Complex mountain sending-out line crossing method

Abstract

The invention discloses a crossing method for a sending-out line in a complex mountain land, and belongs to the technical field of cable laying. According to the method, anchoring points are arranged on the two sides of a gully, two steel cables are synchronously pulled to cross the gully through a tension pay-off method, and cables are fixed to the steel cables in a segmented mode through special cable suspension composite wire clamps. The wire clamp is composed of a supporting plate, a flat steel hoop with a plastic sleeve and a steel wire rope clamping head, and flexible connection of a cable and a steel cable is achieved through bolt combination. During construction, a stable bearing system is formed by pre-tensioning the steel cables, and cable installation is completed synchronously. Compared with a traditional iron tower scheme, the tower construction cost is saved by 30%-40%, and the foundation construction problem is avoided; compared with a direct crossing scheme, the mechanical stress is effectively dispersed through distributed fixation, and the plastic protective layer can reduce the insulating wear risk. The method is especially suitable for 100m-level gully terrains, has the advantages of high construction safety, good dynamic load adaptability, low operation and maintenance cost and the like, and fills the technical blank of cable crossing in medium-span complex terrains.

Description

Technical Field

[0001] The invention relates to a method for crossing a transmission line in a complex mountainous area, and belongs to the technical field of cable laying. Background Art

[0002] In high-voltage cable transmission projects, terrain adaptability is a key factor affecting the selection and economic efficiency of technical solutions. At present, conventional technical solutions have significant limitations for different terrain features such as canyons and ditches: Canyon crossing scheme: usually use transmission towers to connect cables, and use multiple towers to support them in sections to disperse the load. However, the cost of tower construction is high, especially in complex terrain. The foundation engineering needs to deal with challenges such as geotechnical stability and transportation conditions, resulting in the tower cost accounting for 30%-40% of the construction engineering cost. For example, in the cost per kilometer of 500kV line in mountainous terrain, the tower project accounts for more than 40%, and if the tower solution is adopted for the gully terrain width (about 100m), multiple tower positions need to be set up, and the cost of foundation construction and material transportation will increase significantly.

[0003] Small ditch direct crossing solution: Unsupported crossing is achieved by increasing the cable sag or shortening the span. Although this reduces the initial investment, the sag in the middle of the cable due to its own weight can easily cause mechanical stress concentration, and long-term operation may lead to insulation wear or strand breakage. Studies have shown that when overhead cables are unsupported, extreme weather (such as ice and strong winds) will further aggravate the sag problem and increase operation and maintenance costs.

[0004] Technical gap in intermediate terrain: Gully terrain has the characteristics of large width (100m level) and moderate depth. Existing solutions are difficult to balance economy and reliability. If the iron tower solution is used, the foundation engineering needs to deal with the loose soil problem of the gully slope, and pile foundation or reinforcement measures need to be adopted, resulting in a surge in costs (such as the rock geology adjustment coefficient of 3.85 times); while direct crossing faces the problem of cable sag control. Although the traditional method of increasing the cross-section can improve the mechanical strength, it will sacrifice the current carrying capacity and increase the material cost.

[0005] Therefore, there is an urgent need for a high-voltage cable gully crossing technology that takes into account economy, structural stability and construction feasibility to fill the gap in existing technology. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for crossing a complex mountain transmission line to overcome the deficiencies of the prior art.

[0007] The technical solution of the present invention is: a method for crossing a complex mountain transmission line, the method comprising the following steps: S01, set up two sets of anchor points on both sides of the gully; S02. Use the tension stringing method to synchronously tow 2 steel cables from the anchor points on the same side of the gully to the corresponding anchor points on the other side of the gully; S03. After the steel cables reach the anchor points on the other side, use cable suspension composite clamps to fix the cable ends on the 2 steel cables; S4. Continue to pull the steel cables until the cable is completely straightened. During the process of pulling the steel cables, use cable suspension composite clamps to fix the cable on the 2 steel cables at set intervals; S05. Pre-tension the steel cables to keep them in a tensioned state; S06. Fix and connect the two ends of the tensioned steel cables to the anchor points on both sides of the gully.

[0008] Further, the cable suspension composite clamp includes: A support plate, which is a flat steel. The length of the support plate is greater than the distance between the 2 steel cables; A flat steel hoop, which includes 2 cantilevers and a U-shaped part. The 2 cantilevers are symmetrically connected to the 2 ends of the U-shaped part on the left and right respectively. The cantilevers are fixedly connected to the lower surface of the support plate by the first bolts. The inner diameter of the flat steel hoop matches the outer diameter of the cable; Steel wire rope clamps, including 2. The 2 steel wire rope clamps are symmetrically fixed and connected to the lower surfaces of the 2 cantilevers of the flat steel hoop by the second bolts respectively. The diameter of the clamping hole of the steel wire rope clamp matches the diameter of the steel cable.

[0009] Further, the cable suspension composite clamp also includes: A plastic sleeve, which is arranged on the inner side surface of the flat steel hoop surrounded by the flat steel hoop and the support plate.

[0010] The beneficial effects of the present invention are: Compared with the prior art, 1) The present invention anchors the steel cables and fixes the cable with suspension line clamps, which not only avoids the high cost brought by the construction of traditional iron towers, but also avoids the increase in operating costs caused by the cable suspension when directly using the cable to cross; 2) In the present invention, the tensioned state of the steel cables can resist dynamic loads and avoid damage to the cable under dynamic loads; 3) The present invention uses the tension stringing method to lay the steel cables. Then, when the steel cables reach the anchor points on the other side, the connection of the steel cables is stabilized at this time. Then, during the process of pulling the steel cables, the cable is fixed on the steel cables by cable suspension composite clamps, and the cable is installed during the process of pulling the steel cables, without the need for high-altitude operation to fix the cable, which is safer; 4) The support plate, flat steel hoop and steel wire rope clamps that make up the cable suspension composite clamp of the present invention are all standard parts that are easy to process or readily available, which is easy to control costs.

[0011] 5) The present invention protects the cable insulation layer from frictional damage through the plastic sleeve. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic structural diagram of the cable composite suspension clamp of the present invention. DETAILED DESCRIPTION

[0013] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0014] Implementation Example 1: This embodiment provides a method for crossing a complex mountain transmission line, and the specific implementation steps are as follows: Step S01: Anchor point setting Two groups of anchor points are set up in the stable slope areas on both sides of the gully. Each group of anchor points adopts a deep-buried ground anchor structure with a depth of no less than 3m and is reinforced by pouring concrete. The spacing between anchor points is determined based on the gully width and cable load calculation to ensure that the steel cables are evenly stressed.

[0015] Step S02: Cable traction The tension wire method is used to synchronously pull two high-strength galvanized steel cables 6 with a diameter of 18mm and a breaking force (≥150kN). The traction equipment uses a double traction machine system, which is arranged behind the anchor points on the same side of the gully. The synchronous control system ensures that the traction speed of the steel cable 6 is consistent to avoid deviation or entanglement of the steel cable 6. The tension of the steel cable 6 is monitored in real time during the traction process and controlled within the range of 20%-30% of the rated value.

[0016] Step S03: Cable end fixing After the steel cable 6 is pulled to the opposite anchor point, a cable suspension composite clamp (structure as shown in the figure) is used. Figure 1 The specific operation includes: 1. Install the support plate 1 horizontally between the two steel cables 6. The support plate is made of Q235B flat steel (specification 50mm×5mm), and its length is 200mm longer than the spacing between the steel cables 6; 2. The cable 2-1 is clamped by the flat steel clamp 4, and the optical cable 2-2 can also be clamped at the same time. The inner wall of the flat steel clamp 4 is provided with a 5mm thick EPDM plastic sleeve 3 to prevent the insulation layer of the cable 2-1 from being worn; 3. Use wire rope clamps 8 to connect the support plate to the steel cable 6, and each clamp is fastened with two sets of stainless steel second bolts 8.

[0017] Step S04: Cable Continuous Fixing During the pulling back of the steel cable 6, a set of cable suspension composite wire clamps is installed every 20m. The tension of the steel cable 6 is dynamically adjusted by the tension machine to ensure that the cable sag meets the design requirements (such as the maximum sag ≤ 8m). The wire clamp installation adopts the ground pre-assembly + mechanical lifting method to avoid the risk of high-altitude operations.

[0018] Step S05: Cable pre-tensioning After the cable is fixed, the steel cable 6 is pre-tensioned in stages: 1. In the first stage, load to the design tension (such as 40% of the breaking tension of cable 6), and hold the load for 10 minutes to eliminate creep; 2. The second stage is loading to the final tension (50% of the breaking force), and precise control is achieved through the hydraulic tensioner; 3. Use strain gauges to monitor the stress distribution of the steel cable 6 to ensure that the unevenness is ≤5%.

[0019] Step S06: Anchor point locking The end of the tensioned steel cable 6 is connected to the anchor point through a shackle, fixed with a double nut anti-loosening bolt, and injected with anti-corrosion grease. Finally, vegetation restoration is carried out around the anchor point to reduce the impact of soil erosion.

[0020] Cable suspension composite clamp structure description Figure 1 As shown, the cable clamp contains the following core components: 1. Support plate 1: flat steel structure, the length is customized according to the spacing of the steel cables 6, and the surface is hot-dip galvanized; 2. Flat steel clamp 4: The inner diameter of the U-shaped part matches the outer diameter of the cable (e.g. Φ120mm), the cantilever length is 150mm, and it is connected to the support plate through the M12 first bolt 7; 3. Wire rope clamp 8: GB / T5976 standard, clamp hole diameter 18mm, interference fit with wire rope 6; 4. Plastic sleeve 3: EPDM material, Shore hardness 70±5, vulcanized and bonded to the inner wall of the clamp after compression molding.

[0021] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for crossing a complex mountainous transmission line, characterized in that: The method comprises the following steps: S01, set up two sets of anchor points on both sides of the gully; S02, using the tension wire method to simultaneously pull two steel cables (6) from the anchor points on the same side of the gully to the corresponding anchor points on the other side of the gully; S03, when the steel cable (6) reaches the anchor point on the other side, use a cable suspension composite wire clamp to fix the cable end on the two steel cables (6); S4, continue to pull the steel cable (6) until the cable is completely straightened, and use the cable suspension composite wire clamp to fix the cable on the two steel cables (6) at set intervals during the pulling process; S05, pre-tensioning the steel cable (6) to put the steel cable (6) in a tensioned state; S06. The two ends of the tensioned steel cable (6) are fixedly connected to the anchor points on both sides of the gully.

2. The complex mountain transmission line crossing method according to claim 1 is characterized in that: The cable suspension composite clamp comprises: A support plate (1), wherein the support plate (1) is a flat steel, and the length of the support plate (1) is greater than the distance between the two steel cables (6); A flat steel hoop (4), the flat steel hoop (4) comprising two cantilevers and a U-shaped portion, the two cantilevers being symmetrically connected to the two ends of the U-shaped portion, the cantilevers being fixedly connected to the lower surface of the support plate by means of first bolts (7), and the inner diameter of the flat steel hoop (4) matching the outer diameter of the cable; A wire rope clamp (8), the wire rope clamp (8) comprising two wire rope clamps (8), the two wire rope clamps (8) being respectively and symmetrically fixedly connected to the lower surfaces of two cantilevers of the flat steel clamp (4) via second bolts (5), and the clamping hole diameter of the wire rope clamp (8) matches the diameter of the steel cable (6).

3. The complex mountain transmission line crossing method according to claim 2 is characterized in that: The cable suspension composite clamp also includes: The plastic sleeve (3) is arranged on the inner side surface of the flat steel clamp (4) surrounded by the flat steel clamp (4) and the support plate.

Images