connecting vertical bars 33, and a plurality of guiding horizontal bars 32 are cross-connected with connecting vertical bars 33 to form a grid-like inner layer of reinforcing mesh. The horizontal bars 32 are arranged in parallel, and the connecting vertical bars 33 are arranged between the guiding horizontal bars 32 at the top and the bottom of the inner layer of steel mesh; Connecting vertical bars 33 arranged in parallel, multiple guiding horizontal bars 32 and multiple connecting vertical bars 33 are vertically cross-connected to form an inner reinforcement mesh. The guide transverse rib 32 of inner layer reaming reinforcement cage 24 circumferences is arranged in guide rail 22. In an embodiment of the present invention, the guide transverse reinforcement 32 in the circumferential direction of the inner layer reaming reinforcement cage 24 refers to the guide transverse reinforcement 32 that can be directly contacted from the outside of the inner reaming reinforcement cage 24. These guide reinforcements are positioned at the outermost layer of the inner layer reaming reinforcement cage 24 .

In the embodiment of the present invention, in order to further increase the connection strength between the concrete of the extended reaming steel bar 4 in the annular external reaming hole 21 and the vertical pile body reinforced concrete of variable cross-section cast-in-situ piles, the inner layer reaming reinforcement cage 24 After stretching out to the annular outer reaming hole 21, there is a partial overlap with the outer layer reaming reinforcement cage 23. After being arranged in follow-up pouring concrete like this, can make variable cross-section cast-in-place pile vertical pile body reinforced concrete form high-strength connection with the externally extended reaming reinforcement bar 4 concrete in the annular external reaming hole 21.

Further, the cast-in-situ pile with variable cross-section is provided with a reinforcement cage displacement rod protection tube 17 along the axial direction, and the extended reaming reinforcement cage 4 also includes a reinforcement cage displacement rod 16, and the reinforcement cage displacement rod 16 includes a main rod 34 and an auxiliary rod 35 , the main rod 34 is arranged in the steel cage displacement pull rod protective tube 17 and slides freely along the steel cage displacement pull rod protective tube 17, the two ends of the main rod 34 protrude from the steel cage displacement pull rod protective tube 17, and the bottom end of the main rod 34 is located outside Within a certain range of the upper and lower elevations of the connection between the layer reaming reinforcement cage and the variable cross-section vertical pile body equal diameter reinforcement cage, one end of the auxiliary rod 35 is hinged to the bottom end of the main rod 34, and the other end is connected to the inner reaming reinforcement cage 24 hinged. The reinforcement cage displacement tie rod protective tube 17 not only protects the reinforcement cage displacement tie rod 16, but also ensures the free sliding of the pull rod in the vertical direction.

Further, the guide rail 22 is a guide rail with a rectangular groove, and the guide rail 22 is arranged (preferably welded) on the upper and lower end faces in the outer steel reinforcement cage 23, and is a plurality of pairs of upper and lower guide rails 22 arranged oppositely, symmetrical along the center line of the cross section of the outer layer reinforcement cage 23 Arranged in pairs, the guide rails 22 protect and guide the inner reaming reinforcement cage 24, and the friction coefficient of the surface of the sliding guide rail 22 in contact with the guide transverse rib 32 is low, which is conducive to the sliding of the inner reaming reinforcement cage 24 .

The top of the main rod 34 exposes the top of the vertical pile body, the main rod 34 is connected with the lifting stretching device, the lifting device is started, the lifting device drives the main rod 34 to move upward, and the main rod 34 drives the secondary rod hinged thereto 35 also moves upwards simultaneously, and sub-rod 35 drives the inner layer reaming reinforcement cage 24 hinged with it to launch along the guide rail and stretch out in the annular outer reaming hole 21.

The present invention also provides a kind of construction method of novel variable section cast-in-place pile, and this construction method comprises the following steps:

Step S1, use a drilling machine to drill pile holes, and partially ream the side walls of the foundation pit within a certain range of upper and lower elevations at the junction of the outer reaming reinforcement cage 4 and the vertical pile body of variable cross-section cast-in-situ piles with equal diameter reinforcement cages to form a ring Outer hole expansion 21, the hole expansion process is high-pressure rotary spraying hole expansion, mechanical hole expansion. After the pile hole is drilled to the design elevation, replace the drill bit, and carry out high-pressure rotary jet reaming or mechanical reaming. Water or cement slurry can be used for high-pressure jet reaming. When the cement grout reaming process is used, the hole should be reamed up and down at least twice; when the water reaming process is used, the cement grout should be used to ream the hole at the end, and finally the hole cleaning and pile hole acceptance should be carried out.

Step S2, lowering the steel cage with the same diameter as the vertical pile body of the variable cross-section cast-in-place pile into the foundation pit, and extending the extended reaming steel cage 4 into the annular external reaming hole 21; The rod 34 is mechanically stretched in the vertical direction to obtain the state of the inner reaming reinforcement cage 24 and the displacement pull rod 16 of the reinforcement cage as shown in FIG. 6 . Fig. 9 and Fig. 10 have reflected the state of inner layer reaming reinforcement cage 24 and reinforcement cage displacement pull bar 16 before and after inner layer reaming reinforcement cage 24 stretches out, and Fig. 10 is the inner layer reaming reinforcement after mechanical stretching of Fig. 9 Cage 24 status. After the reinforcement cage displacement pull rod 16 is stretched, due to the pushing action of the auxiliary rod 35 on the inner reaming reinforcement cage 24, the inner reaming reinforcement cage 24 slides to the annular outer reaming hole 21 along the guide rail 22, and the outer reaming reinforcement cage 23. Because of the vertical connecting rib 27, it is restrained by the vertical pile reinforcement cage of the variable-section cast-in-place pile and remains stationary all the time. After sliding is finished, outer layer reaming reinforcement cage 23 and inner layer reaming reinforcement cage 24 keep the overlap of a certain length to overlap, guarantee the integrity of reinforcement cage. In the present invention, immediately after the steel cage with the same diameter as the vertical pile body of the variable cross-section cast-in-place pile is lowered, the outwardly extending reaming steel cage 4 is opened immediately, so as to prevent soil and other sundries from entering the annular outer reaming hole 21 during subsequent construction, which will affect the inner reaming steel cage 24's normal open.

Step S3, through the grouting system 26 and the concrete grouting pipe 25, concrete is poured into the circular external expansion hole 21 where the vertical pile reinforcement cage of the variable cross-section cast-in-place pile is located and the external expansion reaming reinforcement cage 4 is located. The vertical pile reinforcement cage and the extended reaming reinforcement cage 4 are poured together to form a new type of cast-in-place pile with variable cross-section, which jointly bears the uplift force and the downforce bearing capacity, and significantly improves the compressive pullout capacity of the cast-in-situ pile .

In order to facilitate the inner reaming reinforcement cage 24 to stretch out through the guide rail 22 more quickly relative to the outer reaming reinforcement cage 23, as shown in Figures 5 and 6, during specific implementation, the outer reaming reinforcement cage 23 can be a cuboid Frame structure, the outer layer reaming reinforcement cage 23 is arranged radially along the pile hole, two inner layer reaming reinforcement cages 24 are respectively arranged at the two ends of the outer layer reaming reinforcement cage 23, extending from the outer layer reaming reinforcement cage 23 Long to the annular outer expansion hole 21. Outer reaming reinforcement cage 23 is provided with two, and two outer reaming reinforcement cages 23 are arranged crosswise to form a cross-shaped transverse reinforcement cage sliding system, and two outer reaming reinforcement cages 23 are all along the radial direction of the pile hole. set up.

Example 2

In order to increase the overall coverage area after the extended reaming steel cage 4 is extended, as shown in Fig. 7, Fig. 8, Fig. 13 and Fig. 14, during specific implementation, the transverse outer layer of steel mesh can also be a fan ring, correspondingly The adjacent two inner layers of steel mesh are connected by connecting transverse reinforcement 31, which is a telescopic structure. The connecting transverse reinforcement 31 includes A sliding rib, B sliding rib and sliding sleeve 28, and the fixed ends of A sliding rib and B sliding rib are respectively Connected with the inner layer steel mesh, the free ends of the A sliding rib and the B sliding rib penetrate into the sliding sleeve 28 from the two ends of the sliding sleeve 28 respectively, and the A sliding rib and the B sliding rib slide along the sliding sleeve 28 to realize the connection The elongation and shortening of the horizontal bars 31; the connecting horizontal bars 31 are arranged at the joints of the guiding horizontal bars 32 and the connecting vertical bars 33 in two adjacent inner layer steel meshes.

When in use, the inner reaming reinforcement cage 24 is guided by the guide rail 22, and the inner reaming reinforcement cage 24 protrudes from the outer reaming reinforcement cage 23 into the annular outer reaming hole 21. The connecting cross bar 31 elongation between the steel mesh, specifically A sliding bar, B sliding bar all stretches out relative to the sliding sleeve, in order to prevent that the A sliding bar and/or B sliding bar breaks away from the sliding sleeve, it can be placed on the sliding sleeve The side wall is provided with a guide groove, and a guide pin is provided at the free ends of the A sliding rib and the B sliding rib, and the guide pin is arranged in the guide groove, so as to prevent the A sliding rib and/or B sliding rib from detaching from the sliding sleeve. Of course, other methods can achieve the above Purpose schemes are also possible. The A and B sliding bars can be mechanically bent first with a steel bar bending machine. Of course, the A sliding rib and the B sliding rib can also be made into a straight line. Other structures and construction method are identical with embodiment 1, do not repeat them here.

In summary, the novel variable cross-section cast-in-place pile and its construction method provided by the present invention are based on a certain range of elevations at the connection between the extended reaming reinforcement cage 4 and the vertical reinforcement cage 1 in the vertical pile body of the variable-section cast-in-place pile. The side wall of the pit is expanded to form an annular reaming hole 21, and the reaming reinforcement cage 4 is connected with the vertical reinforcement cage 1 in the vertical pile body of the variable-section cast-in-place pile. The connection position is flexibly arranged according to the actual situation of the project, as shown in Figures 1 to 4 Show. The extended reaming reinforcement cage 4 includes an outer reaming reinforcement cage 23 and an inner reaming reinforcement cage 24 , and the inner reaming reinforcement cage 24 slides relative to the outer reaming reinforcement cage 23 and protrudes into the annular outer reaming hole 21 . The reinforcement cage displacement pull rod 16 is set to connect with the inner layer reaming reinforcement cage 24, thereby realizing the sliding of the inner layer reinforcement cage controlled remotely (controlling the inner layer reinforcement cage in the deep pile hole from the ground), and the reinforcement cage displacement pull rod 16 has a simple structure , the cost is lower. After the concrete is poured, the externally extended reaming steel bar 4 concrete in the annular external reaming hole 21 is connected with the vertical pile body reinforced concrete of the variable cross-section cast-in-place pile to form a whole, which greatly enhances the compression resistance and durability of the cast-in-place pile during subsequent use. Tensile bearing capacity. Adopt outer layer reaming reinforcement cage 23 and inner layer reaming reinforcement cage 24 as overhanging device, device is simple and easy, easy to process and bind, overall structure is simple, and construction cost is lower. Moreover, the reinforced concrete formed after subsequent pouring of concrete has stronger integrity and greater strength. The outer reaming reinforcement cage 23 is connected with the vertical pile body reinforcement cage of the variable cross-section cast-in-place pile, so that the foundation pit where the vertical pile body reinforcement cage of the variable-section cast-in-place pile is located is integrated with the annular external expansion hole structure pouring, which significantly improves Improving the compressive pullout capacity of cast-in-situ piles and improving the bearing capacity of cast-in-place piles has a good application prospect in engineering applications.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1. A novel variable cross-section cast-in-place pile is characterized in that, the cast-in-place pile is positioned in the foundation pit, and the cast-in-place pile comprises a vertical pile body and a laterally extended reaming reinforcement cage, and the reaming reinforcement cage extending outward is arranged on In the annular reaming hole, the foundation pit expands radially outward at the elevation where the reaming reinforcement cage is located to form a circular reaming hole; The extended reaming reinforcement cage includes an inner reaming reinforcement cage and an outer reaming reinforcement cage, the outer reaming reinforcement cage has the same diameter as the vertical pile body and is arranged in the foundation pit. Layer reaming reinforcement cages are connected to the vertical reinforcement cages in the vertical pile body, guide rails are arranged on the outer reaming reinforcement cages, and the inner reaming reinforcement cages protrude into the annular outer reaming holes along the guide rails. 2. The novel variable cross-section cast-in-place pile as claimed in claim 1, wherein the outer reaming reinforcement cage comprises guiding main reinforcements, vertical connecting reinforcements and transverse connecting reinforcements, and the guiding main reinforcements and the horizontal connecting reinforcements Cross-connect to form a horizontal outer layer of steel mesh; the guide main bars and the vertical connecting bars are cross-connected to form a vertical outer layer of steel mesh, two of the horizontal outer layer of steel mesh and two of the vertical outer Layers of reinforcement mesh are enclosed to form a cylindrical outer reaming reinforcement cage. 3. The novel cast-in-place pile with variable cross-section according to claim 2, characterized in that, the outer reaming reinforcement cage is connected to the vertical reinforcement cage by binding or welding. 4. The novel variable cross-section cast-in-place pile as claimed in claim 2, wherein the inner layer reaming reinforcement cage comprises an inner layer reinforcement mesh and connecting transverse bars, and a plurality of inner layer reinforcement meshes are arranged at intervals, and a plurality of the inner layer reinforcement cages are arranged at intervals. The layers of steel mesh are connected together by connecting transverse bars to form an inner reaming reinforcement cage; The inner reinforcement mesh includes guiding horizontal bars and connecting vertical bars, and a plurality of guiding horizontal bars are cross-connected with the connecting vertical bars to form a grid-like inner layer reinforcing mesh. The guiding horizontal bars and the connecting vertical bars on the top of the inner layer reinforcing mesh The guide horizontal bars at the bottom are arranged in parallel, and the connecting vertical bars are arranged between the top and bottom guide bars of the inner reinforcement mesh; The guide cross bars on the top and bottom of the inner reaming reinforcement cage are arranged in the guide rail; Preferably, the guide rail is a guide rail with a rectangular groove. 5. The novel variable cross-section cast-in-place pile as claimed in claim 2, characterized in that, the outer reaming reinforcement cage is a cuboid frame structure, and two inner reaming reinforcement cages are arranged on the outer reaming reinforcement cage respectively. The two ends of the hole reinforcement cage extend from the inside of the outer reaming reinforcement cage to the annular outer reaming hole; preferably, the outer reaming reinforcement cage is provided with two, and the two outer reaming reinforcement cages The reaming reinforcement cages are arranged crosswise, and the two outer layer reaming reinforcement cages are arranged along the radial direction of the vertical pile body. 6. The novel variable cross-section cast-in-situ pile as claimed in claim 4, wherein the transverse outer layer steel mesh is a fan ring structure, and a plurality of connecting transverse bars are passed between two adjacent inner layer steel meshes. connection, the connecting transverse reinforcement is a telescopic structure, the connecting transverse reinforcement comprises A sliding reinforcement, B sliding reinforcement and a sliding sleeve, the fixed ends of the A sliding reinforcement and the B sliding reinforcement are respectively connected with the inner steel mesh, the The free ends of the A sliding rib and the B sliding rib penetrate into the sliding sleeve from both ends of the sliding sleeve respectively, and the A sliding rib and the B sliding rib are free along the sliding sleeve. sliding to realize the elongation and shortening of the connecting transverse reinforcement; Preferably, the connecting horizontal reinforcement is arranged at the junction of the guiding horizontal reinforcement and the connecting vertical reinforcement in two adjacent inner reinforcement meshes. 7. The new variable cross-section cast-in-place pile according to claim 6, wherein the inner reaming reinforcement cage partially overlaps with the outer reaming reinforcement cage after reaching out to the annular outer reaming hole. 8. The new variable cross-section cast-in-situ pile according to any one of claims 1 to 6, wherein the extended reaming reinforcement cage also includes a reinforcement cage displacement tie rod, and the reinforcement cage displacement pull rod includes a main rod and an auxiliary rod. Rod, the main rod is set in the steel cage displacement rod protection tube and slides freely along the reinforcement cage displacement rod protection tube, both ends of the main rod protrude from the reinforcement cage displacement rod protection tube, the main The bottom end of the rod is located at the elevation of the annular outer reaming hole, one end of the secondary rod is hinged to the bottom end of the main rod, and the other end is hinged to the inner reaming reinforcement cage. 9. The construction method of the novel variable cross-section cast-in-place pile according to any one of claims 1 to 8, wherein the construction method comprises the following steps: Step S1, drilling and setting an annular outer reaming hole, performing reaming at the connection level of the outer reaming reinforcement cage and the vertical reinforcement cage to form an annular outer reaming hole; Step S2, lowering the vertical reinforcement cage in the vertical pile body into the foundation pit, and extending the extended reaming reinforcement cage into the annular outer reaming hole in step S1; In step S3, the vertical reinforcement cage in the vertical pile body of the variable cross-section cast-in-place pile and the outwardly extending reaming reinforcement cage are poured in an integrated way to obtain the variable cross-section cast-in-situ pile.