CN111576404A - Nodular cast iron screw pile - Google Patents

Abstract

The invention relates to the field of screw piles, in particular to a nodular cast iron screw pile which comprises a guide pipe, a rotor wing and a rotor wing sleeve, wherein the guide pipe is made of nodular cast iron, the rotor wing is spiral, the rotor wing is fixedly connected with the rotor wing sleeve, and the rotor wing sleeve is sleeved with the guide pipe and is fixedly connected with the guide pipe through a threaded connecting piece. Compared with the prior art, the nodular cast iron screw pile has the beneficial effects that: the rotor passes through threaded connection spare fixed mounting on the stand pipe to realize rotor and the separately shipment and the quick on-the-spot assembly of stand pipe, the space that can make full use of transport means reduces the freight cost, improves the conveying efficiency, and, can the higher corrosion resisting ability of make full use of nodular cast iron, avoid nodular cast iron because of the fracture problem that the welding leads to.

Description

A ductile iron screw pile

technical field

The invention relates to the field of screw piles, in particular to a ductile iron screw pile.

Background technique

At present, there are many types of foundation piles commonly used in the engineering field, such as cement pouring piles, steel screw piles, steel hammering piles and ductile iron hammering piles.

The construction process of cement pouring piles is complicated. The lower steel pipe is drilled and cement is injected for sealing, which not only has a long construction period, but also is not environmentally friendly.

Steel screw piles and steel hammer piles are made of steel. The advantage is that the material has high strength and is easy to weld; the disadvantage is that the corrosion resistance is poor, and the application range is affected. If the surface of the product is galvanized and anti-corrosion Cost of production.

The ductile iron hammering pile is a new foundation pile in recent years. The two adjacent pile pipes are connected by socket and socket, and the bearing uplift force is small; the hammering pile has no rotor, and the bearing downforce is small. In order to improve the bearing capacity of the hammered pile, during the construction process, cement is poured into the pile pipe, and the outer wall surrounded by cement increases the friction force with the soil, or a hammering base is installed at the front end of the pile pipe, and the hammering is deep until the stressed rock layer. until.

CN106987761A discloses a ductile iron screw pile, see paragraphs 0075 and 0076 of the specification of the document, the ductile iron screw pile includes a guide pipe, and the guide pipe is a straight guide pipe 1 , and the straight guide pipe 1 The lower end has a slope-type apex 1.1, the angle between the plane where the slope-type apex 1.1 is located and the horizontal plane is 45°, the upper end of the straight guide tube 1 has a socket 1.2, and the socket 1.2 of the straight guide tube 1 is at There are 4 bolt holes, and two spirally ascending rotors 2 are sequentially arranged along the axis of the straight guide tube 1. The number of turns of the rotors 2 is equal to 1. The height difference is 150mm. The straight guide tube 1 is connected to the rotor 2 by welding. The disadvantage of the ductile iron screw pile is that due to the irregular shape of the rotor, the ductile iron screw pile occupies a large space for loading and is difficult to transport.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the above-mentioned deficiencies of the prior art, provide a ductile iron screw pile, the rotor is fixedly installed on the guide pipe through a threaded connection, so as to realize the separate shipment of the rotor and the guide pipe and rapid on-site assembly, so as to fully Utilize the space of transportation tools, reduce transportation costs, improve transportation efficiency, and make full use of the high corrosion resistance of ductile iron to avoid the cracking problem of ductile iron caused by welding.

The technical problem to be solved by the present invention is realized by the following technical solutions: a ductile iron helical pile, comprising a guide tube, a rotor and a rotor sleeve, the guide tube is made of ductile iron, the rotor is helical, and the rotor is in a spiral shape. It is fixedly connected with the rotor sleeve, and the rotor sleeve is sleeved with the guide tube and fixedly connected by a threaded connection.

The technical solution of the present invention is as follows: the rotor sleeve and the guide tube are respectively provided with a plurality of connection holes matching with the threaded connecting pieces, the axis of the connection hole is horizontal and intersects with the axis of the guide tube, and any two connection holes are connected. The axes of the holes are not coplanar. With this technical solution, when the screw pile is subjected to forces such as downward pressure and upward pulling, a plurality of connecting holes whose axes are not coplanar can be used to disperse the force of the threaded connection on the guide tube and the rotor casing, preventing the guide tube from or Rotor casing cracked.

The technical solution of the present invention is as follows: the rotor sleeve and the guide tube are fixedly connected through a bolt-nut assembly, the bolt-nut assembly includes a bolt and a nut, the connecting hole is a through hole, and the bolt passes through a The through holes on the rotor sleeve and the guide tube are locked with nuts. Compared with the connection between the screw and the threaded hole, the gap between the bolt and the through hole is larger, so it is easier to connect the rotor sleeve and the guide tube by using the bolt-nut assembly connection.

The technical solution of the present invention is as follows: the rotor sleeve and the guide pipe are fixedly connected by screws, the connection holes are threaded holes, and the screws are threadedly matched with the threaded holes provided on the rotor sleeve and the guide pipe. Compared with the connection between the screw and the threaded hole, the gap between the bolt and the through hole is larger, so the use of the screw connection can effectively prevent the damage of the guide tube or the rotor casing due to excessive stress at the individual bolt connection.

The technical solution of the present invention further includes an extension pipe and a connection sleeve, the connection sleeve is respectively sleeved with the guide pipe at both ends and the extension pipe or two extension pipes and is fixedly connected by a threaded connection. The extension pipe is used to lengthen the total length of the screw pile. According to the soil conditions and the bearing capacity of the foundation, the number of the extension pipe is one or more.

The technical solution of the present invention is as follows: the connecting sleeve includes a straight sleeve and a reducing sleeve; the large diameter end of the reducing sleeve is sleeved on the outside of the guide pipe or extension pipe at its lower end and is fixedly connected by screws , the screw is threaded with the threaded hole provided on the reducing sleeve and the guide pipe or the extension pipe; the upper end of the straight sleeve is sleeved on the outside of the extension pipe at its upper end and is fixedly connected by a screw, and the screw is The threaded holes provided on the straight sleeve and the extension pipe are threaded; the small diameter end of the reducing sleeve is sleeved inside the straight sleeve and is fixedly connected by a bolt-nut assembly, which includes a bolt and a nut , the bolts pass through the through holes provided on the reducing sleeve and the straight sleeve and are locked by nuts. Compared with the connection between the screw and the threaded hole, the gap between the bolt and the through hole is large. In the field construction, for the two large pipe fittings to be connected, it is difficult to align the holes of the corresponding threaded fittings. Therefore, through the bolt- Nut assemblies are easy to connect two large pipe fittings, but there is a problem with overstressing individual bolted joints, which can lead to pipe damage. By adopting this technical solution, firstly, the smaller volume reducing sleeve is connected with the guide tube or the extension tube by screws, and the smaller volume straight sleeve and the extension tube are connected by screws, so as to reduce the part of the guide tube or the extension tube. If the stress is too large, then the extension pipe is hoisted, and the straight sleeve and the reducing sleeve are connected by the bolt-nut assembly. Since the volume of the straight sleeve and the reducing sleeve are both small, the wall thickness can be made larger. Some to resist excessive local stress caused by bolts.

The technical solution of the present invention is as follows: the length of the guide tube is 4-6m, the outer diameter of the guide tube is 150-300mm, the wall thickness of the guide tube is 8-14mm; the length of the extension tube is 4-6m, the outer diameter of the extension pipe is 150-300mm, and the wall thickness of the extension pipe is 8-14mm.

The technical solution of the present invention is as follows: the rotor and the rotor casing are made of ductile iron, and the rotor and the rotor casing are integrally formed by casting. The welding performance of ductile iron is poor, so the rotor and the rotor casing are integrally cast, which can effectively avoid the cracking problem caused by welding.

The technical solution of the present invention is as follows: the rotor and the rotor casing are made of steel, and the rotor and the rotor casing are welded and fixed. Steel has the advantages of high strength and ease of welding. Although it has poor corrosion resistance, it can be galvanized on its surface. Due to the small number and volume of rotors, the damage to the environment is low.

The technical solution of the present invention is as follows: the diameter of the rotor is 300-800mm, and the thickness of the rotor is 12-20mm.

The technical solution of the present invention is as follows: a plurality of the rotors are provided, the distance between the upper and lower ends of the rotors is a pitch, and the distance between the plurality of rotors is an integer multiple of the pitch of the rotors.

Compared with the prior art, the beneficial effect of the ductile iron helical pile of the present invention is that the rotor is fixedly installed on the guide pipe through a threaded connection, so as to realize the separate shipment and rapid on-site assembly of the rotor and the guide pipe, and can make full use of the space of the transportation tool. , reduce transportation costs, improve transportation efficiency, and can make full use of the high corrosion resistance of ductile iron to avoid the cracking problem of ductile iron caused by welding.

Description of drawings

FIG. 1 is a front view of the ductile iron screw pile in the first embodiment.

FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 1 .

3 is a perspective view of the rotor in the first embodiment.

FIG. 4 is a front view of the rotor in the first embodiment.

5 is a top view of the rotor in the first embodiment.

6 is a front view and a partial cross-sectional view of the ductile iron screw pile in the first embodiment.

In the picture: 1. Guide tube, 2. Rotor, 3. Rotor sleeve, 4. Connecting hole, 5. Bolt, 6. Nut, 7. Screw, 8. Extension tube, 9. Straight sleeve, 10. Variable diameter casing.

Detailed ways

The following examples are to further illustrate the present invention, but the present invention is not limited thereto. Because the present invention is relatively complex, the embodiments only describe the invention points of the present invention in detail, and the existing technology can be adopted for the parts that are not described in detail in the present invention.

Example 1:

As shown in Figures 1-5, a ductile iron screw pile includes a guide tube 1, a rotor 2, a rotor sleeve 3, an extension tube 8 and a connecting sleeve. The guide tube 1 and the extension tube 8 are made of ductile iron, and the rotor 2, the rotor sleeve 3 and the connecting sleeve are made of Q345 steel.

The rotor 2 is in a spiral shape, and the rotor 2 is welded with the rotor sleeve 3 , and each rotor sleeve 3 is provided with a rotor 2 . The rotor sleeve 3 is sleeved with the guide tube 1 and is fixedly connected by a threaded connection. Specifically, as shown in Figures 3-5, the rotor sleeve 3 and the guide tube 1 are respectively provided with three threaded connections. The axis of the connecting hole 4 is horizontal and intersects with the axis of the guide tube 1, and the axes of any two connecting holes 4 are not coplanar. In the first embodiment, the rotor sleeve 3 is fixedly connected to the guide tube 1 with a bolt-nut assembly, the bolt-nut assembly includes a bolt 5 and a nut 6, and the connecting hole 4 is a through hole, as shown in FIG. 2 . , the bolt 5 passes through the through hole provided on the rotor sleeve 3 and the guide tube 1 and is locked by the nut 6 . Since the gap between the bolt 5 and the through hole is large, it is easier to connect the rotor sleeve 3 and the guide tube 1 by using the bolt-nut assembly connection.

The distance between adjacent rotors 2 is an integral multiple of the pitch of the rotors 2 . The distance traveled by the rotor 2 for one rotation in the soil is one pitch.

As shown in FIG. 1 , the connecting sleeve includes a straight sleeve 9 . The two ends of the straight sleeve 9 are respectively sleeved on the outside of the guide pipe 1 or the extension pipe 8 at both ends and are fixedly connected by a bolt-nut assembly. The bolt-nut assembly includes a bolt 5 and a nut 6. The bolt 5 Pass through the through holes provided on the straight sleeve 9 and the guide tube 1 or the extension tube 8 and lock with the nut 6 .

Application example 1:

The State Grid has built a new 110KV power transmission line project, which includes 20 bases of high-voltage tower foundations, each base tower has 4 tower feet, and the design life is 50 years. According to the geological test, the soil in this area is weakly acidic, which is not suitable for the use of steel screw piles; the bearing capacity of ductile iron hammering is insufficient and cannot be used; the construction period of cement pouring piles is long, which will adversely affect the surrounding environment. After technical analysis, engineers and technicians decided to use the ductile iron screw pile in Example 1 as the foundation of the electric tower. Considering the corrosion effect of soil on steel materials, engineers and technicians have considered the corrosion amount of rotor 2, rotor casing 3 and connecting casing for 50 years.

Each base tower foundation consists of 4 tower feet, each base tower foot foundation adopts a set of ductile iron screw piles, each base tower has a total of 4 sets of ductile iron screw piles, and 20 base towers have a total of 80 sets of ductile iron screw piles.

For the influence of the electric tower on the direction of the foundation force, the engineers and technicians inclined the angle of the ductile iron screw pile to the outside and kept it at 75° with the horizontal plane.

According to the bearing capacity and geological conditions of the tower foundation, the total design length of the ductile iron screw pile is 11m, which is composed of a guide pipe 1, an extension pipe 8, a connecting sleeve and three rotors 2. The length of the guide tube 1 is 6m, the outer diameter is 170mm, and the wall thickness is 9.7mm. The length of the extension pipe 8 is 5m. Considering the uncertain factors of on-site construction, the length of the extension pipe is made 6m, and the remaining part is removed after construction, as shown in Figure 1. The outer diameter of the extension tube 8 is 170 mm, and the wall thickness is 9.7 mm. The tensile strength of the guide tube 1 and the extension tube 8 is Rm≥460MPa, the yield strength Rp0.2≥320MPa, and the elongation A≥10%. The diameter of the rotor 2 is 508mm, the wall thickness is 16mm, and the pitch is 152mm. The length of the rotor sleeve 3 is 350 mm. The distance between adjacent rotors 2 is 1824 mm.

The construction equipment of the ductile iron screw pile is converted from an engineering excavator. The excavator model is PC300-6, and the total weight of the equipment exceeds 30t. The excavating bucket is replaced with a hydraulic power head. The power head bracket is pre-made. After removing the bucket, the power head bracket is connected to the forearm of the excavator with a pin shaft. The hydraulic power head is installed on the bracket. The hydraulic pipeline of the excavator is connected with the hydraulic pipeline of the power head. The hydraulic system drives the rotation, and the bracket together with the power head can swing freely forward and backward. There is a sleeve under the power head, and the guide tube 1 or the extension tube 8 is inserted into the sleeve and locked with a pin, and the power head drives it to rotate.

Install a torque detection device, and use the oil supply and return oil pressure difference of the hydraulic system to measure the rotational torque of the power head from time to time. An angle measuring device is installed on the power head bracket to detect the angle of the screw pile from time to time.

Install the guide tube 1 and the rotor 2, tighten the three rotors 2 with 9 M24 bolts, adjust the excavator, power head, torque detection device and angle detection device, adjust the power head to a horizontal position and place it on the ground. First, install the guide tube 1 on the sleeve of the power head and lock it with a pin, control the excavator to hoist the power head together with the installed guide tube 1 and keep it in a vertical state, and lift the guide tube 1 to the construction position. 1 Align the center of the front end with the construction point and keep it vertical.

Move the excavator, adjust the angle between the guide pipe 1 and the horizontal plane to keep at 75°, and the orientation of the guide pipe 1 should meet the requirements of the drawing.

Turn on the power head, drive the guide tube to rotate, control the excavator and maintain a certain downward pressure on the guide tube 1, the guide tube 1 rotates into the soil, and then the rotor 2 cuts the soil and gradually rotates into the soil. During the construction process, operate The personnel observe the torque detection device and the angle measurement device at any time, keep the angle between the guide tube 1 and the horizontal plane at 75°, and observe the change of the torque value at any time. When the top of the guide pipe 1 is about 0.8m away from the ground, the power head stops rotating, and the power head sleeve is separated from the guide pipe 1. At this time, the guide pipe 1 has been screwed into the soil, and the construction of the guide pipe 1 is completed. After the straight sleeve 9 and the extension pipe 8 are inserted, tighten them with three M24 bolts, install the extension pipe 8 on the power head sleeve according to the above method, and hang it to the top of the guide pipe 1. After the guide pipe 1 is inserted, tighten it with three M24 bolts. At this time, the guide pipe 1 is connected with the extension pipe 8, and then the extension pipe 8 is gradually screwed into the soil according to the above method. When the rotation torque reaches the design value, The power head stops rotating, remove the casing of the power head from the extension pipe 8, cut off the excess part, leave a height of 300mm on the ground of the extension pipe 8, and complete the construction of a screw pile at the foot of the tower. Use the same method to complete the remaining 3 base tower feet. When the 4 base tower feet are completed, uniformly cut, grind and level, install the cap, and complete the foundation of a tower base.

Use the above method to complete the construction of the remaining 19-base towers, and assemble the towers after the acceptance is passed.

Example 2:

As shown in Figure 6, a ductile iron screw pile includes a guide tube 1, a rotor 2, a rotor sleeve 3, an extension tube 8 and a connecting sleeve. The guide pipe 1 , the rotor 2 , the rotor sleeve 3 , the extension pipe 8 and the connecting sleeve are all made of ductile iron, so the manufacturing cost of the screw pile in this embodiment is low.

The rotor 2 is in a helical shape, and the rotor 2 and the rotor sleeve 3 are integrally cast. Each rotor casing 3 is provided with a rotor 2 . The rotor sleeve 3 is sleeved with the guide pipe 1 and is fixedly connected by a threaded connection. Specifically, as shown in FIG. 6 , the rotor sleeve 3 and the guide pipe 1 are respectively provided with three threaded connections. The connection hole 4, the axis of the connection hole 4 is horizontal and intersects with the axis of the guide tube 1, and the axes of any two connection holes 4 are not coplanar. In the second embodiment, the rotor sleeve 3 and the guide tube 1 are fixedly connected by screws 7, the connecting holes 4 are threaded holes, and the screws 7 are connected to the threaded holes provided on the rotor sleeve 3 and the guide tube 1. Thread fit. Since the gap between the screw 7 and the threaded hole is very small, the screw connection has high stability and can effectively prevent damage to the guide tube 1 or the rotor sleeve 3 due to excessive stress of the individual connection hole 4 .

The distance between adjacent rotors 2 is an integral multiple of the pitch of the rotors 2 . The distance traveled by the rotor 2 for one rotation in the soil is one pitch.

As shown in FIG. 6 , the connecting sleeve includes a straight sleeve 9 and a reducing sleeve 10 . The large diameter end of the reducing sleeve 10 is sleeved on the outside of the guide pipe 1 or the extension pipe 8 at its lower end and is fixedly connected by a screw 7, and the screw 7 is connected to the reducing sleeve 10 and the guide pipe 1 or the extension pipe. The threaded holes on the pipe 8 are threaded. The upper end of the straight sleeve 9 is sleeved outside the extension pipe 8 at the upper end and is fixedly connected by a screw 7 , and the screw 7 is threaded with the threaded holes provided on the straight sleeve 9 and the extension pipe 8 . The small diameter end of the reducing sleeve 10 is sleeved inside the straight sleeve 9 and is fixedly connected by a bolt-nut assembly. The bolt-nut assembly includes a bolt 5 and a nut 6. The through holes on the sleeve 10 and the straight sleeve 9 are locked by the nut 6 .

The difference between the construction process of this embodiment and the application example 1 is that the smaller volume reducing sleeve 10 is first connected to the guide tube 1 or the extension tube 8 by screws 7, and the smaller volume straight sleeve 9 is connected to the extension tube. 8 is connected by screw 7. Then, the extension pipe 8 is hoisted, and the straight sleeve 9 and the reducing sleeve 10 are connected by a bolt-nut assembly. Since the volumes of the straight sleeve 9 and the reducing sleeve 10 are both small, the wall thickness of the straight sleeve 9 and the reducing sleeve 10 can be made larger. larger to resist excessive local stress caused by the bolt.

The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments, and can also be made within the scope of knowledge possessed by those of ordinary skill in the art without departing from the purpose of the present invention. Various changes.

Claims (10)

1. a ductile iron helical pile, comprising a guide pipe (1) and a rotor (2), the guide pipe (1) is a ductile iron material, and the rotor (2) is helical, and is characterized in that: also comprises a rotor A casing (3), the rotor (2) is fixedly connected with the rotor casing (3), and the rotor casing (3) is sleeved with the guide pipe (1) and is fixedly connected by a threaded connection. 2. The ductile iron screw pile according to claim 1, characterized in that: the rotor sleeve (3) and the guide pipe (1) are respectively provided with a plurality of connecting holes (4) matched with the threaded connection parts, The axis of the connection hole (4) is horizontal and intersects with the axis of the guide tube (1), and the axes of any two connection holes (4) are not coplanar. 3. The ductile iron screw pile according to claim 2, characterized in that: the rotor sleeve (3) and the guide tube (1) are fixedly connected by a bolt-nut assembly, and the bolt-nut assembly comprises a bolt (5). ) and a nut (6), the connecting hole (4) is a through hole, and the bolt (5) passes through the through hole provided on the rotor sleeve (3) and the guide tube (1) and passes through the nut (6) lock. 4. The ductile iron screw pile according to claim 2, characterized in that: the rotor sleeve (3) and the guide pipe (1) are fixedly connected by screws (7), and the connection holes (4) are threaded holes and the screw (7) is threadedly matched with the threaded holes provided on the rotor sleeve (3) and the guide tube (1). 5. The ductile iron screw pile according to claim 1, characterized in that it further comprises an extension pipe (8) and a connection sleeve, the connection sleeve and the guide pipes (1) and extension pipes (8) at both ends thereof respectively. Or the two extension pipes (8) are sleeved and fixedly connected by threaded connectors. 6. The ductile iron screw pile according to claim 5, characterized in that: the connecting sleeve comprises a straight sleeve (9) and a reducing sleeve (10); The diameter end is sleeved on the outside of the guide tube (1) or the extension tube (8) at its lower end and is fixedly connected by a screw (7), the screw (7) is connected with the reducing sleeve (10) and the guide tube (1) ) or the threaded holes on the extension pipe (8) are threaded; the upper end of the straight sleeve (9) is sleeved outside the extension pipe (8) at its upper end and is fixedly connected by a screw (7), the screw (7) ) is threadedly matched with the threaded holes provided on the straight sleeve (9) and the extension pipe (8); the small diameter end of the reducing sleeve (10) is sleeved inside the straight sleeve (9) and passed through the bolt-nut The components are fixedly connected, the bolt-nut assembly includes a bolt (5) and a nut (6), the bolt (5) passes through the through holes provided on the reducing sleeve (10) and the straight sleeve (9) and is Tighten with nut (6). 7. The ductile iron screw pile according to claim 5, characterized in that the length of the guide pipe (1) is 4-6m, the outer diameter of the guide pipe (1) is 150-300mm, and the guide pipe (1) is 150-300mm long. The wall thickness of the pipe (1) is 8-14mm; the length of the extension pipe (8) is 4-6m, the outer diameter of the extension pipe (8) is 150-300mm, and the wall of the extension pipe (8) is 150-300mm. Thick 8-14mm. 8. The ductile iron screw pile according to any one of claims 1-7, wherein the rotor (2) and the rotor sleeve (3) are made of ductile iron, and the rotor (2) and the rotor sleeve are made of ductile iron. The tube (3) is integrally formed by casting. 9. The ductile iron helical pile according to any one of claims 1-7, wherein the rotor (2) and the rotor casing (3) are made of steel, and the rotor (2) and the rotor casing are made of steel. (3) Welding and fixing. 10 . The ductile iron screw pile according to claim 1 , wherein the diameter of the rotor ( 2 ) is 300-800 mm, and the thickness of the rotor is 12-20 mm. 11 .

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