A kind of anti-pullout anchor rod and construction method thereof

Abstract

The present invention discloses an anti-pullout anchor rod, which includes an anti-pullout end head, a rod body and a pile body. The anti-pullout end head is directly sunk into the soil body that maintains its original state along an axial direction by a pile pipe, and the rod body is sunk into the soil body together with the anti-pullout end head. The two opposite ends of the rod body are respectively formed as a connecting end and an anchor head end. The connecting end of the rod body is fixedly connected to the anti-pullout end head, and the anchor head end of the rod body extends in a direction away from the anti-pullout end head along the axial direction. The pile body partially wraps the rod body, and the anchor head end exceeds the rod body. The anti-pullout end head has a cylindrical outer peripheral surface extending along the axial direction, and the pile body has no contact with the outer peripheral surface of the anti-pullout end head. The present application also discloses a construction method of the anti-pullout anchor rod. The tensile anchor rod in the present application has a higher pull-out bearing capacity, thereby reducing the number of anti-pullout anchor rods to reduce construction costs and improve construction efficiency.

Description

Technical Field

[0001] The invention relates to an anti-pullout anchor rod and a construction method thereof. Background Art

[0002] As a type of support system, anchor rods are widely used in foundation structures. At present, in order to generate sufficient friction between the anchor rod and the soil, jet grouting piles or cast-in-place piles are generally used as anchor connection structures. During construction, the anchor hole is first drilled using a drilling rig, and then the high-pressure liquid generated by the high-pressure grouting pump is used to form a high-pressure jet stream through the nozzle to cut the soil at the bottom of the anchor hole, so that the bottom space of the anchor hole is larger than the front space, and then the anchor cable is extended into the anchor hole, and finally the entire soil cavity is filled with cement slurry to form an anchor cable enlarged head. In order to enhance the connection ability between the anchor rod and the cement slurry, an end is also set at the bottom of the anchor rod.

[0003] This method mainly utilizes the obstruction of the soil to the enlarged head to maintain the stability of the anchor rod, prevent the anchor rod from moving upward or downward, and make the anchor rod have sufficient pull-out resistance. However, this construction method has many steps, all of which require pre-drilling, and then using an expansion drill, high-pressure rotary spraying or tamping to form the enlarged head, which makes the construction steps complicated and cannot effectively improve construction efficiency. Summary of the invention

[0004] In order to solve the above problems, the present invention first proposes an anti-pullout anchor rod, which includes an anti-pullout end, a rod body and a pile body. The anti-pullout end is directly sunk into the soil body that maintains its original state along an axial direction by a pile pipe, and the rod body is sunk into the soil body together with the anti-pullout end. The opposite ends of the rod body are respectively formed as a connecting end and an anchor head end. The connecting end of the rod body is fixedly connected to the anti-pullout end, and the anchor head end of the rod body extends in the direction away from the anti-pullout end along the axial direction. The pile body partially wraps the rod body, and the anchor head end exceeds the rod body. The anti-pullout end has a cylindrical outer peripheral surface extending along the axial direction, and the pile body has no contact with the outer peripheral surface of the anti-pullout end. Preferably, the pile body is formed by a rotary jet pile. Preferably, the anti-pullout end is sunk into a dense soil layer.

[0005] In the present application, a dense soil layer is a soil layer with a higher bearing capacity. When the soil layer is clay, the liquid index IL of the clay is ≤0.25, that is, the clay is at least in a hard plastic state; when the soil layer is silt or sand, the density of the silt or sand is medium dense or dense.

[0006] The rod body is preferably made of high-strength precision-rolled threaded steel bars or steel strands, and a protective sleeve may be sleeved on the rod body.

[0007] In the present application, when observed along the axial direction, the pull-out end cap covers the pile body, that is, the edge of the pile body can at most only reach the edge of the pull-out end cap, or there is a distance between the edge of the pile body and the edge of the pull-out end cap.

[0008] The pull-out end in the present application carries the rod body and is first sunk into the soil body that remains in its original state, and then the pile body is constructed, which can reduce the construction steps of the pull-out anchor rod. The pile body in the present application has no contact with the outer peripheral surface of the pull-out end, and the soil body where the pull-out end is located is in its original state, and can form a relatively tight connection with the pull-out end. In particular, when the pull-out end is sunk into the dense soil layer, due to the high density of the dense soil layer, especially after being squeezed again by the pull-out end, it can generate a large friction force with the soil body, so that the soil layer forms a large holding force on the pull-out end, which can make the rod body resist a larger upward pulling force, which is conducive to improving the pull-out bearing capacity of the pull-out anchor rod. In this way, the number of pull-out anchor rods can be reduced to reduce construction costs and improve construction efficiency.

[0009] Specifically, the two opposite ends of the anti-pullout terminal are respectively formed as a sinking end and a pressing end, and an anti-slipping piece is arranged on the pressing end, and the anti-slipping piece can be freely connected to one end of the pile driving pipe and can be freely detached from the pile driving pipe. After the anti-slipping piece is arranged, when the pile driving pipe is used to sink the anti-pullout terminal, since the anti-slipping piece and the pile driving pipe are mutually sleeved together, it can be avoided that the anti-pullout terminal deviates from the set sinking path due to the misalignment of the anti-pullout terminal and the pile driving pipe during the sinking process. By mutually sleeved the anti-slipping piece and the pile driving pipe, the anti-pullout terminal is made to sink to the set position along the set path.

[0010] Furthermore, the anti-slipping piece is annular, and the pile driving pipe is a round pipe; the anti-slipping piece can be freely sleeved on one end of the pile driving pipe and can freely leave the pile driving pipe; or, the anti-slipping piece can be freely lined in the inner cavity of the pile driving pipe and can freely leave the pile driving pipe.

[0011] After the pile driving pipe adopts a round pipe, the existing round steel pipe can be used as the pile driving pipe, and the existing pile driving equipment for sinking steel pipe piles can be used to complete the sinking of the anti-pull-out end. The anti-dropout part can freely leave the pile driving pipe to avoid the anti-pull-out end from deviating from the sinking position due to the movement of the anti-pull-out end when the pile driving pipe is pulled out.

[0012] Furthermore, the pile body is formed by at least two jet grouting piles overlapped radially, and the central axes of the at least two jet grouting piles are arranged around the rod body. Due to the obstruction of the rod body, the rod body cannot be located at the center of a single jet grouting pile during the construction of the jet grouting pile. This design allows the rod body to be located at the center of the pile body, so that the pressure of the soil on the pull-out anchor rod can be evenly transmitted to the rod body, and in the up and down direction, since the rod body is located at the center of the pile body, it can be avoided that the external force in the vertical direction is evenly applied to the pull-out anchor rod, and the formation of inclined pressure on the pull-out anchor rod can be avoided.

[0013] Furthermore, the pull-out resistant end head comprises a metal shell and concrete filled in the metal shell, the rod body is installed with a fastener after passing through the pull-out resistant end head, and the metal shell has a cylindrical portion extending along the axis direction. The metal shell is preferably a steel shell.

[0014] The use of concrete-filled metal shells can reduce the production cost of the pull-out end and reduce the amount of metal used. After the cylindrical portion is provided, at least part of the pull-out end can be formed into a cylindrical shape to have a greater friction force with the surrounding soil in the axial direction, so that the pull-out end can be stably maintained in the soil, thereby improving the pull-out resistance of the pull-out anchor.

[0015] Secondly, the present application also provides a construction method of an anti-pullout anchor rod, which is used to construct the anti-pullout anchor rod in the above scheme, wherein the opposite ends of the pile driving pipe are respectively formed as a down-pressing end and a force-applying end, and a rod body cavity is provided in the pile driving pipe, and the rod body can be sleeved on the rod body through the rod body cavity, and the down-pressing end is abutted against the anti-pullout end head;

[0016] The construction method comprises the following steps:

[0017] (1) The lower pressing end of the pile driving pipe is pressed against the anti-pulling end head, so that the rod body cavity is sleeved on the rod body, and the pile driving pipe is forced by the pile driving equipment to sink the anti-pulling end head to a set position, and then the pile driving pipe is removed; the soil at the set position is not stirred or loosened; the pile driving equipment can be a static pile driver or a vibrating pile driver;

[0018] (2) Use a high-pressure rotary jet pile machine to complete the pile body so that the pile body is wrapped around the rod body.

[0019] By using this construction method, the soil at the set position can generate a strong holding force on the anti-pullout end, so that the anti-pullout end is stabilized at the set position. When a high-pressure rotary jet pile machine is used to construct the pile body, the cement slurry sprayed from the spray pipe of the pile body can be mixed with the surrounding soil to form cement soil, and part of the cement slurry bypasses the rod body and mixes with the soil around the rod body, thereby holding the rod body in the pile body, so that the rod body and the pile body form a whole.

[0020] In the construction method, the pull-out end head and the rod body are first sunk into the soil as a whole, and the production of the pull-out end head and the rod body can be completed in advance to ensure that the connection between the pull-out end head and the rod body is stable and reliable. Since the construction only includes the steps of sinking the pull-out end head and constructing the pile body, compared with the existing technology, the construction steps can be reduced, the construction efficiency can be accelerated, and the project cost can be reduced.

[0021] In order to reduce the amount of cement slurry, after the pile driving pipe is removed, the pile hole formed after the pile driving pipe is removed is first filled with soil, and then the pile body is constructed. Of course, according to needs, it is also possible to directly construct the pile body in the pile hole without filling the soil, but this construction method will consume more cement slurry and increase construction costs.

[0022] Furthermore, the pull-out end cap includes a metal shell and concrete filled in the metal shell, and a fastener is installed after the rod body passes through the pull-out end cap. The metal shell has a cylindrical portion extending along the extension direction of the rod body; when the pile body is constructed, the soil in the radial direction of the cylindrical portion is kept intact, the soil in the radial direction of the cylindrical portion shall not be disturbed, and cement slurry shall not be sprayed on the soil in the radial direction of the cylindrical portion.

[0023] Fasteners can be used to enhance the connection strength between the rod and the pull-out end, prevent the rod from detaching from the concrete, and reduce the stability of the pull-out anchor in the soil. During pile construction, the soil around the pull-out end needs to be kept in its original state, and no loosening of the soil around the pull-out end is allowed. If the soil around the pull-out end is loosened, even if cement slurry is sprayed on the soil around the pull-out end, the pull-out end and the surrounding soil cannot be restored to their original stress state due to the obstruction of the pull-out end. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the pull-out anchor.

[0025] Figure 2 It is a simplified structural diagram of the pull-out resistant end.

[0026] Figure 3 yes Figure 1 The AA view is shown in the figure below. Figure 3 No hatching is done.

[0027] Figure 4 is a cross-sectional view of another embodiment of the anti-pullout anchor rod. Figure 4 No hatching is done.

[0028] Figure 5 It is the construction flow chart of pull-out anchor rod.

[0029] Figure 6 It is a schematic diagram of the connection structure between the pull-out anchor rod and the base plate.

[0030] Figure 7 This is a cross-sectional view of a pull-out anchor rod of another embodiment. Figure 7 No hatching is done. DETAILED DESCRIPTION

[0031] The following first describes the pull-out anchor rod. Figure 1 The pull-out anchor includes a pull-out end 80, a rod body 83 and a pile body 30. The pull-out end 80 is directly sunk into the soil body that remains in its original state along an axial direction M by a pile-pressing pipe 11. The pile-pressing pipe 11 will be described in detail below. The rod body 83 is sunk into the soil body together with the pull-out end 80. The opposite ends of the rod body 83 are respectively formed as a connecting end 832 and an anchor head end 831. The connecting end 832 of the rod body 83 is connected to the pull-out end, and the anchor head end 831 of the rod body 83 extends in a direction away from the pull-out end 80 along the axial direction M. The pile body 30 partially wraps the rod body 83, and the anchor head end 831 exceeds the rod body. In the accompanying drawings, the mark 100 represents the ground.

[0032] See also Figure 2 In this embodiment, the pull-out resistant end cap 80 includes a steel shell 81 and a first concrete 82 filled in the metal shell 81. The metal shell 81 includes a cylindrical portion 810 extending along the axial direction M and a first end plate 811 and a second end plate 812 respectively installed at opposite ends of the cylindrical portion 810. The rod body 83 passes through the pull-out resistant end cap and is installed with a fastener 85. In this embodiment, the rod body 83 is made of high-strength precision-rolled threaded steel bars, and the fastener 85 is a steel bar nut. It can be understood that in other embodiments, steel strands can also be used to make the rod body.

[0033] The outer peripheral surface of the cylindrical portion 810 is formed as the outer peripheral surface 819 of the anti-pulling end head, and the pile body 30 has no contact with the outer peripheral surface of the anti-pulling end head.

[0034] The end where the first end plate 811 is located is formed as a pressing end 801, and the end where the second end plate 812 is located is formed as a sinking end 802. An anti-slipping piece 86 is installed on the side of the first end plate 811 away from the second end plate. In this embodiment, the anti-slipping piece 86 is a steel ring welded on the first end plate 811, that is, the slipping piece is ring-shaped. The anti-slipping piece can be freely connected to one end of the pile driving pipe and can be freely separated from the pile driving pipe.

[0035] In this embodiment, the pile driving pipe 11 is a circular steel pipe, and the anti-dropping member 86 can be freely lined in the inner cavity 111 of the pile driving pipe 11 and can freely leave the pile driving pipe 11 .

[0036] It can be understood that in other embodiments, the anti-dropping component can be freely sleeved on one end of the pile driving pipe and can freely leave the pile driving pipe.

[0037] In this embodiment, the pile body 30 is formed by jet grouting. Figure 3The pile body 30 is formed by two rotary jet piles, a first rotary jet pile 31 and a second rotary jet pile 32, which are overlapped with each other in the radial direction. The rod body 83 is located at the symmetric center of the two rotary jet piles. The casting conditions of the first rotary jet pile 31 and the second rotary jet pile 32 are the same, so that the central axes of the two rotary jet piles are arranged around the rod body 83.

[0038] It can be understood that in other embodiments, the pile body can also be formed by three radially overlapping jet grouting piles. Figure 4 The pile body D35 shown is formed by three jet grouting piles, namely, a third jet grouting pile 36, a fourth jet grouting pile 37 and a fifth jet grouting pile 38, which are overlapped with each other in the radial direction. The three jet grouting piles have the same casting conditions, and the central axes of the three jet grouting piles are evenly arranged around the rod body D39.

[0039] In this embodiment, a protective sleeve 84 is sleeved on the rod body 83 , and the lower end of the protective sleeve 84 extends into the second concrete to close the lower end of the protective sleeve 84 .

[0040] The construction method of the anti-pullout anchor cable in this embodiment is described below.

[0041] First, the pile driving pipe is described. In this embodiment, the pile driving pipe 11 is a circular steel pipe, the inner cavity of the circular steel pipe is formed as a rod body cavity 111 of the pile driving pipe, and the opposite ends of the circular steel pipe are respectively formed as a downward pressing end 112 and a force applying end 113.

[0042] See also Figure 5 The construction method specifically includes the following steps:

[0043] (1) Please refer to Figure 5 In step (a), the pressing end 112 of the pile driving pipe 11 is pressed against the pressing end 801 of the anti-pullout end 80, so that the rod body cavity 111 is sleeved on the rod body 83, and the anti-slip member 86 is lined in the rod body cavity of the pile driving pipe.

[0044] The pile driving device is used to apply force to the pile driving pipe 11, the anti-pullout end 80 is sunk to a set position, and then the pile driving pipe 11 is removed. In the present application, the pile driving device is a static pile driving machine.

[0045] Before sinking the anti-pullout end head 80, no equipment shall be used to stir or loosen the soil at the set position to keep the soil at the set position in its original state. In this embodiment, the set position is located in a dense soil layer, that is, the anti-pullout end head is sunk into the dense soil layer.

[0046] See also Figure 5 In steps (b) and (c), in this embodiment, after the pile driving pipe 11 is removed, a pile hole 21 is formed, and soil 22 is first filled into the pile hole 21 to meet the soil required for the subsequent jet grouting pile production and reduce the amount of cement slurry.

[0047] (2) Please refer to Figure 5 In steps (d) and (e), a high-pressure rotary jet pile machine is used to sequentially produce a first rotary jet pile 31 and a second rotary jet pile 32 to form a pile body 30, so that the pile body 30 is wrapped around the rod body 83.

[0048] When constructing the pile body, the soil in the radial direction of the cylindrical part shall be kept in its original state, the soil in the radial direction of the cylindrical part shall not be disturbed, and cement slurry shall not be sprayed on the soil in the radial direction of the cylindrical part.

[0049] The construction of all pull-out anchors is completed according to arrangements (1) and (2), wherein steps (1) and (2) can be performed alternately, i.e., after the sinking of one pull-out end is completed, the sinking of the next pull-out end is continued, and at the same time, the pile body corresponding to the pull-out end that has been sunk is poured.

[0050] Please continue reading Figure 5 In step (f), after completing the construction of the pull-out anchor, the foundation pit is then excavated. Figure 6 After the excavation of the foundation pit is completed, the cushion layer 40 is laid, and the basement floor steel mesh 50 is tied. The floor steel mesh 50 includes an upper steel surface layer 51, a lower steel surface layer 56, and anchor steel bars 52 for connecting the pull-out anchor rod. The anchor steel bars 52 are located between the upper steel surface layer 51 and the lower steel surface layer 56, and are tied to the upper steel surface layer 51. A nut 55 as a fastener is screwed on the anchor head end 831 of the rod body 83, and a gasket 54 is provided under the nut 55.

[0051] After the laying and binding of the bottom plate steel mesh 50 is completed, the second concrete 58 is poured to complete the construction of the bottom plate 510 .

[0052] In this embodiment, soil is filled in the formed pile hole, see Figure 3 , when viewed along the vertical direction, the edge of the pile body 30 only reaches the edge of the pull-out end head 80, that is, when viewed along the axis direction, the pull-out end head covers the pile body. It can be understood that in other embodiments, there is a distance between the edge of the pile body and the edge of the pull-out end head, see Figure 7 , in this Figure 7 In the illustrated embodiment, the pile body E63 is formed by four rotary jet piles, namely the sixth rotary jet pile 64, the seventh rotary jet pile 65, the eighth rotary jet pile 66 and the ninth rotary jet pile 67. The four rotary jet piles overlap each other in the radial direction, the casting conditions of the four rotary jet piles are the same, and the central axes of the four rotary jet piles are evenly arranged around the rod body E62; and there is a distance between the edge of the pile body and the edge of the pull-out end.

[0053] When a distance is provided between the edge of the pile body and the edge of the pull-out end, the pile hole formed when the pull-out end needs to be sunk has soil, which can be formed by the collapse of the hole wall of the pile hole or by filling the pile hole with soil.

[0054] It is understandable that in other embodiments, when the pile hole collapses after the pile driving pipe is removed and the pile hole is partially or completely buried, there is no need to fill the pile hole with soil and the jet grouting pile can be directly produced.

[0055] In this embodiment, the pile hole formed when the anti-pullout end head is sunk is filled with soil. It can be understood that in other embodiments, even if the hole wall in the pile hole does not collapse, the pile hole may not be filled with soil, that is, the pile hole is kept in a soil-free state, and then the pile body is poured. At this time, when the pile body is poured, the cement slurry will naturally fill the entire pile hole to form a pile body with the same cross-section shape as the pile hole cross-section. Only one jet grouting pile pouring can complete the construction of the entire pile body, but more cement slurry is required. Although this construction method using no soil in the pile hole consumes more cement slurry, since only one jet grouting pile pouring is required to complete the construction of the pile body, the construction speed can be increased. Therefore, in specific construction, the method of pouring the pile body without soil can be used for part or all of the pile holes under the condition of comprehensive consideration of construction speed and cost.

Claims

1. A pull-out anchor, characterized in that: The invention comprises an anti-pullout end head, a rod body and a pile body, wherein the pile body is formed by a rotary jet pile; the anti-pullout end head is directly sunk into the soil body which is kept in the original state along an axial direction by a pile-pressing pipe, and the rod body is sunk into the soil body together with the anti-pullout end head; the opposite two ends of the anti-pullout end head are respectively formed as a sinking end and a pressing end, and an anti-slipping piece is arranged on the pressing end, and the anti-slipping piece can be freely connected to one end of the pile-pressing pipe and can be freely detached from the pile-pressing pipe; the anti-slipping piece is The pile driving pipe is annular, and the pile driving pipe is a round pipe; the anti-slipping piece can be freely sleeved on one end of the pile driving pipe and can freely leave the pile driving pipe; or the anti-slipping piece can be freely lined in the inner cavity of the pile driving pipe and can freely leave the pile driving pipe; the opposite ends of the pile driving pipe are respectively formed as a pressing end and a force-applying end, and a rod body cavity is provided in the pile driving pipe, and the pile driving pipe can be sleeved on the rod body through the rod body cavity, and the pressing end is abutted against the anti-pullout end head; The pull-out resistant end head comprises a metal shell and concrete filled in the metal shell, the rod body is installed with a fastener after passing through the pull-out resistant end head, and the metal shell has a cylindrical portion extending along the axial direction; The opposite ends of the rod body are respectively formed as a connecting end and an anchor head end, the connecting end of the rod body is fixedly connected to the anti-pull-out end head, and the anchor head end of the rod body extends along the axial direction in a direction away from the anti-pull-out end head; the pile body partially wraps the rod body, the anchor head end exceeds the rod body, and the anti-pull-out end head has a cylindrical outer peripheral surface extending along the axial direction, and the pile body has no contact with the outer peripheral surface of the anti-pull-out end head; observed along the axial direction, the anti-pull-out end head covers the pile body, that is, the edge of the pile body can only reach the edge of the anti-pull-out end head at most, or there is a distance between the edge of the pile body and the edge of the anti-pull-out end head.

2. The pull-out anchor according to claim 1, characterized in that: The pile body is formed by at least two jet grouting piles overlapping each other in radial direction, and the central axes of the at least two jet grouting piles are arranged around the rod body.

3. The pull-out anchor according to claim 1, characterized in that: The pull-out end is sunk into the compacted soil layer.

4. A method for constructing an anti-pullout anchor rod, which is used to construct the anti-pullout anchor rod according to claim 1, characterized in that: The construction method comprises the following steps: (1) The lower pressing end of the pile driving pipe is placed against the anti-pulling end head, so that the rod body cavity is sleeved on the rod body, and the pile driving pipe is forced by the pile driving equipment to sink the anti-pulling end head to the set position, and then the pile driving pipe is removed; the soil at the set position is not stirred or loosened; (2) Use a high-pressure rotary jet pile machine to complete the pile body so that the pile body is wrapped around the rod body.

5. The construction method according to claim 4, characterized in that: After the pile driving pipe is removed, the pile hole formed after the pile driving pipe is removed is first filled with soil, and then the pile body is constructed.

6. The construction method according to claim 4, characterized in that: The pull-out resistant end head comprises a metal shell and concrete filled in the metal shell, a fastener is installed after the rod body passes through the pull-out resistant end head, and the metal shell has a cylindrical portion extending along the extension direction of the rod body; When constructing the pile body, the soil in the radial direction of the cylindrical part shall be kept in its original state, the soil in the radial direction of the cylindrical part shall not be disturbed, and cement slurry shall not be sprayed on the soil in the radial direction of the cylindrical part.

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