A small-curvature, fully self-anchoring flexible joint pipe suitable for horizontal directional drilling construction

Abstract

This invention discloses a small-curvature, fully self-anchored flexible joint pipe suitable for horizontal directional drilling construction, belonging to the field of trenchless high-pressure pipeline technology. This invention employs a pipe section with a weld-free, fully self-anchored flexible mechanical joint. The maximum controllable swing angle of a single joint is 2°. By using distributed cornering at multiple joints to replace the forced bending of the traditional steel pipe wall, the superimposed stress from high-pressure bending is significantly reduced. The joint is equipped with an all-around self-anchoring and high-pressure sealing structure, capable of withstanding 13.5MPa internal pressure and directional drilling drag loads, eliminating the need for concrete thrust supports. This invention eliminates on-site connection welds, residual stress, and allows for section-by-section splicing and pullback, solving the industry pain points of traditional high-pressure welded pipes, such as limited curvature, excessive stress, limited construction sites, and poor seismic settlement performance. It is suitable for complex urban areas, trenchless crossing projects, and pipeline engineering projects involving buried pipes and pipe corridors. It is particularly suitable for use in seismically active zones and seismic fault zones for trenchless ultra-long pipelines, offering significant safety and economic benefits.

Description

Technical Field

[0001] This invention belongs to the fields of pressure pipeline, trenchless crossing engineering and seismic resistance of pipeline network. Specifically, it relates to a modular flexible self-locking steel pipe structure that can achieve low-curvature and low-stress laying, welding-free, fully self-anchored pull-out resistance, adaptive uneven settlement, and is compatible with high-pressure directional drilling construction. Background Technology

[0002] Large-diameter, high-grade steel pipes for pressurized water transmission are widely used in urban main water supply, road and river crossings, and long-distance high-pressure water transmission projects. Existing high-pressure pipelines generally employ on-site welded rigid steel pipe laying, which presents significant technical drawbacks:

[0003] Traditional welded steel pipes are rigid, integral structures, and pipeline bends rely entirely on the bending deformation of the pipe itself. Under conditions of X70 high-grade steel and ultra-high internal pressure of 13.5MPa, the combined bending stress of the pipe wall and the internal pressure membrane stress can easily exceed the material's yield strength. Therefore, engineering specifications impose extremely high minimum curvature radius restrictions on welded steel pipes, resulting in rigid trajectory layouts that are difficult to adapt to complex underground obstacles in urban areas, small curvature radius avoidance, and dense pipeline crossing scenarios.

[0004] Meanwhile, traditional welded steel pipes have a large number of circumferential welds on site. These welds have inherent defects such as residual stress, microcracks, incomplete penetration, and corrosion damage. Under the action of high-pressure water hammer, foundation settlement, and soil displacement, they are prone to cracking and leakage. 100% non-destructive testing and on-site anti-corrosion repair are required throughout the process. The construction process is complicated, the construction period is long, and the cost is high.

[0005] In addition, traditional high-pressure steel pipe directional drilling construction requires the prefabrication of ultra-long pipe sections of hundreds of meters on the ground and the overall back-pulling, which has extremely high requirements for the construction site and cannot be adapted to construction in narrow urban spaces, areas with short-term traffic restrictions, and densely packed structures; rigid integral pipe networks have no deformation redundancy, have extremely poor seismic resistance and resistance to uneven settlement, and have a high failure rate in long-term service.

[0006] Conventional socket-type steel pipes and ordinary self-anchoring pipes cannot withstand ultra-high internal pressure of 13.5MPa and lack controllable swing angle capability, making them unsuitable for high-pressure trenchless directional drilling projects. The industry has long faced technical bottlenecks such as excessive bending stress in high-pressure steel pipes, significant limitations on rigidity and curvature, numerous welding defects, limited construction sites, and a lack of settlement adaptability. A completely new structural system is urgently needed to solve these problems. Summary of the Invention

[0007] The purpose of this invention is to address the technical pain points of existing high-pressure rigid welded steel pipes, such as strict curvature constraints, easy exceedance of bending stress, high risk of weld defects, strong dependence on construction sites, poor seismic and settlement resistance, and the necessity of setting up thrust supports. This invention provides a flexible interface steel pipe system with a 2° controllable swing angle and 25mm controllable movement, fully self-anchored and self-locking, weld-free modular design, low resistance, low stress laying, and compatibility with 13.5MPa high-pressure directional drilling, breaking through the limitations of traditional high-pressure steel pipe laying.

[0008] This invention patent discloses a small-curvature, fully self-anchored flexible joint pipe suitable for horizontal directional drilling construction. It comprises several pipe sections with end-to-end socket assembly and adapted lengths, with hinged interfaces between adjacent sections. Each hinged interface features a radial limiting swing angle compensation structure and an axial limiting expansion compensation structure. A single hinged interface can achieve ±2° radial swing angle and 25mm axial displacement compensation. Multiple sets of hinged interfaces with continuously superimposed micro-angles form a smooth laying arc, resulting in a chain-like stress structure for the entire pipeline. Distributed interface deformation offsets additional internal forces from the terrain, preventing stress concentration and leakage in the pipe wall. By using pipe sections of adapted lengths, high-pressure pipes of different diameters can be laid efficiently through the pilot guide pipe with small curvature, low resistance, and low stress during horizontal directional drilling construction.

[0009] Furthermore, its articulated interface has a staged energy release structure that is first flexible and then rigid; when the interface is subjected to bending moment, it first releases energy through angular displacement, and after reaching the angular limit, the remaining bending moment is transferred to the next interface for gradual release; when the interface is subjected to axial force, it first releases energy through axial expansion and contraction displacement, and after reaching the displacement limit, the axial force is carried over to the subsequent pipe section for distribution, thereby reducing the axial stress of the pipe wall.

[0010] Furthermore, the hinged interface includes a socket, a insertion port, a self-locking retaining ring, and a sealing ring; a hook is provided inside the socket, and an insertion port protrusion is provided on the outside of the insertion port. The self-locking retaining ring is engaged between the hook and the insertion port protrusion to form a bidirectional axial limiting and locking structure. The self-locking retaining ring remains in contact and does not disengage throughout the entire swing angle process.

[0011] Furthermore, the bidirectional self-locking clasp adopts a high-strength alloy structure to form an axial bidirectional limiting lock, which can withstand 13.5MPa hydrostatic pressure and instantaneous water hammer impact load for a long time. The chain structure balances the force and automatically offsets the high-pressure axial thrust, eliminating the need for the traditional pipeline thrust support structure.

[0012] Furthermore, for a DN600 trenchless circular arc pipeline, when the swing angle Θ of its interface is 2°, the radius of curvature R of the arc is 171.9m, and the length L0 of its suitable pipe section is 6m (… When the pipeline sinking inclination angle α is 14°, the horizontal distance a of its single arc segment is 41.6m. The single-segment circular arc depression height b is 5.1m. The pipeline settlement height h is 10.2m. According to CECS 382, ​​the minimum radius of curvature R of DN600 trenchless welded steel pipe is 750m (R=1250DN). This patented pipe shortens the minimum radius of curvature R by 77% compared to welded steel pipe, breaking through the limit of the minimum radius of curvature of traditional pipelines, allowing pipelines to flexibly pass through even very complex environments.

[0013] Furthermore, all pipe section connections adopt a mechanical self-locking assembly structure, with no welding, no circumferential welds, and no residual welding stress throughout the entire process. This eliminates the need for on-site weld flaw detection and anti-corrosion repair, thereby eliminating the risk of weld cracking and leakage failure in high-pressure pipelines from the source.

[0014] Furthermore, the modular short-section structure allows for segment-by-segment connection and simultaneous connection and dragging during directional drilling construction, eliminating the need for large prefabrication sites and making it suitable for construction projects involving narrow spaces and complex underground pipeline obstacles in urban areas.

[0015] Furthermore, the multi-section flexible hinged structure forms an integral deformable pipe network system, which can adapt to uneven foundation settlement, lateral soil displacement, and slight rotation and misalignment caused by seismic loads. By absorbing loads through displacement deformation, it achieves long-term service performance with soft load shedding, high seismic resistance, high settlement resistance, and anti-leakage.

[0016] Furthermore, by adding a jacking device to one side of the working well, the crossing pipeline can move forward under the traction force P2 or the jacking force P1 or the resultant force of both. While converting the forward force, it can release the bending friction resistance generated by the pipeline moving forward at an angle, thus avoiding pipe jamming accidents. By adopting a working method in which the pipeline moves forward continuously with the connection pipe and the traction shaft retraction process staggered, the static friction resistance of restarting the pipeline can be avoided, thus breaking through the limit of the crossing pipeline length.

[0017] Furthermore, the protruding side of the socket is a bevel or an arc surface, and the self-locking ring is squeezed to generate a radial force that tightly adheres to the inner side of the hook to prevent it from coming off; the inner diameter of the socket seal is larger than the outer diameter of the socket, and the gap between the two forms a ±2° swing angle allowance.

[0018] Furthermore, a sealing groove is provided in the socket, and clearance is reserved on both sides of the sealing groove; multiple annular pits are set at the bottom of the sealing groove, so that the friction between the inner circle of the sealing ring and the socket is greater than the friction between the outer circle of the sealing ring and the socket, and the sealing ring moves synchronously with the socket under swing angle, expansion and contraction and seismic conditions.

[0019] Furthermore, gaps are reserved between the end face of the socket and the step of the socket, and between the protrusion of the socket and the self-locking retaining ring, to provide a total axial expansion and contraction compensation of 25mm.

[0020] Furthermore, the self-locking clasp is a high-strength alloy component that can withstand a continuous internal pressure of 13.5MPa and instantaneous water hammer load. It relies on the chain pipeline to balance the high-pressure axial thrust and does not require a matching concrete thrust support.

[0021] Furthermore, the pipe sections are assembled only through a mechanical self-locking structure, without circumferential welding seams, eliminating residual welding stress and weld leakage defects, and eliminating the need for on-site non-destructive testing and anti-corrosion repair processes.

[0022] Furthermore, the multi-section articulation forms a deformable pipe network system, which can adapt to uneven foundation settlement, lateral soil displacement and seismic loads by compensating for interface swing angle and expansion.

[0023] Furthermore, the interface pipe described in this patent is compatible with high-pressure, medium-pressure, and low-pressure working conditions, and can be used for trenchless crossing, underground laying, and pipe gallery installation projects of water supply and drainage and gas transmission pipelines.

[0024] Furthermore, the bending deformation, expansion and contraction, and displacement deformation of the entire pipeline are accomplished through the distributed hinge deflection and displacement superposition of each interface, rather than the forced bending and stretching deformation of the pipe body itself. This avoids the drawback of traditional trenchless pipelines where the superposition of pipe wall bending stress and internal pressure membrane stress can easily exceed the material yield strength.

[0025] Furthermore, when the sockets are inserted into each other and installed in place, there should be gaps between the protruding side of the socket and the self-locking ring tightly attached to the inside of the socket hook, and between the end face of the socket and the step of the socket.

[0026] Furthermore, by configuring a jacking device at the working well, the pipeline can move forward under the traction force, the jacking force, or the combined force of both. The bending friction resistance is released by the interface swing angle to avoid pipe jamming accidents. The pipe section connection process and the traction shaft collection process are carried out in staggered shifts. The pipeline maintains a dynamic friction travel state throughout the crossing, avoiding the static friction resistance of restarting the pipeline and extending the single crossing length.

[0027] The beneficial effects of this invention are as follows:

[0028] 1. This invention is the first to propose a low-stress mechanism that replaces pipe wall bending with an interface corner. By dispersing pipeline deformation through a 2° controllable deflection of a single interface, it significantly reduces the superimposed stress on the pipe wall under high-pressure conditions. It breaks through the forced constraint of the ultra-large curvature radius of traditional high-pressure welded pipes and solves the industry bottleneck of high-pressure steel pipes being prone to excessive stress when turning.

[0029] 2. The bidirectional self-anchoring structure can simultaneously resist the axial thrust of 13.5MPa ultra-high internal pressure and the drag force of large tonnage directional drilling. The interface locking is reliable and the sealing is stable. There is no need to pour concrete thrust supports, which greatly reduces the project cost and construction period.

[0030] 3. By adopting a fully weld-free and zero-circumferential-weld design, the main failure modes of high-pressure pipelines, such as residual welding stress, micro-cracks, and corrosion damage, are completely eliminated, significantly improving the structural reliability and service life of the high-pressure pipeline network.

[0031] 4. The 6m modular segment-by-segment pipe-dragging process reduces the radius of curvature by more than 77% compared to welded steel pipes, eliminating the site limitations of traditional long pipe prefabrication. It is suitable for narrow urban areas, short construction periods, and complex obstacle crossings, greatly expanding the application scenarios of trenchless construction of high-pressure steel pipes.

[0032] 5. The flexible multi-hinged structure has deformation redundancy, can adapt to foundation settlement and seismic displacement, has no stress concentration, and its seismic and settlement resistance performance is far superior to that of rigid welded pipe networks, making it suitable for soft soil, fill geology and earthquake zone engineering.

[0033] 6. Eliminating processes such as welding, flaw detection, anti-corrosion repair, and pier pouring significantly improves construction efficiency, reduces leakage and failure rates throughout the entire life cycle, and results in outstanding overall economic benefits.

[0034] 7. By adopting a construction method that combines dragging and jacking and staggers the connection of pipe sections with the collection of traction shafts, the static friction resistance of repeated pipeline starts is avoided, the limit of the pipeline length is broken, the construction period is shortened, and the project cost is significantly reduced. Attached Figure Description

[0035] Figure 1 A schematic diagram of the trajectory of the small-curvature fully self-anchored flexible interface pipe passing through the pilot hole in the horizontal directional drilling method of this invention.

[0036] L0 is the length of the pipe segment that makes up the crossing pipeline; R is the radius of curvature of the crossing pipeline; a is the horizontal length of a single arc segment; b is the height of a single arc segment; h is the settlement of the crossing pipeline; α is the settlement tilt angle of the pipe segment; P1 is the jacking force acting on the tail of the crossing pipe segment; P2 is the traction force acting on the front of the crossing pipe segment.

[0037] Figure 2 Schematic diagram of the high-pressure, low-curvature, fully self-anchored flexible interface structure of the present invention.

[0038] 1. Socket; 2. Spigot; 3. Self-locking retaining ring; 4. Sealing ring; 5. Clearance; 6. Inner circle of socket sealing; 7. Outer circle of spigot mating; 8. Spigot end face; 9. Socket step; 10. Hook; 11. Spigot sealing groove; 12. Protruding side of spigot; 13. Recessed bottom of sealing groove

[0039] Figure 3 Schematic diagram of the low-pressure, small-curvature, fully self-anchored flexible interface structure of the present invention.

[0040] 1. Socket; 2. Spigot; 3. Self-locking retaining ring; 4. Sealing ring; 5. Clearance; 6. Inner circle of socket sealing; 7. Outer circle of spigot mating; 8. Spigot end face; 9. Socket step; 10. Hook; 11. Spigot sealing groove; 12. Protruding side of spigot Detailed Implementation

[0041] Example 1: Crossing Conditions Using Large-Diameter X70 High-Pressure Directional Drilling

[0042] This embodiment uses D640 steel pipe with a wall thickness of 24mm and X70 material. The length of a single pipe section is 6m. The pipe sections are equipped with fully self-anchoring flexible mechanical interfaces, and the maximum controllable swing angle of a single interface is 2°.

[0043] Under continuous internal pressure of 13.5MPa, the bidirectional self-locking clasp of the interface provides bidirectional limiting and locking, stably offsetting the high-pressure axial thrust, eliminating the need for thrust bearings; during directional drilling and pullback, the dragging force is borne by the self-anchoring structure as a whole, without damaging the pipe wall and anti-corrosion layer.

[0044] The pipeline crossing curve trajectory is formed by the superposition of multiple sets of interface micro-angles of 2° to create a smooth arc. When the pipe section length L0 is 6m, the interface swing angle Θ is ±2°, the pipe section sinking inclination angle α is 14°, and the radius of curvature R of the arc is 171.9m. The settlement H of the pipe section is 10.2m. Pipeline deformation is concentrated at the mechanical interface, and there is almost no forced bending strain in the pipe wall. This effectively avoids the problems of excessive stress and pipe yielding in traditional welded pipe laying with small curvature. The combined stress of the pipe wall is always controlled within the allowable range of the specification, meeting the requirements of high pressure, long distance, small curvature, low resistance and low stress crossing.

[0045] Example 2: High-pressure pipeline laying in complex geological subsidence areas

[0046] This embodiment is applied to areas with uneven settlement of soft soil, and the pipeline network is composed of multiple 6m pipe sections flexibly hinged together. When the foundation experiences slight settlement and lateral displacement of the soil, each interface absorbs structural displacement through an adaptive swing angle of 0-2°, dispersing pipeline deformation and preventing local stress concentration. At the same time, the gaps between the protruding side of the spigot and the self-locking ring, and between the spigot end face and the socket step, allow for a 25mm expansion and contraction displacement at the interface to compensate for the thermal expansion and contraction of the pipeline and the change in the settlement length of the pipe section. This avoids the weld cracking, pipe bursting, and leakage problems of traditional rigid welded pipes, significantly improving the operational safety of pipeline networks in complex geological conditions.

[0047] Example 3: Trenchless Pipeline Engineering for Ultra-Long Pipelines

[0048] This embodiment employs adding a jacking device to one side of the working shaft (see...). Figure 1This allows the pipe section to move forward under the combined action of pushing P1, pulling P2, or both. When the pipe section is subjected to the forward force, it can release the frictional bending moment it bears when moving forward at an angle, avoiding pipe jamming accidents and allowing the pipe section to pass through flexibly. By staggering the pipe connection and traction shaft retraction operations, the pipe section can maintain dynamic friction during the entire forward movement, avoiding the resistance of restarting the pipeline, improving construction efficiency, and breaking through the limit of the length of the pipeline to be crossed.

Claims

1. A small-curvature, fully self-anchoring flexible joint pipe suitable for horizontal directional drilling construction, characterized in that: The system comprises several pipe sections with end-to-end socket assembly and matching lengths, with hinged interfaces between adjacent sections. These hinged interfaces feature radial limiting and axial limiting expansion compensation structures. A single hinged interface can achieve ±2° radial sway angle and 25mm axial displacement compensation. Multiple sets of hinged interfaces with continuously superimposed micro-angles form a smooth laying arc, resulting in a chain-like stress structure for the pipeline. Distributed interface deformation offsets additional internal forces from the terrain, preventing stress concentration and leakage in the pipe wall. Using pipe sections of matching lengths allows for the efficient laying of high-pressure pipes of different diameters through the pilot guide with low curvature, low resistance, and low stress during horizontal directional drilling.

2. The small-curvature fully self-anchoring flexible joint pipe suitable for horizontal directional drilling construction according to claim 1, characterized in that: The articulated interface has a staged energy release structure that is first flexible and then rigid. When the interface is subjected to bending moment, it first releases energy through angular displacement. After reaching the angular limit, the remaining bending moment is transferred to the next interface for gradual release. When the interface is subjected to axial force, it first releases energy through axial expansion and contraction displacement. After reaching the displacement limit, the axial force is carried over to the subsequent pipe sections for distribution, thereby reducing the axial stress on the pipe wall.

3. The small-curvature fully self-anchoring flexible joint pipe suitable for horizontal directional drilling construction according to claim 1, characterized in that: The hinged interface includes a socket, a insertion port, a self-locking clasp, and a sealing ring; a hook is provided inside the socket, and an insertion protrusion is provided on the outside of the insertion port. The self-locking clasp is engaged between the hook and the insertion protrusion to form a bidirectional axial limiting and locking structure. The self-locking clasp remains in contact and does not disengage throughout the entire swing angle process.

4. A small-curvature, fully self-anchoring flexible joint pipe suitable for horizontal directional drilling construction according to claim 3, characterized in that: The protruding side of the socket is a bevel or an arc surface. The self-locking ring is squeezed to generate a radial force that tightly adheres to the inner side of the hook to prevent it from coming off. The inner diameter of the socket seal is larger than the outer diameter of the socket, and the gap between the two forms a ±2° swing angle allowance.

5. A small-curvature, fully self-anchoring flexible joint pipe suitable for horizontal directional drilling construction according to claim 3, characterized in that: A sealing groove is provided at the socket, and clearance is reserved on both sides of the sealing groove; multiple annular pits are set at the bottom of the sealing groove, so that the friction between the inner circle of the sealing ring and the socket is greater than the friction between the outer circle of the sealing ring and the socket. Under the conditions of swing angle, expansion and contraction, and earthquake, the sealing ring moves synchronously with the socket.

6. A small-curvature, fully self-anchoring flexible joint pipe suitable for horizontal directional drilling construction according to claim 3, characterized in that: The end face of the socket and the step of the socket, as well as the protrusion of the socket and the self-locking retaining ring, are all reserved with a gap to provide 25mm of axial expansion and contraction compensation.

7. A small-curvature, fully self-anchoring flexible joint pipe suitable for horizontal directional drilling construction according to claim 1, characterized in that: The self-locking clasp is a high-strength alloy component that can withstand continuous internal pressure of 13.5MPa and instantaneous water hammer load. It relies on the chain pipeline to balance the high-pressure axial thrust and does not require a matching concrete thrust support.

8. A small-curvature, fully self-anchoring flexible joint pipe suitable for horizontal directional drilling construction according to claim 1, characterized in that: The pipe sections are assembled only through a mechanical self-locking structure, without circumferential welding seams, eliminating residual welding stress and weld leakage defects, and eliminating the need for on-site non-destructive testing and anti-corrosion repair processes.

9. A small-curvature, fully self-anchoring flexible joint pipe suitable for horizontal directional drilling construction according to claim 1, characterized in that: The single-section, adaptable-length pipe segment and modular short sections can be connected section by section and dragged along while being connected, without the need for a large prefabrication site, making it suitable for narrow construction spaces in urban areas.

10. A small-curvature, fully self-anchoring flexible joint pipe suitable for horizontal directional drilling construction according to claim 1, characterized in that: Multi-section articulation forms a deformable pipe network system, which can adapt to uneven foundation settlement, lateral soil displacement and seismic loads by compensating for interface swing angle and expansion.

11. A small-curvature, fully self-anchoring flexible joint pipe suitable for horizontal directional drilling construction according to claim 1, characterized in that: The interface pipe is suitable for high-pressure, medium-pressure, and low-pressure working conditions and can be used for trenchless crossing, underground laying, and pipe gallery installation of water supply and drainage and gas transmission pipelines.

12. A small-curvature, fully self-anchoring flexible joint pipe suitable for horizontal directional drilling construction according to claim 1, characterized in that: The bending deformation, expansion and contraction, and displacement of the entire pipeline are accomplished through the distributed hinge deflection and displacement superposition of each interface, rather than the forced bending and deformation of the pipe body itself. This avoids the drawback of traditional trenchless pipelines where the bending stress of the pipe wall and the internal pressure membrane stress are superimposed, which can easily exceed the material yield strength.

13. A horizontal directional drilling construction method for a small curvature fully self-anchoring flexible joint pipe as described in any one of claims 1 to 12, characterized in that: By configuring a jacking device at the working well, the pipeline can move forward under the traction force, the jacking force, or the combined force of both. The bending friction resistance is released by the swing angle of the interface, thus avoiding pipe jamming accidents. The pipe section connection process and the traction shaft collection process are carried out in staggered shifts. The pipeline maintains a dynamic friction travel state throughout the crossing, avoiding the static friction resistance of restarting the pipeline and extending the single crossing length.

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