Steel jacking pipe retaining device based on alternating magnetic field

Abstract

The invention relates to a steel jacking pipe retaining device based on an alternating magnetic field, the steel jacking pipe retaining device is installed at the position, corresponding to a jacking inlet of a steel jacking pipe, in a working well and used for retaining operation in the jacking process of the steel jacking pipe, and the steel jacking pipe retaining device comprises an electromagnet assembly and an embedded bolt; the electromagnet assembly comprises at least one arc-shaped electromagnet which is annularly arranged in the circumferential direction of the top inlet. The embedded bolts are embedded in the side wall of the working well in the circumferential direction of the corresponding top inlet; according to the device, the arc-shaped electromagnets which are annularly distributed are fixedly mounted at the top inlet corresponding to the jacking of the steel jacking pipe, an alternating magnetic field can be generated by alternating current through the arc-shaped electromagnets which are annularly distributed, and the magnetic field generates eddy current on the surface of the steel jacking pipe so as to generate reverse Lorentz force to resist the water and soil pressure of the excavation surface of the steel jacking pipe; the non-contact type steel jacking pipe retaining device has the advantages of being fast, efficient and large in application range, and the retaining requirement of the actual engineering steel jacking pipe can be met.

Description

Technical Field

[0001] The invention relates to the technical field of pipe jacking construction, in particular to a steel pipe jacking preventing device based on an alternating magnetic field. Background Art

[0002] When the jacking starts or the jacking route has an upward slope, during the extension welding of the jacking pipe segment, the main jack hydraulic cylinder is in a contracted state, and the side friction resistance of the pipeline is less than the water and soil pressure in front of the face. The jacking pipe segment has a tendency to retreat. If there is no anti-retreat measure, it is easy to cause the face to become unstable. At present, the main methods for stopping the retreat of jacking pipes are the bottom plate welding anti-retreat method, the clamp method, the bracket method and other measures. Among them, the bottom plate welding anti-retreat method is the most commonly used method. When welding and extending, the bottom of the jacking pipe segment is directly welded to the base bottom plate, and a cable hook is set above the hole to hook the upper part of the pipe segment to achieve the anti-retreat effect. The construction process damages the external anti-corrosion coating, and the bottom plate needs to be separated from the steel pipe during jacking. Distance, repeated welding will affect the flatness and strength of the base plate; the clamp method is mostly used to stop the retreat of small-diameter jacking pipes. A clamp ring is set at the hole, and pressure is applied to increase the friction between the clamp ring and the pipe surface to achieve the purpose of stopping retreat. It occupies a large area and is not suitable for double-line jacking pipes with small clearance; the bracket method is more commonly used in concrete jacking pipes. When used in steel jacking pipes, "ears" are usually welded on the surface of both sides of the steel pipe, and a jack bracket is set at the hole door. The jacks are used to support the "ears" welded on both sides of the steel pipe to prevent retreat. For deeply buried large-diameter jacking pipes, the "ears" are easy to crack when stopping retreat, and the "ears" on the outside of the steel pipe need to be cut when resuming jacking after the stopping is completed, affecting construction efficiency.

[0003] Based on the traditional anti-retreat method, many improvement measures have been proposed in the actual construction process, such as improving the base of the bottom plate to set anti-retreat clips and changing the anti-retreat bracket to a mobile type. However, with the continuous increase in pipeline diameter and length, the existing scheme has been difficult to meet the needs of actual projects; therefore, in the process of pipe jacking anti-retreat, it is necessary to consider a new anti-retreat method that can not only meet the construction requirements, but also ensure uniform force on the steel pipe and have higher economic benefits. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a steel pipe jacking prevention device based on an alternating magnetic field to solve the problem that the conventional prevention method in the prior art is difficult to meet actual engineering needs as the pipe diameter and length continue to increase.

[0005] To achieve the above-mentioned purpose, the present invention provides a steel jacking pipe anti-retraction device based on an alternating magnetic field, which is installed in a working pit at a top entrance corresponding to the steel jacking pipe, and is used to perform anti-retraction operations during the steel jacking process. The steel jacking pipe anti-retraction device includes an electromagnet assembly and embedded bolts; wherein,

[0006] The electromagnet assembly includes at least one arc-shaped electromagnet arranged in a ring shape along the circumference of the top inlet;

[0007] The embedded bolt is embedded in the side wall of the working well corresponding to the circumference of the top inlet, and one end of the embedded bolt extends to the outside of the side wall of the working well;

[0008] The arc-shaped electromagnet is provided with a mounting hole for the embedded bolt to pass through. The arc-shaped electromagnet cooperates with one end of the embedded bolt extending to the outside of the working well side wall through the mounting hole to be fixedly connected to the working well side wall corresponding to the circumference of the top inlet.

[0009] By adopting this technical solution, a fixed circular arc electromagnet is installed at the top entrance position corresponding to the steel jacking. An alternating current can be used to pass through the circular arc electromagnet to generate an alternating magnetic field. The magnetic field generates eddy currents on the surface of the steel jacking pipe, thereby producing reverse Lorentz magnetic force to resist the water and soil pressure on the excavation surface of the steel jacking pipe, thereby achieving the purpose of non-contact steel jacking withdrawal. It is fast, efficient and has a wide range of applications, and can meet the withdrawal needs of steel jacking pipes in actual engineering projects.

[0010] Furthermore, the embedded bolt includes an embedded nut embedded in the side wall of the working well, a screw with one end threadedly connected to the embedded nut, and an external nut connected to the other end of the screw;

[0011] After one end of the screw is threadedly connected to the embedded nut, the other end passes through the mounting hole and is threadedly connected to the external nut to complete the fixation of the arc-shaped electromagnet on the side wall of the working well.

[0012] By adopting this technical solution, the embedded nuts in the embedded bolts are embedded while the working well is being constructed, so that a connection position for the screw rod is available after the construction of the working well is completed. The arc-shaped electromagnet is then stably connected to the inner wall of the working well through the cooperation of the screw rod, the embedded nuts and the external nuts.

[0013] Furthermore, the steel pipe anti-retraction device also includes a water stop ring that is sleeved with the top inlet;

[0014] The outer portion of the water stop hole ring corresponding to the top inlet is provided with a connecting ring that fits with the inner wall of the working well, and the connecting ring is provided with a through hole for the screw to pass through;

[0015] After one end of the screw is threadedly connected to the embedded nut, the other end passes through the connection hole and the mounting hole in sequence and is threadedly connected to the external nut to complete the simultaneous fixation of the water stop hole ring and the arc-shaped electromagnet on the side wall of the working well.

[0016] By adopting the technical scheme, the waterproof hole ring structure is additionally arranged, which can provide water stop at the jacking position and replace the direct contact between the arc-shaped electromagnet and the inner wall of the working well, thereby protecting the arc-shaped electromagnet.

[0017] Further, the steel pipe stop device further comprises an electromagnetic shielding ring arranged around the periphery of the electromagnet assembly.

[0018] The electromagnetic shielding ring is fixed to the inner bottom wall of the working well, and the electromagnetic field of the electromagnet assembly is shielded by the electromagnetic shielding ring.

[0019] By adopting the technical scheme, the electromagnetic shielding ring is arranged to shield the outward electromagnetic field of the electromagnet assembly, thereby offsetting the influence of the generated electromagnetic field on the surrounding environment.

[0020] Further, the electromagnetic shielding ring comprises a ring plate and a base plate.

[0021] The bottom of the ring plate is opened to form two ends, and the base plate is fixedly connected to the two ends of the ring plate.

[0022] Expansion screws are arranged on the base plate, and the base plate is fixedly connected to the inner bottom wall of the working well through the expansion screws.

[0023] By adopting the technical scheme, the base plate is arranged as a connecting piece of the ring plate, and is fixedly connected to the inner bottom wall of the working well through the expansion screws, so as to complete the fixed installation of the electromagnetic shielding ring in the working well.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] 1. The steel pipe stop device is installed and fixed at the jacking position corresponding to the jacking of the steel pipe, and the arc-shaped electromagnet arranged in a ring shape is arranged, an alternating current is passed through the arc-shaped electromagnet arranged in a ring shape to generate a alternating magnetic field, eddy current is generated on the surface of the steel pipe to generate a reverse Lorentz magnetic force, which is used to resist the water and soil pressure of the excavation surface of the steel pipe, so as to achieve the purpose of non-contact steel pipe stop, has the characteristics of fast, efficient and wide application range, and can meet the stop requirement of the actual engineering steel pipe.

[0026] 2. The stop mode formed by the steel pipe stop device does not need to perform auxiliary stop processing such as welding and bolt connection on the steel pipe, has the characteristics of reducing construction time and increasing construction efficiency. DETAILED DESCRIPTION

[0027] Figure 1 is a three-dimensional schematic view of the installation of the steel pipe stop device based on the alternating magnetic field in the present application;

[0028] Figure 2It is a three-dimensional exploded schematic diagram of the electromagnet of the steel pipe jacking prevention device based on the alternating magnetic field in the present invention;

[0029] Figure 3 The figure is a schematic diagram of the electromagnetic shielding ring structure and expansion screw distribution of the steel jacking pipe retaining device based on the alternating magnetic field in the present invention.

[0030] Explanation of the accompanying reference numerals: 1. Electromagnet assembly; 11. Arc-shaped electromagnet; 12. External nut; 13. Screw; 14. Water-stop hole ring; 15. Embedded nut; 2. Electromagnetic shielding ring; 21. Magnetic field shielding layer; 22. Expansion screw; 3. Working well. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0032] Please see the attached Figure 1 The present invention provides a steel pipe jacking prevention device based on an alternating magnetic field, which is installed in a working shaft 3 at a top inlet position corresponding to the top inlet of the steel pipe jacking, and is used to perform a prevention operation during the top inlet process of the steel pipe jacking. The steel pipe jacking prevention device includes an electromagnet assembly 1 and embedded bolts; wherein the electromagnet assembly 1 includes at least one arc-shaped electromagnet 11 arranged in a ring shape along the circumference of the top inlet; the embedded bolt is embedded in the side wall of the working shaft 3 corresponding to the circumference of the top inlet, and one end of the embedded bolt extends to the outside of the side wall of the working shaft 3; a mounting hole for the embedded bolt to pass through is opened on the arc-shaped electromagnet 11, and the arc-shaped electromagnet cooperates with one end of the embedded bolt extending to the outside of the side wall of the working shaft 3 through the mounting hole to be fixedly connected to the side wall of the working shaft 3 corresponding to the circumference of the top inlet.

[0033] At the top entrance position corresponding to the steel jacking pipe, a fixed annular arc electromagnet 11 is installed. An alternating current can be used to pass through the annular arc electromagnet 11 to generate an alternating magnetic field. The magnetic field generates eddy currents on the surface of the steel jacking pipe, thereby producing a reverse Lorentz magnetic force to resist the water and soil pressure on the excavation surface of the steel jacking pipe, thereby achieving the purpose of non-contact steel jacking withdrawal. It has the characteristics of fast, high efficiency and wide application range, and can meet the withdrawal needs of actual engineering steel jacking.

[0034] The formula for reverse Lorentz magnetic force produced by eddy current is: in,

[0035] B is the intensity of the alternating magnetic field, A is the surface area of ​​the alternating magnetic field acting on the steel pipe, σ is the material conductivity, δ is the skin depth, ω is the frequency of the alternating current, and μ is the magnetic permeability of the material.

[0036] Please see the attached Figure 1 and 2The embedded bolt includes an embedded nut 15 embedded in the side wall of the working well 3, a screw 13 with one end threadedly connected to the embedded nut 15, and an external nut 12 connected to the other end of the screw 13; after one end of the screw 13 is threadedly connected to the embedded nut 15, the other end passes through the mounting hole and is threadedly connected to the external nut 12 to complete the fixation of the arc electromagnet 11 on the side wall of the working well 3; the embedded nut 15 is embedded in the embedded bolt while the working well 3 is being constructed, so that the connection position of the screw 13 is available after the construction of the working well 3 is completed, and then the arc electromagnet 11 is stably connected to the inner wall of the working well 3 through the cooperation of the screw 13, the embedded nut 15 and the external nut 12.

[0037] Furthermore, the steel pipe retreat preventing device also includes a water-stop hole ring 14 that is sleeved with the top inlet; the outside of the water-stop hole ring 14 corresponding to the top inlet has a connecting ring that fits the inner wall of the working well 3, and the connecting ring is provided with a through hole for the screw 13 to pass through; after one end of the screw 13 is threadedly connected to the embedded nut 15, the other end passes through the through hole and the mounting hole in turn and is threadedly connected to the external nut 12 to complete the simultaneous fixation of the water-stop hole ring 14 and the arc-shaped electromagnet 11 on the side wall of the working well 3; the water-stop hole ring 14 structure is added. On the one hand, the water-stop hole ring 14 can provide water stopping at the top position, and on the other hand, it can replace the arc-shaped electromagnet 11 to directly contact the inner wall of the working well 3, and can play a role in protecting the arc-shaped electromagnet 11.

[0038] Please see the attached Figure 1 and 3 The steel pipe retreat preventing device also includes an electromagnetic shielding ring 2 arranged around the periphery of the electromagnet assembly 1; the electromagnetic shielding ring 2 is fixed on the inner bottom wall of the working well 3, and shields the outward electromagnetic field of the electromagnet assembly 1 through the electromagnetic shielding ring 2; the electromagnetic shielding ring 2 is set to block the outward electromagnetic field of the electromagnet assembly 1, thereby offsetting the impact of the electromagnetic field on the surrounding environment.

[0039] Furthermore, the electromagnetic shielding ring 2 includes a ring plate 21 and a base plate; the bottom opening of the ring plate 21 forms two ends, and the base plate is horizontally fixedly connected to the two ends of the ring plate 21; expansion screws 22 are evenly distributed on the base plate, and are fixedly connected to the inner bottom wall of the working well 3 through the expansion screws 22; the base plate is set as a connecting part of the ring plate 21, so as to cooperate with the expansion screws 22 to be fixedly connected to the inner bottom wall of the working well 3, so as to complete the fixed installation of the electromagnetic shielding ring 2 inside the working well 3.

[0040] The present invention has been described in detail above with reference to the embodiments of the accompanying drawings. A person skilled in the art can make various modifications to the present invention based on the above description. Therefore, certain details in the embodiments should not be construed as limiting the present invention. The scope of protection of the present invention shall be determined by the scope defined in the appended claims.

Claims

1. A steel pipe jacking prevention device based on an alternating magnetic field, installed in a working pit at a position corresponding to the top entrance of the steel pipe jacking, for preventing the steel pipe from retreating during the jacking process, characterized in that: The steel jacking pipe anti-retraction device includes an electromagnet assembly and embedded bolts; wherein, The electromagnet assembly includes at least one arc-shaped electromagnet arranged in a ring shape along the circumference of the top inlet; The embedded bolt is embedded in the side wall of the working well corresponding to the circumference of the top inlet, and one end of the embedded bolt extends to the outside of the side wall of the working well; The arc-shaped electromagnet is provided with a mounting hole for the embedded bolt to pass through. The arc-shaped electromagnet cooperates with one end of the embedded bolt extending to the outside of the working well side wall through the mounting hole to be fixedly connected to the working well side wall corresponding to the circumference of the top inlet.

2. The steel pipe jacking prevention device based on alternating magnetic field according to claim 1 is characterized in that: The embedded bolt includes an embedded nut embedded in the side wall of the working well, a screw with one end threadedly connected to the embedded nut, and an external nut connected to the other end of the screw; After one end of the screw is threadedly connected to the embedded nut, the other end passes through the mounting hole and is threadedly connected to the external nut to complete the fixation of the arc-shaped electromagnet on the side wall of the working well.

3. The steel pipe jacking prevention device based on alternating magnetic field according to claim 2 is characterized in that: The steel pipe retreat prevention device also includes a water stop ring that is sleeved with the top inlet; The outer portion of the water stop hole ring corresponding to the top inlet is provided with a connecting ring that fits with the inner wall of the working well, and the connecting ring is provided with a through hole for the screw to pass through; After one end of the screw is threadedly connected to the embedded nut, the other end passes through the connection hole and the mounting hole in sequence and is threadedly connected to the external nut to complete the simultaneous fixation of the water stop hole ring and the arc-shaped electromagnet on the side wall of the working well.

4. The steel pipe jacking prevention device based on alternating magnetic field according to claim 1 is characterized in that: The steel pipe retreat preventing device further comprises an electromagnetic shielding ring arranged around the periphery of the electromagnet assembly; The electromagnetic shielding ring is fixed on the bottom wall of the working well, and the electromagnetic shielding ring shields the outward electromagnetic field of the electromagnet assembly.

5. The steel pipe jacking prevention device based on alternating magnetic field according to claim 4 is characterized in that: The electromagnetic shielding ring includes a ring plate and a base plate; The bottom opening of the ring plate forms two ends, and the base plate is horizontally fixedly connected to the two ends of the ring plate; Expansion screws are evenly distributed on the base plate, and the base plate is fixedly connected to the bottom wall of the working well through the expansion screws.

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