Nodular iron pipe jacking pipe

Abstract

The utility model discloses a ductile iron pipe jacking pipe applied to the field of pipelines. Wrapping the socket with a reinforced concrete pouring section; a concrete double-layer section is wrapped outside the pipe body, the outer layer is a cement pipe, and the inner layer is foamed cement. And a pushing ring is welded at the junction of the pipe body and the socket. The contact surfaces of the cement pipe and the pouring section are in groove convex positioning connection, and a gap between the cement pipe and the pouring section is filled with cement paste, and meanwhile, a gap between the contact surfaces of the pushing ring and the cement pipe is filled with cement paste. The cement pipe is provided with an injection hole, the reinforcing mesh extends out of the inner surface of the cement pipe, and transition sections with inclined or cambered inner surfaces are arranged at two ends of the cement pipe. During pushing operation, the outer stress ring is installed between the pushing ring and the end face of the socket, and the inner stress ring is installed between the end face of the spigot and the inner bottom plane of the socket. The device is good in appearance and light in overall weight, and weld cracks are avoided through overall pushing.

Description

Technical Field

[0001] This utility model is applied to the field of municipal pipelines and relates to pipe jacking installation, specifically a ductile iron pipe jacking system suitable for socket connection of ductile iron pipes. Background Technology

[0002] Ductile iron pipe, also known as ductile iron pipe, is a primary material for municipal pipeline construction due to its excellent properties such as flexible spigot and socket connections and corrosion resistance. Previously, pipeline laying primarily employed open-cut construction. However, with advancements in pipe jacking technology, this process has become the mainstream for pipeline laying, leading to the industry trend of manufacturing ductile iron pipes for jacking. Examples include CN104197118A (a ductile iron jacking pipe), CN204062216U (a ductile iron jacking pipe), CN204477492U (a ductile iron pipe jacking pipe), and CN104565535A (a ductile iron pipe jacking pipe and its preparation method). All these methods involve adding reinforced concrete to the outer wall of the pipe to eliminate the difference in outer diameter between the socket and spigot, resulting in a jacking pipe with a uniform outer wall. Since the ductile iron pipe is 6 meters long, the length of the jacking pit needs to be no less than 12 meters. In order to reduce the size of the construction pit working area, CN220816757U provides a ductile iron micro jacking pipe with a length of 1-2 meters. However, the micro jacking pipe increases the number of pipeline socket connections and is only suitable for short-distance pipe jacking construction.

[0003] The above-mentioned ductile iron pipe jacking has the following defects:

[0004] 1) Heavy weight. Especially for large-diameter ductile iron pipes, the weight of the outer concrete casing is comparable to the weight of the pipe itself. Taking a DN1400 (K9 wall thickness) ductile iron pipe as an example, the pipe weighs 3.67 tons. After being encased in concrete, the weight increases by approximately 5.2 tons, bringing the total weight of the pipe jacking to 8.9 tons. This increased weight not only increases transportation costs but, more importantly, increases the difficulty of pipe jacking and the costs of jacking equipment and construction.

[0005] 2) Poor appearance. When the ductile iron pipe is encased in concrete, the ductile iron pipe is erected, covered with a steel mesh, and the formwork is installed before the concrete is poured. Because the ductile iron pipe is nearly 6 meters long, it is difficult to vibrate and compact the poured concrete. After the formwork is opened, there are a lot of pits on the outer surface of the concrete, which need to be repaired later.

[0006] 3) Weld cracking. Currently, in ductile iron pipe jacking systems, a jacking flange is welded near the spigot end of the ductile iron pipe. The jacking flange transmits the jacking force to the socket end face. To increase the strength of the jacking flange, stiffening plates are welded to the back side. Due to the poor weldability of ductile iron, the weld becomes a weak point in the jacking force. Moreover, in actual jacking construction, it is difficult to ensure planar stress, so weld cracking is unavoidable. Utility Model Content

[0007] The technical problem solved by this utility model is to provide a ductile iron pipe jacking pipe and a manufacturing method thereon, so as to solve the above-mentioned problem.

[0008] The technical solution adopted in this utility model is as follows: The ductile iron pipe jacking system consists of a ductile iron pipe encased in concrete. Specifically, at the socket of the ductile iron pipe, a reinforced concrete pouring section is encased; the pipe body is encased in a double-layer section with two layers of concrete. The outer layer of this double-layer section is a pre-formed, commercially available high-strength cement pipe, and the inner layer is foamed cement to reduce the weight of the concrete. A jacking ring is welded to the outer surface of the junction between the ductile iron pipe body and the socket. The contact surfaces of the cement pipe and the pouring section are connected by a groove and protrusion, and the gap between their contact surfaces is filled with cement grout. The gap between the jacking ring and the cement pipe contact surface is filled with cement grout, using the cement grout and foamed cement to integrate the ductile iron pipe and the concrete.

[0009] Furthermore, to enhance the integrity of the foamed cement and the cement pipe, a steel mesh extends from the inner surface of the cement pipe, using the steel mesh to connect the foamed cement and the cement pipe into one unit.

[0010] Furthermore, to facilitate the injection of foamed cement into the cement pipe, evenly distributed injection holes are provided on the cement pipe, which also have a pressure relief function.

[0011] Furthermore, to increase the jacking force area and avoid stress concentration, transition sections with inclined or curved inner surfaces are provided at both ends of the cement pipe.

[0012] Furthermore, during the jacking operation, an elastic outer force-bearing ring is installed between the jacking ring and the socket end face of the front pipe, and an elastic inner force-bearing ring is installed between the spigot end face and the inner bottom plane of the socket of the front pipe. During the jacking operation, the ductile iron pipe and the surrounding concrete as a whole bear the jacking force, which ensures both uniform stress on the ductile iron pipe during jacking and straight jacking, thus facilitating the jacking operation.

[0013] The beneficial effects of this utility model are: This utility model uses foamed cement to reduce the overall weight of the ductile iron pipe jacking pipe, and adopts a method of bearing the jacking force as a whole, thus avoiding weld cracks. The cement pipe pouring section is only the height of the socket, making vibratory rod construction convenient. The cement pipe is centrifugally poured, resulting in a smooth appearance of the ductile iron pipe jacking pipe without pits. Attached Figure Description

[0014] Figure 1 This is a structural schematic diagram of Example 1;

[0015] Figure 2 This is a schematic diagram of a socket connection;

[0016] Figure 3 This is a structural schematic diagram of Example 2.

[0017] Attached reference numerals: 1-Socket, 2-Spigot, 3-Pipe body, 4-Sealing ring;

[0018] 11-Pouring section, 12-Cement pipe, 13-Foamed cement, 14-Steel mesh, 15-Injection hole, 16-Pushing ring, 17-Cement slurry;

[0019] 21-External force ring, 22-Internal force ring. Detailed Implementation

[0020] Example 1

[0021] The structure of this utility model ductile iron pipe jacking pipe is shown in the attached figure. Figure 1 As shown, the ductile iron pipe includes a socket 1, a spigot 2, and a pipe body 3 connecting the socket and spigot. A reinforced concrete casting section 11 is wrapped around the outside of the socket 1. Two layers of concrete are wrapped around the outside of the pipe body 3: an outer layer of cement pipe 12 and an inner layer of foamed cement 13. A jacking ring 16 is welded at the junction of the pipe body 3 and the spigot 2. During pipe jacking operations, the jacking ring 16 contacts the socket end face of the preceding pipe to apply jacking force. The spigot 2 is not covered with cement and is used for a flexible connection with the socket. The cement pipe and the casting section are connected using a groove-and-convex positioning connection. The gap between them is filled with cement grout 17 to ensure tight contact between the cement pipe and the casting section. The gap between the cement pipe and the jacking ring 16 is also filled with cement grout 17 to ensure tight contact between the cement pipe and the jacking ring. Micro-expansion cement is recommended as the cement grout.

[0022] The cement pipe 12 is purchased externally and manufactured by a professional factory. It is centrifugally cast using high-grade cement and a reinforcing mesh 14, and its strength meets the requirements for jacking force. The reinforcing mesh 14 extends beyond the inner surface of the cement pipe. Purchased foamed cement is injected into the inner cavity of the cement pipe through evenly distributed injection holes 15. The foamed cement is used to reduce the weight of the cement on the outer layer of the ductile iron pipe. Under the connecting action of the reinforcing mesh 14, the cement pipe and the foamed cement become a single unit.

[0023] The manufacturing steps for ductile iron pipe jacking are as follows:

[0024] 1) Construction of the socket pouring section. Erect the spherical iron pipe on the platform, install the socket formwork, insert reinforcing bars between the formwork and the socket, pour concrete, and vibrate with a vibrator to ensure compaction. Smooth the top concrete, cover the annular top opening with two half-formworks with annular bosses, and vibrate with a vibrator to form the annular groove on the upper surface of the pouring section. After the concrete in the pouring section has solidified and reached its strength, remove the formwork.

[0025] 2) Installing the cement pipe. Cement grout is added to the annular groove of the casting section. The purchased cement pipe is then installed on top of the casting section, with the convex ring of the cement pipe fitting into the annular groove. Under the weight of the cement pipe, the cement grout in the annular groove is squeezed out, ensuring close contact between the end face of the cement pipe and the upper surface of the casting section. Since installing the cement pipe onto the vertical cast iron pipe requires considerable operating space, a socket template and cement pipe can also be installed onto a horizontally laid cast iron pipe. After connection, the cast iron pipe is erected, and the cement pipe is supported before pouring the bottom socket casting section. Once the socket casting section has solidified and reached its strength, the cover mold is removed, and the cement pipe is installed.

[0026] 3) Welding the jacking ring. Weld the jacking ring at the predetermined position. This position is where the jacking ring can contact the end face of the socket after the spigot is inserted into the socket. During the jacking operation, the spigot and the jacking ring apply the jacking force simultaneously, so that both the cast pipe and the outer concrete layer bear the jacking force.

[0027] 4) Injecting foamed cement. After sealing the gap between the push ring and the end face of the cement pipe with cement grout, inject foamed cement into the cement pipe through the injection hole on the cement pipe. The foamed cement expands and foams between the cement pipe and the pipe body, filling the gap between them. The injection hole can partially relieve pressure. Alternatively, no injection hole is provided on the cement pipe. An injection hose extends into the gap between the push ring and the end face of the cement pipe, and foamed cement is injected through the hose. The hose is withdrawn while being injected.

[0028] 5) Removal of socket formwork. After cement curing, the socket formwork is removed. The micro-expansion cement slurry and foamed cement make the casting section, cement pipe, jacking ring and pipe body become one.

[0029] When using this utility model, as shown in the attached... Figure 2As shown, a sealing ring 4 is installed in the socket sealing groove of the front pipe, and an elastic inner force-bearing ring 22 is installed on the inner bottom plane of the socket. An elastic outer force-bearing ring 21 is fitted onto the spigot. The inner force-bearing ring 22 and the outer force-bearing ring 21 should preferably be made of elastic hard rubber or plastic, which will not affect water quality and has good corrosion resistance. The spigot is inserted into the socket of the front pipe, and the sealing ring 4 seals the socket and spigot. The outer force-bearing ring 21 contacts the plane of the jacking ring and the plane of the socket end face, and the inner force-bearing ring 22 contacts the end face of the spigot and the inner bottom plane of the socket. When a jacking force is applied to the jacking pipe, the jacking ring applies the jacking force to the socket end face of the front pipe through the outer force-bearing ring 21. At the same time, the spigot end face applies the jacking force to the inner bottom plane of the socket of the front pipe through the inner force-bearing ring 22. In this way, the ductile iron pipe and the outer concrete layer both bear the jacking force, achieving integrated bearing of the jacking force. The functions of the inner and outer force-bearing rings are: 1) To eliminate manufacturing errors and deviations, and to ensure that both the ductile iron pipe and the outer concrete casing bear the jacking force using their elasticity. 2) To ensure that the entire ring plane bears the jacking force using the elasticity of the inner and outer force-bearing rings, eliminating localized stress caused by manufacturing errors or deviations, and making the jacking force evenly distributed, thereby maintaining the straight-line movement of the jacking pipe. 3) When the ductile iron pipe bears the jacking force, the weld of the jacking ring does not bear the jacking force, or bears a small force, so as not to cause the weld to crack. Foamed cement also has strength, and through the steel mesh, it becomes an integral part of the cement pipe, which can also transmit the jacking force. Between the socket casting section and the cement pipe, the groove is used for positioning, and the micro-expansion cement slurry evenly transmits the jacking force.

[0030] Example 2

[0031] This embodiment is a partial structural improvement based on Embodiment 1, as shown in the attached figure. Figure 3 As shown. During the jacking process, in order to avoid stress concentration on the two ends of the cement pipe, this embodiment increases the contact area at both ends of the cement pipe and sets transition sections with inclined or curved inner surfaces at both ends to increase the planar jacking force area of ​​the casting section and the jacking ring.

[0032] This invention utilizes foamed cement, reducing the weight of the double-layer section and the overall weight of the ductile iron pipe jacking pipe. For a DN1400 (K9 grade) ductile iron pipe jacking pipe, the weight is reduced from 8.9 tons to 6.9 tons, a concrete weight reduction of 2.0 / 5.2 = 38.5%. The ductile iron pipe jacking pipe as a whole bears the jacking force, avoiding weld cracks in the jacking ring. The socket casting section only has the height of the socket, approximately 40cm, facilitating vibratory construction. Together with the centrifugally fabricated cement pipe, this results in a smooth, dent-free ductile iron pipe jacking pipe surface, eliminating the need for repairs.

Claims

1. A ductile iron pipe push pipe characterized by: In the socket of the nodular cast iron pipe, a concrete pouring section (11) is wrapped outside; in the pipe body of the nodular cast iron pipe, a double-layered concrete section is wrapped outside, the outer layer of which is a cement pipe (12) and the inner layer is foamed cement (13); at the joint between the pipe body of the nodular cast iron pipe and the socket, a jacking ring (16) is welded; the contact surface groove of the cement pipe (12) and the pouring section (11) is positioned and connected, and the gap between them is filled with cement slurry (17); the gap between the contact surface of the jacking ring (16) and the cement pipe (12) is filled with cement slurry (17).

2. A ductile iron pipe jacking pipe according to claim 1, characterized in that: The reinforcing mesh (14) of the cement pipe (12) extends out of the inner surface of the cement pipe.

3. A ductile iron pipe jacking pipe according to claim 1, characterized in that: Uniformly distributed injection holes (15) are arranged on the cement pipe (12).

4. A ductile iron pipe jacking pipe according to claim 1, characterized in that: The two ends of the cement pipe (12) are provided with transition sections with inclined or arc-shaped inner surfaces.

5. A ductile iron pipe socket according to claim 1, wherein: During jacking operation, an elastic outer force ring (21) is installed between the jacking ring (16) and the end surface of the socket of the previous pipe; an elastic inner force ring (22) is installed between the end surface of the socket of the nodular cast iron pipe and the inner bottom plane of the socket of the previous pipe.

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