A support system for an existing railway and a construction method thereof

Abstract

The present invention discloses a support system for an existing railway, including a support structure and a grouting compensation structure; the support structure includes a support structure, a longitudinal beam and a cross beam; the support structure includes a support beam, a crown beam and a steel pipe pile; the steel pipe pile is longitudinally buried in the foundation, and the steel pipe pile is fixedly connected to the crown beam; the two ends of the cross beam are respectively connected to the longitudinal beams on both sides, and a number of cross beams are evenly distributed; fixed on the cross beam; the grouting compensation structure includes a grouting pipe and a prefabricated pipe segment; the prefabricated pipe segment is fixed in a shield tunnel passing under the railway, and a number of through holes are provided on the prefabricated pipe segment, and the grouting pipe can be inserted into the through hole for grouting compensation. The present invention also provides a construction method for the support system of an existing railway, the steps of which are drilling an installation hole; installing a steel pipe pile; constructing a crown beam; constructing a support beam; erecting a longitudinal beam and a cross beam; and grouting the grouting compensation area. The present invention has low construction difficulty, low engineering cost, can effectively compensate for post-construction settlement, and has high overall structural safety.

Description

Technical Field

[0001] The invention belongs to the technical field of railway construction, and in particular relates to a support system of an existing railway and a construction method thereof. Background Art

[0002] At present, the construction of high-speed railways in China is rapid, and the mileage of high-speed railways put into operation nationwide reached 25,000 kilometers by the end of 2017. With the development of cities, the number of new urban and inter-city projects such as urban rail transit projects and municipal road projects that pass under existing high-speed railways by means of shield, pipe jacking, and dark excavation tunnels has increased year by year.

[0003] In the face of high settlement requirements for high-speed railways, current existing technologies often use active underpinning, active reinforcement or passive reinforcement. Among them, the active underpinning method includes two methods: portal frame bridge combined with D-type temporary beam, or elastic foundation beam combined with D-type temporary beam; the active reinforcement method includes grouting consolidation, jet grouting pile ground reinforcement and MJS underground reinforcement; the passive reinforcement method usually adopts increasing the cross-sectional stiffness of the lining components.

[0004] The above methods are difficult to construct and have high project costs during the construction phase; during the use phase, there are no effective compensation measures for post-construction settlement during long-term use, and the overall structure has safety hazards.

[0005] Therefore, a new technology is needed to solve the above problems. Summary of the invention

[0006] In order to solve the above problems in the prior art, the present invention provides a support system for an existing railway and a construction method thereof, which has low construction difficulty and low engineering cost, can effectively compensate for post-construction settlement, and has high overall structural safety.

[0007] The present invention adopts the following technical solutions:

[0008] A support system for an existing railway, comprising a support structure and a grouting compensation structure;

[0009] The underpinning structure comprises a supporting structure, a longitudinal beam and a cross beam; the supporting structure and the longitudinal beam are both fixed on both sides of the track area along the existing railway; the supporting structure comprises a joist, a crown beam fixed on both sides of the joist, and a plurality of steel pipe piles; the steel pipe piles are longitudinally buried in the foundation, and the upper ends of the steel pipe piles are fixedly connected to the crown beam; the longitudinal beam is fixed to the upper end surface of the joist; the two ends of the cross beam are respectively connected to the longitudinal beams on both sides, and a plurality of the cross beams are evenly distributed; the steel rails of the existing railway are fixed on the cross beam;

[0010] The grouting compensation structure includes a grouting pipe and a prefabricated pipe segment; the prefabricated pipe segment is fixed in a shield tunnel passing under the railway, and a plurality of through holes are provided on the prefabricated pipe segment; a grouting compensation area is provided above the shield tunnel corresponding to the track area, and the grouting compensation area is located below the supporting structure, and the grouting pipe can be inserted into the through hole to perform grouting into the grouting compensation area.

[0011] As a further improvement of the technical solution of the present invention, the steel pipe pile includes a steel pipe and a longitudinal steel bar group; the longitudinal steel bar group is inserted into the steel pipe, and the upper end of the longitudinal steel bar group exceeds the upper end surface of the steel pipe and is inserted into the crown beam and fixed to the crown beam.

[0012] As a further improvement of the technical solution of the present invention, the longitudinal steel bar group includes a plurality of longitudinal steel bars and a plurality of fixing rings, the fixing rings are coaxially arranged, the longitudinal steel bars are evenly arranged around the axis, and the fixing rings are fixedly connected to the longitudinal steel bars.

[0013] As a further improvement of the technical solution of the present invention, a plurality of slurry outlet holes are provided on the steel pipe.

[0014] As a further improvement of the technical solution of the present invention, the lower ends of the steel pipe piles above the shield tunnel stop outside the grouting compensation area; the lower ends of the steel pipe piles on both sides of the shield tunnel are lower than the arch waist line of the shield tunnel.

[0015] As a further improvement of the technical solution of the present invention, a plain concrete cushion layer is provided under the support beam.

[0016] As a further improvement of the technical solution of the present invention, each of the through holes is radially arranged on the prefabricated tube segment.

[0017] As a further improvement of the technical solution of the present invention, the longitudinal beam is a D-shaped beam.

[0018] As a further improvement of the technical solution of the present invention, an insulating pad is provided between the longitudinal beam and the supporting beam.

[0019] A construction method for a support system of an existing railway comprises the following steps:

[0020] S1. Level the construction site and drill holes for steel pipe piles along the existing railway;

[0021] S2. Insert the steel pipe pile into the installation hole and fix the steel pipe pile by grouting;

[0022] S3. Excavate the foundation pit and construct the crown beam, and fix the upper end of the steel pipe pile to the crown beam;

[0023] S4. construct the joist and connect the joist with the cap beam;

[0024] S5. Install longitudinal beams and cross beams in sequence, and fix the existing railway rails on the cross beams;

[0025] S6. Carry out the construction of the shield tunnel. After the construction of the shield tunnel is completed, grouting is performed on the grouting compensation area through the grouting pipe.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The support system of the existing railway and the construction method thereof of the present invention adopt steel pipe piles to replace the bored piles in the prior art, so that the site and vertical space required for construction are small, the engineering difficulty is reduced, and the social impact is small; the steel pipe of the steel pipe pile is provided with grouting holes, which can be used for infiltration grouting of the stratum around the steel pipe, and the loose stratum that may exist around the steel pipe pile is consolidated, and the engineering safety is high; the steel pipe pile can enclose the supporting beam in the early stage of construction, and can form an integral frame bridge with the supporting beam in the later stage, thereby reducing the temporary enclosure structure required for the supporting beam construction, and the engineering economy is high; after the shield tunnel construction is completed, the stratum outside the pipe segment is compensated for by grouting through the grouting pipe, which is conducive to alleviating the post-construction settlement and improving the safety of the whole structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The technology of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0029] Figure 1 is a cross-sectional view of the present invention and a shield tunnel;

[0030] Figure 2 It is a structural schematic diagram of the supporting structure and the longitudinal beam of the present invention;

[0031] Figure 3 is a cross-sectional view of a steel pipe pile of the present invention;

[0032] Figure 4 is a longitudinal section view of the present invention and a shield tunnel;

[0033] Figure 5 yes Figure 4 A magnified schematic diagram of center A.

[0034] Reference numerals:

[0035] 1-underpinning structure; 11-longitudinal beam; 111-steel corbel; 112-insulating pad; 12-cross beam; 13-supporting structure; 131-supporting beam; 1311-plain concrete cushion; 132-crown beam; 133-steel pipe pile; 1331-steel pipe; 1332-longitudinal reinforcement; 1333-fixing ring; 1334-grouting hole; 2-grouting compensation structure; 21-grouting pipe; 22-prefabricated pipe segment; 23-grouting compensation area; 3-rail; 4-shield tunnel. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments and drawings to clearly and completely describe the concept, specific structure and technical effects of the present invention, so as to fully understand the purpose, scheme and effect of the present invention. It should be noted that the embodiments in this application and the features in the embodiments can be combined with each other without conflict. The same reference numerals used throughout the drawings indicate the same or similar parts.

[0037] It should be noted that, unless otherwise specified, when a feature is referred to as being "fixed" or "connected" to another feature, it may be directly fixed or connected to the other feature, or it may be indirectly fixed or connected to the other feature. In addition, the descriptions of up, down, left, right, etc. used in the present invention are only relative to the relative positional relationship of the components of the present invention in the drawings.

[0038] Reference Figures 1 to 5 , a support system for an existing railway, including a replacement structure 1 and a grouting compensation structure 2.

[0039] Among them, Figure 1 and Figure 2 The underpinning structure 1 includes a supporting structure 13, a longitudinal beam 11 and a cross beam 12. The supporting structure 13 and the longitudinal beam 11 are fixed on both sides of the track area along the existing railway. In this embodiment, the longitudinal beam 11 is a D-shaped beam, and the cross beam 12 is an H-shaped steel cross beam.

[0040] Specifically, Figure 2 and Figure 3 As shown, the supporting structure 13 includes a joist 131 , a cap beam 132 fixed on both sides of the joist 131 , and a plurality of steel pipe piles 133 .

[0041] The steel pipe pile 133 is longitudinally buried in the foundation, and the upper end of the steel pipe pile 133 is fixedly connected to the crown beam 132. The longitudinal beam 11 is fixed to the upper end surface of the joist 131, and an insulating pad 112 is provided between the longitudinal beam 11 and the joist 131. The insulating pad 112 can be a rubber pad to prevent the track circuit from short-circuiting. Preferably, a plain concrete cushion layer 1311 is provided under the joist 131 for reinforcement.

[0042] Steel brackets 111 are fixed to the inner sides of the two longitudinal beams 11, and both ends of the cross beam 12 are respectively mounted on the steel brackets 111 of the longitudinal beams 11 to achieve connection with the longitudinal beams 11, and a plurality of cross beams 12 are evenly distributed. The steel rails 3 of the existing railway are fixed on the cross beams 12, and the steel rails 3 of the existing railway are supported by the supporting structure 13.

[0043] Among them, Figure 2 and Figure 3As shown, the steel pipe pile 133 includes a steel pipe 1331 and a longitudinal steel bar group. The longitudinal steel bar group is inserted into the steel pipe 1331, and the upper end of the longitudinal steel bar group exceeds the upper end surface of the steel pipe 1331 and is inserted into the crown beam 132 and fixed to the crown beam 132. The longitudinal steel bar group includes a plurality of longitudinal steel bars 1332 and a plurality of fixing rings 1333, each fixing ring 1333 is coaxially arranged, each longitudinal steel bar 1332 is evenly arranged around the axis, and the fixing ring 1333 is fixedly connected to the longitudinal steel bar 1332, and the sum of the outer diameter of the fixing ring 1333 and the diameter of the longitudinal steel bar 1332 is equal to the inner radius of the steel pipe 1331. In this embodiment, a group of longitudinal steel bars uses four longitudinal steel bars 1332.

[0044] Preferably, a plum blossom hole (not shown) is provided every 40 cm on the lower end of the steel pipe 1331, and each plum blossom hole is composed of a plurality of grouting holes 1334. When grouting the steel pipe pile 133, the stratum outside the pipe wall of the steel pipe 1331 can be penetrated and grouted through the grouting holes to consolidate the loose stratum that may exist around the steel pipe pile 133, thereby improving the safety of the project.

[0045] Through the above structure, the steel pipe piles 133 can enclose the joist 131 in the early stage of construction to prevent the soil layer from loosening. In the later stage, they can form an integral frame bridge with the joist 131, reducing the temporary enclosure structure required for the construction of the joist 131, and the project has high economic efficiency. Moreover, compared with the bored piles used in the prior art, the steel pipe piles 133 require a smaller construction site and vertical space, reduce the engineering difficulty, and have less social impact.

[0046] Among them, Figure 4 and Figure 5 As shown, the grouting compensation structure 2 includes a grouting pipe 21 and a prefabricated pipe segment 22. The prefabricated pipe segment 22 is provided with a plurality of radial through holes. The prefabricated pipe segment 22 is installed in the shield tunnel 4 during the construction of the shield tunnel 4 as a lining force-bearing structure of the shield tunnel 4. Between the pipe segment 22 and the steel pipe pile 133 is a grouting compensation area 23. The grouting pipe 21 can be inserted into the through hole to grout the grouting compensation area 23. The grouting pipe 21 is provided with a plurality of openings for grouting. During grouting, a hole is first drilled in the grouting compensation area 23 above the shield tunnel 4 through the through hole, and then compensation grouting is performed through the grouting pipe 21 to alleviate post-construction settlement and improve the overall safety of the structure. The grouting pipe 21 is disassembled after grouting and can be reused.

[0047] Through the above-mentioned grouting compensation structure 2, deep grouting reinforcement can be carried out on the strata outside the pipe segment through the grouting pipe 21 to improve the physical and mechanical parameters of the disturbed strata, restore the bearing capacity of the strata around the tunnel, and thus reduce the disturbance of the tunnel excavation to the strata at the bottom of the roadbed and the settlement of the roadbed.

[0048] In order to prevent the steel pipe piles 133 from obstructing the grouting compensation drilling, the grouting compensation area 23 needs to be avoided when setting the steel pipe piles 133. Therefore, the lengths of the steel pipe piles 133 in different areas are set. The lower end of the steel pipe pile 133 above the shield tunnel 4 stops at the grouting compensation area 23, that is, the steel pipe pile 133 above the grouting compensation area 23 is not inserted into the grouting compensation area 23 to avoid obstruction of the subsequent drilling; and the lower ends of other steel pipe piles 133, such as the steel pipe piles 133 on both sides of the shield tunnel 4, are lower than the arch waist line of the shield tunnel 4 to increase the supporting force.

[0049] A construction method for a support system of an existing railway comprises the following steps:

[0050] S1. Level the construction site, calculate and determine the length and diameter of the steel pipe piles 133 and the spacing between the steel pipe piles 133 according to the actual situation, and use a small drilling machine to drill holes along the existing railway according to the calculated results. The diameter of the drill hole is 200 mm. If quicksand, silty soil and other easily collapsed soil layers are encountered during drilling, bentonite mud wall protection is used to drill the installation holes of the steel pipe piles 133;

[0051] S2. The steel pipe pile 133 is made in advance, and a grouting hole is drilled on the lower side of the steel pipe 1331 of the steel pipe pile 133. A grouting hole 1334 is set in a plum blossom shape every 40 cm within a range of 4 m below the steel pipe pile 133. The diameter of the grouting hole 1334 is 15 mm, and the steel pipe pile 133 is inserted into the installation hole in sections. If the length of the steel pipe pile 133 is not enough, two steel pipe piles 133 can be connected and welded and fixed at the connection with a larger sleeve. After the steel pipe pile 133 is installed, a grouting pipe 21 is used to grout the steel pipe pile 133. The grouting pipe 21 adopts a 90 mm steel pipe 1331, and the grouting amount is not less than 40 kg / m. The grouting cement for construction adopts PO42.5 grade cement; the water-cement ratio of the grouting cement slurry is 0.5 to 1.0;

[0052] S3. When excavating to the lower elevation of crown beam 132, excavate the foundation pit and construct crown beam 132, anchor the longitudinal steel bar 1332 at the upper end of steel pipe pile 133 into crown beam 132 and fix it to crown beam 132, and reserve the connection sleeve for connecting with support beam 131; when excavating the foundation pit, the excavation should be carried out in layers and sections, with a section length of 10 to 20 meters. Over-excavation is strictly prohibited. C20 10cm thick concrete wall protection is sprayed with mesh between piles. The exposure time of the pit wall soil after excavation should not exceed 6 hours. Before spraying concrete support on the slope, the loose soil on the slope should be removed.

[0053] S4. After the foundation pit is excavated to the base, a plain concrete cushion layer 1311 is constructed, and then the joist 131 is constructed, and the joist 131 is connected to the crown beam 132 through a connecting sleeve;

[0054] S5 sequentially erect longitudinal beams 11, beams 12, and the existing railway rails 3 are fixed to the beam 12;

[0055] S6. Construction of shield tunnel 4 is carried out. The segments provided with through holes are used in the construction of shield tunnel 4. After the construction of shield tunnel 4 is completed, the grouting compensation area 23 is punched through the through holes, and then the grouting pipe 21 is inserted, and the grouting compensation area 23 is grouted through the grouting pipe 21. The grouting slurry is mainly a composite slurry, supplemented by ordinary cement-water glass double liquid slurry; the slurry water-cement ratio is 0.6:1~1:1, and the grouting pressure is controlled at 0.5~0.8Mpa. The end standard of single-hole grouting is controlled by combining quantitative and pressure control. The end standard of full-section grouting is to core test 2~5% of the total grouting holes, and the unconfined compressive strength at 28 days of age should be greater than 0.5MPa. At the same time, geological radar can be used to scan the uniformity of the reinforcement body, and no large loose un-grouted area will appear. If the requirements are not met, grouting should be supplemented in time.

[0056] The support system of the existing railway and the construction method thereof of the present invention adopt steel pipe piles 133 to replace the bored piles in the prior art, so that the construction site and vertical space required are small, the engineering difficulty is reduced, and the social impact is small; grouting holes are provided on the steel pipe 1331 of the steel pipe pile 133, and grouting can be infiltrated into the stratum around the steel pipe 1331 to consolidate the loose stratum that may exist around the steel pipe pile 133, and the engineering safety is high; the steel pipe pile 133 can enclose the support beam 131 in the early construction, and can form an integral frame bridge with the support beam 131 in the later stage, reducing the temporary enclosure structure required for the construction of the support beam 131, and the engineering economy is high; after the construction of the shield tunnel 4 is completed, compensatory grouting is performed on the stratum outside the pipe segment through the grouting pipe 21, which is conducive to alleviating post-construction settlement and improving the safety of the entire structure.

[0057] For other contents of the support system of the existing railway and the construction method thereof described in the present invention, please refer to the prior art and will not be described in detail here.

[0058] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Therefore, any modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A support system for an existing railway, characterized in that: Including underpinning structure and grouting compensation structure; The underpinning structure comprises a supporting structure, a longitudinal beam and a cross beam; the supporting structure and the longitudinal beam are both fixed on both sides of the track area along the existing railway; the supporting structure comprises a joist, a crown beam fixed on both sides of the joist, and a plurality of steel pipe piles; the steel pipe piles are longitudinally buried in the foundation, and the upper ends of the steel pipe piles are fixedly connected to the crown beam; the longitudinal beam is fixed to the upper end surface of the joist; the two ends of the cross beam are respectively connected to the longitudinal beams on both sides, and a plurality of the cross beams are evenly distributed; the steel rails of the existing railway are fixed on the cross beam; The longitudinal beam is a D-shaped beam; The cross beam is an H-shaped steel cross beam; A plain concrete cushion layer is provided below the joist; An insulating pad is provided between the longitudinal beam and the joist; The steel pipe pile comprises a steel pipe and a longitudinal steel bar group; the longitudinal steel bar group is inserted into the steel pipe, and the upper end of the longitudinal steel bar group exceeds the upper end surface of the steel pipe and is inserted into the crown beam and fixed to the crown beam; The longitudinal steel bar group includes a plurality of longitudinal steel bars and a plurality of fixing rings, each fixing ring is coaxially arranged, each longitudinal steel bar is evenly arranged around the axis, and the fixing ring is fixedly connected to the longitudinal steel bars; The steel pipe is provided with a plurality of slurry outlet holes; The grouting compensation structure includes a grouting pipe and a prefabricated pipe segment; the prefabricated pipe segment is fixed in a shield tunnel passing under the railway, and a plurality of through holes are provided on the prefabricated pipe segment; a grouting compensation area is formed between the through hole and the steel pipe pile, and the grouting pipe can be inserted into the through hole to perform grouting in the grouting compensation area; The lower ends of the steel pipe piles above the shield tunnel stop outside the grouting compensation area; the lower ends of the steel pipe piles on both sides of the shield tunnel are lower than the arch waist line of the shield tunnel; Each of the through holes is radially arranged on the prefabricated tube segment.

2. The construction method of the existing railway support system according to claim 1, characterized in that: The following steps are involved: S1. Level the construction site, calculate and determine the length and diameter of the steel pipe piles, the spacing between the steel pipe piles according to the actual situation, and drill the installation holes of the steel pipe piles along the existing railway using a small drilling machine; the drilling diameter is 200mm; if a soil layer prone to collapse is encountered, the installation holes of the steel pipe piles are drilled using bentonite mud wall protection; S2. Insert the steel pipe pile into the mounting hole and fix the steel pipe pile by grouting using a grouting pipe; wherein the grouting pipe is a 90mm steel pipe, the grouting amount is not less than 40kg / m, and the grouting cement is PO42.5 grade cement; the water-cement ratio of the grouting cement slurry is 0.5 to 1.0; S3. Excavate the foundation pit and construct the cap beam, fix the upper end of the steel pipe pile to the cap beam, and reserve a connection sleeve for the connecting piece with the joist; when the foundation pit is excavated, the excavation should be carried out in layers and sections, with a section length of 10 to 20 meters, and C20 10 cm thick concrete wall should be sprayed with a mesh between the piles; the soil of the pit wall should be exposed for no more than 6 hours after excavation; before spraying concrete support on the slope, the loose soil on the slope should be removed; S4. Construction of the joist, and connecting the joist to the crown beam through the connecting sleeve; S5. Sequentially erect the longitudinal beams, the cross beams, and fix the existing railway rails on the cross beams; S6. Carry out the construction of the shield tunnel. After the construction of the shield tunnel is completed, the grouting compensation area is drilled through the through hole, and then the grouting pipe is inserted, and the grouting compensation area is grouted through the grouting pipe; wherein, the grouting slurry is mainly composite slurry, supplemented by ordinary cement-water glass double liquid slurry; the slurry water-cement ratio is 0.6:1~1:1, and the grouting pressure is controlled at 0.5~0.8Mpa; the end standard of single-hole grouting is controlled by combining quantitative and constant pressure, and the end standard of the whole section grouting is to core test 2~5% of the total grouting holes, and the unconfined compressive strength at 28 days of age should be greater than 0.5MPa.

Images