Striking-in type steel floral tube soil nail for loose foundation

Abstract

The invention relates to the technical field of slope supporting engineering, and particularly discloses a driving-in type steel floral tube soil nail for a loose foundation, which comprises a soil nail body, an anti-pulling plate and a sleeve, the sleeve is sleeved outside the soil nail body, the anti-pulling plate is positioned in an annular gap between the sleeve and the soil nail body, the anti-pulling plate is rotatably connected with the soil nail body, and the anti-pulling plate is fixedly connected with the soil nail body. The soil nail comprises a soil nail body and a plurality of anti-pulling plates, elastic pieces for bouncing off the anti-pulling plates are arranged between the anti-pulling plates and the soil nail body, the anti-pulling plates are at least located at two different heights, the soil nail further comprises binding ropes for attaching the anti-pulling plates to the soil nail body, and a cutting knife is fixed to the sleeve and used for cutting off the binding ropes. The scheme is used for solving the problems that a grouting hole of an existing traditional steel floral tube soil nail is prone to being blocked, the early-stage anti-pulling performance is poor, and a structure capable of improving the early-stage anti-pulling performance in the new technology is large in actual manufacturing difficulty and the strength of a steel floral tube is low.

Description

Technical Field

[0001] The invention relates to the technical field of slope support engineering, and in particular to a driving-in steel flower tube soil nail used for a loose foundation. Background Art

[0002] In the design and construction of soil nail support for foundation pit slopes in soft soil layers such as silty soil and saturated soft soil, steel pipes are often used instead of general soil nails due to reasons such as hole formation, slope stability control, and prevention of soil erosion. Cement slurry or other chemical cementitious slurry is injected into the pipe under pressure, and the slurry diffuses in the soil layer around the pipe body. After a period of time, the slurry binds the original loose soil particles or cracks into a whole, and then through slope mesh hanging, shotcrete spraying and other processes, the soil and steel pipes form an effective soil nail support wall.

[0003] Traditional drive-in steel pipe soil nails require V-shaped angle steel to be welded on the outer periphery of the steel pipe to provide early strength. On the one hand, this V-shaped angle steel is used to protect the grouting holes on the outer wall of the steel pipe to prevent the grouting holes from being blocked by the soil during the driving process of the steel pipe. On the other hand, it can also improve the anchoring force of the steel pipe and have a certain effect on improving the early strength of the steel pipe. However, this type of angle steel is relatively cumbersome to process on site and its quality is difficult to guarantee. In addition, for soft foundations, the early strength of this V-shaped angle steel is still relatively weak.

[0004] According to the understanding of the prior art, the patent announcement number CN111188348A applied for in 2020 is "Steel Flower Pipe for Weak Slopes". The steel flower pipe has fins fixed on the outside to cover the grouting holes, and there are guards outside the fins to protect the fins. The guardrails of the guards are elastic and can protect the fins. This method is similar to the current method of welding V-shaped angle steels, and guards are set on the basis of the current welding of V-shaped angle steels to protect the fins. However, this method brings greater resistance to the driving operation of the steel flower pipe.

[0005] For this purpose, the patent announcement number CN118835616A applied for in 2024 is "A drive-in steel pipe soil nail for foundation pit slope support". The steel pipe soil nail is provided with a protective plate that can be rotatably opened. During the driving process of the steel pipe, the protective plate is tightened by a tightening member to press the protective plate against the soil nail body, so that the protective plate blocks the grouting hole, thereby avoiding the large resistance caused by the presence of the protective plate during the driving process of the steel pipe, and also avoiding the grouting hole being blocked by the soil during the driving process; after being driven into place, the tightening member is loosened, and then all the axial protective plates are squeezed into the soil by the elastic force of the spring itself or by the upward movement of the pull rod, and the opened protective plates are inserted into the soil, thereby improving the early pull-out resistance of the soil nail.

[0006] However, this method is currently difficult to manufacture due to its complex structure, especially since many structures are located in the inner space of the soil nail body. It is extremely difficult to operate in the inner space of the steel tube soil nail, which is already small in size (the inner diameter of the steel tube is only a few centimeters). Therefore, the manufacturing process is difficult and the cost is high.

[0007] And the opening degree of the protection plate depends on the elastic force of the spring or the extrusion amplitude of the pull rod. If the spring is simply used to open, the protection plate needs to be opened on the soil that has been squeezed by the soil nail, and the high elastic force of the spring is required to ensure that the punching angle is large enough to improve the pull-out resistance. However, the high elastic force of the spring will increase the difficulty of tightening the tightening part, and the increased tightening difficulty will further increase the difficulty of operating in the air inside the soil nail body.

[0008] If the opening of the protection plate relies on the upward movement of the pull rod to push it open, on the one hand, there is the problem that the upward pulling action of the pull rod will pull the soil nail body, which has poor pull-out resistance, upward; on the other hand, even if the soil nail body is pulled upward by a small amount and does not affect the insertion depth of the soil nail, there is still the problem that the distance the protection plate is pushed open is too small and the pull-out resistance is still not very high.

[0009] In addition to the grouting holes, the soil nail body also needs to be equipped with a clearance groove to facilitate the rotation of the protective plate, which makes the soil nail, which is originally hollow and thin-walled, even weaker in strength, and increases the probability of bending and deformation of the long and thin soil nail body during the hammering process (the length of the steel pipe is about 6 meters, but the wall thickness is about 6 mm). Summary of the invention

[0010] The present invention is intended to provide a drive-in steel pipe soil nail for loose foundations to solve the problems that the grouting holes of traditional steel pipe soil nails are easily blocked and the early pull-out resistance is poor, while the new technology that can improve the early pull-out resistance has the problems of great practical difficulty in production and low strength of the steel pipe.

[0011] In order to achieve the above object, the present invention adopts the following technical scheme:

[0012] A driven steel flower tube soil nail for loose foundations comprises a soil nail body, an anti-pullout plate and a sleeve, wherein the sleeve is sleeved outside the soil nail body, the anti-pullout plate is located in the annular space gap between the sleeve and the soil nail body, the anti-pullout plate is rotatably connected to the soil nail body, an elastic member for springing the anti-pullout plate open is arranged between the anti-pullout plate and the soil nail body, there are multiple anti-pullout plates, and the multiple anti-pullout plates are located at at least two different heights, and also comprises a binding rope for sticking the anti-pullout plate to the soil nail body, and a cutting knife is fixed on the sleeve, and the cutting knife is used to cut the binding rope.

[0013] The principle and advantage of this scheme are: when adopting this scheme, before the steel flower tube soil nail is hammered into the soil, the binding rope is first used to overcome the elastic force of the elastic part and stick the anti-pullout plate to the soil nail body, and then the sleeve is put on the soil nail body with the anti-pullout plate tied; when hammering, the sleeve and the soil nail body are hammered into the foundation synchronously, and during the driving process, because the soil nail body is covered with the sleeve, the hammering force borne by the steel flower tube soil nail can be distributed to the soil nail body and the sleeve, which can greatly reduce or even avoid the problem of deformation of the soil nail body due to hammering; during the hammering process, the grouting holes on the soil nail body are completely blocked by the sleeve, and the sleeve and the soil nail body enter the soil synchronously, so the grouting holes will not be blocked by the soil during the driving process.

[0014] After the steel pipe soil nail is driven into place, the sleeve is lifted upward alone, so that the cutting knife fixed on the sleeve cuts the binding rope. After the binding rope is cut, the anti-pullout plate will bounce open relative to the soil nail body under the elastic force of the elastic member, thereby improving the early pullout resistance of the steel pipe soil nail. In order to further improve the pullout resistance, the sleeve is controlled to press the anti-pullout plate that has been rotated open downward, so that the larger the opening angle of the anti-pullout plate, the stronger the pull-out resistance. The control of the pull-out resistance of the present invention is determined by the depth of the downward movement of the sleeve, so the requirements on the elastic member are lower, which not only reduces the difficulty of overcoming the elastic force for binding, but also helps to reduce costs.

[0015] The invention only requires the installation of rotatably connected anti-pullout plates at different heights of the soil nail body, and then the anti-pullout plates are tied up from the outside with binding ropes to prevent them from falling apart, and then the sleeve is put on the soil nail body. The assembly method is very simple, and there is no need to open a plurality of give way grooves on the soil nail body, which helps to maintain the strength of the soil nail body; the used parts are also very simple and the parts consumption is small; during the driving process, the sleeve and the soil nail body simultaneously bear the hammering force, which helps to avoid the deformation or bending of the steel flower pipe soil nails during the hammering, and also forms protection for the grouting holes to avoid clogging of the grouting holes; after the driving is completed, the sleeve can be reused after being pulled out, and the binding rope is cut off by a cutter during the sleeve pulling out process, which is convenient for the initial opening of the anti-pullout plate, and the sleeve moves downward again to press the anti-pullout plate, which can increase the anti-pullout force of the soil nail body remaining in the soil. It can be seen that the entire present invention is simple and convenient to manufacture, uses fewer parts, and has low cost, and the operation during construction is also simple and fast. Therefore, the present invention not only solves the problem of grouting hole blockage during the driving process of steel pipe soil nails, but also solves the problem of insufficient early pull-out strength of steel pipe soil nails. The pull-out strength can also be adjusted by controlling the pressing depth of the sleeve to the pull-out plate according to actual use requirements, which greatly improves the applicability of steel pipe soil nails on foundations of varying degrees of looseness. In addition, it also takes into account the advantages of simple manufacture, low process difficulty, and low cost.

[0016] In addition, because the early pull-out performance of the steel pipe soil nails is good, and after grouting into the steel pipe soil nails, a grouting area like sharp teeth can be formed after grouting, which greatly improves the strength of the steel pipe soil nails during the working stage, thereby reducing the use of steel pipe soil nails.

[0017] Preferably, as an improvement, the bottom end of the soil nail body has a pointed cone structure.

[0018] Beneficial effect: It is convenient to drive the steel pipe soil nails into the foundation during hammering, reducing the hammering resistance.

[0019] Preferably, as an improvement, the soil nail body is formed with a step at the boundary between the nail body and the pointed cone structure, and the bottom end of the sleeve can abut against the step.

[0020] Beneficial effect: The step set above the pointed cone structure allows the sleeve to rest firmly on it. This design not only facilitates the effective transmission of the hammering force to the pointed cone structure, but also prevents the soil from entering the matching part between the sleeve and the soil nail body. Therefore, even if the grouting hole is not blocked by the anti-pullout plate, soil blockage can be completely avoided, ensuring the smooth flow of the grouting hole.

[0021] Preferably, as an improvement, the pointed cone structure is detachably connected to the soil nail body to facilitate on-site assembly of the soil nail body and the pointed cone structure after they are formed separately, and to facilitate the fitting of the sleeve to the soil nail body.

[0022] Preferably, as an improvement, it also includes at least two groups of guide structures located at different heights, each group of guide structures includes at least two guide beads / guide columns evenly distributed around the soil nail body, and when the guide beads / guide columns are installed on the soil nail body, the guide beads / guide columns are in contact with the inner wall of the sleeve, and when the guide beads / guide columns are installed on the sleeve, the guide beads / guide columns are in contact with the outer wall of the soil nail body. If the guide structure is a guide bead, rolling friction is generated, and if the guide structure is a guide bead, sliding friction is generated under point contact.

[0023] Beneficial effect: through at least two sets of guide structures of different heights, when the sleeve and the soil nail body are assembled or disassembled, the guide structure has a guiding function for taking and placing the sleeve relative to the soil nail body, ensuring that the sleeve is centered relative to the soil nail body.

[0024] Preferably, as an improvement, the sleeve and the soil nail body each have at least one set of guide structures, and the guide structures are installed on a section close to the end.

[0025] Beneficial effects: By setting the specific position of the guide structure, the number of guide structures is reduced as much as possible, reducing the cost of steel pipe parts and processing costs, and ensuring that the construction and use of steel pipe soil nails are simple and reliable.

[0026] Preferably, as an improvement, each set of guide structures has 2 guide beads / guide columns, the guide beads / guide columns on the sleeve are staggered with the guide beads / guide columns on the soil nail body, and all guide structures are staggered with the anti-pullout plates, so that the number of guide beads / guide columns used is minimized and the sleeve and soil nail body can be easily assembled.

[0027] Preferably, as an improvement, the top section of the sleeve is provided with a lifting hole and / or a lifting column and / or a threaded section, so as to facilitate the connection of a lifting rope through the lifting hole and / or the lifting column, and to facilitate the connection with the lifting equipment through the threaded section, thereby facilitating the upward withdrawal of the sleeve after it is driven into place with the soil nail body.

[0028] Preferably, as an improvement, a lifting hole is provided on the top section of the sleeve for convenient lifting, and a lifting hole is also provided on the soil nail body. The lifting hole on the sleeve can be aligned with the lifting hole on the soil nail body, and the lifting hole is used to insert the connecting rod. The presence of the lifting hole in this scheme allows the soil nail body and the sleeve to be integrated through the connecting rod after the steel flower tube soil nail is assembled, which facilitates the internal and external structures to form a whole during the transportation stage of the steel flower tube soil nail; it is also convenient to use the lifting hole to take out the sleeve when the sleeve is taken out separately.

[0029] Preferably, as an improvement, the elastic member is a spring, and the spiral seat portion at the end of the spring can be screwed onto the grouting hole. The size of the spring is larger than the size of the grouting hole, so that the multi-turn structure of the spiral seat of the spring can be used to clamp on the grouting hole, which facilitates the installation of the elastic member and reduces the difficulty of installation. The spring will not affect the subsequent slurry discharge.

[0030] Preferably, as an improvement, the binding rope is a rubber band, so that the cutting knife can easily cut the binding rope. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the three-dimensional structure of the first embodiment of the present invention (the soil nail body and the sleeve are already assembled and the connecting rod is inserted in the figure).

[0032] Figure 2 for Figure 1 Schematic diagram of the three-dimensional structure after the sleeve is removed (also a schematic diagram after completing steps S01-S02).

[0033] Figure 3 This is a schematic diagram of the three-dimensional structure of the steel pipe soil nail without a sleeve.

[0034] Figure 4 This is a schematic diagram of the three-dimensional structure when only springs and guide beads are installed on the soil nail body.

[0035] Figure 5 Schematic diagram of the construction process of an embodiment of the present invention.

[0036] Figure 6 for Figure 5 Front partial sectional view.

[0037] Figure 7 This is a schematic diagram of a sharp-toothed grouting area formed after grouting in an embodiment of the present invention.

[0038] Figure 8 for Figure 5 AA section view in.

[0039] Fig. 9 It is a three-dimensional structural schematic diagram of the installation of the guide beads and the cutting knife used in the sleeve of the embodiment of the present invention.

[0040] Fig.10 for Fig. 9 Top view of the .

[0041] Fig.11 for Fig. 9 Exploded diagram. DETAILED DESCRIPTION

[0042] The following is further described in detail through specific implementation methods:

[0043] The reference numerals in the drawings of the specification include: soil nail body 1, grouting hole 10, pointed cone structure 11, step 111, anti-pullout plate 2, sleeve 3, spring 4, binding rope 5, cutting knife 6, cutting knife seat 61, guide bead 7, lifting hole 8, connecting rod 9.

[0044] Implementation example Figures 1 to 11 shown.

[0045] Combination Figures 1 to 4 A driven steel flower tube soil nail for loose foundation, comprising a soil nail body 1, an anti-pullout plate 2, a sleeve 3, a spring 4, a binding rope 5 and a cutting knife 6, the sleeve 3 is sleeved outside the soil nail body 1, the anti-pullout plate 2 is located in the annular gap between the sleeve 3 and the soil nail body 1, the anti-pullout plate 2 is rotatably connected to the soil nail body 1, the rotation center line of the anti-pullout plate 2 is perpendicular to the central axis of the soil nail body 1, a spring 4 for popping the anti-pullout plate 2 open is arranged between the anti-pullout plate 2 and the soil nail body 1, the inner diameter of the spring 4 is larger than the aperture of the grouting hole 10, the end spiral seat part of the spring 4 can be screwed on the grouting hole 10, so that the spring 4 is installed on the soil nail body 1 by using the grouting hole 10, and the elastic deformation direction of the spring 4 after the spring 4 is installed is consistent or substantially consistent with the radial direction of the soil nail body 1.

[0046] There are multiple anti-pullout plates 2, which are divided into multiple groups and located at different heights. Each group has 3-4 anti-pullout plates 2 evenly distributed around the soil nail body 1. In this embodiment, each group has 4 anti-pullout plates 2, and each anti-pullout plate 2 is an arc-shaped plate. Each group of anti-pullout plates 2 is tied to the soil nail body 1 by a tying rope 5, and the tying rope 5 is an easily cut rubber band.

[0047] Combination Figures 8 to 11 A cutting knife 6 is fixedly installed at the bottom of the sleeve 3. In this embodiment, there are two cutting knives 6 and they are symmetrically distributed. The cutting knives 6 are used to cut the binding rope 5.

[0048] The bottom end of the soil nail body 1 is threadedly connected with a pointed cone structure 11 . The soil nail body 1 forms a step 111 at the boundary between the nail body and the pointed cone structure 11 . The bottom end of the sleeve 3 can abut against the step 111 .

[0049] In order to facilitate the concentricity of the soil nail body 1 and the sleeve 3 during the insertion and removal of the soil nail into the sleeve 3, a set of guide structures is installed on the bottom section of the sleeve 3, and a set of guide structures is installed on the top section and the bottom section of the soil nail body 1. Each set of guide structures has two guide beads 7 / guide columns. This embodiment uses guide beads 7, which are miniature universal balls, so that when used, relative rolling can reduce friction and thus reduce wear on the sleeve 3. The guide beads 7 on the sleeve 3 are staggered from the guide beads 7 on the soil nail body 1, and all guide structures are staggered from the anti-pullout plate 2.

[0050] In order to facilitate the lifting of the sleeve 3 during the lifting stage and to facilitate the sleeve 3 to form an integral whole with the soil nail body 1, two pairs of lifting holes 8 that can be aligned are opened on the top section of the sleeve 3 and the top section of the soil nail body 1, and a connecting rod 9 can be inserted into each pair of lifting holes 8.

[0051] Combination Figures 5 to 8 The construction process of this embodiment includes the following steps:

[0052] S0, Preparation stage - Assembling steel pipe soil nails:

[0053] S01, take the soil nail body 1, and install the spring 4 on the grouting hole 10 of the soil nail body 1;

[0054] S02, the anti-pullout plate 2 is connected to the outer periphery of the soil nail body 1, and then the anti-pullout plate 2 is tied to the soil nail body 1 by using the binding rope 5 to overcome the elastic force of the spring 4 (such as Figure 2 shown);

[0055] S03. A pair of guide beads 7 are installed at a section of the bottom of the sleeve 3, and a cutter 6 is installed in the sleeve 3. In this embodiment, the cutter 6 can be clamped on the cutter seat 61. The cutter seat 61 is provided with a mounting hole, and the cutter 6 is provided with a locking hole. After the cutter 6 is clamped on the cutter seat 61, the cutter 6 is fixed by screws through the mounting hole and the locking hole. The cutter seat 61 with the cutter 6 and the guide beads 7 have mounting holes at the same position, so that when the guide beads 7 on the sleeve 3 are installed, the cutter 6 is fixedly installed at the same time;

[0056] The guide bead 7 on the soil nail body 1 can adopt a simpler structure, and the guide bead 7 can be directly detached from the soil nail body 1. The installation of the guide bead 7 on the soil nail body 1 only needs to be completed before step S04.

[0057] S04, inserting the soil nail body 1 into the sleeve 3: inserting the soil nail body 1 into the sleeve 3 from the top of the sleeve 3. After the insertion is completed, adjust the angle between the soil nail body 1 and the sleeve 3 so that the cutter 6 installed on the sleeve 3 is located in the gap between the anti-pullout plates 2, so that the lifting hole 8 on the sleeve 3 is aligned with the lifting hole 8 on the soil nail body 1, and then insert the connecting rod 9 into the lifting hole 8 (obtained as shown in the figure). Figure 1 status shown).

[0058] S1. Take the assembled steel pipe soil nails, use the lifting equipment to lift the steel pipe and put it into the down-the-hole drilled by the down-the-hole drill.

[0059] S2. Use an impact air hammer to hammer the steel pipe soil nails into the soil to the target depth.

[0060] S3, release the anti-pullout plate 2 and recover the sleeve 3: first lift the sleeve 3 upward for recovery. During the rising process of the sleeve 3, the cutting knife 6 on the sleeve 3 will cut the binding rope 5, so that the anti-pullout plate 2 is initially opened and inserted into the soil under the action of the elastic member, and then the sleeve 3 is controlled to move downward to press the initially opened anti-pullout plate 2, so that the anti-pullout plate 2 can rotate at a larger angle relative to the soil nail body 1. After pressing into place, the sleeve 3 is lifted again to the adjacent anti-pullout plate 2 at a higher position, and the binding rope 5 and the downward pressing of the sleeve 3 are repeated until all the axial anti-pullout plates 2 are pressed open, and the sleeve 3 is completely removed and recovered.

[0061] In this step, the rotation angle of the anti-pullout plate 2 is determined by the degree of pressing. Different opening angles of the anti-pullout plate 2 can be controlled according to the softness of different soft foundations, thereby ensuring good early anti-pullout performance under different loose foundations.

[0062] S4 Grouting: After step S3 is completed, grouting is injected into the soil nail body 1. After the grouting is completed, the top of the soil nail body 1 and the lifting hole 8 are sealed to prevent the slurry from flowing back or foreign matter from entering. Figure 7 Schematic representation of the serrated grouting area.

[0063] The advantages of the present invention are as follows:

[0064] 1. Simple assembly, few parts, low cost: only need to install the rotatably connected pull-out plate 2 at different axial heights of the soil nail body 1, install the spring 4 on the existing grouting hole 10, and fix it with the binding rope 5, and then insert the sleeve 3 to complete the assembly. The assembly method is simple and convenient, and there is no need to open many holes and grooves on the soil nail body 1, so as to maintain the strength of the soil nail body 1. In addition, the steel flower tube soil nail of this embodiment has a simple structure, and the sleeve 3 can be recycled after use, so it is simple to assemble, has low construction difficulty, and low cost.

[0065] 2. It is not easy to deform during the hammering process and the grouting hole 10 will not be blocked during the hammering process: the sleeve 3 is consistent with the nail body length of the soil nail body 1, so that the sleeve 3 and the soil nail body 1 can bear the hammering force synchronously. Even if the current soil nail body 1 is an extremely long and thin structure, the steel flower tube soil nail is not easy to deform by the simultaneous force of the two. In addition, the grouting hole 10 is covered by the sleeve 3, so the grouting hole 10 will not be blocked by the soil during the hammering process. In addition, due to the protection of the sleeve 3, the installation position of the anti-pull plate 2 is not required, and there is no need to specially set the position of the grouting hole 10, which reduces the cost.

[0066] 3. The early pull-out resistance is strong and the pull-out resistance can be adjusted independently. In addition, the strength of the steel pipe soil nails in the working stage after the construction is completed is also very good, which can reduce the number of steel pipe soil nails used in slope support, thereby greatly reducing costs and shortening construction period.

[0067] In summary, the present invention not only solves the problem of blockage of the grouting hole 10 during the driving process of the steel flower pipe, but also significantly improves the early pull-out strength and the strength in the working stage, and has the advantages of simple production, low process difficulty and low cost, taking into account both economic benefits and construction convenience.

[0068] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A driven steel pipe soil nail for loose foundation, comprising a soil nail body, characterized in that: It also includes an anti-pullout plate and a sleeve, the sleeve is sleeved outside the soil nail body, the anti-pullout plate is located in the annular space gap between the sleeve and the soil nail body, the anti-pullout plate is rotatably connected to the soil nail body, an elastic member for popping the anti-pullout plate open is arranged between the anti-pullout plate and the soil nail body, there are multiple anti-pullout plates, and the multiple anti-pullout plates are located at at least two different heights, and also includes a binding rope for sticking the anti-pullout plate to the soil nail body, a cutting knife is fixed on the sleeve, and the cutting knife is used to cut the binding rope.

2. The driven steel pipe soil nail for loose foundation according to claim 1, characterized in that: The bottom end of the soil nail body is provided with a pointed cone structure.

3. The driven steel pipe soil nail for loose foundation according to claim 2, characterized in that: The soil nail body is formed with a step at the boundary between the nail body and the pointed cone structure, and the bottom end of the sleeve can abut against the step.

4. The driven steel pipe soil nail for loose foundation according to claim 3, characterized in that: The pointed cone structure is detachably connected to the soil nail body.

5. The driven steel pipe soil nail for loose foundation according to claim 3, characterized in that: It also includes at least two groups of guide structures located at different heights, each group of guide structures includes at least two guide beads / guide columns evenly distributed around the soil nail body. When the guide beads / guide columns are installed on the soil nail body, the guide beads / guide columns are in contact with the inner wall of the sleeve. When the guide beads / guide columns are installed on the sleeve, the guide beads / guide columns are in contact with the outer wall of the soil nail body. If the guide structure is a guide bead, rolling friction is generated. If the guide structure is a guide bead, sliding friction is generated under point contact.

6. The driven steel pipe soil nail for loose foundation according to claim 5, characterized in that: The sleeve and the soil nail body both have at least one set of guide structures, and the guide structures are all installed on a section close to the end.

7. The driven steel pipe soil nail for loose foundation according to claim 6, characterized in that: Each set of guide structures has two guide beads / guide columns, the guide beads / guide columns on the sleeve are staggered with the guide beads / guide columns on the soil nail body, and all guide structures are staggered with the anti-pullout plate.

8. The driven steel pipe soil nail for loose foundation according to any one of claims 1 to 7, characterized in that: The top section of the sleeve is provided with a lifting hole and / or a lifting column and / or a threaded section.

9. The driven steel pipe soil nail for loose foundation according to claim 8, characterized in that: The top section of the sleeve is provided with a lifting hole for convenient lifting, and the soil nail body is also provided with a lifting hole. The lifting hole on the sleeve can be aligned with the lifting hole on the soil nail body, and the lifting hole is used to insert the connecting rod.

10. The driven steel pipe soil nail for loose foundation according to any one of claims 1 to 7, characterized in that: The elastic member is a spring, the spiral seat portion at the end of the spring can be screwed on the grouting hole, and the size of the spring is larger than the size of the grouting hole.

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