A construction method for expanding and reconstructing a catenary system of a busy heavy-load railway

Abstract

The application provides a construction method for expanding and reconstructing a catenary of a busy heavy-load railway, and belongs to the technical field of railway expansion and reconstruction, and comprises a replacement method for a tunnel inner cantilever, a replacement method for a tunnel section conductor, a replacement method for a phase conductor, and a synchronous replacement method for a station soft cross and a conductor; and solves the key and difficult problems in the construction of the catenary of the busy heavy-load railway.

Description

Technical Field

[0001] This invention belongs to the technical field of railway expansion and renovation, and specifically discloses a construction method for the overhead contact system of a busy heavy-haul railway expansion and renovation project. Background Technology

[0002] The overhead contact system is the main framework of railway electrification engineering. It is a special type of power transmission line that is erected above the railway line to supply power to electric locomotives. It mainly includes contact suspension, support devices, positioning devices, pillars, and foundations. With economic development, the demand for railway freight volume is gradually increasing, especially the freight volume of busy heavy-haul railways, which urgently needs to be increased. Therefore, it is necessary to expand and upgrade busy heavy-haul railways.

[0003] The expansion and renovation project requires the use of maintenance windows to completely replace the worn contact wires, which presents the following technical challenges.

[0004] 1. Replacement of the cantilever arm inside the tunnel Busy heavy-haul railways face limited construction windows and high safety pressures. Normal train operation must be maintained before construction begins, and the railway must be able to handle 10,000-ton trains after completion. Simultaneously, dynamic monitoring of the overhead contact system must not exceed level three limits, presenting high technical requirements. Limited clearance within tunnels prevents the cantilever arms from being installed as a whole, and workers cannot stand on the suspension columns as is customary for cantilever arm installation, posing significant safety challenges during construction.

[0005] 2. Replacement of conductor rail in tunnel section The construction environment in the plains is favorable, and the replacement of the conductor can be carried out using the traditional "same-up, same-down" method, which involves erecting a new conductor and adjusting and removing the existing conductor within a single maintenance window, ensuring traffic flow. However, the existing equipment in the tunnel is old, and the tunnel walls are thin. When the existing equipment simultaneously supports four conductors, there is a possibility that the lifting columns may tilt or fall. Therefore, the "same-up, same-down" method cannot safely complete the replacement of the conductor in the same anchor section within the same maintenance window. At the tunnel entrance, the external support pillars are located on both sides of the track, while the internal suspension pillars are located in the center. When installing new catenary cables, they intersect with existing conductors, causing wear and tear. Traditionally, installing new catenary cables requires sequentially removing the existing catenary cables from their supports at each positioning point within the tunnel, dismantling the existing positioning clamps, flipping the new catenary cables to the other side, and then installing suspension for fixation. This construction process is extremely cumbersome, resulting in a waste of manpower and resources, and increasing the pressure on track maintenance windows.

[0006] 3. Replacement of conductors in separate locations When replacing the conductor involves phase replacement, the weight of the conductor and phase insulator increases while maintaining the same tension. Furthermore, the existing structural height at the positioning point is insufficient, making it easy for the shortest dropper string to fail to meet technical requirements at the phase insulator installation location. Because phase insulators are inherently difficult to install and adjust, if insufficient structural height is discovered during replacement, the process of replacing the dropper string and adjusting the phase insulator takes a considerable amount of time. Moreover, the adjusted phase conductor spacing reaches the limit for phase installation, severely impacting the safe operation of the phase. Simultaneously, the limited construction time during maintenance windows makes this situation prone to delays and damage, affecting the normal operation of the line.

[0007] 4. The station's flexible cross span and conductor were replaced simultaneously. When the existing conductor wear exceeds the standard and the capacity of the existing flexible cross span supports cannot meet the load-bearing requirements of the new line, there are significant safety and quality hazards. The traditional method of replacing the flexible cross span and conductor involves lowering the newly erected conductor onto the existing flexible cross span for suspension and fixation, adjusting the parameters of each track to ensure smooth operation, and then lowering it onto the new flexible cross span after its pre-installation for secondary adjustments. This construction process occupies all tracks of the station, requires a large amount of manpower, adds a secondary adjustment procedure, places significant safety pressure on the line, and has a substantial impact on existing equipment. Summary of the Invention

[0008] This invention provides a construction method for expanding and upgrading the overhead contact system of a busy heavy-haul railway, in order to overcome the technical difficulties described in the background art.

[0009] The above-mentioned construction methods for the expansion and renovation of the overhead contact system of busy heavy-haul railways include methods for replacing cantilever arms in tunnels, methods for replacing conductors in tunnel sections, methods for replacing conductors in separate sections, and methods for the synchronous replacement of soft cross spans and conductors in stations. The method for replacing the cantilever arm inside the tunnel includes the following steps: T1, Preliminary Measurement, Calculation and Pre-mixing Before the construction window, measure the tunnel clearance, hanging column clearance, protective line height, and conductor height parameters, and optimize the cantilever installation height using CAD simulation to prevent the inclined cantilever insulator from scraping the bow. Measure the existing guide height, pull-out value, catenary height, curve outer rail superelevation, and base installation height inside the tunnel, and calculate the pre-configuration data of the cantilever arm. The existing guide height is taken into account in the calculation to ensure that the guide height of the contact network remains the same and the pull-out value meets the design requirements after the cantilever arm is replaced. Measure existing data, fill in the position data of each component in the overhead contact line cantilever arm pre-configuration data table and the overhead contact line positioning pre-configuration data table, and mark the corresponding positions in the tunnel; The wrist arms are pre-assembled in a centralized manner and shipped out as complete sets. T2, Remove the existing cantilever arm and base. (1) Before removing the old cantilever arm, measure the distance from the top of the ladder truck or work vehicle platform to the existing flat cantilever arm and record it as S1, and measure the distance from the top of the ladder truck or work vehicle platform to the contact line and record it as S2; (2) The operator stands on the ladder truck or work vehicle platform to loosen the bolts of the load-bearing cable seat cover plate and the positioning clamp bolts, and removes the load-bearing cable; (3) On the outer section of the curve, fix the catenary to the hanging column; (4) Remove the wrist arm and wrist arm base; T3, Install new base (1) The upper cantilever arm base is installed at a distance S1 from the top of the ladder truck or work vehicle platform to ensure that the height of the catenary cable is maintained. (2) Install the lower carpal base according to the designed spacing between the upper carpal base and the lower carpal base; T4, with separate installation of flat and angled wrist arms. (1) The flat cantilever arm is connected to the insulator and installed together on the upper cantilever arm base; (2) The inclined bracket arm is connected to the insulator and installed together on the lower bracket arm base; (3) Connect the horizontal wrist arm and the oblique wrist arm, and use a spirit level to check the horizontal state of the horizontal wrist arm; T5, restore the load-bearing cable; T6, Installation and positioning; T7, suspension adjustment; T8, check torque The cantilever arm uses a cone-clamping anti-loosening bolt. After the suspension adjustment is completed, use a torque wrench to tighten the main nut and lock nut of the cone-clamping anti-loosening bolt according to the torque table, and then check the torque of the cone-clamping anti-loosening bolt. The method for replacing the conductor in the tunnel section includes the following steps: T1, Erecting new load-bearing cables and pre-embedding chemical anchors. (1) Install the lower anchor angle steel on the lower anchor arm. The starting end is connected to the existing anchor arm with a hard anchor. The old bearing wire remains unchanged. The two ends of the new bearing cable are connected with two silicone rubber insulators. The hard anchor steel wire sleeve or steel wire rope with connectors is connected to the insulator on the lower anchor angle steel. (2) Install pulleys at the tunnel entrance and erect load-bearing cables The operation is carried out by using one work vehicle with a line-laying mechanism to stay at the anchoring position, and another work vehicle to thread the line end of the line-laying mechanism towards the anchoring direction. Support-type line-laying pulleys are installed at the first hanging column and the first concrete column at the tunnel entrance, and suspension pulleys are installed on the existing catenary at the intersection to ensure that the new catenary does not rub against the existing equipment when it crosses the existing catenary. (3) Pre-lay the suspension wires and install the equipotential bonding wire; (4) Install hooked chemical anchors directly above the tunnel conversion column for contact wire installation; T2, remove the tension of the existing load-bearing cable and anchor the new load-bearing cable; T3, install a new contact line; T4, Remove the existing conductor wire; T5, adjust the suspension; The replacement method for the conductor in a split-type connection includes the following steps: T1, measure the contact wire height, catenary height, span, load and load distance at the positioning points at both ends of the existing phase separation, and use the dropper calculation software to calculate the shortest dropper length when installing on the existing equipment. T2, when the shortest dropper length is lower than the design value, adjustments should be made through the following measures: (1) Adjust the height of the cantilever arm in advance: one day in advance, increase the installation height of the cantilever arm base and increase the structural height at the positioning point to ensure that the shortest suspension string length at the phase insulator is greater than the design value, and install a height reduction structure to ensure that the existing equipment parameters remain unchanged and the line operates normally while the height of the load-bearing cable seat is raised; (2) If the shortest dropper length is still less than the design value after step (1), the foundation pit is excavated in advance at the mid-span position, a new support is erected and the slope, clearance, span, and load of the new support are measured and recorded. The height of the catenary on the new support is calculated when the shortest dropper length is equal to the design value. The height of the catenary at the mid-span is raised by the new support to ensure the standard of the line parameters. The new cantilever is calculated by the slope, clearance, and catenary installation height of the new support. The new cantilever only suspends the catenary and does not install the positioning device. T3, Erecting new support cables (1) When using a rail work vehicle or rail flatbed vehicle to pre-lay new support cables, if the cantilever base is raised, the new support cables are installed in the existing support cable seats; if a new support is erected, the new support cables are installed in the new support cable seats. (2) After the new catenary is pre-installed, install the catenary terminal anchoring clamp and rod-type suspension insulator at the existing phase separation position, install the old positioning tube on the flat cantilever arm, and push out the new catenary so that the horizontal distance between the new catenary and the old catenary is above the design value. T4, Calculate the new dropper and pre-fit it. (1) Calculate the dropper data when the cantilever base is raised by using the height of the new load cable, the existing span, the existing load moment, and the design guide height; (2) Calculate the dropper data when erecting the new support column by using the new span, new load distance, existing load cable height, existing load cable height at the positioning point, and design guide height; (3) Pre-fit the droppers on a professional pre-fitting platform according to the dropper calculation data; T5, install a new contact line; T6, Installation and Adjustment of Component-Based Phase Separation (1) After the new catenary and contact wire are anchored, install the new droppers; (2) Based on the installation position of the catenary insulator, determine the installation position of the new phase insulator, and use a hand-operated hoist to tighten the wires and install the phase insulators in sequence by cutting the wires; (3) After the phase-separating insulator is installed, the suspension strings at both ends are finely adjusted according to the phase-separating center height, so that the phase-separating insulator is in a tension state after the whole machine is installed, and the negative dimension of the phase-separating insulator is within the design value; The method for synchronously replacing the station's flexible cross span and conductor includes the following steps: T1, Erect and straighten the steel columns; T2, soft cross-mount; T3, install the equipotential line between the new soft crossbar and the old soft crossbar; T4, erecting the support cables for each track. Both the starting and ending anchor ends adopt the hard anchor method. The old bearing wire remains unchanged. In order to prevent the insulation distance between the new bearing wire and the old bearing wire from being insufficient due to temperature changes, two silicone rubber insulators are used to connect the two ends of the new bearing wire. The hard anchor steel wire rope with connectors is connected to the insulators on the lower anchor angle steel. When the new catenary is being erected, the railcar unit stops at the lower anchor support and disassembles. One work vehicle with the wire-laying mechanism stays, while another work vehicle with the wire-laying mechanism pulls, threades, and lays the wire. The new catenary is laid out over the soft cross span and passes over the upper fixed rope of the existing soft cross span. The work vehicle moves forward at a constant speed. When the new catenary cable is installed to the anchorage, the new catenary cable is tightened and anchored. After anchoring, the new load-bearing cable is fixed to the cantilever arm. The new load-bearing cable located at the soft cross span is fixed to the suspension pulley installed on the new soft cross span. The new load-bearing cable and the old load-bearing cable in the middle of the span are tied into a loop with iron wire. The equipotential line is installed. Then, the drop wire is installed according to the calculated drop wire position and the coil is tied and fixed to the new load-bearing cable. T5, erecting contact lines for each track. The contact wire will be installed at the next maintenance window after the catenary cable is installed. When anchoring, unload several weights of the existing bearing cable compensation, and anchor the new contact line with the new compensation. The new contact line is suspended at the new soft cross span. At the same time, the two ends of the new bearing cable are changed to compensation anchors. When the new contact line is erected to the anchoring point, the pulley block is used to tighten the line and anchor it. The new contact line is anchored using the newly installed compensation. After the anchoring is completed, the middle anchor is installed. T6, Remove the existing conductor wire. During the installation of the contact wire, the existing locators are removed, and the existing catenary is pulled out of the catenary seat. At curves, the existing contact wire can be temporarily tied to the locating pipe with iron wire. After the existing catenary is pulled out, it should be on the same side as much as possible. After the new contact wire is anchored, the old catenary is unloaded at the same time under unified command. The middle anchor group starts to cut the wire from the middle anchor. First, cut the existing contact wire, and then cut the existing catenary. When cutting the wire, use a large rope to tighten both ends of the existing catenary. T7, suspension adjustment First, install the new contact wire center anchor. The ladder truck group works alternately from the center anchor to the two lower anchor sides to perform line surface correction, installation positioning, and initial installation of droppers. The dropper calculation is based on the design value. After installation, the overall guide height is slightly higher, but it does not affect the driving on the slope. Then, the suspension adjustment and electrical connection are installed. T8, fine-tuning of the soft cross-span and removal of the existing soft cross-span After all the track conductors were replaced, the parameters of the flexible cross spans and contact wires were fine-tuned to meet the design requirements. After the adjustment, the existing flexible cross spans and supports were removed, and the steel column foundation caps of the new flexible cross spans were installed.

[0010] In the method of replacing the cantilever arm in the tunnel, step T1 uses a contact wire measuring instrument to measure the existing guide height, pull-out value, catenary height, curve outer rail superelevation, and base installation height in the tunnel.

[0011] In the method for replacing the cantilever arm inside the tunnel, step T5 includes: (1) Pour the catenary cable into the new catenary cable seat, and install the cantilever arm offset position according to the offset calculated based on the on-site temperature and the distance of the cantilever arm from the center anchor position; (2) Measure the distance from the catenary to the feeder. If the distance from the catenary to the feeder is less than the design value, replace the spike insulator with an ear-type suspension insulator or add a crossarm. Step T6 includes: (1) Temporarily fix the positioning tube to the inclined cantilever arm, and adjust the positioning tube to be fixed at H1+S2 above the top of the ladder truck or work vehicle platform. H1 is the positioning slope to ensure that the contact line height is maintained. (2) Temporarily install positioning supports and use a spirit level to adjust the positioning tube to a horizontal position. After adjustment, fix the positioning supports in place. (3) Install the locator and fix it after adjusting the locating point to match the bearing wire; (4) Measure the distance from the anti-positioning tube to the tunnel wall. If the distance from the anti-positioning tube to the tunnel wall is less than the design value, cut the exposed part of the anti-positioning tube. If cutting is difficult, adjust by reducing the anti-positioning pull-out value. Step T7 includes: (1) Conductor slope: There is a difference in conductor height inside and outside the tunnel. The conductor height inside and outside the tunnel transitions smoothly. The difference in contact wire height in one span is not greater than the design value. If the difference in conductor height in one span exceeds the design value, it shall be adjusted to the range of the design value. (2) Positioning slope: Adjusted according to the design values ​​for positive and negative positioning; (3) The guide height remains as it is, and the pull-out value meets the design requirements; (4) Check whether the existing equipment is misaligned or properly secured, and take appropriate action; (5) Measure the distance from the center of the line to the mid-span of the protection line and the height difference between the mid-span of the protection line and the adjacent contact line, and deal with any non-compliance with the standards; (6) Measure the distance between the lower anchor arm and the catenary, and measure the distance between the lower anchor line and the catenary. If the distance is less than the design value, adjust the catenary pull-out value. (7) When crossarm insulators are installed at both adjacent positioning points, it is necessary to check whether the suspension bottle of the feeder in the middle of the span is under stress. If it is not under stress, the bottom bar insulator of the suspension bottle in the middle of the span should be replaced with an ear-type suspension insulator to ensure that the suspension bottle of the positive feeder in the middle of the span is under stress.

[0012] In the method of replacing the conductor in the tunnel section, in step T1 (2), when encountering existing reverse positioning or existing reverse soft positioning during the laying process, if the new conductor cable rubs against the existing inclined guy line or existing V-shaped guy line, the old locator is installed in the flat cantilever tube, the laying pulley is pushed out and fixed, and the distance between the new conductor cable and the existing inclined guy line or existing V-shaped guy line is increased. It also includes (5) adjustment and re-inspection.

[0013] In the method for replacing the conductor in the tunnel section, step T2 includes: The anchoring team used a lever hoist to lift the weight to the design value at the steering pulley, and fixed the existing bearing cable. They then used a tensioner and a lever hoist to slowly release the tension of the existing bearing cable, and the new bearing cable was anchored using the existing compensation. Step T3 includes: When anchoring, temporary hard anchors are used when the tension of the existing contact wire is partially relieved during the anchoring and lowering. The new contact wire is connected to the new compensating anchor. After the anchoring is completed, the anchoring and lowering team changes the two ends of the new catenary to the compensating lower anchor. The newly erected contact wire uses the newly installed compensating lower anchor. When anchoring in the tunnel, iron wire and pulley are added to the hooked chemical anchor bolts installed at the previous tunnel window to temporarily suspend the new contact wire. Step T4 includes: After the existing catenary tension is unloaded, confirm that the existing catenary at each positioning point has been pulled out of the catenary seat. Use pulley blocks and main ropes to fix both ends of the break point at the middle anchor. After the line is broken, slowly release it and then break the line from the middle anchor to the lower anchor side to avoid the cantilever base in the tunnel from tilting. After the line is broken, remove the existing catenary, contact wire and locator, and place the catenary, contact wire and locator on the side of the adjacent line and between the two lines. Step T5 includes: After the line is broken, the ladder truck assembly performs line and surface correction, positioning and installation, dropper arrangement and electrical connection installation from the center anchor to both sides; installation and adjustment are carried out according to design standards. Due to the insulation distance issues between the tunnel wall, positive feeder, protective line and other existing equipment, the parameters are kept as existing as possible. For positioning points with large parameter changes, the distance between them and each existing equipment should be measured.

[0014] In the method for replacing the conductor in a split-phase connection, step T6 also includes: (4) After installation, use a file to grind the bottom of the junction between the connecting plate and the contact wire to ensure that the pantograph passes smoothly at this point; (5) After the phase insulator is installed, use a level to slide along the bottom of the phase insulator from one end to the other to ensure that the level can contact the two guide rails at the same time. Carefully check whether there is any bowing or scraping at the bottom of the phase insulator.

[0015] In the method for synchronously replacing the station's flexible cross span and conductor, step T1 includes: (1) Perform electrical testing and grounding. After grounding is completed, the crane is stopped at the preset position. Pads are installed under the support legs to ensure that the support legs are stable and secure. (2) Put the wire sleeve on the upper part of the support column, lift the support column with a crane, move it directly above the foundation and slowly lower it. The distance between the support column and the foundation reaches the design value. The operator holds the support column, and according to the orientation of the support column, aligns the support column hole with the anchor bolt and installs the nut to ensure that the support column is upright. After confirmation, lower the hook so that the support column base sits on the foundation. The operator removes the wire sleeve. (3) Pillar adjustment First, measure the slope of the support along and perpendicular to the line. The support must be upright. When adjusting, loosen the nut first, and then pry the support with a crowbar according to the slope. When adjusting the slope of the support, the nut must only be loosened, not removed. (4) Safety distance inspection After the support column is erected, check the safe distance between the support column and each existing piece of equipment. If the safety distance between the auxiliary line and the support column is insufficient, a shoulder scaffold can be used to prop the auxiliary line out. If the safety distance between the support column and other existing equipment is insufficient, appropriate measures should be taken in a timely manner. Step T2 includes: (1) Measurement a. Create a data recording table based on the design floor plan; b. On-site measurement; ① Measurement of the superelevation of the electrified track curve Measure and record using a laser measuring instrument; ② Measure the lateral span of the soft cross span Use a steel tape measure to measure the clearance and spacing values ​​of each line in sequence. The steel column is measured from the outer edge of the support and ends at the outer edge of the support. Then, use a steel tape measure to measure and verify the entire length on the highest rail surface elevation line of the support to ensure the accuracy of the measurement. ③ Measure the longitudinal span; ④ Measure the slope of the support column; (2) Calculation of soft cross span Based on the actual site conditions, modify the relevant parameters in the soft cross span prefabrication calculation software database, input the measured parameters into the soft cross span prefabrication calculation software, calculate the segment length of the soft cross span node and the position of the double cross bearing cable, upper and lower fixed rope positioning rings, and output the soft cross span prefabrication drawing. (3) Precast soft cross span a. Before prefabrication, clean the site, support the steel strand reel with a reel bracket, prefabricate under tension, and mark the position according to the calculated data; b. Starting from the end where the back is finished, two people pull the steel tape measure, one person reads the dimensions of each section in the soft cross-section precast drawing, and the other person marks it with paint; c. Install the horizontal load-bearing cable clamps or positioning ring clamps according to the paint markings and cutting diagrams, and prefabricate the horizontal load-bearing cables or upper fixing ropes; d. Install the upper suspension line inside the U-shaped ring of the horizontal load-bearing cable clamp, prefabricate the upper fixing rope, and install the inclined guy line inside the ring of the positioning ring clamp; e. Tie two turns of stainless steel wire at each end of the steel strand break mark, then cut the wire with wire cutters and bend it back; f. Write the support column number on the wedge clamps at both ends of the transverse load-bearing cable or the upper fixing rope, and then coil the prefabricated transverse load-bearing cable or the upper fixing rope into a circle and tie it tightly with iron wire for easy transportation. (4) New soft cross-mounted installation a. Transport the prefabricated transverse load-bearing cables, upper fixing ropes, and insulators to the site and distribute them to each support according to the markings; b. Unwind the coiled transverse support cable and upper fixing rope, and connect the transverse support cable and upper fixing rope one by one according to the length of the straight suspension line in the soft cross span prefabrication drawing; c. When assembling the insulator, make the threads of the upper fixing rope the longest possible position; d. Workers at the top of the support use small ropes to hoist and install the wire rope sleeve and large pulley, and then hoist the large rope and pass it to the large pulley; e. The workers located below the support column, after the main rope is threaded into the large pulley, tie the insulator string with the first end of the main rope, pull the second end of the main rope to lift the transverse load cable. When it is lifted to the top of the support column, the workers at the top of the support column grab the pestle rod or pestle ring, insert the pestle rod into the fixing hole or connect the pestle ring to the double-ear connector, and install the washer and nut. f. When installing the transverse support cable, the worker at the upper fixed rope angle steel of the support grabs the end of the upper fixed rope. After the transverse support cable is installed, connect the top rod of the upper fixed rope to the hole of the fixed angle steel, install the ball washer, and then tighten the two nuts. The installation of one side of the soft cross span is then completed. g. Install the wire sleeve, large pulley, and large rope at the top of the support spanning the other side according to steps e and f. Install the wire sleeve and pulley at the upper fixed rope location. h. The large rope on the other side of the soft cross-bracing support is thrown to the already installed end, and the large rope is connected to the other end of the transverse support cable and the upper fixing rope. i. Use a ladder truck to pull the soft crossbar above the existing catenary cable. The workers below the support pull the second end of the rope to connect the cross catenary cable with the upper fixed rope to each track. j. When the transverse support cable is hoisted to the top of the support column, the worker at the top of the support column grabs the spike rod or spike ring, inserts the spike rod into the fixing hole or connects the spike ring to the double-ear connector, and installs the washer and nut, unties the large rope binding the transverse support cable, and removes the pulley and wire sleeve at the upper fixing rope. k. After the horizontal support cable is installed, the workers at the upper fixed rope angle steel of the support use one end of the pulley block to pull the spring compensator, while the workers below the support begin to gradually tighten the upper fixed rope. In coordination with the workers at the upper fixed rope angle steel of the support, the spring compensator is connected to the fixed base, inserted into the fixed angle steel hole, and the spherical pad, washer, and nut are installed. The nuts are tightened and the anti-loosening nuts are installed. l. Install the lower fixing rope according to step ch; m. After all the new soft cross spans are erected, the station conductor replacement work will be carried out. The new conductor will be hung on the new soft cross spans, the old conductor will remain as it is, and equipotential lines will be added between the new and old conductors. Step T3 includes: After the new flexible cross span is installed, it is connected to the old flexible cross span with jumpers and parallel groove clamps. The lower fixing rope is lifted with iron wire to ensure that it does not affect the operation of the train.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The replacement of the cantilever arm in the tunnel adopts the method of separate erection of horizontal and inclined cantilever arms to realize the replacement construction of the cantilever arm under the condition of limited clearance in the tunnel. 2. The replacement of the conductor in the tunnel section abandons the traditional "same-up, same-down" replacement mode and replaces the conductors separately, which enhances the flexibility of construction organization and significantly improves the safety factor of construction. When constructing tunnel groups, a line-end-first laying method is adopted to avoid the cumbersome wire-threading process when entering and exiting the tunnel, which greatly reduces the workload. Support-type laying pulleys are used. When entering the first hanging column in the tunnel, the pulley combination solves the problem of the new catenary cable rubbing against the existing equipment when crossing the existing conductor. 3. The replacement of the phase insulator conductors adopts a data classification method. By raising the installation height of the cantilever base and erecting a new support column at the mid-span, the parameter requirements of the dropper are met, avoiding a large number of adjustments to the dropper and the conductor after the phase insulator is installed. The complex and tedious process is completed in steps, reducing the amount of construction work at a single skylight point and improving the construction safety factor. 4. To ensure the line can be opened on time after the replacement of the flexible cross span and conductor, the new flexible cross span is first pre-installed, then the catenary cables for each track are erected and suspended on the new flexible cross span, then the new contact wire is erected and suspended on the new flexible cross span, and the parameters are adjusted to ensure on-time opening. Finally, the new flexible cross span is adjusted, and the existing flexible cross span and supports are removed. By carrying out the work simultaneously, the problems of the traditional replacement method—such as occupying several tracks at the same time, significant impact on existing equipment, numerous maintenance windows, increased manpower, and reduced secondary adjustment procedures—are solved. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 A flowchart illustrating the construction method for expanding and upgrading the overhead contact system of a busy heavy-haul railway. Figure 2 A schematic diagram of the threading of the new catenary in the replacement method of the catenary in the tunnel section; Figure 3 A schematic diagram showing the process of adjusting the height of the cantilever arm and installing the height-lowering structure in advance during the replacement of the conductor bearing in separate sections; Figure 4 This is a schematic diagram of the installation of the new flexible cross span in the synchronous replacement method of the station's flexible cross span and the conductor.

[0019] 1-Supported type wire laying pulley; 2-Suspension pulley; 3-Center anchor clamp for the catenary; 4-70 steel strand; 5-Transverse catenary; 6-Insulator; 7-Main rope; 8-Hand lever hoist and main rope; 9-Existing conductor; 10-Upper fixing rope; 11-Roadbed; 12-Foundation. Detailed Implementation

[0020] This embodiment takes the expansion and renovation of the Shuohuang Railway as an example to describe in detail the construction method of the overhead contact system for the expansion and renovation of a busy heavy-haul railway.

[0021] The replacement method for the cantilever arm inside the tunnel is as follows: the flat cantilever arm and the angled cantilever arm are connected to the insulators respectively, and the insulator bolts are tightened in place. During installation, the flat cantilever arm and the angled cantilever arm are installed separately, and finally the flat cantilever arm and the angled cantilever arm are connected. The specific steps are as follows.

[0022] T1, Preliminary Measurement, Calculation and Pre-mixing Before the construction window, measure the tunnel clearance, hanging column clearance, protective line height, and conductor height parameters, and optimize the cantilever installation height using CAD simulation to prevent the inclined cantilever insulator from scraping the bow. The existing guide height, pull-out value, catenary height, curve outer rail superelevation, and base installation height in the tunnel are measured using a catenary measuring instrument. The pre-configuration data of the cantilever arm is calculated. The existing guide height is taken into account in the calculation to ensure that the catenary guide height remains the same and the pull-out value meets the design requirements after the cantilever arm is replaced. Measure existing data, fill in the position data of each component in the overhead contact line cantilever arm pre-configuration data table and the overhead contact line positioning pre-configuration data table, and mark the corresponding positions in the tunnel; The wrist and arm components are pre-assembled in a centralized manner and then shipped out as complete sets.

[0023] T2, Remove the existing cantilever arm and base. (1) Before removing the old cantilever arm, measure the distance from the top of the ladder truck or work vehicle platform to the existing flat cantilever arm and record it as S1, and measure the distance from the top of the ladder truck or work vehicle platform to the contact line and record it as S2; (2) The operator stands on the ladder truck or work vehicle platform to loosen the bolts of the load-bearing cable seat cover plate and the positioning clamp bolts, and removes the load-bearing cable; (3) On the outer section of the curve, the load-bearing cable is held in place by iron wire and pulley or hand-cranked hoist and fixed to the hanging column; (4) Remove the cantilever arm and its base, place them on the platform of the ladder truck or work vehicle, or lower them onto the road shoulder with a rope.

[0024] T3, Install new base (1) The upper cantilever arm base is installed at a distance S1 from the top of the ladder truck or work vehicle platform to ensure that the height of the catenary cable is maintained. (2) Install the lower carpal base according to the design spacing between the upper carpal base and the lower carpal base.

[0025] T4, with separate installation of flat and angled wrist arms. (1) The flat cantilever arm is connected to the insulator and installed together on the upper cantilever arm base; (2) The inclined bracket arm is connected to the insulator and installed together on the lower bracket arm base; (3) Connect the flat wrist arm and the oblique wrist arm, and use a level to check the horizontal state of the flat wrist arm.

[0026] T5, restore the load-bearing cable (1) Pour the catenary cable into the new catenary cable seat, and install the cantilever arm offset position according to the offset calculated based on the on-site temperature and the distance of the cantilever arm from the center anchor position; (2) Measure the distance from the catenary to the feeder. If the distance from the catenary to the feeder is less than 500mm, replace the spike insulator with an ear-type suspension insulator or add a crossarm.

[0027] T6, Installation Positioning (1) Temporarily fix the positioning tube to the inclined cantilever arm, and adjust the positioning tube to be fixed at H1+S2 above the top of the ladder truck or work vehicle platform. H1 is the positioning slope to ensure that the contact line height is maintained. (2) Temporarily install positioning supports and use a spirit level to adjust the positioning tube to a horizontal position. After adjustment, fix the positioning supports in place. (3) Install the locator and fix it after adjusting the locating point to match the bearing wire; (4) Measure the distance from the anti-positioning tube to the tunnel wall. If the distance from the anti-positioning tube to the tunnel wall is less than 300mm, cut the exposed part of the anti-positioning tube. If cutting is difficult, adjust by reducing the anti-positioning pull-out value.

[0028] T7, Adjust the suspension (1) Conductor slope: There is a difference in conductor height inside and outside the tunnel. The conductor height inside and outside the tunnel should be smoothly transitioned. The difference in the height of the contact wire in one span should not be greater than 50mm. If the difference in the height of the existing conductor exceeds 50mm in one span, it should be adjusted to within the range of 50mm. (2) Positioning slope: Adjust according to positive positioning 220+2 / 3H2, and reverse positioning 350+2 / 3H2, where H2 is the outer rail superelevation; (3) The guide height remains as it is, and the pull-out value meets the design requirements; (4) Check whether existing equipment such as dropper clamps and electrical connection clamps are misaligned or not properly secured, and take appropriate action; (5) Measure the distance from the center of the line to the mid-span of the protection line and the height difference between the mid-span of the protection line and the adjacent contact line, and deal with any non-compliance with the standards; (6) Measure the distance between the anchor arm and the catenary and the distance between the anchor line and the catenary. If the distance is less than 300mm, the catenary pull-out value can be adjusted to 400mm. (7) When crossarm insulators are installed at both adjacent positioning points, it is necessary to check whether the suspension bottle of the feeder in the middle of the span is under stress. If it is not under stress, the bottom bar insulator of the suspension bottle in the middle of the span should be replaced with an ear-type suspension insulator to ensure that the suspension bottle of the positive feeder in the middle of the span is under stress.

[0029] T8, check torque The wrist arm uses a cone-pressure clamping anti-loosening bolt. After the suspension adjustment is completed, use a torque wrench to tighten the main nut and lock nut of the cone-pressure clamping anti-loosening bolt according to the torque table, and then check the torque of the cone-pressure clamping anti-loosening bolt.

[0030] The method for replacing the conductor in the tunnel section includes the following steps.

[0031] T1, Erecting new load-bearing cables and pre-embedding chemical anchors. (1) Install the lower anchor angle steel on the lower anchor arm. The starting end is connected to the existing anchor arm with a hard anchor. The old bearing wire remains unchanged. The two ends of the new bearing cable are connected with two silicone rubber insulators. The hard anchor is connected to the lower anchor angle steel with a steel wire sleeve or steel wire rope with connectors of sufficient strength. (2) Install pulleys at the tunnel entrance and erect load-bearing cables Since the positioning points inside and outside the tunnel are located on opposite sides of the line, there is a situation where the new catenary cable intersects with the existing equipment during the laying process. According to the traditional laying method, the positioning points inside the tunnel need to be temporarily removed and the new catenary cable needs to be flipped to the other side of the existing line. This method involves using one work vehicle with a line-laying mechanism stationed at the anchoring position, while another work vehicle carries the line end of the line-laying mechanism and threads it towards the anchoring direction. This avoids the cumbersome procedure of flipping the line. Support-type line-laying pulleys 1 are installed at the first hanging column and the first concrete column at the tunnel entrance, and suspension pulleys 2 are installed on the existing catenary at the tunnel intersection to ensure that the new catenary does not rub against the existing equipment when it crosses the existing catenary. A dedicated person is assigned to observe the line laying situation and report any problems in a timely manner. During the laying process, if there are existing reverse positioning or existing reverse soft positioning, such as when the new load-bearing cable rubs against the existing inclined guy line or existing V-shaped guy line, install the old positioning device in the flat cantilever tube, push out and fix the laying pulley, and increase the distance between the new load-bearing cable and the existing inclined guy line or existing V-shaped guy line. During the anchoring process, attention should be paid to the tension of the cable, and the sag of the new and old catenary cables should be kept basically consistent to prevent jamming or damage to the cable; avoid scraping between the new and old insulators, and the anchoring personnel should pay attention to the changes in the anchor arm; after the anchoring is completed, the ladder truck group will connect the new catenary cable to the flat cantilever arm, with the new catenary cable located on the same side as the existing line. The new catenary cable will be fixed to the flat cantilever arm with iron wire, 100mm-150mm away from the catenary cable seat. Similarly, the new and old catenary cables will be tied together with iron wire in the middle of the span, but the new and old catenary cables can be pulled to avoid excessive temperature difference and insufficient insulation distance between the new catenary cable and the existing contact wire; (3) Pre-install droppers, install equipotential bonding wires, add 4 sets of equipotential bonding wires at both ends of the joint, add 2 sets of equipotential bonding wires at the middle anchor, and add 1 set of equipotential bonding wires at each 1 / 4 anchor section, for a total of 8 sets of equipotential bonding wires. When installing equipotential bonding wires, the old equipotential bonding wires should be polished, cleaned and coated with conductive paste. (4) Install hooked chemical anchors directly above the tunnel conversion column for contact wire installation; (5) Adjustment and re-inspection.

[0032] T2, release the existing tension on the conductor cable and anchor the new catenary cable. The anchoring team used a lever hoist to lift the weight 500mm at the steering pulley, securing the existing conductor cable. They then used a tensioner and lever hoist to slowly release the tension in the existing conductor cable, allowing the new catenary cable to be anchored using the existing compensation cable.

[0033] T3, erecting a new contact line When anchoring, temporary hard anchors are used when the tension of the existing contact wire is partially relieved during the anchoring and lowering. The new contact wire is connected to the new compensating anchor. After anchoring is completed, the anchoring and lowering team changes the two ends of the new catenary to the compensating lower anchor. The newly erected contact wire uses the newly installed compensating lower anchor. When anchoring in the tunnel, iron wire and pulley are added to the hooked chemical anchor bolts installed at the previous tunnel window to temporarily suspend the new contact wire.

[0034] T4, Remove the existing conductor wire. After the existing catenary tension is unloaded, confirm that the existing catenary at each positioning point has fallen out of the catenary seat. Use pulley blocks and main ropes to fix both ends of the break point at the middle anchor. After the line is broken, slowly release it and then break the line from the middle anchor to the lower anchor side to avoid the cantilever base in the tunnel from tilting. After the line is broken, remove the existing catenary, contact wire and locator, and place them on the side of the adjacent line and between the two lines, taking care not to connect the rails.

[0035] T5, Adjust suspension After the line is broken, the ladder truck assembly performs line and surface correction, positioning and installation, dropper arrangement and electrical connection installation from the center anchor to both sides; installation and adjustment are carried out according to design standards. Due to the insulation distance issues between the tunnel wall, positive feeder, protective line and other existing equipment, the parameters are kept as existing as possible. For positioning points with large parameter changes, the distance between them and each existing equipment should be measured.

[0036] The specific steps for replacing the conductor in each case include the following.

[0037] T1 measures the contact wire height, catenary height, span, load, and load distance at the positioning points at both ends of the existing phase separation, and uses dropper calculation software to calculate the shortest dropper length for installation on the existing equipment.

[0038] T2, when the shortest dropper length is less than 400mm, adjustments should be made using the following methods: (1) Adjust the height of the cantilever arm in advance: one day in advance, increase the installation height of the cantilever arm base and increase the structural height at the positioning point to ensure that the shortest suspension string length at the phase insulator is greater than 400mm, and install a height reduction structure to ensure that the existing equipment parameters remain unchanged and the line operates normally while the height of the load-bearing cable seat is raised. (2) If the shortest dropper length is still less than 400mm after step (1), the foundation pit is excavated in advance at the mid-span position, a new support is erected and the slope, clearance, span, and load of the new support are measured and recorded. The height of the catenary on the new support is calculated when the shortest dropper length is equal to 400mm. The height of the catenary at the mid-span is raised by the new support to ensure the standard of the line parameters. The new cantilever is calculated by the slope, clearance, and catenary installation height of the new support. The new cantilever only suspends the catenary and does not install a positioning device.

[0039] T3, Erecting new support cables (1) When using a rail work vehicle or rail flatbed vehicle to pre-lay new support cables, if the cantilever base is raised, the new support cables are installed in the existing support cable seats; if a new support is erected, the new support cables are installed in the new support cable seats. (2) After the new catenary is pre-installed, install the catenary terminal anchoring clamp and rod-type suspension insulator at the existing phase separation position, install the old positioning tube on the flat cantilever arm, and push out the new catenary so that the horizontal distance between the new catenary and the old catenary is more than 300mm, and ensure that the distance between the new catenary and the old catenary and the insulator is more than 300mm.

[0040] T4, Calculate the new dropper and pre-fit it. (1) Calculate the dropper data when the cantilever base is raised by using the height of the new load cable, the existing span, the existing load moment, and the design guide height; (2) Calculate the dropper data when erecting the new support column by using the new span, new load distance, existing load cable height, existing load cable height at the positioning point, and design guide height; (3) Based on the calculation data of the dropper, pre-assemble the dropper on the professional pre-assembly platform. After the dropper is pre-assembled, measure the length of the dropper according to the regulations. The prefabrication error is within ±2mm.

[0041] T5, installation of new contact line The following two points should be noted during the installation process: Tension gauges are attached to the end for tension detection and anchoring. When traffic density is high, infrared thermometers are used to check important connections to control the tension and sag of the catenary and contact wire. When installing new contact lines and removing existing conductors, the suspension wires at the conductors at the phase separation locations should not be adjusted initially. Adjustments should be made based on measurement data after the device-type phase separation installation is completed.

[0042] T6, Installation and Adjustment of Component-Based Phase Separation (1) After the new catenary and contact wire are anchored, install the new droppers; (2) Based on the installation position of the catenary insulator, determine the installation position of the new phase insulator, and use a hand-operated hoist to tighten the wires and install the phase insulators in sequence by cutting the wires; (3) Since the weight of the phase-separation insulator was taken into account when calculating the suspension wire, the suspension wire does not need to be adjusted a lot. After the phase-separation insulator is installed, the suspension wires at both ends are finely adjusted according to the phase center height. The phase-separation insulator should be under tension after the whole machine is installed. The phase-separation insulator should have a negative dimension of about 10mm-15mm. (4) After installation, the bottom of the junction between the connecting plate and the contact wire must be polished with a file to ensure that the pantograph passes smoothly at this point; (5) After the phase insulator is installed, use a level to slide along the bottom of the phase insulator from one end to the other, and slide back and forth twice to ensure that the level can contact the two guide rails at the same time. Carefully check whether there is any bowing or scraping at the bottom of the phase insulator.

[0043] The method for synchronously replacing the station's flexible cross span and conductor includes the following steps.

[0044] T1, Erect and straighten the steel columns. (1) Perform electrical testing and grounding. After grounding is completed, the crane is stopped at the preset position. Pads are installed under the support legs to ensure that the support legs are stable and secure. (2) Put the wire sleeve on the upper part of the support column, lift the support column with a crane, move it directly above the foundation and slowly lower it. When the support column is 1m-1.5mm away from the foundation, the operator holds the support column, and according to the orientation of the support column, align the support column hole with the anchor bolt and install the nut to ensure that the support column is upright. After confirmation, lower the hook so that the support column base sits on the foundation, and the operator removes the wire sleeve. (3) Pillar adjustment First, measure the slope of the support along and perpendicular to the line. The support must be upright. When adjusting, loosen the nut first, and then pry the support with a crowbar according to the slope. When adjusting the slope of the support, the nut must only be loosened, not removed. (4) Safety distance inspection After the support column is erected, check the safe distance between the support column and each existing piece of equipment. If the safety distance between the auxiliary line and the support column is insufficient, a support frame can be used to extend the auxiliary line. If the safety distance between the support column and other existing equipment is insufficient, appropriate measures should be taken in a timely manner.

[0045] T2, Soft Transverse Installation (1) Measurement a. Create a data recording table based on the design floor plan; b. On-site measurement; ① Measurement of the superelevation of the electrified track curve Measured and recorded using a DJJ-8 laser measuring instrument; ② Measure the lateral span of the soft cross span Use a steel tape measure to measure the clearance and spacing values ​​of each line in sequence. The steel column is measured from the outer edge of the support and ends at the outer edge of the support. Then, use a steel tape measure to measure and verify the entire length on the highest rail surface elevation line of the support to ensure the accuracy of the measurement. ③ Measure the longitudinal span; ④ Measure the slope of the support column; (2) Calculation of soft cross span Based on the actual site conditions, modify the relevant parameters in the soft cross span prefabrication calculation software database, input the measured parameters into the soft cross span prefabrication calculation software, calculate the segment length of the soft cross span node and the position of the double cross bearing cable, upper and lower fixed rope positioning rings, and output the soft cross span prefabrication drawing. (3) Precast soft cross span a. Before prefabrication, the site should be cleaned, the steel strand reel should be supported with a reel bracket, prefabrication should be carried out under tension, and the position should be marked according to the calculated data; b. Starting from the end where the back is finished, two people pull the steel tape measure, one person reads the dimensions of each section in the soft cross-section precast drawing, and the other person marks it with paint; c. Install the horizontal load-bearing cable clamps or positioning ring clamps according to the paint markings and cutting diagrams, and prefabricate the horizontal load-bearing cable 5 or the upper fixing rope 10. d. Install the upper suspension line inside the U-shaped ring of the horizontal load-bearing cable clamp, prefabricate the upper fixing rope 10, and install the inclined guy line inside the ring of the positioning ring clamp; e. Tie two turns of Φ1.6 stainless steel wire at each end of the steel strand break mark, then cut the wire with wire cutters and bend it back; f. Write the support column number on the wedge clamps at both ends of the transverse load-bearing cable 5 or the upper fixing rope 10 respectively, and then coil the prefabricated transverse load-bearing cable 5 or the upper fixing rope 10 into a circle and tie it tightly with iron wire for easy transportation. (4) New soft cross-mounted installation a. Transport the prefabricated transverse load-bearing cables 5, upper fixing ropes 10, and insulators 6 to the site and distribute them to each support according to the markings; b. Unwind the coiled transverse support cable 5 and the upper fixing rope 10, and connect the transverse support cable 5 and the upper fixing rope 10 one by one according to the length of the straight suspension line in the soft cross span prefabrication drawing. c. Assemble the insulator 6 and other connecting parts, and put the threaded end of the upper fixing rope 10 into the longest position; d. Workers at the top of the support should fasten their safety belts and use small ropes to hoist and install the wire rope sleeve and large pulley. Then, hoist the large rope 7 and pass it to the large pulley. e. The workers located below the support column, after the main rope 7 is threaded into the large pulley, use the first end of the main rope 7 to tie the insulator string, pull the second end of the main rope 7 to lift the transverse load cable 5. When it is lifted to the top of the support column, the workers at the top of the support column grab the pestle rod or pestle ring, insert the pestle rod into the fixing hole or connect the pestle ring to the double ear connector, and install the washer and nut. f. When installing the transverse load-bearing cable 5, the workers located at the upper fixed rope angle steel of the support should fasten their safety belts, grab the end of the upper fixed rope 10, and after the transverse load-bearing cable 5 is installed, connect the top rod of the upper fixed rope 10 to the fixed angle steel hole, install the spherical washer, and then tighten the two nuts. The installation of one side of the soft cross span is then completed. g. Install the wire loop, large pulley, and large rope 7 at the top of the support spanning the other side according to steps e and f. Install the wire loop and pulley at the upper fixed rope 10. h. The large rope 7 on the other side of the soft cross-bracing support is thrown to the installed end, and the large rope 7 is connected to the other end of the transverse load-bearing cable 5 and the upper fixing rope 10. i. Use a ladder truck to pull the soft crossbar above the existing support cable. The workers below the support pull the second end of the rope 7 to connect the transverse support cable 5 and the upper fixed rope 10 to each track. j. When the transverse support cable 5 is hoisted to the top of the support column, the worker at the top of the support column grabs the pestle rod or pestle ring, inserts the pestle rod into the fixing hole or connects the pestle ring to the double ear connector, and installs the washer and nut, unties the large rope 7 binding the transverse support cable 5, and removes the pulley and wire sleeve at the upper fixing rope 10. k. After the horizontal support cable 5 is installed, the workers at the upper fixed rope angle steel of the support use one end of the pulley block to pull the spring compensator, and the workers at the lower part of the support begin to gradually tighten the upper fixed rope 10. In coordination with the workers at the upper fixed rope angle steel of the support, the spring compensator is connected to the fixed base, inserted into the fixed angle steel hole, and the spherical pad, washer, and nut are installed. The nuts are tightened and the anti-loosening nuts are installed. l. Install the lower fixing rope according to step ch; m. After all the new soft cross spans are erected, the station conductor replacement work will be carried out. The new conductor will be hung on the new soft cross spans, while the old conductor will remain as it is. An equipotential line will be added between the new and old conductors.

[0046] T3, Install the equipotential line between the new and old soft cross spans. After the new soft cross span is installed, the new soft cross span and the old soft cross span are connected by a 70-type jumper and a JB-2 type parallel groove clamp. The lower fixing rope is lifted by iron wire to ensure that it does not affect the operation of the train.

[0047] T4, erecting the support cables for each track. Both the starting and ending anchors use hard anchors. The old catenary remains unchanged. To prevent the insulation distance between the new and old catenary from being insufficient due to temperature changes, the two ends of the new catenary are connected by two silicone rubber insulators. The hard anchor is made of a steel wire rope of sufficient strength with connectors and connected to the insulator on the lower anchor angle steel. When erecting the new catenary cable, the railcar unit stops at the lower anchor support and disassembles. One work vehicle with the cable laying mechanism stays, while the other work vehicle with the cable laying mechanism pulls, threades, and lays the cable. The new catenary cable is laid across the soft cross span and passes over the upper fixed rope of the existing soft cross span. The tension of the new catenary cable should be moderate during the threading process to avoid the new catenary cable being dragged too low. The work vehicle moves forward at a constant speed, and the speed should not exceed 5 km / h. If there is no railcar when erecting a new catenary, a tensioner and auxiliary rope can be used to pull the catenary, and a ladder car can be equipped with pulleys at the positioning point to coordinate with the line erection process. When the new catenary is erected to the anchorage, it should be tightened and anchored. During the anchoring process, attention should be paid to the tension of the new catenary to prevent it from getting stuck or damaged, and to avoid the backlash of the anchor post and the scraping between the old and new insulators. The sag of the new catenary should be basically consistent with that of the existing catenary. After anchoring, the new load-bearing cable is fixed to the cantilever arm. The new load-bearing cable located at the soft cross span is fixed to the suspension pulley installed on the new soft cross span. The new load-bearing cable and the old load-bearing cable in the middle of the span are tied into a loop with iron wire. The equipotential line is installed. Then, the drop wire is installed according to the calculated drop wire position and the coil is tied and fixed to the new load-bearing cable.

[0048] T5, erecting contact lines for each track. The contact wire will be installed at the next maintenance window after the catenary cable is installed. When anchoring, unload 8-10 weights from the existing catenary and compensator. The new contact wire is anchored with the new compensation and suspended at the new soft cross span. At the same time, the two ends of the new catenary are converted to compensation anchors. When the new contact wire is erected to the anchoring point, the pulley block is used to tighten the line and anchor it. The new contact wire is anchored using the newly installed compensation. After anchoring is completed, the middle anchor is installed.

[0049] T6, Remove the existing conductor wire. During the installation of the contact wire, the existing locators are removed, and the existing catenary cables are pulled out of the catenary cable seats. At curves, the existing contact wires can be temporarily tied to the locating pipes with iron wire. After the existing catenary cables are pulled out, they should be on the same side as much as possible to facilitate dismantling. After the new contact wire is anchored, the old catenary cables are unloaded simultaneously under unified command. The middle anchor group starts to cut the wires from the middle anchor point, cutting the existing contact wires first, and then the existing catenary cables. When cutting the wires, use a large rope 7 to tighten both ends of the existing catenary cables to avoid excessive impact force and damage to the existing equipment.

[0050] T7, suspension adjustment First, install the new contact wire center anchor. The ladder truck team works alternately from the center anchor to the lower anchor sides to perform line surface correction, installation positioning, and initial installation of droppers. The dropper calculation is based on the design value. After installation, the overall guide height is slightly higher, but it does not affect the operation of the vehicle when driving downhill. Then, the suspension adjustment and electrical connection installation are carried out.

[0051] T8, fine-tuning of the soft cross-span and removal of the existing soft cross-span After all the track conductors were replaced, the parameters of the flexible cross spans and contact wires were fine-tuned to meet the design requirements. After the adjustment, the existing flexible cross spans and supports were removed, and the steel column foundation caps of the new flexible cross spans were installed.

[0052] The above-mentioned scheme has been adopted on the Shuohuang Railway, and the replacement of 721.798 kilometers of overhead contact lines has been completed. After each maintenance window, the parameters of the contact network were measured and all met the acceptance standards, meeting the conditions for power supply and commissioning of the line. This provides a successful example for the replacement of overhead contact lines on subsequent busy heavy-haul railways.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art can make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A construction method for the overhead contact system of a busy heavy-haul railway undergoing expansion and renovation, characterized in that, This includes methods for replacing cantilever arms inside tunnels, methods for replacing conductor rails in tunnel sections, methods for replacing conductor rails in separate sections, and methods for synchronously replacing soft cross spans and conductor rails at stations. The method for replacing the cantilever arm inside the tunnel includes the following steps: T1, Preliminary Measurement, Calculation and Pre-mixing Before the construction window, measure the tunnel clearance, hanging column clearance, protective line height, and conductor height parameters, and optimize the cantilever installation height using CAD simulation to prevent the inclined cantilever insulator from scraping the bow. Measure the existing guide height, pull-out value, catenary height, curve outer rail superelevation, and base installation height inside the tunnel, and calculate the pre-configuration data of the cantilever arm. The existing guide height is taken into account in the calculation to ensure that the guide height of the contact network remains the same and the pull-out value meets the design requirements after the cantilever arm is replaced. Measure existing data, fill in the position data of each component in the overhead contact line cantilever arm pre-configuration data table and the overhead contact line positioning pre-configuration data table, and mark the corresponding positions in the tunnel; The wrist arms are pre-assembled in a centralized manner and shipped out as complete sets. T2, Remove the existing cantilever arm and base. (1) Before removing the old cantilever arm, measure the distance from the top of the ladder truck or work vehicle platform to the existing flat cantilever arm and record it as S1, and measure the distance from the top of the ladder truck or work vehicle platform to the contact line and record it as S2; (2) The operator stands on the ladder truck or work vehicle platform to loosen the bolts of the load-bearing cable seat cover plate and the positioning clamp bolts, and removes the load-bearing cable; (3) On the outer section of the curve, fix the catenary to the hanging column; (4) Remove the wrist arm and wrist arm base; T3, Install new base (1) The upper cantilever arm base is installed at a distance S1 from the top of the ladder truck or work vehicle platform to ensure that the height of the catenary cable is maintained. (2) Install the lower carpal base according to the designed spacing between the upper carpal base and the lower carpal base; T4, with separate installation of flat and angled wrist arms. (1) The flat cantilever arm is connected to the insulator and installed together on the upper cantilever arm base; (2) The inclined bracket arm is connected to the insulator and installed together on the lower bracket arm base; (3) Connect the horizontal wrist arm and the oblique wrist arm, and use a spirit level to check the horizontal state of the horizontal wrist arm; T5, restore the load-bearing cable; T6, Installation and positioning; T7, suspension adjustment; T8, check torque The cantilever arm uses a cone-clamping anti-loosening bolt. After the suspension adjustment is completed, use a torque wrench to tighten the main nut and lock nut of the cone-clamping anti-loosening bolt according to the torque table, and then check the torque of the cone-clamping anti-loosening bolt. The method for replacing the conductor in the tunnel section includes the following steps: T1, Erecting new load-bearing cables and pre-embedding chemical anchors. (1) Install the lower anchor angle steel on the lower anchor arm. The starting end is connected to the existing anchor arm with a hard anchor. The old bearing wire remains unchanged. The two ends of the new bearing cable are connected with two silicone rubber insulators. The hard anchor steel wire sleeve or steel wire rope with connectors is connected to the insulator on the lower anchor angle steel. (2) Install pulleys at the tunnel entrance and erect load-bearing cables The operation is carried out by using one work vehicle with a line-laying mechanism to stay at the anchoring position, and another work vehicle to thread the line end of the line-laying mechanism towards the anchoring direction. Support-type line-laying pulleys are installed at the first hanging column and the first concrete column at the tunnel entrance, and suspension pulleys are installed on the existing catenary at the intersection to ensure that the new catenary does not rub against the existing equipment when it crosses the existing catenary. (3) Pre-lay the suspension wires and install the equipotential bonding wire; (4) Install hooked chemical anchors directly above the tunnel conversion column for contact wire installation; T2, remove the tension of the existing load-bearing cable and anchor the new load-bearing cable; T3, install a new contact line; T4, Remove the existing conductor wire; T5, adjust the suspension; The replacement method for the conductor in a split-type connection includes the following steps: T1, measure the contact wire height, catenary height, span, load and load distance at the positioning points at both ends of the existing phase separation, and use the dropper calculation software to calculate the shortest dropper length when installing on the existing equipment. T2, when the shortest dropper length is lower than the design value, adjustments should be made through the following measures: (1) Adjust the height of the cantilever arm in advance: one day in advance, increase the installation height of the cantilever arm base and increase the structural height at the positioning point to ensure that the shortest suspension string length at the phase insulator is greater than the design value, and install a height reduction structure to ensure that the existing equipment parameters remain unchanged and the line operates normally while the height of the load-bearing cable seat is raised; (2) If the shortest dropper length is still less than the design value after step (1), the foundation pit is excavated in advance at the mid-span position, a new support is erected and the slope, clearance, span, and load of the new support are measured and recorded. The height of the catenary on the new support is calculated when the shortest dropper length is equal to the design value. The height of the catenary at the mid-span is raised by the new support to ensure the standard of the line parameters. The new cantilever is calculated by the slope, clearance, and catenary installation height of the new support. The new cantilever only suspends the catenary and does not install the positioning device. T3, Erecting new support cables (1) When using a rail work vehicle or rail flatbed vehicle to pre-lay new support cables, if the cantilever base is raised, the new support cables are installed in the existing support cable seats; if a new support is erected, the new support cables are installed in the new support cable seats. (2) After the new catenary is pre-installed, install the catenary terminal anchoring clamp and rod-type suspension insulator at the existing phase separation position, install the old positioning tube on the flat cantilever arm, and push out the new catenary so that the horizontal distance between the new catenary and the old catenary is above the design value. T4, Calculate the new dropper and pre-fit it. (1) Calculate the dropper data when the cantilever base is raised by using the height of the new load cable, the existing span, the existing load moment, and the design guide height; (2) Calculate the dropper data when erecting the new support column by using the new span, new load distance, existing load cable height, existing load cable height at the positioning point, and design guide height; (3) Pre-fit the droppers on a professional pre-fitting platform according to the dropper calculation data; T5, install a new contact line; T6, Installation and Adjustment of Component-Based Phase Separation (1) After the new catenary and contact wire are anchored, install the new droppers; (2) Based on the installation position of the catenary insulator, determine the installation position of the new phase insulator, and use a hand-operated hoist to tighten the wires and install the phase insulators in sequence by cutting the wires; (3) After the phase-separating insulator is installed, the suspension strings at both ends are finely adjusted according to the phase-separating center height, so that the phase-separating insulator is in a tension state after the whole machine is installed, and the negative dimension of the phase-separating insulator is within the design value; The method for synchronously replacing the station's flexible cross span and conductor includes the following steps: T1, Erect and straighten the steel columns; T2, soft cross-mount; T3, install the equipotential line between the new soft crossbar and the old soft crossbar; T4, erecting the support cables for each track. Both the starting and ending anchor ends adopt the hard anchor method. The old bearing wire remains unchanged. In order to prevent the insulation distance between the new bearing wire and the old bearing wire from being insufficient due to temperature changes, two silicone rubber insulators are used to connect the two ends of the new bearing wire. The hard anchor steel wire rope with connectors is connected to the insulators on the lower anchor angle steel. When the new catenary is being erected, the railcar unit stops at the lower anchor support and disassembles. One work vehicle with the wire-laying mechanism stays, while another work vehicle with the wire-laying mechanism pulls, threades, and lays the wire. The new catenary is laid out over the soft cross span and passes over the upper fixed rope of the existing soft cross span. The work vehicle moves forward at a constant speed. When the new catenary cable is installed to the anchorage, the new catenary cable is tightened and anchored. After anchoring, the new load-bearing cable is fixed to the cantilever arm. The new load-bearing cable located at the soft cross span is fixed to the suspension pulley installed on the new soft cross span. The new load-bearing cable and the old load-bearing cable in the middle of the span are tied into a loop with iron wire. The equipotential line is installed. Then, the drop wire is installed according to the calculated drop wire position and the coil is tied and fixed to the new load-bearing cable. T5, erecting contact lines for each track. The contact wire will be installed at the next maintenance window after the catenary cable is installed. When anchoring, unload several weights of the existing bearing cable compensation, and anchor the new contact line with the new compensation. The new contact line is suspended at the new soft cross span. At the same time, the two ends of the new bearing cable are changed to compensation anchors. When the new contact line is erected to the anchoring point, the pulley block is used to tighten the line and anchor it. The new contact line is anchored using the newly installed compensation. After the anchoring is completed, the middle anchor is installed. T6, Remove the existing conductor wire. During the installation of the contact wire, the existing locator is removed, the existing catenary is pulled out of the catenary seat, and the existing contact wire is temporarily tied to the locating pipe with iron wire at the curve. After the existing catenary is pulled out, it should be on the same side as much as possible. After the new contact wire is anchored, the old catenary is unloaded at the same time under unified command. The middle anchor group starts to cut the wire from the middle anchor. First, cut the existing contact wire, then cut the existing catenary. When cutting the wire, use a large rope to tighten both ends of the existing catenary. T7, suspension adjustment First, install the new contact wire center anchor. The ladder truck group works alternately from the center anchor to the two lower anchor sides to perform line surface correction, installation positioning, and initial installation of droppers. The dropper calculation is based on the design value. After installation, the overall guide height is slightly higher, but it does not affect the driving on the slope. Then, the suspension adjustment and electrical connection installation are carried out. T8, fine-tuning of the soft cross-span and removal of the existing soft cross-span After all the track conductors were replaced, the parameters of the flexible cross spans and contact wires were fine-tuned to meet the design requirements. After the adjustment, the existing flexible cross spans and supports were removed, and the steel column foundation caps of the new flexible cross spans were installed.

2. The construction method for the overhead contact system of a busy heavy-haul railway expansion and renovation project according to claim 1, characterized in that, In the method of replacing the cantilever arm in the tunnel, step T1 uses a contact wire measuring instrument to measure the existing guide height, pull-out value, catenary height, curve outer rail superelevation, and base installation height in the tunnel.

3. The construction method for the overhead contact system of a busy heavy-haul railway expansion and renovation project according to claim 2, characterized in that, In the method for replacing the cantilever arm inside the tunnel, step T5 includes: (1) Pour the catenary cable into the new catenary cable seat, and install the cantilever arm offset position according to the offset calculated based on the on-site temperature and the distance of the cantilever arm from the center anchor position; (2) Measure the distance from the catenary to the feeder. If the distance from the catenary to the feeder is less than the design value, replace the spike insulator with an ear-type suspension insulator or add a crossarm. Step T6 includes: (1) Temporarily fix the positioning tube to the inclined cantilever arm, and adjust the positioning tube to fix it at H1+ S2 above the top of the ladder truck or work vehicle platform. H1 is the positioning slope to ensure that the contact line height is maintained. (2) Temporarily install positioning supports and use a spirit level to adjust the positioning tube to a horizontal position. After adjustment, fix the positioning supports in place. (3) Install the locator and fix it after adjusting the locating point to match the bearing wire; (4) Measure the distance from the anti-positioning tube to the tunnel wall. If the distance from the anti-positioning tube to the tunnel wall is less than the design value, cut the exposed part of the anti-positioning tube. If cutting is difficult, adjust by reducing the anti-positioning pull-out value. Step T7 includes: (1) Conductor slope: There is a difference in conductor height inside and outside the tunnel. The conductor height inside and outside the tunnel transitions smoothly. The difference in contact wire height in one span is not greater than the design value. If the difference in conductor height in one span exceeds the design value, it shall be adjusted to the range of the design value. (2) Positioning slope: Adjusted according to the design values ​​for positive and negative positioning; (3) The guide height remains as it is, and the pull-out value meets the design requirements; (4) Check whether the existing equipment is misaligned or properly secured, and take appropriate action; (5) Measure the distance from the center of the line to the mid-span of the protection line and the height difference between the mid-span of the protection line and the adjacent contact line, and deal with any non-compliance with the standards; (6) Measure the distance between the lower anchor arm and the catenary, and measure the distance between the lower anchor line and the catenary. If the distance is less than the design value, adjust the catenary pull-out value. (7) When crossarm insulators are installed at both adjacent positioning points, it is necessary to check whether the suspension bottle of the feeder in the middle of the span is under stress. If it is not under stress, the bottom bar insulator of the suspension bottle in the middle of the span should be replaced with an ear-type suspension insulator to ensure that the suspension bottle of the positive feeder in the middle of the span is under stress.

4. The construction method for the overhead contact system expansion and renovation of a busy heavy-haul railway according to claim 1, characterized in that, In the method of replacing the conductor in the tunnel section, in step T1 (2), when encountering existing reverse positioning or existing reverse soft positioning during the laying process, if the new conductor cable rubs against the existing inclined guy line or existing V-shaped guy line, the old locator is installed in the flat cantilever tube, the laying pulley is pushed out and fixed, and the distance between the new conductor cable and the existing inclined guy line or existing V-shaped guy line is increased. It also includes (5) adjustment and re-inspection.

5. The construction method for the overhead contact system of a busy heavy-haul railway expansion and renovation project according to claim 4, characterized in that, In the method for replacing the conductor in the tunnel section, step T2 includes: The anchoring team used a lever hoist to lift the weight to the design value at the steering pulley, and fixed the existing bearing cable. They then used a tensioner and a lever hoist to slowly release the tension of the existing bearing cable, and the new bearing cable was anchored using the existing compensation. Step T3 includes: When anchoring, temporary hard anchors are used when the tension of the existing contact wire is partially relieved during the anchoring and lowering. The new contact wire is connected to the new compensating anchor. After the anchoring is completed, the anchoring and lowering team changes the two ends of the new catenary to the compensating lower anchor. The newly erected contact wire uses the newly installed compensating lower anchor. When anchoring in the tunnel, iron wire and pulley are added to the hooked chemical anchor bolts installed at the previous tunnel window to temporarily suspend the new contact wire. Step T4 includes: After the existing catenary tension is unloaded, confirm that the existing catenary at each positioning point has been pulled out of the catenary seat. Use pulley blocks and main ropes to fix both ends of the break point at the middle anchor. After the line is broken, slowly release it and then break the line from the middle anchor to the lower anchor side to avoid the cantilever base in the tunnel from tilting. After the line is broken, remove the existing catenary, contact wire and locator, and place the catenary, contact wire and locator on the side of the adjacent line and between the two lines. Step T5 includes: After the line is broken, the ladder truck assembly will perform line and surface correction, positioning and installation, dropper arrangement and electrical connection installation from the center anchor to both sides; installation and adjustment will be carried out according to the design standards. Due to the insulation distance issues between the ladder truck and the existing equipment such as the tunnel wall, positive feeder and protective line, the parameters should be maintained as much as possible. For positioning points with large parameter changes, the distance between the ladder truck and each existing equipment should be measured.

6. The construction method for the overhead contact system of a busy heavy-haul railway expansion and renovation project according to claim 1, characterized in that, In the method for replacing the conductor in a split-phase connection, step T6 also includes: (4) After installation, use a file to grind the bottom of the junction between the connecting plate and the contact wire to ensure that the pantograph passes smoothly at this point; (5) After the phase insulator is installed, use a level to slide along the bottom of the phase insulator from one end to the other to ensure that the level can contact the two guide rails at the same time. Carefully check whether there is any bowing or scraping at the bottom of the phase insulator.

7. The construction method for the overhead contact system of a busy heavy-haul railway expansion and renovation project according to claim 1, characterized in that, In the method for synchronously replacing the station's flexible cross span and conductor, step T1 includes: (1) Perform electrical testing and grounding. After grounding is completed, the crane is stopped at the preset position. Place pads under the support legs to ensure that the support legs are stable and secure. (2) Put the wire sleeve on the upper part of the support column, lift the support column with a crane, move it directly above the foundation and slowly lower it. The distance between the support column and the foundation reaches the design value. The operator holds the support column, and according to the orientation of the support column, aligns the support column hole with the anchor bolt and installs the nut to ensure that the support column is upright. After confirmation, lower the hook so that the support column base sits on the foundation. The operator removes the wire sleeve. (3) Pillar adjustment First, measure the slope of the support along and perpendicular to the line. The support must be upright. When adjusting, loosen the nut first, and then pry the support with a crowbar according to the slope. When adjusting the slope of the support, the nut must only be loosened, not removed. (4) Safety distance inspection After the support column is erected, check the safe distance between the support column and each existing piece of equipment. If the safety distance between the auxiliary line and the support column is insufficient, use a shoulder scaffold to support the auxiliary line. If the safety distance between the support column and other existing equipment is insufficient, take appropriate measures in a timely manner. Step T2 includes: (1) Measurement a. Create a data recording table based on the design floor plan; b. On-site measurement; ① Measurement of the superelevation of the electrified track curve Measure and record using a laser measuring instrument; ② Measure the lateral span of the soft cross span Use a steel tape measure to measure the clearance and spacing values ​​of each line in sequence. The steel column is measured from the outer edge of the support and ends at the outer edge of the support. Then, use a steel tape measure to measure and verify the entire length on the highest rail surface elevation line of the support to ensure the accuracy of the measurement. ③ Measure the longitudinal span; ④ Measure the slope of the support column; (2) Calculation of soft cross span Based on the actual site conditions, modify the relevant parameters in the soft cross span prefabrication calculation software database, input the measured parameters into the soft cross span prefabrication calculation software, calculate the segment length of the soft cross span node and the position of the double cross bearing cable, upper and lower fixed rope positioning rings, and output the soft cross span prefabrication drawing. (3) Precast soft cross span a. Before prefabrication, clean the site, support the steel strand reel with a reel bracket, prefabricate under tension, and mark the position according to the calculated data; b. Starting from the end where the back is finished, two people pull the steel tape measure, one person reads the dimensions of each section in the soft cross-section precast drawing, and the other person marks it with paint; c. Install the horizontal load-bearing cable clamps or positioning ring clamps according to the paint markings and cutting diagrams, and prefabricate the horizontal load-bearing cables or upper fixing ropes; d. Install the upper suspension line inside the U-shaped ring of the horizontal load-bearing cable clamp, prefabricate the upper fixing rope, and install the inclined guy line inside the ring of the positioning ring clamp; e. Tie two turns of stainless steel wire at each end of the steel strand break mark, then cut the wire with wire cutters and bend it back; f. Write the support column number on the wedge clamps at both ends of the transverse load-bearing cable or the upper fixing rope, and then coil the prefabricated transverse load-bearing cable or the upper fixing rope into a circle and tie it tightly with iron wire for easy transportation. (4) New soft cross-mounted installation a. Transport the prefabricated transverse load-bearing cables, upper fixing ropes, and insulators to the site and distribute them to each support according to the markings; b. Unwind the coiled transverse support cable and upper fixing rope, and connect the transverse support cable and upper fixing rope one by one according to the length of the straight suspension line in the soft cross span prefabrication drawing; c. When assembling the insulator, make the threads of the upper fixing rope the longest possible position; d. Workers at the top of the support use small ropes to hoist and install the wire rope sleeve and large pulley, and then hoist the large rope and pass it to the large pulley; e. The workers located below the support column, after the main rope is threaded into the large pulley, tie the insulator string with the first end of the main rope, pull the second end of the main rope to lift the transverse load cable. When it is lifted to the top of the support column, the workers at the top of the support column grab the pestle rod or pestle ring, insert the pestle rod into the fixing hole or connect the pestle ring to the double-ear connector, and install the washer and nut. f. When installing the transverse support cable, the worker at the upper fixed rope angle steel of the support grabs the end of the upper fixed rope. After the transverse support cable is installed, connect the top rod of the upper fixed rope to the hole of the fixed angle steel, install the ball washer, and then tighten the two nuts. The installation of one side of the soft cross span is then completed. g. Install the wire sleeve, large pulley, and large rope at the top of the support spanning the other side according to steps e and f. Install the wire sleeve and pulley at the upper fixed rope location. h. The large rope on the other side of the soft cross-bracing support is thrown to the already installed end, and the large rope is connected to the other end of the transverse support cable and the upper fixing rope. i. Use a ladder truck to pull the soft crossbar above the existing catenary cable. The workers below the support pull the second end of the rope to connect the cross catenary cable with the upper fixed rope to each track. j. When the transverse support cable is hoisted to the top of the support column, the worker at the top of the support column grabs the spike rod or spike ring, inserts the spike rod into the fixing hole or connects the spike ring to the double-ear connector, and installs the washer and nut, unties the large rope binding the transverse support cable, and removes the pulley and wire sleeve at the upper fixing rope. k. After the horizontal support cable is installed, the workers at the upper fixed rope angle steel of the support use one end of the pulley block to pull the spring compensator, while the workers below the support begin to gradually tighten the upper fixed rope. In coordination with the workers at the upper fixed rope angle steel of the support, the spring compensator is connected to the fixed base, inserted into the fixed angle steel hole, and the spherical pad, washer, and nut are installed. The nuts are tightened and the anti-loosening nuts are installed. l. Install the lower fixing rope according to step ch; m. After all the new soft cross spans are erected, the station conductor replacement work will be carried out. The new conductor will be hung on the new soft cross spans, the old conductor will remain as it is, and equipotential lines will be added between the new and old conductors. Step T3 includes: After the new flexible cross span is installed, it is connected to the old flexible cross span with jumpers and parallel groove clamps. The lower fixing rope is lifted with iron wire to ensure that it does not affect the operation of the train.

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