Elastic long sleeper for ballast track and sleeper pad replacement method thereof

Abstract

The elastic long sleeper for the ballast track comprises a prestressed concrete sleeper, an elastic sleeper cushion layer, a protective layer and a sleeper cushion fixing device, the elastic sleeper cushion layer and the protective layer are sequentially arranged at the bottom of the prestressed concrete sleeper from top to bottom, and the elastic sleeper cushion layer and the protective layer are sequentially arranged at the bottom of the prestressed concrete sleeper from top to bottom. And the elastic sleeper cushion layer and the protective layer are hooped at the bottom of the prestressed concrete sleeper by the sleeper cushion fixing device. Compared with traditional vibration reduction measures, the problems that the laying area of a railway ballast pad is too large, vibration reduction fasteners cannot effectively reduce the inherent frequency of a track system and the like in the traditional vibration reduction measures can be solved to a certain extent, in addition, the elastic sleeper pad layer and the protective layer can be more stably fixed, and the service life of the elastic sleeper pad layer is prolonged. Relative displacement of all parts under the long-term load effect of a train is prevented, and therefore the continuous effectiveness of the vibration reduction function is guaranteed.

Description

Technical Field

[0001] The invention relates to the field of urban rail transit railway track structures, and in particular to an elastic long sleeper for a ballasted track and a method for replacing the sleeper pad thereof. Background Art

[0002] With the rapid development of cities, the requirements for vibration and noise reduction of wheel-rail systems in the development of the upper cover properties related to vehicle depots and surrounding buildings are gradually increasing, and it is urgent to improve the vibration reduction performance of ballasted tracks in urban rail transit and urban rail depots. At the same time, the wheel-rail fatigue load of the vehicle-rail system will cause the ballasted track bed to develop rapidly, resulting in deterioration phenomena such as powdering and sinking of the track bed, which directly affects the stability and service life of the track bed.

[0003] The vibration reduction level is divided into three levels: medium vibration reduction, high vibration reduction and special vibration reduction according to the predicted excess amount of environmental impact assessment. At present, the vibration reduction performance of the ballasted track in the depot is about 5dB. Commonly used further vibration reduction measures include the use of sleeper pads, ballast pads and vibration reduction fasteners. The vibration isolation effect of ballast pads is good, but the laying area is too large, and it is difficult to replace after the rubber material ages and the vibration reduction performance decreases; the vibration reduction fasteners cannot effectively reduce the natural frequency of the track system, and the economy is poor. Traditional elastic long sleepers need to take into account the vibration reduction performance while maintaining the bonding performance with the sleepers. After the polyurethane or rubber material under the sleeper cushion ages, the entire sleeper can only be replaced, which increases the maintenance cost of the depot and is time-consuming and labor-intensive. For this reason, it is urgent to develop an elastic long sleeper for ballasted track and a sleeper pad replacement method, which can maintain the vibration reduction performance of the ballasted track system in the depot for a long time at a low cost and improve the comfort of buildings near the depot.

[0004] There are some relevant patents related to elastic long sleepers in the field of urban rail transit. Patent CN105256670A discloses a sleeper with a replaceable sleeper pad, with a wavy groove between the sleeper pad and the sleeper. When replacing the sleeper pad, the sleeper pad is directly taken out of the groove, but there are problems such as local fatigue damage of the concrete groove during long-term use, and the bonding performance between the sleeper pad and the sleeper is gradually weakened. Patent CN108660867A discloses a composite polyurethane sleeper pad and a preparation method thereof, which prevents the sleeper pad from being pierced by ballast gravel through a non-woven fabric layer, and reinforces the polyurethane material with reinforced sleeper pad fibers to improve its cohesive strength. In this solution, the sleeper pad is combined with the sleeper to form an integral body, and cannot be replaced after the performance of the sleeper pad material decreases. Patent CN117626722A discloses an assemblable elastic sleeper, which is provided with a plurality of embedded sleeves under the sleeper, and the sleeper pad is anchored to the bottom surface of the sleeper by bolts. Although this solution can replace the sleeper pads, it requires a large number of bolts. The polyurethane material of the sleeper pads is relatively soft and the polyurethane layer is in direct contact with the ballast gravel. Under the long-term action of train loads, the sleeper pads are prone to local tearing around the bolts, reducing the service life of the sleeper pads. Summary of the invention

[0005] The object of the present invention is to provide an elastic long sleeper for ballasted track in view of the deficiencies of the prior art.

[0006] The specific technical solutions are as follows:

[0007] A long elastic sleeper for ballasted track comprises: a prestressed concrete sleeper, an elastic sleeper cushion layer, a protective layer and a sleeper cushion fixing device, wherein the elastic sleeper cushion layer and the protective layer are arranged on the bottom of the prestressed concrete sleeper in sequence from top to bottom, and the sleeper cushion fixing device hoops the elastic sleeper cushion layer and the protective layer on the bottom of the prestressed concrete sleeper.

[0008] Optionally, the prestressed concrete sleeper includes a section with a constant width under the rail section, a section with a variable width under the rail section, and a middle section of the sleeper. The width of the end of the section with a constant width under the rail section remains consistent from the end position of the section with a variable width under the rail section to the edge of the middle section of the sleeper.

[0009] Optionally, the elastic sleeper cushion layer is only partially laid in a section with equal width of the rail section.

[0010] Optionally, the adjusting bolt is a high-strength bolt, and a knob for easy operation is provided on the head thereof.

[0011] Optionally, the sleeper pad fixing device includes a hoop and a pre-tightening bolt, the prestressed concrete sleeper is provided with a pre-tightening bolt hole, the hoop is correspondingly provided with a bolt hole, and the pre-tightening bolt passes through the bolt hole and is threadedly connected in the pre-tightening bolt hole.

[0012] Optionally, a limiting groove is provided on the side surface of the prestressed concrete sleeper, and a protrusion matched with the limiting groove is provided on the opposite inner side of the hoop.

[0013] Optionally, the elastic sleeper cushion layer is connected to the prestressed concrete sleeper via a binder.

[0014] Optionally, the elastic sleeper cushion layer is connected to the prestressed concrete sleeper via a dovetail protrusion.

[0015] Optionally, the protective layer material is a polyamide fiberboard or a rubber board.

[0016] A method for replacing a sleeper pad of an elastic long sleeper for a ballasted track comprises the following steps:

[0017] Step 1: Replace the sleeper pads according to the line maintenance plan. First, separate the sleepers that need to be replaced from the rails.

[0018] Step 2: Separate the sleeper pad fixing device from the sleeper;

[0019] Step 3: If the protective layer is found to be damaged during routine inspection and maintenance of the line, the protective layer can be torn off from under the elastic sleeper cushion layer and re-bonded to the sleeper. If the sleeper cushion layer is replaced during the line overhaul period, the elastic sleeper cushion layer can be torn off from the bottom of the sleeper and the new elastic sleeper cushion layer and protective layer can be re-bonded to the sleeper.

[0020] Step 4: Reset the sleeper pad fixing device, retighten the pre-tightening bolts and reinstall the fasteners to ensure continuous use of the elastic long sleeper.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The device of the present invention can effectively connect the elastic polyurethane cushion layer under the sleeper with the sleeper. The prestressed concrete sleeper is provided with bolt holes on the sleeper side. The sleeper cushion fixing device is pre-tightened by bolts. The elastic sleeper cushion layer is hooped on the bottom of the sleeper through the sleeper cushion fixing device. The elastic sleeper cushion layer and the protective layer are bonded by a special adhesive. The elastic sleeper cushion layer and the bottom of the sleeper can be bonded by a special adhesive. A dovetail boss can also be used to connect with the sleeper during the casting of the sleeper to further enhance the connection stability.

[0023] (2) The method of the present invention can realize the rapid replacement of elastic long sleeper pads of ballasted track in the vehicle depot. The replacement of sleeper pads can be carried out in combination with the line maintenance plan. First, loosen the spring bar II type fastener to separate the sleeper whose sleeper pad needs to be replaced from the rail; secondly, loosen the pre-tightening bolts to separate the sleeper pad fixing device from the sleeper; thirdly, if the protective layer is found to be damaged during the daily maintenance of the line, only the protective layer can be torn off from under the polyurethane vibration-damping pad layer and the protective layer can be re-bonded; if the sleeper pad layer is replaced during the line overhaul period, the polyurethane vibration-damping pad layer can be torn off from the bottom of the sleeper, and the new polyurethane vibration-damping pad layer and the protective layer can be re-bonded to the sleeper; finally, the sleeper pad fixing device is reset and the pre-tightening bolts are re-tightened;

[0024] (3) The method of the present invention can meet the vibration reduction requirements of the rail structure of the vehicle depot, block the low-frequency noise transmitted from the rail structure to the subway roof building and the adjacent railway buildings, and reduce the secondary structural noise of the building. In addition, the method of the present invention can carry out targeted vibration reduction decibel design according to the vibration reduction level determined by the project environmental impact assessment, and can be promoted and applied in urban rail transit and urban rail line sections with vibration reduction requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the elastic long sleeper for ballasted track of the present invention;

[0026] Figure 2 It is a schematic diagram of the explosion structure of the elastic long sleeper for ballasted track of the present invention;

[0027] Figure 3 It is a front view structural schematic diagram of an elastic long sleeper for ballasted track of the present invention;

[0028] Figure 4 It is a schematic diagram of the top view of the structure of the elastic long sleeper for ballasted track of the present invention;

[0029] Figure 5 It is a schematic diagram of the cross-sectional structure of the prestressed concrete sleeper at the lower part of the rail of the elastic long sleeper for ballasted track of the present invention;

[0030] Figure 6 It is a schematic diagram of the middle cross-sectional structure of the prestressed concrete sleeper of the elastic long sleeper for ballasted track of the present invention;

[0031] Figure 7 A schematic structural diagram for showing a sleeper pad fixing device in a long elastic sleeper for a ballasted track of the present invention;

[0032] Figure 8 A schematic structural diagram for showing a dovetail-shaped protrusion in a long elastic sleeper for a ballasted track of the present invention;

[0033] Fig. 9 The assembly flow chart of the elastic long sleeper for ballasted track of the present invention;

[0034] Fig.10 The present invention is a flow chart for replacing the sleeper pad of the elastic long sleeper for ballasted track.

[0035] Reference numerals:

[0036] 1. Prestressed concrete sleeper; 1-1. Pre-tightening bolt hole; 1-2. Limiting groove; 1-3. Section width variation of sleeper; 1-4. Section width equal under rail; 1-5. Embedded sleeve; 2. Elastic sleeper cushion; 2-1. Dovetail protrusion; 3. Protective layer; 4. Sleeper pad fixing device; 4-1. Protrusion; 4-2. Bolt hole; 5. Pre-tightening bolt; 6. Embedded sleeve type spring clip II fastener; 7. Rail. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0039] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0040] The elastic long sleeper for ballasted track provided in the present invention is Figure 1-Figure 2 , including a prestressed concrete sleeper 1, a protective layer 3 and a sleeper pad fixing device 4. The elastic sleeper pad 2 and the protective layer 3 are arranged at the bottom of the prestressed concrete sleeper 1 from top to bottom, and the sleeper pad fixing device 4 hoops the elastic sleeper pad 2 and the protective layer 3 at the bottom of the prestressed concrete sleeper 1.

[0041] Specifically, the prestressed concrete sleeper 1 provides stable support for the upper track structure, bears the main pressure from the train load, and transfers it to the lower structure. The elastic sleeper pad 2 adopts a polyurethane elastic sleeper pad 2, which is located at the bottom of the prestressed concrete sleeper 1. Since the polyurethane material has good elasticity and vibration reduction performance, when the train load acts on the prestressed concrete sleeper 1, the elastic sleeper pad 2 can absorb and disperse part of the energy, thereby reducing the transmission of vibration to the lower structure (such as the roadbed, etc.). Its elastic characteristics can effectively buffer the impact force of the train load on the prestressed concrete sleeper 1 and reduce the vibration response of the track system. Compared with traditional vibration reduction measures, it can avoid traditional vibration reduction measures such as excessive ballast pad laying area and vibration reduction fasteners that cannot effectively reduce the natural frequency of the track system. The protective layer 3 is located below the elastic sleeper pad 2 and plays a role in protecting the elastic sleeper pad 2. In a ballasted track environment, the ballast may cause damage such as wear and puncture to the elastic sleeper pad 2. The protective layer 3 can block the direct contact between the ballast and the elastic sleeper pad 2 to prevent the ballast from damaging it, thereby extending the service life of the elastic sleeper pad 2 and ensuring its long-term stable vibration reduction performance. The sleeper pad fixing device 4 hoops the elastic sleeper pad 2 and the protective layer 3 at the bottom of the prestressed concrete sleeper 1. This fixing method ensures a tight connection between the various components. Compared with some existing technologies (such as technologies that require more bolts to fix and are prone to local tearing of the sleeper pad), it can more stably fix the elastic sleeper pad 2 and the protective layer 3, prevent the relative displacement of the various components under the long-term train load, and thus ensure the continued effectiveness of the vibration reduction function.

[0042] Reference Figure 3-Figure 6The prestressed concrete sleeper 1 includes a section 1-4 with a constant width under the rail section, a section 1-3 with a varying width under the rail section, and a middle section of the sleeper. The prestressed concrete sleeper 1 is a specially made ST-II type concrete sleeper. Compared with the design in which the width of the traditional IIIa or XII type sleepers is continuously widened toward the outside of the sleepers, the width of the ST-II type concrete sleepers is always consistent from the end of the section 1-4 with a constant width under the rail section to the edge of the middle section of the sleeper except for the position of the rail support platform. Specifically, while reducing the volume of the prestressed concrete sleeper 1, it can meet the normal use requirements under the action of train loads in the vehicle depot. The cross-section height of the prestressed concrete sleeper 1 is 180mm, the upper bottom width is 210mm, and the lower bottom width is 250mm. The cross-section height under the rail of the prestressed concrete sleeper 1 is 210mm, the width of the rail support platform is 170mm, and the lower bottom width is 260mm; in addition, the prestressed concrete sleeper 1 is arranged with three layers of φ6.25 prestressed steel bars, and is equipped with embedded sleeve-type spring bar II type fasteners that can be easily disassembled. The embedded sleeves 1-5 are embedded in the prestressed concrete sleeper 1 when the prestressed concrete sleeper 1 is cast. The prestressed concrete sleeper 1 is provided with a 350mm long sleeper cross-section width change section 1-3 between the middle cross-section of the sleeper and the cross-section under the rail, so as to evenly change the cross-section size under the rail to the middle cross-section of the sleeper. The equal width design of the equal width section 1-4 under the rail section is conducive to providing a stable support surface in this area. In the track system, the train load is transmitted to the prestressed concrete sleeper 1 through the steel rail 7. The equal width section can evenly disperse the load and reduce the local stress concentration. The design of the variable width section 1-3 of the sleeper section maintains the lateral resistance of the prestressed concrete sleeper 1 at the same level as the existing prestressed concrete sleeper 1. At the same time, the equal width section 1-4 under the rail section width cancels the design of gradually widening the width of the prestressed concrete sleeper 1 outward, which reduces the amount of concrete and facilitates the installation of the sleeper pad fixing device 4. The middle section of the sleeper and the variable width section 1-3 of the sleeper section work together to form the overall structure of the prestressed concrete sleeper 1. The design of the middle section of the sleeper and the synergistic effect of the variable width section 1-3 of the sleeper section ensure the structural stability and load transfer capacity of the prestressed concrete sleeper 1 in the entire length direction. The equal width section 1-4 under the rail section width, the variable width section 1-3 of the sleeper section width and the middle section of the sleeper cooperate with each other, so that the prestressed concrete sleeper 1 can effectively play a role under different working conditions. When bearing train load, the load transferred from the rail 7 first acts on the equal width section 1-4 under the rail, and the equal width section evenly disperses the load and gradually adjusts the stress distribution through the sleeper section width variation section 1-3, and finally transfers it to the middle section of the sleeper. This synergistic effect ensures the structural integrity of the prestressed concrete sleeper 1 under long-term train load, reduces the risk of structural damage caused by stress concentration, and improves the durability and reliability of the prestressed concrete sleeper 1.

[0043] The elastic sleeper pad layer 2 is only partially laid in the equal width section 1-4 under the rail section width. The equal width section 1-4 under the rail section width is one of the main action areas of the train load on the prestressed concrete sleeper 1. Since the ballasted track bed and the prestressed concrete sleeper 1 are partially supported or unsupported in the negative bending moment area of ​​the sleeper, the pressure of the train wheels is mainly concentrated in this section area under the rail, so the vibration in this area is relatively large. Laying the elastic sleeper pad layer 2 only in this area can be targeted to reduce vibration in the area with large vibration. At the same time, compared with the full prestressed concrete sleeper 1 pad under the sleeper, the amount of polyurethane material is reduced, and the economy of the elastic sleeper structure is improved. The polyurethane material has good elasticity and vibration reduction performance, which can effectively absorb and dissipate the vibration energy generated in this area, and reduce the transmission of vibration to other parts of the prestressed concrete sleeper 1 and the structure below. From the perspective of cost, if the elastic sleeper pad 2 is fully laid on the bottom of the entire prestressed concrete sleeper 1, the material cost and construction cost will increase. However, if it is only partially laid in the equal width section 1-4 of the rail section width, the cost can be reduced while meeting the main vibration reduction requirements. This local laying method can effectively treat the key vibration reduction area of ​​the prestressed concrete sleeper 1 at a lower cost, thereby improving the cost performance of the entire ballasted track system. The structural characteristics of the equal width section 1-4 of the rail section width provide better conditions for the laying of the elastic sleeper pad 2. The relatively regular shape and stable structure of the equal width section enable the vibration reduction pad to better fit it, ensuring the stability of the vibration reduction effect. At the same time, this local laying method also avoids the unnecessary structural complexity and potential performance interference that may be caused by laying the vibration reduction pad in other areas where it is not needed or the vibration reduction requirements are small (such as the sleeper section width change section 1-3 and part of the middle section of the sleeper).

[0044] Reference Figure 7The sleeper pad fixing device 4 includes a hoop and a pre-tightening bolt 5. A pre-tightening bolt hole 1-1 is provided on the prestressed concrete sleeper 1, and a bolt hole 4-2 is correspondingly provided on the hoop. The pre-tightening bolt 5 passes through the bolt hole 4-2 and is threadedly connected to the pre-tightening bolt hole 1-1. The hoop can clamp the elastic sleeper cushion layer 2 and the protective layer 3 at the bottom of the prestressed concrete sleeper 1. Through the clamping effect of the hoop, a tight overall structure is formed between the components. Under the long-term load of the train, this clamping effect can prevent the elastic sleeper cushion layer 2 and the protective layer 3 from displacement. For example, when the vibration and impact force generated by the passing of the train attempts to move the cushion layer or the protective layer 3, the hoop can effectively limit their movement, ensuring that the relative position between the components remains stable, thereby maintaining the structural integrity and vibration reduction performance of the entire prestressed concrete sleeper 1. Uniform force transmission: During the tightening process, the hoop can make the force transmission between the components more uniform. Since it connects the components tightly together, when the train load acts on the prestressed concrete sleeper 1, the force can be evenly dispersed to the elastic sleeper cushion 2, the protective layer 3 and the prestressed concrete sleeper 1 through the hoop. This uniform force transmission helps to reduce the situation of local stress concentration, avoid damage to a certain part due to excessive force, and extend the service life of each component. The pre-tightening bolt 5 passes through the bolt hole 4-2 on the hoop and is threadedly connected to the pre-tightening bolt hole 1-1 on the prestressed concrete sleeper 1. This connection method provides a reliable fixing force for the hoop. During the tightening process, the pre-tightening bolt 5 will generate a pre-tightening force, so that the hoop is tightly fixed to the bottom of the prestressed concrete sleeper 1. Compared with other fixing methods, bolt connection has higher reliability and stability. For example, during long-term use, even if it is affected by factors such as train vibration and temperature changes, the bolt connection can maintain the connection relationship between the components and prevent the hoop from loosening.

[0045] In addition, the connection method of the pre-tightening bolt 5 also has a certain degree of adjustability. During the installation process, the tightening degree of the pre-tightening bolt 5 can be adjusted to control the clamping force of the hoop on the elastic sleeper pad 2 and the protective layer 3. This adjustability enables the sleeper pad fixing device 4 to adapt to different working conditions and component tolerances. At the same time, the installation method of the bolt connection is relatively simple, and the construction personnel can conveniently perform the installation operation, which improves the construction efficiency. The hoop and the pre-tightening bolt 5 work together to fix the elastic sleeper pad 2 and the protective layer 3. The hoop first tightens the components to provide a preliminary fixing force so that the components are initially fitted together. Then, the pre-tightening force generated by tightening the pre-tightening bolt 5 further strengthens this fixing effect. Under the action of train load, the hoop bears the lateral force from the cushion layer and the protective layer 3 to prevent them from lateral displacement, while the pre-tightening bolt 5 mainly bears the longitudinal tensile force to ensure that the hoop will not loosen or detach from the prestressed concrete sleeper 1 in the longitudinal direction; this synergistic effect ensures the reliability and stability of the entire sleeper pad fixing device 4 during long-term use, thereby ensuring the vibration reduction performance and structural integrity of the prestressed concrete sleeper 1.

[0046] Reference Figure 7, a limiting groove 1-2 is provided on the side of the prestressed concrete sleeper 1, and a protrusion 4-1 adapted to the limiting groove 1-2 is provided on the relative inner side of the hoop. When installing the sleeper pad fixing device 4, the construction personnel can accurately determine the installation position of the hoop according to the position of the limiting groove 1-2, and ensure that the relative position of the hoop and the prestressed concrete sleeper 1 is accurate. This helps to improve the installation accuracy of the entire elastic long sleeper, thereby ensuring the matching accuracy between the components, which is conducive to achieving the best vibration reduction performance of the elastic long sleeper. In addition, the limiting groove 1-2 can limit the lateral movement of the hoop to a certain extent. When the train load acts on the prestressed concrete sleeper 1, a lateral force will be generated, and this force may cause the hoop to move laterally. The limiting groove 1-2 is adapted to the protrusion 4-1 on the hoop, and the wall of the groove can block the movement of the hoop in the lateral direction, thereby ensuring the position stability of the hoop in the lateral direction, and further maintaining the stability of the entire elastic long sleeper structure. The protrusion 4-1 on the inner side of the hoop is adapted to the limiting groove 1-2. This structural design enhances the connection stability between the hoop and the prestressed concrete sleeper 1. The protrusion 4-1 is embedded in the limiting groove 1-2 to form a connection method similar to a mortise and tenon structure, which increases the contact area between the hoop and the prestressed concrete sleeper 1, making the connection between the hoop and the prestressed concrete sleeper 1 tighter and stronger. Compared with the connection relying solely on the pre-tightening bolts 5, this structure can better resist various forces caused by train loads, such as vibration, impact force, etc., and prevent the hoop from loosening or detaching from the prestressed concrete sleeper 1. Under the action of train loads, stress needs to be transferred between various components. The cooperation between the protrusion 4-1 and the limiting groove 1-2 provides a supplementary way for stress transfer. When the hoop is subjected to the force from the elastic sleeper pad 2 and the protective layer 3, in addition to transmitting stress through the pre-tightening bolts 5, part of the stress can also be transmitted to the prestressed concrete sleeper 1 through the contact between the protrusion 4-1 and the limiting groove 1-2. This multi-path stress transfer method helps to disperse stress more evenly, reduce local stress concentration, and improve the bearing capacity of the entire elastic long sleeper structure.

[0047] The elastic sleeper cushion layer 2 is connected to the prestressed concrete sleeper 1 through a binder, and the binder can be an epoxy resin-based adhesive, a polyurethane adhesive, an acrylate adhesive, etc.; the binder connects the elastic sleeper cushion layer 2 to the prestressed concrete sleeper 1, and its main function is to provide bonding force. During the long-term use of the track system, the continuous operation of the train will generate vibration, impact force and other forces. The bonding force of the binder can resist these forces and prevent the elastic sleeper cushion layer 2 from separating from the prestressed concrete sleeper 1. This bonding force ensures that the relative position between the two is fixed, which is an important factor in maintaining the overall structural integrity of the elastic long sleeper. When the train load acts on the prestressed concrete sleeper 1, the stress will be transferred from the prestressed concrete sleeper 1 to the elastic sleeper cushion layer 2. The binder, as a connecting medium, can make the stress more evenly transferred between the two. Compared with the mechanical connection method, the binder can fill the tiny gap between the elastic sleeper cushion layer 2 and the surface of the prestressed concrete sleeper 1, making the stress transfer more continuous and smooth, avoiding the occurrence of stress concentration, and thus extending the service life of the elastic sleeper cushion layer 2 and the prestressed concrete sleeper 1.

[0048] Reference Figure 8 , the elastic sleeper pad 2 is connected to the prestressed concrete sleeper 1 through the dovetail protrusion 4-1 when the prestressed concrete sleeper 1 is cast. A groove adapted to the dovetail protrusion 4-1 is provided at the bottom of the prestressed concrete sleeper 1, wherein the structural characteristics of the dovetail shape provide better connection stability in both vertical and horizontal directions. In the vertical direction, the dovetail shape can resist the separation force caused by the up and down vibration caused by the train load; in the horizontal direction, the two side walls of the dovetail shape can prevent the elastic sleeper pad 2 from sliding laterally relative to the prestressed concrete sleeper 1. The dovetail protrusion 4-1 also has the function of positioning and guiding during the connection process. When installing the elastic sleeper pad 2, the dovetail protrusion 4-1 can be accurately embedded in the corresponding structure on the prestressed concrete sleeper 1, which helps the construction personnel to quickly and accurately perform the installation operation, and improves the installation efficiency and installation accuracy. At the same time, this structure can also ensure the relative position accuracy of the elastic sleeper pad 2 and the prestressed concrete sleeper 1 after connection, which is conducive to achieving the best vibration reduction performance of the elastic long sleeper.

[0049] The elastic sleeper cushion layer 2 and the protective layer 3 are connected by adhesive. This connection method is commonly used in the field of rail transit. The adhesive can provide good bonding force to ensure a firm connection between the elastic sleeper cushion layer 2 and the protective layer 3, thereby effectively transferring stress and reducing the spread of vibration and noise.

[0050] The material of the protective layer 3 is polyamide fiberboard or rubber board, which can withstand greater pressure and tension, has good wear resistance, is suitable for occasions requiring long-term use, has good corrosion resistance to many chemical substances, has a smooth surface and low friction.

[0051] Reference Figure 9-10 The present invention provides a method for replacing a sleeper pad of an elastic long sleeper for a ballasted track, comprising the following steps:

[0052] Step 1: Replace the sleeper pad in accordance with the line maintenance plan. First, loosen the embedded sleeve type spring clip II type fastener 6 to separate the prestressed concrete sleeper 1 from the rail 7. The embedded sleeve type spring clip II type fastener 6 serves to connect the rail 7 and the prestressed concrete sleeper 1. Loosening it can release the constraint of the rail 7 on the prestressed concrete sleeper 1, making it convenient for subsequent operations on the elastic sleeper cushion layer 2 and the elastic sleeper cushion layer 2. This operation mode according to the line maintenance plan can replace the elastic sleeper cushion layer 2 in an organized and planned manner without affecting the normal railway operation, thereby reducing interference with railway transportation.

[0053] Step 2: loosen the pre-tightening bolts 5 to separate the elastic sleeper pad 2 from the prestressed concrete sleeper 1; the sleeper pad fixing device 4 is firmly connected to the prestressed concrete sleeper 1 through the pre-tightening bolts 5. Only by loosening the pre-tightening bolts 5 can the subsequent elastic sleeper pad 2 be replaced or repaired. This step reflects the reasonable order in the process of replacing the elastic sleeper pad 2. First, the constraints of the fixing device are released, and then the operation of the sleeper pad related components is performed;

[0054] Step 3. If the protective layer 3 is found to be damaged during routine line maintenance, only the protective layer 3 can be torn off from under the elastic sleeper pad 2 and the protective layer 3 can be re-bonded; if the elastic sleeper pad 2 is replaced during the line overhaul period, the elastic sleeper pad 2 can be torn off from the bottom of the sleeper, and the new elastic sleeper pad 2 and the protective layer 3 can be re-bonded to the prestressed concrete sleeper 1; during daily line maintenance, if only the protective layer 3 is found to be damaged, only the protective layer 3 can be torn off from under the elastic sleeper pad 2 and the protective layer 3 can be re-bonded. This treatment method can not only solve the problem of damage to the protective layer 3, but also avoid large-scale replacement of the entire elastic sleeper pad 2, saving maintenance costs and time; and during the line overhaul period, since the sleeper pad may have been used for a long time, the elastic sleeper pad 2 can be torn off from the bottom of the prestressed concrete sleeper 1, and the new elastic sleeper pad 2 and the protective layer 3 can be re-bonded, so that the key components of the elastic sleeper pad 2 can be fully updated, the performance of the elastic long sleeper can be improved, and its service life can be extended;

[0055] Step 4, resetting the sleeper pad fixing device 4, retightening the pre-tightening bolts 5 and reinstalling the fasteners to achieve continuous use of the elastic long sleeper; after completing the replacement or repair of the sleeper pad related parts, resetting the sleeper fixing device 4, retightening the pre-tightening bolts 5 and reinstalling the fasteners are the key finishing steps of the entire replacement process; retightening the pre-tightening bolts 5 can ensure that the sleeper pad fixing device 4 is firmly fixed on the prestressed concrete sleeper 1, and reinstalling the fasteners restores the connection relationship between the rail 7 and the prestressed concrete sleeper 1, so that the elastic long sleeper can work normally again and achieve the purpose of continuous use; this step ensures the integrity of the elastic long sleeper structure and the restoration of functionality.

[0056] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. An elastic long sleeper for ballasted track, characterized in that: The invention comprises a prestressed concrete sleeper, an elastic sleeper cushion layer, a protective layer and a sleeper cushion fixing device. The elastic sleeper cushion layer and the protective layer are arranged on the bottom of the prestressed concrete sleeper in sequence from top to bottom. The sleeper cushion fixing device clamps the elastic sleeper cushion layer and the protective layer on the bottom of the prestressed concrete sleeper.

2. The elastic long sleeper for ballasted track according to claim 1, characterized in that: The prestressed concrete sleeper comprises a section with a constant width of the cross-section under the rail, a section with a varying width of the cross-section under the rail and a middle section of the sleeper. The width of the end of the section with a constant width of the cross-section under the rail is always consistent from the end position of the section with a varying width of the cross-section under the rail to the edge of the middle section of the sleeper.

3. The elastic long sleeper for ballasted track according to claim 2, characterized in that: The elastic sleeper cushion layer is only partially laid in the section with equal width under the rail.

4. The elastic long sleeper for ballasted track according to claim 1, characterized in that: The sleeper pad fixing device includes a hoop and a pre-tightening bolt. The pre-stressed concrete sleeper is provided with a pre-tightening bolt hole, and the hoop is correspondingly provided with a bolt hole. The pre-tightening bolt passes through the bolt hole and is threadedly connected in the pre-tightening bolt hole.

5. The elastic long sleeper for ballasted track according to claim 4, characterized in that: A limiting groove is provided on the side of the prestressed concrete sleeper, and a protrusion matched with the limiting groove is provided on the opposite inner side of the hoop.

6. The elastic long sleeper for ballasted track according to claim 1, characterized in that: The elastic sleeper cushion layer is connected to the prestressed concrete sleeper through a binder.

7. The elastic long sleeper for ballasted track according to claim 1, characterized in that: The elastic sleeper cushion layer is connected to the prestressed concrete sleeper through a dovetail protrusion.

8. The elastic long sleeper for ballasted track according to claim 1, characterized in that: The elastic sleeper cushion layer and the protective layer are connected by adhesive.

9. The elastic long sleeper for ballasted track according to claim 1, characterized in that: The material of the protective layer is a polyamide fiber board or a rubber board.

10. The method for replacing sleeper pads of elastic long sleepers for ballasted track according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: Replace the sleeper pads according to the line maintenance plan. First, separate the sleepers that need to be replaced from the rails. Step 2: Separate the sleeper pad fixing device from the sleeper; Step 3: If the protective layer is found to be damaged during routine inspection and maintenance of the line, the protective layer can be torn off from under the elastic sleeper cushion layer and re-bonded to the sleeper. If the sleeper cushion layer is replaced during the line overhaul period, the elastic sleeper cushion layer can be torn off from the bottom of the sleeper and the new elastic sleeper cushion layer and protective layer can be re-bonded to the sleeper. Step 4: Reset the sleeper pad fixing device, retighten the pre-tightening bolts and reinstall the fasteners to ensure continuous use of the elastic long sleeper.

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