Vertical prestressed ballastless track structure and prestressing design calculation method

Abstract

The invention discloses a vertical prestressed ballastless track structure and a prestressed design and calculation method, wherein the vertical prestressed ballastless track structure comprises a center positioning device arranged in the middle of a prefabricated track plate and a post-tensioning prestressing device arranged around the prefabricated track plate, the center positioning device comprises a center positioning device mounting seat embedded in a foundation, and a positioning boss installed on the center positioning device mounting seat, a center prestressed steel bar is arranged on the positioning boss, a center prestressed tensioning head is installed on the center prestressed steel bar, the center prestressed tensioning head is provided with a center cone head matched with the positioning boss, the center prestressed tensioning head is also provided with a center pretightening head, the center pretightening head is threadedly matched with the center prestressed steel bar, the post-tensioning prestressing device comprises a prestressed device mounting seat embedded in the foundation, a prestressed steel bar is arranged on the prestressed device mounting seat, a prestressed steel bar is installed with a pretightening head, and the pretightening head and the prestressed steel bar are threadedly matched.

Description

Technical Field

[0001] The invention relates to the technical field of ballastless track, in particular to a vertical prestressed ballastless track structure and a prestressed design calculation method. Background Art

[0002] Ballastless track has outstanding advantages such as high track smoothness, simple maintenance, and low life cycle cost, and has been widely used in high-speed railways at home and abroad. In the process of high-speed railway development in my country, CRTSI, CRTSII, and CRTSIII series of slab ballastless track systems have been developed in succession according to railway operating conditions and environmental conditions.

[0003] Generally speaking, slab track is composed of rails, fasteners, prefabricated track slabs, foundations, limit devices, and adjustment isolation layers. The main difference between different types of slab track is the longitudinal and transverse force transmission mechanism. CRTS I slab track transmits longitudinal and transverse forces through convex baffles, and the adjustment layer uses CA mortar. CRTS II slab track adopts longitudinal continuity, and the roadbed section transmits transverse forces through interlayer connections and longitudinal connections, and the bridge section realizes transverse force transmission through blocks. CRTS III slab track realizes the transmission of longitudinal and transverse forces through the limit grooves under the slab, and the adjustment layer uses self-compacting concrete.

[0004] The above-mentioned ballastless track structures all adopt a layered structural system with clear division of labor among the layers and reliable load-bearing. However, some engineering problems have also been exposed during the long-term service process. The more prominent common problems are inter-layer separation, cracking, slurry and even voiding, which have serious harm to the durability and long-term service performance of the ballastless track, and even directly affect the vehicle's operating performance. Track inter-layer diseases are a gradual evolution process, and separation is the root cause of many diseases. After early separation, the inter-layer flapping will occur when the train passes, causing damage to the structure. In addition, rainwater erosion will aggravate the differentiation between layers, which will cause slurry and even cracking.

[0005] The slab track is a stacked structure, and its structural characteristics determine that it can only bear pressure in one direction in the vertical direction, but not tension. When the track plate is thermally warped or the base is partially settled, it will inevitably lead to tension between the layers. This is a common problem of existing track structures. It is extremely necessary to carry out technical innovation based on the existing track structure and develop a track structure and design calculation method that has bidirectional force bearing capacity in the vertical direction and is more integrated. Summary of the invention

[0006] The purpose of the present invention is to provide a vertical prestressed ballastless track structure and a prestressed design calculation method to solve the problems existing in the prior art, so as to enhance the vertical integrity of the slab ballastless track and suppress the uneven vertical deformation between layers.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A vertical prestressed ballastless track structure comprises rails, fasteners, a prefabricated track slab, an adjustment layer and a foundation, and further comprises a center positioning device and a post-tensioning prestressing device, wherein the center positioning device is arranged in the middle of the prefabricated track slab, and the post-tensioning prestressing device is arranged around the prefabricated track slab, and the center positioning device and the post-tensioning prestressing device are both anchored in the foundation and penetrate upward through the adjustment layer and the prefabricated track slab.

[0009] The center positioning device includes a center positioning device mounting seat embedded in the foundation, and a positioning boss mounted on the center positioning device mounting seat, the positioning boss is provided with a center prestressed steel rod, the center prestressed steel rod is provided with a center prestressed tensioning head, the center prestressed tensioning head is provided with a center cone head matched with the positioning boss, the center prestressed tensioning head is also provided with a center pre-tightening head, and the center pre-tightening head is threadedly matched with the center prestressed steel rod.

[0010] The post-tensioning prestressing device includes a prestressing device mounting seat embedded in the four sides of the foundation, a prestressing steel rod is arranged on the prestressing device mounting seat, a prestressing head is installed on the prestressing steel rod, and the prestressing head and the prestressing steel rod are threadedly matched.

[0011] The present invention realizes force transmission in the horizontal and vertical directions through positioning bosses, realizes compressive force transmission in the vertical direction through interlayer stacking, and realizes tensile force transmission through prestressing devices (including center positioning devices and post-tensioning prestressing devices). The rails, prefabricated track plates, adjustment layers and foundations realize bidirectional force transmission in the vertical, horizontal and vertical directions, ensuring coordinated deformation between the track structure layers, preventing interlayer separation, air separation and slurry leakage, and at the same time ensuring the vertical and horizontal stability of the track.

[0012] The track plate deforms into a concave umbrella shape under a positive temperature gradient and into a convex umbrella shape under a negative temperature gradient. The vertical prestressing device of the present invention adopts a central positioning device plus a surrounding post-tensioning prestressing device, which has a significant effect on suppressing the umbrella-shaped deformation of the track plate and can effectively solve the problem of warping of the track plate end.

[0013] As a preferred solution of the present invention, the central prestressed tensioning head is further provided with a central elastic stress element.

[0014] As a preferred solution of the present invention, the preload head is also equipped with an elastic stress element.

[0015] As a preferred solution of the present invention, the central elastic stress element and the elastic stress elements are both springs or rubber pads.

[0016] The prestressing device (including the center positioning device and the post-tensioning prestressing device) of the present invention is provided with a high-precision elastic stress element, and the vertical prestressing of the track system can be accurately set by adjusting the prestressing device. The stress fluctuations generated by the track vibration are borne by the elastic stress element, which can prevent the prestressed steel rod from being overloaded and broken.

[0017] As a preferred embodiment of the present invention, the prefabricated track plate is provided with a through stepped positioning hole, the center positioning device is provided with a center positioning hole waterproof sealing cover, and the post-tensioning prestressing device is provided with a prestressed hole waterproof sealing cover.

[0018] As a preferred solution of the present invention, the center positioning device is arranged at the center position of the prefabricated track slab, and the post-tensioning prestressing device is symmetrically distributed along the center position of the prefabricated track slab.

[0019] The present invention also discloses a prestress design calculation method for a vertical prestressed ballastless track structure, comprising the following steps:

[0020] Step 1: Determine the working environment temperature of the ballastless track through meteorological data and obtain the positive temperature gradient ΔT of the track structure layer + , and negative temperature gradient ΔT - ;

[0021] Step 2: Determine the bending moment of the track slab under positive and negative temperature gradients in the longitudinal and transverse directions using the following formula:

[0022]

[0023]

[0024]

[0025]

[0026] Step 3: Calculate the pretension F of the center positioning device by the following formula c ,

[0027]

[0028] Step 4: Calculate the prestressing force F of the post-tensioning device by the following formula: a ,

[0029]

[0030] In the formula, The track structure layer is under a positive temperature gradient ΔT + The lateral bending moment under The track structure layer is under negative temperature gradient ΔT -The lateral bending moment under The track structure layer is under a positive temperature gradient ΔT + The longitudinal bending moment under The track structure layer is under negative temperature gradient ΔT - The longitudinal bending moment under the load is E, E is the equivalent elastic modulus of the track structure layer, I x is the transverse section inertia moment of the track structure layer, I y is the longitudinal section inertia moment of the track structure layer, α is the equivalent material linear expansion coefficient of the track structure layer, m is the mass of the track structure layer, a is the length of the track structure layer, and b is the width of the track structure layer.

[0031] The prestressed material design and calculation method provided by the present invention can quickly perform prestressed material design and calculation of each prestressed material device according to the service environment temperature of the track structure, the design size of the track plate, etc., with high design accuracy and strong reliability of calculation results.

[0032] As a preferred embodiment of the present invention, when the prefabricated track plate and the adjustment layer are separate structures, the track structure layer only includes the prefabricated track plate; when the prefabricated track plate and the adjustment layer are an integrated structure that carries the load together, the track structure layer includes the prefabricated track plate and the adjustment layer.

[0033] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0034] 1. The present invention realizes force transmission in the horizontal and vertical directions through positioning bosses, realizes compressive force transmission in the vertical direction through interlayer stacking, and realizes tensile force transmission through prestressing devices (including central positioning devices and post-tensioning prestressing devices). The rails, prefabricated track plates, adjustment layers and foundations realize bidirectional force transmission in the vertical, horizontal and vertical directions, ensuring the coordinated deformation between the track structure layers, preventing interlayer separation, air separation and slurry leakage, and at the same time ensuring the longitudinal and lateral stability of the track.

[0035] 2. The track plate deforms into a concave umbrella shape under a positive temperature gradient and into a convex umbrella shape under a negative temperature gradient. The vertical prestressing device of the present invention adopts a central positioning device plus a surrounding post-tensioning prestressing device, which has a significant effect on suppressing the umbrella-shaped deformation of the track plate and can effectively solve the problem of warping of the track plate end.

[0036] 3. The prestressing device (including the center positioning device and the post-tensioning prestressing device) of the present invention is provided with a high-precision elastic stress element, and the vertical prestressing of the track system can be accurately set by adjusting the prestressing device. The stress fluctuations generated by the track vibration are borne by the elastic stress element, which can prevent the prestressed steel rod from being overloaded and broken.

[0037] 4. The prestressing design and calculation method provided by the present invention can quickly perform prestressing design and calculation of each prestressing device according to the service environment temperature of the track structure, the design size of the track plate, etc., with high design accuracy and strong reliability of calculation results.

[0038] 5. The track structure of the present invention is an assembled structure with strong integrity. The assembly work is carried out on the upper surface of the track plate, which makes it easy to replace and repair track components. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is the plan layout of the vertical prestressed ballastless track structure.

[0040] Figure 2 It is a cross-sectional view of the vertical prestressed ballastless track structure.

[0041] Figure 3 It is a cross-sectional view of the vertical prestressed ballastless track structure (vertical prestressing is not set).

[0042] Figure 4 This is a schematic diagram of the installation of the center positioning device.

[0043] Figure 5 This is a schematic diagram of the installation of the post-tensioning device.

[0044] Icons: 1. Rail, 2. Fastener, 3. Track plate, 31. Center stepped positioning hole, 32. Stepped positioning hole, 4. Adjustment layer, 5. Foundation, 6. Center positioning device, 61. Center positioning device mounting seat, 62. Positioning boss, 63. Center prestressed steel rod, 64. Center prestressed tensioning head, 641. Center cone head, 642. Center elastic stress element, 643. Center pretightening head, 65. Center positioning hole waterproof sealing cover, 7. Post-tensioning prestressing device, 71. Prestressed device mounting seat, 72. Prestressed steel rod, 73. Elastic stress element, 74. Pretightening head, 75. Prestressed hole waterproof sealing cover. DETAILED DESCRIPTION

[0045] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0046] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0047] Example 1

[0048] like Figure 1As shown, a vertical prestressed ballastless track structure includes a rail 1, a fastener 2, a precast track slab 3, an adjustment layer 4 and a foundation 5, and also includes a center positioning device 6 and a post-tensioning prestressing device 7. The center positioning device 6 is arranged in the middle of the precast track slab 3, and the post-tensioning prestressing device 7 is arranged around the precast track slab 3. The center positioning device 6 and the post-tensioning prestressing device 7 are both anchored in the foundation 5 and penetrate the adjustment layer 4 and the precast track slab 3 upward.

[0049] like Figure 2 As shown, a through center stepped positioning hole 31 is provided at the center of the prefabricated track plate 3, and the center stepped positioning hole 31 is used to install the center positioning device 6. Through stepped positioning holes 32 are provided around the prefabricated track plate 3, and the stepped positioning holes 32 are used to install the post-tensioning prestressing device 7. The stepped positioning holes 32 are symmetrically distributed along the center position of the prefabricated track plate 3.

[0050] The adjustment layer 4 can be adjusted by using materials such as poured CA mortar or self-compacting concrete. The adjustment layer 4 can be separated from the prefabricated track plate 3 or connected to the prefabricated track plate 3 as a whole through embedded steel bars.

[0051] like Figure 3-5 As shown, the foundation 5 is a reinforced concrete base, in which a center positioning device mounting seat 61 and a prestressed device mounting seat 71 are pre-embedded.

[0052] like Figure 4 As shown, the center positioning device 6 is an assembled structure, including a center positioning device mounting seat 61 embedded in the foundation 5, and a positioning boss 62 mounted on the center positioning device mounting seat 61. The positioning boss 62 is also provided with a center prestressed steel rod 63, and both ends of the center prestressed steel rod 63 are provided with external threads. A center prestressed tensioning head 64 is installed on the center prestressed steel rod 63, and the center prestressed tensioning head 64 includes a center cone head 641, a center elastic stress element 642 and a center pre-tightening head 643. The center cone head 641 is adapted to the positioning boss 62, and the center pre-tightening head 643 is provided with an internal thread. The center pre-tightening head 643 is threadedly matched with the center prestressed steel rod 63, and the center elastic stress element 642 is a spring or a rubber pad. In addition, the center positioning device 6 is also provided with a center positioning hole waterproof sealing cover 65.

[0053] like Figure 5 As shown, the post-tensioning prestressing device 7 is an assembled structure, including a prestressing device mounting seat 71 embedded around the foundation 5, a prestressing steel rod 72 is arranged on the prestressing device mounting seat 71, a prestressing head 74 is installed on the prestressing steel rod 71, and the prestressing head 74 is threadedly matched with the prestressing steel rod 72. In addition, it also includes an elastic stress element 73, which is a spring or a rubber pad, and a prestressing hole waterproof sealing cover 75.

[0054] Example 2

[0055] A prestress design calculation method for a vertical prestressed ballastless track structure, calculating the pretension of the vertical prestressed ballastless track structure as described in Example 1, comprising the following steps:

[0056] Step 1: Determine the working environment temperature of the ballastless track through meteorological data and obtain the positive temperature gradient ΔT of the track structure layer + , and negative temperature gradient ΔT - ;

[0057] Step 2: Determine the bending moment of the track slab under positive and negative temperature gradients in the longitudinal and transverse directions using the following formula:

[0058]

[0059]

[0060]

[0061]

[0062] Step 3: Calculate the pretension F of the center positioning device 6 by the following formula: c ,

[0063]

[0064] Step 4: Calculate the pretension force F of the post-tensioning device 7 by the following formula: a ,

[0065]

[0066] In the formula, The track structure layer is under positive temperature gradient ΔT + The lateral bending moment under The track structure layer is under negative temperature gradient ΔT - The lateral bending moment under The track structure layer is under positive temperature gradient ΔT + The longitudinal bending moment under is the longitudinal bending moment of the track structure layer under negative temperature gradient ΔT-, E is the equivalent elastic modulus of the track structure layer, I x is the transverse section inertia moment of the track structure layer, I y is the longitudinal section inertia moment of the track structure layer, α is the equivalent material linear expansion coefficient of the track structure layer, m is the mass of the track structure layer, a is the length of the track structure layer, and b is the width of the track structure layer.

[0067] When the prefabricated track plate 3 and the adjustment layer 4 are separate structures, the track structure layer only includes the prefabricated track plate 3 ; when the prefabricated track plate 3 and the adjustment layer 4 are an integrated structure that carries the load together, the track structure layer includes the prefabricated track plate 3 and the adjustment layer 4 .

[0068] Taking a certain design project as an example, the vertical prestressing design method proposed by the present invention is explained as follows:

[0069] 1) According to the design scheme, the track structure layer parameters are determined. The prefabricated track plate 3 and the adjustment layer 4 are an integrated structure. The equivalent elastic modulus of the reinforced concrete material of the track structure layer is E = 3.6 × 10 10 N / m 2 , track structure layer mass m = 10850kg, longitudinal section inertia moment I x =0.0062m 4 , transverse section moment of inertia I y =0.0139m 4 , height h = 0.31m, length a = 5.6m, width b = 2.5m.

[0070] 2) Determine the track working environment temperature and the positive temperature gradient ΔT of the track structure layer through meteorological data + =90℃ / m, and negative temperature gradient ΔT - =45℃ / m;

[0071] 3) The bending moment of the track slab under the positive and negative temperature gradients in the longitudinal and transverse directions is determined by the following formula:

[0072]

[0073]

[0074]

[0075]

[0076] 4) Calculate the pre-tension force of the tensioning assembly of the center positioning device 6 by the following formula:

[0077]

[0078] 5) Calculate the pretension force of the tensioning component of the peripheral post-tensioning device 7 by the following formula:

[0079]

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A vertical prestressed ballastless track structure, comprising a rail (1), a fastener (2), a prefabricated track slab (3), an adjustment layer (4) and a foundation (5), characterized in that: It also includes a center positioning device (6) and a post-tensioning prestressing device (7), wherein the center positioning device (6) is arranged in the middle of the prefabricated track plate (3), and the post-tensioning prestressing device (7) is arranged around the prefabricated track plate (3), and the center positioning device (6) and the post-tensioning prestressing device (7) are both anchored in the foundation (5) and penetrate upward through the adjustment layer (4) and the prefabricated track plate (3). The center positioning device (6) comprises a center positioning device mounting seat (61) embedded in the foundation (5), and a positioning boss (62) mounted on the center positioning device mounting seat (61); the positioning boss (62) is provided with a center prestressed steel rod (63); the center prestressed steel rod (63) is provided with a center prestressed tensioning head (64); the center prestressed tensioning head (64) is provided with a center cone head (641) matched with the positioning boss (62); the center prestressed tensioning head (64) is also provided with a center pre-tightening head (643); the center pre-tightening head (643) is threadedly matched with the center prestressed steel rod (63); The post-tensioning prestressing device (7) comprises a prestressing device mounting seat (71) pre-buried around the foundation (5); a prestressing steel rod (72) is arranged on the prestressing device mounting seat (71); a prestressing head (74) is installed on the prestressing steel rod (72); the prestressing head (74) and the prestressing steel rod (72) are threadedly matched.

2. The vertical prestressed ballastless track structure according to claim 1, characterized in that: The central prestressed tensioning head (64) is also provided with a central elastic stress element (642).

3. The vertical prestressed ballastless track structure according to claim 2, characterized in that: The pre-tightening head (74) is also equipped with an elastic stress element (73).

4. The vertical prestressed ballastless track structure according to claim 3, characterized in that: The central elastic stress element (642) and the elastic stress element (73) are both springs or rubber pads.

5. The vertical prestressed ballastless track structure according to claim 4, characterized in that: The prefabricated track plate (3) is provided with a through stepped positioning hole, the center positioning device (6) is provided with a center positioning hole waterproof sealing cover (65), and the post-tensioning prestressing device (7) is provided with a prestressing hole waterproof sealing cover (75).

6. The vertical prestressed ballastless track structure according to any one of claims 1 to 5, characterized in that: The center positioning device (6) is arranged at the center position of the prefabricated track plate (3), and the post-tensioning prestressing device (7) is symmetrically distributed along the center position of the prefabricated track plate (3).

7. A prestress design calculation method for a vertical prestressed ballastless track structure, characterized in that: Calculating the pretension of the vertical prestressed ballastless track structure according to any one of claims 1 to 6 comprises the following steps: Step 1: Determine the working environment temperature of the ballastless track through meteorological data and obtain the positive temperature gradient ΔT of the track structure layer + , and negative temperature gradient ΔT - ; Step 2: Determine the bending moment of the track slab under positive and negative temperature gradients in the longitudinal and transverse directions using the following formula: Step 3: Calculate the pretension F of the center positioning device (6) by the following formula: c , Step 4: Calculate the pretension force F of the post-tensioning device (7) by the following formula: a , In the formula, The track structure layer is under a positive temperature gradient ΔT + The lateral bending moment under The track structure layer is under negative temperature gradient ΔT - The lateral bending moment under The track structure layer is under a positive temperature gradient ΔT + The longitudinal bending moment under The track structure layer is under negative temperature gradient ΔT - The longitudinal bending moment under the load is E, E is the equivalent elastic modulus of the track structure layer, I x is the transverse section inertia moment of the track structure layer, I y is the longitudinal section inertia moment of the track structure layer, α is the equivalent material linear expansion coefficient of the track structure layer, m is the mass of the track structure layer, a is the length of the track structure layer, and b is the width of the track structure layer.

8. The prestress design calculation method for a vertical prestressed ballastless track structure according to claim 7 is characterized in that: When the prefabricated track plate (3) and the adjustment layer (4) are separate structures, the track structure layer only includes the prefabricated track plate (3); when the prefabricated track plate (3) and the adjustment layer (4) are an integrated structure that carries the load together, the track structure layer includes the prefabricated track plate (3) and the adjustment layer (4).

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