A ballastless track subgrade transition section filler replacement structure and its construction method

Abstract

A ballastless track subgrade transition section filler replacement structure and its construction method provided by the present invention, wherein the replacement structure is supported under the track support layer and includes a pre-support structure and an enclosure structure. The pre-support structure includes two groups of support piles on both sides of the track, a cross beam and a longitudinal beam connected between the tops of the two groups of support piles; detachable pads are connected between the two ends of the cross beam and the support piles. The enclosure structure includes side walls, a top plate and a bottom plate, and there is a limiting member between the top plate of the enclosure structure and the support layer; during construction, the setting of the pre-support structure can ensure the bearing capacity of the upper structure of the track during subsequent underground excavation and replacement, and the setting of the enclosure structure ensures the lateral, top and bottom forces of the excavation section. The setting of the limiting member between the enclosure structure and the support layer and the pads on the cross beam can adjust the height and plane position of the track and restore the smoothness of the line; the construction structure of the present invention is simple to install, is conducive to on-site construction, and does not require the removal of the original upper track, saving project cost and construction time.

Description

Technical Field

[0001] The invention belongs to the field of track construction, and particularly relates to a ballastless track subgrade transition section filler replacement structure and a construction method thereof. Background Art

[0002] In the ballastless track project, due to the combined action of upper dynamic loads, soil composition, temperature, precipitation and other conditions, the subgrade filler under the track structure will expand and deform, which will cause the arching deformation of the track structure, thus affecting the normal operation and use of the track. Especially in the culvert transition section, due to the complex construction technology and various types of materials, arching deformation is likely to occur in some areas; for the deeper and continuous deformation parts, the deep fillers need to be excavated or replaced.

[0003] The previous track adjustment methods were to remove the original track and then replace the filler or adjust the track fasteners, which would cause line interruption or limited adjustment range, and also result in high construction costs. Summary of the Invention

[0004] The invention provides a ballastless track subgrade transition section filler replacement structure and a construction method thereof to solve the technical problems such as the structural stability at the filler excavation and replacement site of the ballastless track subgrade transition section, the accuracy of deformation treatment, the force stability of the track support layer during adjustment, and the smoothness and convenient construction of the upper road during replacement. The specific technical solutions are as follows:

[0005] A ballastless track subgrade transition section filler replacement structure is supported under the track support layer. The replacement structure includes a pre-support structure and an enclosure structure. The pre-support structure includes two groups of support piles respectively arranged on both sides of the track, a cross beam horizontally connected between the corresponding tops of the two groups of support piles, and a longitudinal beam connected between the cross beams. A backing plate is arranged between the cross beam and the support pile; the enclosure structure is located inside the support structure and below the track, and is arranged along the track direction throughout the length. A limiting member is arranged between the enclosure structure and the support layer.

[0006] Further, the cross beam is located below the support layer and is arranged in parallel at intervals; the longitudinal beam is symmetrically arranged below both sides of the support layer; different thickness backing plates are detachably connected between the two ends of the cross beam and the support pile, and the number and thickness of the backing plates are adapted to the number of times of track lowering adjustment and the adjustment deformation amount.

[0007] Further, the support piles are arranged in parallel at intervals along the track direction; a group of support piles is arranged between adjacent tracks, and the group of support piles is shared by connecting the beam ends of the two tracks on both sides.

[0008] Further, the enclosure structure includes side walls, roof slabs, and floor slabs cast with concrete on the side, top, and bottom surfaces of the excavation section; when the casting strength of the roof slab is greater than 70% of the design strength, spacers are inserted between the bottom of the cross beam under the track and the roof slab.

[0009] Further, the cross-sectional width of the enclosure range of the enclosure structure corresponds to the excavation width of the subgrade design excavation section, and the height of the roof slab and the supporting layer is adapted to the installation height of the limiting members.

[0010] Further, the limiting members are distributed at intervals between the roof slab and the supporting layer. The limiting members are adjustable support members, and their vertical height is adapted to adjust the deformation amount of the track; the adjustable support rod is a threaded sleeve or a threaded sleeve with a support steel plate at the end.

[0011] Further, before the enclosure structure is cast, shotcrete with wire mesh and arch support are connected to the side wall of the excavation section.

[0012] Further, support members are arranged inside the arch support of the excavation section. The support members are vertical supports or / and horizontal supports; the vertical supports or / and horizontal supports are steel pipes or steel beams.

[0013] Further, advanced support is provided in the excavation section. The advanced support is pipe shed, small duct, horizontal jet grouting pile or arch support.

[0014] Further, the construction method of the ballastless track subgrade transition section filler replacement structure is as follows:

[0015] Step 1: Support piles and pads at the upper ends of the support piles are erected on both sides of the track deformation section, and manual tunneling method is used to excavate in sections at the lower part and the transverse side of the supporting layer. Cross beams and longitudinal beams are inserted into the manually excavated trenches, and the ends of the cross beams are connected to the spacers, thereby forming a pre-support structure; among them, vertical shafts are arranged at intervals during excavation for the excavation of the subgrade replacement section and the passage of personnel and materials.

[0016] Step 2: Open holes between the corresponding support piles and below the supporting layer, and then longitudinally excavate the subgrade filler along the track. Pre-vertical support is installed before the excavation process, and arch support is used in the excavation section.

[0017] Step 3: Vertical supports and horizontal supports are arranged inside the arch support. Shotcrete with wire mesh is carried out after excavation, and at the same time, side walls, roof slabs, and floor slabs are cast to form a surrounding enclosure structure. When the soil stability is poor, advanced support is carried out.

[0018] Step 4: When the roof slab is cast and reaches 70% of the strength, spacers are inserted between the bottom of the cross beam and the roof slab, and the roof slab, cross beam, and longitudinal beam jointly bear the load; the height during the casting of the roof slab is adapted to the installation of the limiting members.

[0019] Step 5: Excavate the subgrade filling between the roof slab and the supporting layer, and arrange limiters at intervals on the upper surface of the roof slab. The position and height of the limiters are determined according to the position and deformation amount of the arching of the track structure to be adjusted;

[0020] Step 6: According to the adjustment height and number of times of the deformation of the supporting layer, measure and adjust the vertical height of the cross beam. The adjustment method is to support the cross beam with a jack and disassemble the cross beam cushion plate in sequence;

[0021] Step 7: Repeat Step 5 and Step 6 to carry out the lowering adjustment of the arching deformed track until the flatness and smoothness of the track meet the specified requirements;

[0022] Step 8: Trim the end cross section of the excavation section, pour the end side wall for enclosure and fill the inside of the subgrade; after a seasonal cycle, confirm that the arching deformation is stable, and then backfill the inner chamber of the enclosure structure of the excavation section.

[0023] The present invention has the following beneficial effects:

[0024] 1) The setting of the pre-support structure in the present invention can ensure that the upper structure of the track is stressed during the subsequent cut-and-cover replacement construction, and the setting of the enclosure structure during the cut-and-cover construction ensures the stability of the excavation on the side, top and bottom during the cut-and-cover replacement of the excavation section;

[0025] 2) By arranging cushion blocks between the roof slab and the cross beam in the present invention, the enclosure structure and the pre-support structure can share the force, maintaining the integrity and stability of the force action;

[0026] 3) The setting of the vertical support and the horizontal support in the present invention both ensures the stability of the enclosure structure when the upper load acts on the enclosure structure after the subgrade filling is excavated;

[0027] 4) By arranging limiters between the enclosure structure and the supporting layer in the present invention, the arching deformation amount can be effectively restricted, improving the control accuracy of the deformation amount during the deformation rectification. The setting of the cushion plate on the cross beam can limit the lowering height of the track supporting layer, thereby ensuring the support and force during the deformation adjustment process.

[0028] In addition, the replacement construction structure and the arching deformation adjustment component of the present invention are simple to install, the construction process is easy to operate, which is conducive to on-site construction, and there is no need to demolish the original upper track and interrupt the train operation, minimizing the impact on the operation to the greatest extent, saving the project cost and construction time. Description of the Drawings

[0029] Figure 1 It is a schematic cross-sectional view of the construction of the filler replacement structure of the ballastless track subgrade transition section;

[0030] Figure 2 It is a schematic diagram of the excavation direction;

[0031] Figure 3 It is the distribution diagram of the longitudinal connection of the support piles;

[0032] Figure 4 It is the schematic diagram of the connection of the pre-support structure.

[0033] Reference numerals: 1 - track; 2 - roadbed slab; 3 - support layer; 4 - longitudinal beam; 5 - cross beam; 6 - support pile; 7 - excavation section; 8 - retaining structure; 9 - culvert; 10 - vertical support; 11 - backing plate; 12 - limit piece; 13 - cushion block. Specific implementation manner

[0034] See Figure 1 As shown, a subgrade filler replacement structure is provided at the subgrade replacement area of the ballastless track culvert section in the upper and lower two rows. The parts where the subgrade filler expands are mainly located in the cushion layer and the filler above the cushion layer. Therefore, the subgrade filler replaced this time is mainly all the fillers from below the track structure to the bottom surface of the cushion layer, and the excavation direction is Figure 2 the direction of the arrow in Figure 1 , that is, excavation is carried out longitudinally along the culvert; combined with Figure 3 and Figure 4 As shown, the replacement structure includes a pre-support structure and a retaining structure 8. The pre-support structure includes two groups of support piles 6 arranged at intervals on both sides of the track 1 respectively, a cross beam 5 horizontally connected between the corresponding tops of the two groups of support piles 6, and a longitudinal beam 4 connected between the cross beams 5; the support piles 6 in the same group are arranged parallel to each other at intervals along the track direction of the track 1; the retaining structure 8 is located inside the support structure and below the track 1, and is arranged longitudinally along the track direction of the track 1.

[0035] In this embodiment, the support piles 6 are arranged on both sides of the track 1. Among them, the support piles 6 between the two track lines are arranged at the center line position of the track 1, and the support piles 6 here are shared by the cross beams 5 of the upper and lower tracks 1; the support piles 6 are bored cast-in-place piles manually dug, with a pile depth of 7m and a pile spacing of 3 - 5m. The subgrade bed under the support layer 3 is manually excavated by the cut-and-cover method, with an excavation width of 1 - 1.5m and a center spacing of the grooves of 2 - m. After excavation, the cross beam 5 is inserted, and the longitudinal beam 4 is also placed by the method of excavating the manual groove. Among them, the longitudinal beam 4 is located below both sides of the support layer 3 and is symmetrically arranged, and the center line of the longitudinal beam 4 is aligned with the edge line of the roadbed slab 2. The cross beam 5 and the longitudinal beam 4 are both made of steel profiles. Among them, square steel backing plates are bolted to the two ends of the cross beam 5 and the support piles 6.

[0036] In this embodiment, the subgrade bed filler between the top plate of the retaining structure 8 and the support layer 3 is removed and a limit piece 12 is provided. The limit piece 12 is an adjustable-height threaded sleeve or a threaded sleeve with a support steel plate at the end, and the height of the sleeve is adjusted according to the deformation amount of the track 1; the limit piece 12 is welded to the top plate through a connecting steel plate.

[0037] In this embodiment, the enclosure structure 8 includes a concrete side wall, a top plate, and a bottom plate cast on the side, top, and bottom surfaces of the excavation section 7; the cross-sectional size of the enclosed area of the enclosure structure 8 corresponds to the cross-sectional size of the excavation range of the subgrade excavation section 7, where the height is from below the track structure to the bottom surface of the cushion, and the height of the top plate is adapted to the installation height of the limiting member 12; when the casting strength of the top plate is greater than 70% of the design strength, steel square pads 13 are inserted at intervals between the bottom of the cross beam 5 below the track 1 and the top plate.

[0038] In this embodiment, support members are provided in the excavation section 7 within the excavation cross-section. The support members are vertical supports and horizontal supports, both of which are made of steel pipes; before the enclosure structure 8 is cast, shotcrete with wire mesh is provided on the side walls of the excavation section 7; when the soil quality is poor, advanced pipe shed support can also be provided.

[0039] Combined Figures 1 to 4 , a construction method of a ballastless track subgrade transition section filler replacement structure is further described. The specific steps are as follows:

[0040] Step 1: Support piles 6 and pads 11 on the support piles 6 are erected on both sides of the deformation section of the culvert 9 of the track 1. By excavating artificial trenches under the bearing layer 3 and on the transverse side, the cross beam 5 and the longitudinal beam 4 are inserted and installed. The cross beam 5 is supported on the bottom surface of the bearing layer 3, and both ends are supported on the pads 11 of the support piles 6. Each part of the cross beam 5 is in close contact with the bottom surface of the bearing layer 3. Then, by adjusting the pads 11 under the cross beam 5, a pre-supporting force is formed on the track structure; among them, shafts are arranged at intervals during excavation for the excavation of the subgrade replacement section and the passage of personnel and materials.

[0041] Step 2: Open holes between the corresponding support piles 6 of the culvert 9 and below the bearing layer 3, reinforce and vertically support 10 the periphery of the hole and the culvert 9, and then longitudinally excavate the subgrade filler along the track 1.

[0042] Step 3: The excavation footage per step is 2 - 3 m. For each excavation footage of 1 m, steel arch support is installed in a timely manner. Vertical steel pipe supports and horizontal steel pipe supports are arranged inside the steel arch support. After excavation, shotcrete with wire mesh is carried out, and at the same time, a concrete side wall and a top plate are cast to form a surrounding enclosure structure 8.

[0043] Step 4: When the top plate is cast and reaches 70% of its strength, steel square pads are inserted between the bottom of the cross beam 5 below the track 1, and the top plate, the cross beam 5, and the longitudinal beam 4 jointly bear the load; among them, the casting height of the top plate is adapted to the installation height of the limiting member 12.

[0044] Step 5: Excavate the subgrade filler between the top plate and the bearing layer 3, and arrange limiting members 12 at intervals on the upper surface of the top plate. The position and height of the limiting members 12 are determined according to the required position of the upward arch and the deformation amount of the track structure to be adjusted.

[0045] Step 6: Adjust the height according to the deformation of the supporting layer 3, measure and adjust the vertical height of the cross beam 5. The adjustment method is to support the cross beam 5 with a jack and remove the backing plate 11 under the cross beam 5.

[0046] Step 7: Repeat Step 5 and Step 6 to conduct lowering adjustment of the upward-arching deformed track 1 until the flatness and smoothness of the track 1 meet the specified requirements.

[0047] Step 8: Trim the end section of the excavation section 7, pour the end side wall for enclosure and fill the interior of the subgrade; after a seasonal cycle, confirm the stability of the upward-arching deformation, and then backfill the inner chamber of the retaining structure 8 of the excavation section 7.

[0048] Obviously, the above embodiments are only explanations for clearly illustrating the prominent features of the present invention, rather than limitations on the implementation manners of the present invention; for those skilled in the art, other different forms of changes or variations can still be made based on the above description. If no creative improvement is made, they all fall within the protection scope of the present invention.

Claims

1. A construction method for a filler replacement structure of a transition section of a ballastless track subgrade, the replacement structure being supported below the track (1) and the support layer (3), characterized in that: It includes a pre - support structure and an enclosure structure (8). The pre - support structure includes two groups of support piles (6) respectively arranged on both sides of the track (1), a cross - beam (5) horizontally connected between the corresponding tops of the two groups of support piles (6), and a longitudinal beam (4) connected between the cross - beams (5). A backing plate (11) is arranged between the cross - beam (5) and the support pile (6); The enclosure structure (8) is located inside the support structure and below the track (1), and is arranged along the track direction of the track (1) throughout the length. A limiting member (12) is arranged between the enclosure structure (8) and the bearing layer (3); The construction method of applying the ballastless track subgrade transition section filler replacement structure is as follows: Step 1: Support the support piles (6) and the backing plates (11) at the upper ends of the support piles (6) on both sides of the deformed section of the track (1), and segmentally excavate the lower part and the transverse side of the bearing layer (3) by the manual tunneling method. Insert the cross - beam (5) and the longitudinal beam (4) into the manually excavated trench, and connect the end of the cross - beam (5) to the cushion block (13), thus forming a pre - support structure; Among them, vertical shafts are arranged at intervals during excavation for the soil excavation of the subgrade replacement section and the passage of personnel and materials; Step 2: Open holes between the corresponding support piles (6) and below the bearing layer (3), and then longitudinally excavate the subgrade filler along the track (1). Install a pre - vertical support (10) before the excavation process, and use arch supports in the excavation section (7); Step 3: Set vertical supports and horizontal supports inside the arch support. After excavation, install wire mesh and shotcrete, and at the same time pour the side walls, roof and floor to form a surrounding enclosure structure (8). When the soil stability is poor, carry out advanced support; Step 4: When the roof is poured and reaches 70% of its strength, insert cushion blocks (13) between the bottom of the cross - beam (5) and the roof, and jointly bear the load through the roof, cross - beam (5) and longitudinal beam (4); Among them, the height during the roof pouring is adapted to the installation of the limiting member (12); Step 5: Excavate the subgrade filler between the roof and the bearing layer (3), and arrange the limiting members (12) at intervals on the upper surface of the roof. The position and height of the limiting members (12) are determined according to the required position of the upward arch and the deformation amount of the track structure to be adjusted; Step 6: According to the height and number of times of the deformation adjustment of the bearing layer (3), measure and adjust the vertical height of the cross - beam (5). The adjustment method is to support the cross - beam (5) with a jack and sequentially remove the backing plates (11) under the cross - beam (5); Step 7: Repeat Step 5 and Step 6 to carry out the downward track adjustment of the upward - arched deformed track until the flatness and smoothness of the track (1) meet the specified requirements; Step 8: Trim the end section of the excavation section (7), and pour the end side wall for sealing and fill the inside of the subgrade; After a seasonal cycle, after confirming that the upward - arch deformation is stable, backfill the inner chamber of the enclosure structure (8) of the excavation section (7).

2. The construction method of a ballastless track subgrade transition section filler replacement structure according to claim 1, characterized in that: The cross - beam (5) is located below the bearing layer (3) and is arranged in parallel at intervals; The longitudinal beam (4) is symmetrically arranged on both sides and below the bearing layer (3); Among them, different - thickness backing plates (11) are detachably connected between the two ends of the cross - beam (5) and the support pile (6). The number and thickness of the backing plates (11) are adapted to the number of times of the downward track adjustment and the adjustment deformation amount.

3. The construction method of a ballastless track subgrade transition section filler replacement structure according to claim 2, characterized in that: The support piles (6) are arranged in parallel at intervals along the track direction of the track (1); a group of support piles (6) is arranged between adjacent tracks (1), and the group of support piles (6) is connected and shared at the ends of the cross beams (5) on both sides of the track (1).

4. The construction method of a ballastless track subgrade transition section filler replacement structure according to claim 1, characterized in that: The enclosure structure (8) includes side walls, top plates and bottom plates cast with concrete on the sides, top and bottom of the excavation section (7); when the casting strength of the top plate is greater than 70% of the design strength, a spacer block (13) is inserted between the bottom of the cross beam (5) below the track (1) and the top plate.

5. The construction method of a ballastless track subgrade transition section filler replacement structure according to claim 4, characterized in that: The cross-sectional width of the enclosure range of the enclosure structure (8) corresponds to the excavation width of the subgrade design excavation section (7), and the height of the top plate is adapted to the installation height of the limit member (12) with the support layer (3).

6. The construction method of a ballastless track subgrade transition section filler replacement structure according to claim 5, characterized in that: The limit members (12) are distributed at intervals between the top plate and the support layer (3), and the limit members (12) are adjustable support members and their vertical height is adapted to adjust the deformation amount of the track (1); the adjustable support is a threaded sleeve.

7. The construction method of a ballastless track subgrade transition section filler replacement structure according to claim 5, characterized in that: Before the enclosure structure (8) is cast, shotcrete with wire mesh and arch support are connected to the side wall of the excavation section (7).

8. The construction method of a ballastless track subgrade transition section filler replacement structure according to claim 7, characterized in that: A support member is arranged inside the arch support of the excavation section (7), and the support member is a vertical support or / and a horizontal support.

9. The construction method of a ballastless track subgrade transition section filler replacement structure according to claim 8, characterized in that: The excavation section (7) is provided with advanced support.

Images