Novel prestressed ballastless track structure crack repairing structure and reinforcing method

Abstract

The invention discloses a novel prestressed ballastless track structure crack repairing and reinforcing method. A track plate body, prestressed Fe-SMA ribs, a clamping type power-on interface, a protective sleeve and a cement mortar covering layer are included. A plurality of track slab cracks are formed in a track slab body, a plurality of prestressed Fe-SMA ribs are reinforced at the track slab cracks, each prestressed Fe-SMA rib is divided into two sections, namely a reinforcing excitation area and an anchoring monitoring area, and a stable shape memory effect can be generated after a series of processes such as heat treatment. Internal crystal lattices are converted into austenite phases from martensite phases through temperature rise excitation of the pre-deformed Fe-SMA ribs, the pre-stressed Fe-SMA ribs generate martensite phase transformation under large stress and fatigue load, and the pre-stressed Fe-SMA ribs undergo certain circulation on the track slab which is a component bearing fatigue load for a long time. After the prestress loss occurs, excitation is conducted again, the prestress loss can be compensated, through the arrangement method that one rib has two purposes, the integration of inspection, repair, monitoring and prevention can be achieved, and the economic benefits are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-speed railway ballastless track structure reinforcement, and in particular to a novel prestressed ballastless track structure crack repair structure and reinforcement method. Background Art

[0002] As the primary load-bearing component of high-speed rail systems, ballastless track slabs, exposed to various environmental influences (such as wind and sand, salinity, ice and snow), temperature loads, and train dynamic loads, have developed cracks of varying degrees over time. These cracks degrade the physical and mechanical properties of the concrete, corrode the steel reinforcement, and cause water seepage through the cracks, accelerating the settlement of the underlying foundation. This significantly impacts the safety, smoothness, and stability of high-speed rail operations.

[0003] According to the "Ballastless Track Maintenance Rules," the primary methods for treating cracks in ballastless track slabs are surface sealing and pressureless grouting, which involves filling the cracks with various repair materials (e.g., cement mortar, epoxy resin, etc.). However, in actual projects, due to the inherent durability issues of these repair materials, the ballastless track slabs, which primarily bear the fatigue loads of trains, are prone to cracking again after repair, resulting in less than ideal repair results. Furthermore, due to the limited railway window period, significant inspection and maintenance costs are still required later. Furthermore, traditional prestressed reinforcement technology is difficult to implement due to the large tensioning equipment and complex construction process. Summary of the Invention

[0004] Purpose of the invention: The present invention proposes a novel prestressed ballastless track structure crack repair structure and reinforcement method, which completes the crack repair and reinforcement work of the cracked track plate within a limited track window period, saving the subsequent inspection and maintenance costs.

[0005] Technical solution: The present invention proposes a novel prestressed ballastless track structure crack repair structure, comprising a track plate main body and a prestressed repair structure, wherein the prestressed repair structure comprises prestressed Fe-SMA tendons; the track plate main body comprises a track plate crack, a track plate notch and a drilled hole, wherein the track plate notch intersects with the track plate crack, the track plate notch is formed by being recessed downward from the surface of the track plate main body, the drilled hole is located at both ends of the track plate notch and is recessed downward from the surface of the track plate main body, the prestressed Fe-SMA tendons are placed in the track plate notch, and the two ends of the prestressed Fe-SMA tendons are bent and inserted into the drilled holes; the prestressed Fe-SMA tendons comprise a reinforcement excitation area and an anchoring excitation area, wherein the anchoring excitation area is located at both ends of the prestressed Fe-SMA tendons, and the reinforcement excitation area is located in the middle of the prestressed Fe-SMA tendons, clamping-type power supply interfaces are provided at both ends of the reinforcement excitation area, and a strain sensor and a temperature sensor are installed on the anchoring excitation area.

[0006] Preferably, the track plate notch depth is 3-5 cm, and the drilled hole depth is 10-15 cm.

[0007] Preferably, the length of the prestressed Fe-SMA tendon is greater than 80 cm, and the bending length is greater than 10 cm.

[0008] Preferably, the clamping power supply interface is clamped at both ends of the reinforced excitation area by a clamp.

[0009] Preferably, the clamping power supply interface further includes a bolt and a conductive copper plate, and the conductive copper plate is fixedly connected to the external excitation power supply via the bolt.

[0010] Preferably, a protective sleeve is provided on the outside of the clamping power supply interface, and holes on both sides of the protective sleeve are used to install bolts.

[0011] Preferably, the surface of the track plate notch is provided with a cement mortar covering layer.

[0012] Preferably, the cement mortar covering layer is made of cement mortar with a water-cement ratio of 0.14, and the cement mortar is added with a volume content of 0.2% PVA and PP fiber.

[0013] A novel reinforcement method for a crack repair structure of a prestressed ballastless track structure comprises the following steps:

[0014] Step 1: Confirm the number and location of track slab cracks;

[0015] Step 2: Grooving is performed on the upper surface of the track plate body at the position of the track plate crack to form a track plate groove intersecting with the track plate crack, and drilling holes downward at both ends of the track plate groove to form drill holes;

[0016] Step 3: Cut and bend the prestressed Fe-SMA tendons, determine the length and position of the reinforcement excitation area and anchoring excitation area on the prestressed Fe-SMA tendons, and arrange the strain sensor, temperature sensor, and clamp-type power supply interface;

[0017] Step 4: Clean the main working surface of the track plate, clean the track plate grooves and track plate cracks;

[0018] Step 5: Place the prestressed Fe-SMA reinforcement into the groove of the track plate, and insert the bent end of the prestressed Fe-SMA reinforcement into the drilled hole;

[0019] Step 6: Prepare cement mortar grouting material, pour the cement mortar grouting material with a water-cement ratio of 0.14 and 0.2% by volume of PVA and PP fiber into the track slab groove, and form a cement mortar cover layer after static curing;

[0020] Step 7: After curing, connect the power supply to the clamping power interface. Power on to heat the prestressed Fe-SMA bars in the reinforcement excitation area to generate prestress. The temperature and prestress are transmitted to the anchor monitoring area through the reinforcement excitation area. The strain sensors and temperature sensors attached to the anchor monitoring area start working synchronously.

[0021] Step 8: Disconnect the power supply until the cracks in the track plate are closed. After the power is turned on, put the protective sleeve on the clamping power interface.

[0022] Preferably, the temperature range of the prestressed Fe-SMA tendons in step seven is 200°C to 400°C.

[0023] Beneficial effects: The present invention discloses a novel method for repairing and reinforcing cracks in prestressed ballastless track structures. This method can, on the basis of the original "passive" repair, "actively" apply prestress to resist track plate cracking caused by the coupling of environmental factors and train running loads, thereby effectively improving the track plate repair and reinforcement effect. Moreover, when prestress loss occurs, it is only necessary to re-energize the excitation to compensate for the prestress loss, thereby reducing the subsequent detection and maintenance costs. A "one-rebar dual-purpose" method is proposed, that is, the prestressed Fe-SMA tendons not only provide structural reinforcement function, but also serve as structural monitoring components, equipped with necessary sensor elements to reduce the subsequent monitoring and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the track slab before reinforcement and repair according to the present invention;

[0025] Figure 2 Schematic diagram of track plate reinforcement and repair according to the present invention

[0026] Figure 3 This is a schematic diagram of the track slab after reinforcement and repair according to the present invention;

[0027] Figure 4 This is a schematic diagram of local slotting and drilling of the track plate of the present invention;

[0028] Figure 5 Schematic diagram of the track slab reinforcement and rebar planting method of the present invention;

[0029] Figure 6 This is a schematic diagram of the prestressed Fe-SMA reinforcement installation of the present invention;

[0030] Figure 7 This is a schematic diagram of the clamping power interface of the present invention;

[0031] Figure 8 A top view of the clamping power interface of the present invention;

[0032] Figure 9 Schematic diagram of the protective sleeve of the present invention. DETAILED DESCRIPTION

[0033] like Figures 1 to 8 As shown, the present invention discloses a novel prestressed ballastless track structure crack repair structure, comprising a track plate body 1 and a prestressed repair structure 7, the prestressed repair structure 7 comprising a prestressed Fe-SMA rib 2, a clamping power interface 3, a protective sleeve 4, a strain sensor 5 and a temperature sensor 6; the track plate body 1 comprises a track plate crack 11, a track plate notch 12 and a drilled hole 13, the track plate notch 12 intersects with the track plate crack 11 and is located on the surface of the track plate crack 11, the drilled hole 13 is located at both ends of the track plate notch 12, the prestressed Fe-SMA rib 2, a clamping power interface 3, a protective sleeve 4, a strain sensor 5 and a temperature sensor 6; the track plate body 1 comprises a track plate crack 11, a track plate notch 12 and a drilled hole 13, the track plate notch 12 intersects with the track plate crack 11 and is located on the surface of the track plate crack 11, the drilled hole 13 is located at both ends of the track plate notch 12, The MA reinforcement 2 is placed in the track plate groove 12, and the two ends of the prestressed Fe-SMA reinforcement 2 are bent and inserted into the drilled hole 13. The surface of the track plate groove 12 is provided with a cement mortar covering layer 7; the prestressed Fe-SMA reinforcement 2 includes a reinforcement excitation area 21 and an anchoring excitation area 22. The anchoring excitation area 22 is located at both ends of the prestressed Fe-SMA reinforcement 2, and the reinforcement excitation area 21 is located in the middle of the prestressed Fe-SMA reinforcement 2. Clamping power interfaces 3 are provided on both ends of the reinforcement excitation area 21, and strain sensors 5 and temperature sensors 6 are installed on the anchoring excitation area 22.

[0034] The track slab notch 12 has a depth of 3-5 cm, the drilled hole 13 has a depth of 10-15 cm, the prestressed Fe-SMA bar 2 is greater than 80 cm long, and the bending length is greater than 10 cm. The prestressed Fe-SMA bar is an iron-based shape memory alloy that produces a stable shape memory effect (SME) through a series of heat treatment processes. Unlike traditional steel bars that apply prestress through tensioning equipment, the prestressing effect is achieved by heating the pre-deformed Fe-SMA bar to transform the internal lattice from the martensite phase to the austenite phase. At this time, the deformation of the Fe-SMA bar is constrained, thereby achieving the prestressing effect. In addition, under high stress and fatigue loads, the prestressed Fe-SMA bar undergoes a martensitic phase transformation, rather than the lattice slip phenomenon of traditional prestressed steel bars. Therefore, prestressed Fe-SMA bars have a natural advantage when used for components such as track slabs that are subjected to long-term fatigue loads. After a certain number of cycles, if prestress is lost, re-excitation can compensate for the prestress loss.

[0035] The prestressed Fe-SMA tendon 2 is divided into two sections, including a reinforcement excitation zone 21 and an anchorage monitoring zone 22; the reinforcement excitation zone 21 provides reinforcement and repair of the track plate structure, and the anchorage monitoring zone 22 provides later monitoring and maintenance. Through the "one tendon, two uses" arrangement method, the integration of "inspection, repair, monitoring, and prevention" can be achieved. When the excitation temperature of the prestressed Fe-SMA tendon 2 is 200°C, the effective prestress after cooling can reach 320-350MPa; when the excitation temperature is 300°C, the effective prestress after cooling can reach 380-400MPa.

[0036] The clamp-type power supply interface 3 is clamped at both ends of the reinforced excitation zone 21 by a fixture 31. The clamp-type power supply interface 3 also includes bolts 32 and a conductive copper plate 33. The conductive copper plate 33 is fixedly connected to the external excitation power source via the bolts 32. A protective sleeve 4 is positioned outside the clamp-type power supply interface 3, with holes on both sides for mounting the bolts 32. The fixture 31 is made of a high-temperature resistant ceramic-based composite material, which provides insulation and can withstand temperatures exceeding 300°C without deformation. The protective sleeve 4 is made of rubber and is placed over the power supply interface after excitation is completed as a protective device to facilitate multiple subsequent excitations.

[0037] The cement mortar covering layer is used for grouting and caulking the track plate notch 12 after reinforcement by planting reinforcement to protect the internal prestressed Fe-SMA tendons 2. The cement mortar covering layer is made of cement mortar with a water-cement ratio of 0.14, and the cement mortar is added with a volume content of 0.2% PVA and PP fiber.

[0038] A novel reinforcement method for a crack repair structure of a prestressed ballastless track structure comprises the following steps:

[0039] Step 1: First, determine the number, width, and location of the track slab cracks 11 and calculate the amount of prestressed Fe-SMA bars 2 required to close the cracks;

[0040] Step 2: Grooving is performed on the upper surface of the track plate body 1 at the position of the track plate crack 11 to form a track plate notch 12 intersecting the track plate crack 11, and drilling holes 13 are formed downwardly at both ends of the track plate notch 12;

[0041] Step 3: Cut and bend the prestressed Fe-SMA tendon 2, determine the length and position of the reinforcement excitation area 21 and the anchoring excitation area 22 on the prestressed Fe-SMA tendon 2, and arrange the strain sensor 5, temperature sensor 6 and clamping power interface 3;

[0042] Step 4: Clean the working surface of the track plate body 1, clean the track plate notches 12 and the track plate cracks 11;

[0043] Step 5: Place the prestressed Fe-SMA tendon 2 in the track plate notch 12, and insert the bent end of the prestressed Fe-SMA tendon 2 into the drilled hole 13;

[0044] Step 6: Prepare cement mortar grouting material, pour the cement mortar grouting material with a water-cement ratio of 0.14 and 0.2% by volume of PVA and PP fiber into the track plate groove 12, and form a cement mortar covering layer after static curing;

[0045] Step 7: After the curing is completed, the power supply is connected to the clamping power interface 3. The power is turned on to excite the prestressed Fe-SMA tendons 2 in the reinforcement excitation area 21 to heat up and generate prestress. The temperature and prestress are transmitted to the anchor monitoring area 22 through the reinforcement excitation area 21. The strain sensor 5 and temperature sensor 6 attached to the anchor monitoring area 22 start working synchronously.

[0046] Step 8: Disconnect the power supply until the crack 11 of the track plate is closed. After the power supply is turned on, put the protective sleeve 4 on the clamping power supply interface 3.

[0047] First, determine the number and location of the cracks 11 on the track plate body 1 and calculate the required amount of prestressed Fe-SMA tendons 2. After cleaning the surface of the track plate body 1, use a concrete saw or other tool to cut grooves at the locations of the cracks 11. The track plate grooves 12 must be able to accommodate the prestressed Fe-SMA tendons 2 to be placed. Then, use a drill bit to drill holes at the ends of the track plate grooves 12. The drilled holes 13 need to avoid the internal reinforcement of the track plate body 1 and ensure that the prestressed Fe-SMA tendons can be fully inserted at the bends. Then, use tools such as high-pressure water guns and vacuum cleaners to clean the track plate body 1, the track plate cracks 11, the track plate grooves 12 and the drilled holes 13 to prevent foreign matter from interfering when pouring cement mortar, which may affect the reinforcement and repair effect.

[0048] Bend the ends of the prestressed Fe-SMA tendons 2 at a bending angle of 90 degrees, and do not bend repeatedly; plan the reinforcement excitation area 21 and the anchor monitoring area 22, and use a high-temperature resistant ceramic clamp 31 to clamp the clamping power interface 3 at both ends of the reinforcement excitation area 22; install the strain sensor 5 and the temperature sensor 6 in the anchor monitoring area 22; then implant the prestressed Fe-SMA tendons 2 into the track plate slot 12, and insert the bent end into the drilled hole 13.

[0049] Some track slab cracks 11 may be wider and denser. In this case, the track slab notches 12 should be widened and more prestressed Fe-SMA bars 2 should be placed inside. Monitoring parameters may exceed those described in this disclosure. Sensors that can collect and monitor these other parameters through the prestressed Fe-SMA bars 2 fall within the scope of this disclosure.

[0050] Cement mortar grouting material is prepared on site and injected slowly and steadily into the track slab cracks 11, track slab notches 12 and drilled holes 13, with continuous vibration during the process, and then left to stand for curing to form a cement mortar covering layer.

[0051] Connect the power supply to the clamping power interface 3, clamp the internal conductive copper plate 33 with the power clip, and tighten it with the stainless steel hand-tightened bolt 32 to ensure normal contact during the excitation process; use the temperature sensor 6 to determine the temperature of the prestressed Fe-SMA tendon 2 at this time, and end the power supply after reaching the expected temperature; use the strain sensor 5 to determine whether the prestressing force meets the established requirements at this time. The power interface may have other forms, in which case the layout of the conductive copper plate 33 in the corresponding clamping power interface 3 needs to be changed accordingly. Put the protective sleeve 4 on the clamping power interface 3 after the power is turned on to prevent rust and damage. When a second excitation is needed in the future, remove it and repeat the above power-on excitation steps.

Claims

1. A new type of prestressed ballastless track structure crack repair structure, characterized in that: The invention comprises a track plate body (1) and a prestressed repair structure (7), wherein the prestressed repair structure (7) comprises a prestressed Fe-SMA rib (2); the track plate body (1) comprises a track plate crack (11), a track plate notch (12) and a drilled hole (13), wherein the track plate notch (12) intersects with the track plate crack (11), the track plate notch (12) is formed by being recessed downward from the surface of the track plate body (1), the drilled hole (13) is located at both ends of the track plate notch (12) and is recessed downward from the surface of the track plate body (1), and the prestressed Fe-SMA rib (2) is placed in the track plate body (1). The prestressed Fe-SMA tendon (2) is placed in the track plate notch (12), and the two ends of the prestressed Fe-SMA tendon (2) are bent and then inserted into the drilled hole (13); the prestressed Fe-SMA tendon (2) includes a reinforcement excitation area (21) and an anchoring excitation area (22), the anchoring excitation area (22) is located at the two ends of the prestressed Fe-SMA tendon (2), and the reinforcement excitation area (21) is located in the middle of the prestressed Fe-SMA tendon (2), a clamping power supply interface (3) is provided on both ends of the reinforcement excitation area (21), and a strain sensor (5) and a temperature sensor (6) are installed on the anchoring excitation area (22).

2. The novel prestressed ballastless track structure crack repair structure according to claim 1 is characterized in that: The track plate notch (12) has a depth of 3-5 cm, and the drilled hole (13) has a depth of 10-15 cm.

3. The novel prestressed ballastless track structure crack repair structure according to claim 1 is characterized in that: The length of the prestressed Fe-SMA tendon (2) is greater than 80 centimeters, and the bending length is greater than 10 centimeters.

4. The novel prestressed ballastless track structure crack repair structure according to claim 1 is characterized in that: The clamping-type power supply interface (3) is clamped at both ends of the reinforcement excitation area (21) by a clamp (31).

5. The novel prestressed ballastless track structure crack repair structure according to claim 1 is characterized in that: The clamping power supply interface (3) further comprises a bolt (32) and a conductive copper plate (33), and the conductive copper plate (33) is fixedly connected to an external excitation power source via the bolt (32).

6. The novel prestressed ballastless track structure crack repair structure according to claim 5 is characterized in that: The clamping type power supply interface (3) is provided with a protective sleeve (4) on the outside, and the holes on both sides of the protective sleeve (4) are used to install bolts (32).

7. The novel prestressed ballastless track structure crack repair structure according to claim 1 is characterized in that: The surface of the track plate notch (12) is provided with a cement mortar covering layer.

8. The novel prestressed ballastless track structure crack repair structure according to claim 1 is characterized in that: The cement mortar covering layer is made of cement mortar with a water-cement ratio of 0.14, and the cement mortar is added with a volume content of 0.2% PVA and PP fiber.

9. A reinforcement method for a novel prestressed ballastless track structure crack repair structure according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: Confirm the number and location information of the track slab cracks (11); Step 2: Slotting the upper surface of the track plate body (1) at the position of the track plate crack (11) to form a track plate notch (12) intersecting the track plate crack (11), and drilling downward at both ends of the track plate notch (12) to form drill holes (13); Step 3: cutting and bending the prestressed Fe-SMA tendon (2), determining the length and position of the reinforcement excitation area (21) and the anchoring excitation area (22) on the prestressed Fe-SMA tendon (2), and arranging the strain sensor (5), the temperature sensor (6) and the clamping power interface (3); Step 4: Clean the working surface of the track plate body (1), clean the track plate notches (12) and track plate cracks (11); Step 5: Place the prestressed Fe-SMA tendon (2) in the track plate notch (12), and insert the bent end of the prestressed Fe-SMA tendon (2) into the drilled hole (13); Step 6: preparing cement mortar grouting material, pouring the cement mortar grouting material with a water-cement ratio of 0.14 and adding 0.2% by volume of PVA and PP fiber into the track plate groove (12), and forming a cement mortar covering layer after static curing; Step 7: After the maintenance is completed, the power supply is connected to the clamping power interface (3), and the power is turned on to excite the prestressed Fe-SMA tendons (2) in the reinforcement excitation area (21) to heat up and generate prestress. The temperature and prestress are transmitted to the anchor monitoring area (22) through the reinforcement excitation area (21), and the strain sensor (5) and temperature sensor (6) attached to the anchor monitoring area (22) start working synchronously; Step 8: Disconnect the power supply until the crack (11) of the track plate is closed. After the power supply is turned off, put the protective sleeve (4) on the clamping power supply interface (3).

10. The reinforcement method of the novel prestressed ballastless track structure crack repair structure according to claim 9 is characterized in that: The temperature range of the prestressed Fe-SMA tendons (2) in step seven is 200°C to 400°C.

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