The first paper on the new technology of catenary
Technology and analysis of catenary transition construction
Abstract: In order to cooperate with the line construction in the project, according to the actual situation of line reconstruction, many different transition construction technologies are adopted in the catenary transition project. In order to cooperate with the track reconstruction project, create open conditions for construction and ensure the smooth progress of catenary reconstruction construction. Firstly, this paper analyzes the types of rail line reconstruction projects, and emphatically introduces the catenary transition construction technology and the guarantee measures for catenary transition, for the reference of peers.
Keywords: catenary; Transition method; technology
I. Overview of Catenary Transition Project
In the construction of railway electrification project, the catenary transition project is mainly caused by the transformation of curve radius of section and station lines and the replacement of turnout. Because the two pillars affect the transformation of the railway catenary, the opening of the new catenary after the transformation must be synchronized, so the catenary project must cooperate with the track reconstruction project to ensure the smooth construction of the catenary. The close cooperation between catenary construction and railway transportation is an important condition to ensure that the normal railway transportation order is not affected by construction, and it is also a prerequisite for the smooth implementation of line relocation. Catenary transition project plan must be based on the overall construction deployment of the construction unit, combined with the busy degree of existing transportation, catenary transition project and new construction project should be closely organized and carefully arranged.
Catenary transition project is mainly a temporary measure to meet the requirements of off-line civil engineering and track engineering construction and safe driving. The catenary equipment set in the transition measures will be dismantled (or partially dismantled) after the formal project is completed. The guiding ideology of catenary temporary transition project is "combining permanence with temporality, saving investment and facilitating construction", and the basic principle is to ensure smooth train flow, traffic safety and construction quality.
Second, the catenary reconstruction project exceeding the standard method
2. 1 catenary construction conditions and transition mode
Because the catenary reconstruction project is implemented according to the construction plan of the line construction unit, all the catenary reconstruction projects must be completed in the construction site, so the catenary construction unit is required to conduct detailed investigation before construction and make careful construction preparations to ensure the transition between the catenary and the existing line during the power outage, and the catenary must meet the requirements of normal traffic before the end of the construction skylight. The transition construction of catenary transformation adopts transition soft crossing or single pillar mode, depending on the amount of road drawing. The premise is that the catenary transition scheme should be attached to the steps of line construction and transformation, and based on this. According to the characteristics of catenary transition project and the construction experience of previous projects, the catenary transition project mainly has the following situations:
(1) When the rail pulling amount of the line is less than 2m, directly pull the existing line into place. At this point, the catenary adopts single pillar transition or direct construction in place.
(2) When the line drawing amount is 2m or more, the pre-setting method should be adopted for construction. At this time, the catenary is temporarily suspended by transitional pillars or soft gears, so as to dismantle the existing pillars and provide a site for the line construction unit. In the section where the line has been pre-paved, the catenary pillar will be re-erected according to the design requirements, online equipment will be installed, and the newly erected catenary in this section will be adjusted in place before the wiring at both ends of the line is unplugged. At the same time, the catenary is connected and adjusted to ensure that the catenary can be opened safely in time after transfer.
(3) The distance between the transition column of the transition section and the center of the existing line should be more than 5m, so as to ensure that the line and the catenary do not interfere with each other during construction.
(4) When the catenary in the transition section is restored. In order to install and adjust the contact suspension accurately, the variation factors of line profile should be considered.
2.2 catenary transition construction method
When the distance between (1) lines is 0 ~ 0.5m, according to the technical standard of catenary, the minimum clearance is not less than 2.5m, and when the maximum clearance is greater than 3.5m, the existing pillars can be considered. The line connection construction section is located near the line transfer point. 3 ~ 5 days before the change of the line (depending on the workload), measure the pillar clearance based on the pile in the line, pre-install the wrist arm, temporarily fix the wrist arm on the pillar along the line by using the power outage point, and tie it firmly with iron wire to avoid wind shaking. On the day when the line is upside down, the contact suspension in this area will be switched to the newly set wrist arm by using the power outage point, and the existing catenary will be opened after fine adjustment, so as to ensure the pantograph-catenary relationship and traffic safety.
(2) When the line spacing is 0.5 ~ 2m, it is necessary to set up new catenary pillars, and the existing catenary adopts single pillar or soft span transition. Firstly, the existing catenary suspension (including additional suspension) is rearranged on the transition pillar or soft span, the existing pillar is removed, the new pillar is set and the new wrist arm is installed. On the day of rewinding, pull the contact suspension to the designated position by using the power failure point. After the line is switched, the catenary in the transformation section will be gradually switched to the newly built pillar, and the transitional pillar or soft span will be removed.
(3) When the line displacement is more than 2m, the construction shall be organized according to the construction flow of the new project, and only when the plugs are unplugged at both ends, the two ends of the line shall be switched according to the above method.
Three, catenary transition construction technology
The concrete scheme of catenary transition project includes six parts, namely, internal transition in interval curve, external transition in interval curve, simultaneous transition in interval double lines, transition construction scheme in station yard, transition construction scheme in interval uplink and downlink, and connection scheme between new network and existing catenary. However, the construction scheme of interval curve internal dialing and interval curve external dialing is the same, so the following only introduces interval curve internal dialing.
(1) Interval Dial
When the new pillar is located outside the newly laid line in the reconstruction section and turns in the interval, it should be installed according to the relevant requirements before the line changes. In order to ensure the smooth opening of the catenary on the day of line change, the catenary should be moved to the new pillar on the day of line change. Then, the catenary of the reconstruction section is fine-tuned and anchored, and the additional suspension of this section needs to be crossed and replaced twice, so as to ensure the loop connectivity. Finally, remove the existing columns and clean up the construction site.
When the newly-built pillar is located in the newly-laid line in the reconstruction section, and the interval shifts, in order not to affect the existing catenary shift and line laying, the newly-built pillar may not be assembled in advance, but temporary pillar transition shall be added. This requires adding temporary pillars outside the line, hanging catenary, and then dismantling the existing pillars. On the day of line transfer, in order to ensure the smooth opening of catenary, it is necessary to transfer catenary from temporary pillar to new formal pillar. Like the above method, the last step is to fine-tune the catenary of this section and anchor it to adapt to the changing contact clues. This shows that this is a reasonable and concise scheme, which meets the actual situation and needs of construction.
(2) Dial at the same time with two lines at intervals
Interval double-line simultaneous dialing seems to be a combination of interval curve internal dialing and interval curve external dialing, but there is a great difference between them. At the same time, the section double-track transfer adopts temporary soft transition. First, carry out the construction and installation of temporary soft span, and then hang the catenary of the upper and lower existing lines on the temporary soft span. Then, it will provide a site for the pre-laying of the line and the shift of the catenary, and dismantle the existing pillars in the upstream and downstream. In order to ensure the smooth opening of catenary on the day of line transfer, catenary should be transferred from temporary pillar to new formal pillar. Then fine-tune and anchor the catenary in this section, then dismantle the temporary soft span and clean up the inspection site.
(3) Transition construction scheme of station yard
When the existing pillars affect the laying of lines, because the existing lines cannot be dismantled for normal operation, the new pillars cannot bear the weight of the suspension network at this time, and the catenary project will need temporary transition. At this time, the construction scheme is: when the construction unit in front of the station can hand over the piles on site, it will make a transition by setting up a single column. When a single pillar cannot be erected on site, a soft crossing transition should be implemented at a certain distance from the line. During the reconstruction of the throat area of the station, the existing catenary clues in some sections are not long enough, so it is temporarily impossible to set up new clues. At this time, joints can be made temporarily to extend the length of clues and ensure the traffic demand, and the catenary project needs temporary transition. The specific scheme is as follows: when the turnout in the throat area of the station is renovated, the catenary should adopt small-scale temporary transition. There are four transition modes: using existing pillars, shifting existing catenary, extending the length of existing catenary anchor section and adding temporary small anchor section. One or a combination of them can be selected for catenary construction transition.
(4) Construction scheme of edge exchange in upstream and downstream sections
When the interval curve is reconstructed, the existing downlink is changed and then becomes a part of the reconstructed uplink, which often happens. There are three schemes for the construction transition of the variable side section: ① short-distance displacement of the existing catenary, using the existing catenary to change the variable side phenomenon; (2) By extending the existing catenary, the problem of insufficient length of extended clue is solved; ③ Install the formal catenary in place first, then make it overlap with the existing catenary, and then install the overlapping part in place on the day of line handover.
Conclusion: Because the catenary construction of electrified railway project is complex, involving many related units, it is necessary to go through detailed field investigation, combined with the design requirements and construction schemes of other majors, to ensure that the transition scheme is feasible, safe and reliable.
New technology of catenary (part two)
Study on catenary suspension construction technology
Abstract: With the continuous progress of social economy, the construction of high-speed railway in China has also accelerated, and the catenary suspension project has made new development. The main purpose of contact suspension construction technology is to strictly control the quality, especially to strengthen the supervision of the construction process by using the characteristics of electric traction power supply specialty of high-speed rail lines. This paper will analyze the relevant points of catenary suspension technology, theoretically introduce the construction technology such as punching and pouring in the hole and bus bar installation, and give practical suggestions.
Keywords: catenary suspension; Construction technology; Quality supervision; High-speed railway; engineering
Catenary suspension construction technology is mainly used in high-speed railway and subway engineering, which has the characteristics of good safety and small maintenance workload. This paper will analyze the difficulties in the construction process with practical cases, and briefly introduce the construction technology of rigid suspension of catenary, providing reference for the development of this industry.
1 catenary suspension type
Catenary is an indispensable overhead equipment in the operation of high-speed railway, and it is the most difficult link in the traction power supply system, with relatively weak technology. According to the development of catenary suspension technology in China, the most commonly used technologies are mainly divided into the following categories.
First, multi-chain suspension. This process structure is complicated, the parts are scattered, and the initial investment cost is high, the maintenance cost is expensive, and the cost pressure on enterprises is great, so it has not been popularized. Second, the elastic chain is suspended. This technology mainly relies on elastic slings for suspension engineering, which requires high precision, complicated construction technology and difficult debugging. At the same time, the length and tension of elastic sling are easily disturbed by external environmental factors, that is, it changes with the change of temperature and may be deformed. Third, simple chain suspension. Compared with the first two methods, this technology has the advantages of small gap in current collection quality, simple structure and low engineering cost, and can change the running track of pantograph in the environment of increasing contact line tension.
2 Key points and technical points of construction quality control
The key operation points of catenary suspension technology are as follows: (1) punching, that is, using 5mm steel plate as the base, designing 4 bolt holes, and punching with electric hammer in one step. When the surface of the tunnel is found to be damaged, displacement treatment can be carried out, but the displacement distance should not exceed 0.25m .(2) When setting out, it is necessary to ensure that the conductor cannot be hard bent. That is, the conductor will be fixed on the rigid beam and column after paying off, and the prepared conductive grease will be connected to the rigid slot through the paying-off trolley and fixed with bolts. (3) Adjustment is mainly to measure and adjust the accuracy of the suspension position again. The key point is that the anti-loosening heat ring of the bolt needs to be firm and reliable, which can effectively prevent the parts from falling off due to long-term vibration and improve the technological process as much as possible.
In addition, in the control of construction quality, we should pay attention to the following two aspects, namely, the installation of positioning device and the erection of carrier cable and contact line. Specifically, the function of the locator is not to hinder the passage of the pantograph. When the slope of the positioner is large, the pantograph will directly harden the positioning point at high speed, which will aggravate the wear of the equipment. On the contrary, when the gap between the locators is small, it will cause friction between the pantograph and the contact line. Therefore, in the process of positioning and installation, the height and spacing should be scientifically designed and arranged to realize the optimization of technology. The erection of contact wire should be determined according to the physical properties, mechanical properties and processing technology of materials. In addition, the deviation of steel wire tension should be less than 8% as far as possible, and keep running at a constant speed. In the choice of materials, the hardness of copper and magnesium is higher than other materials, making them the first choice. At the same time, in the construction process, we usually ask the construction unit to carry out the construction according to the scheme in the installation curve. For the extension of new lines, we usually adopt the method of falling weight and overstretching, which has achieved good results.
3 catenary suspension construction technology analysis
3. 1 Tunnel Piercing and Pouring
The main operation flow of drilling and grouting in the tunnel is as follows: the construction personnel draw the hanging drilling type table according to the measured data, and then the construction team needs to check the hanging type marked on the tunnel wall, and then use the impact bit and drilling plate to carry out the operation according to the pre-designed drilling depth after confirmation. In the process of using the template, we need to drill a 3-5 mm slot hole on it. After removing the formwork, we need a laser measuring locator to ensure the vertical state between the borehole and the wall of the cave, and we also need a hand to hold the soot blower to blow out the dust generated by the borehole. After drilling, we should record relevant data and install bolts. See table 1 for the main tools.
3.2 Bus bar installation
The configuration of the bus requires the operator to check the length of the anchor segment first. After the positioning device of rigid suspension is completed, it is necessary to measure the distance between suspension segments on site, and pay attention to the expansion and contraction allowance that may be caused by temperature. The bus bar installation length shall be based on: bus bar installation length = (total length-bus bar length at both ends -n? Bus bar length), to ensure that the length of the bus bar is not too short, that is, to keep the minimum distance of 600 mm In addition, the installation of the short bus bar should be as close as possible to the suspension anchor point, and its cutting surface should form a 90-degree angle with the center of the bus bar, so that the whole section can be smoother. For prefabricated bus, it is necessary to use 12m bus for processing, cut according to the actual length, and the last procedure is completed with drilling tools. After reaching the corresponding standards, it is necessary to check the joints to ensure that there is no dislocation and deviation.
For the installation of bus (as shown in figure 1), it is necessary to place a rigid-flexible transition bus at the tunnel entrance first, and add a tight bus according to the drawing. At this time, it is necessary to connect the two, that is, install a bolt in the middle of the bus, and each bolt needs to be equipped with an elastic washer. In addition, it is necessary to pay attention to the direction of the bus. Specifically, the small head of the inclined plane should be close to the flat side of the bus, and vice versa. At this time, it is necessary to keep the joint loose without reinforcing bolts. When connecting buses, they should be kept on the same horizontal plane, the openings should be smooth, and the screws should be installed in turn to avoid skew.
In addition, when we find that the notch of the bus bar is deformed and damaged, we can't continue to use it. Be careful when handling the bus to reduce collision.
4 conclusion
With the progress of science and technology, we have a further understanding of catenary suspension construction technology. In many experiments, we know that catenary rigid suspension has the characteristics of small tunnel clearance and high safety. In addition, its maintenance process is convenient, which can reduce the maintenance cost in the operation process, and it has high recognition and is worth popularizing. The maturity of catenary suspension technology is of great significance to the development of this industry.
refer to
Liu Desheng. Discussion on construction technology of rigid suspension moving catenary [J]. Electrified Railway, 2007(2).
[2] Liu Guofu. Thinking and discussion on the development of catenary of high-speed electrified railway in China [J]. Journal of Railway Engineering Society, 2008(3).
[3] Wang. Construction technology and quality control of catenary suspension for passenger dedicated line [a]. Proceedings of the 2008 Railway Engineering Seminar of China Railway Society [C].2008(2).
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