A semi-covered and excavated urban tunnel structure and construction method adjacent to a subway

Abstract

The present invention discloses a semi-covered and excavated urban tunnel structure and construction method adjacent to a subway, and relates to the field of urban tunnel engineering design and construction technology. Grouting plates, pre-grouting pipes, and tracking grouting pipes are located adjacent to the subway piers and abutments around the periphery, with pre-grouting pipes arranged in a single row and tracking grouting pipes arranged in double rows; a second crown beam and a semicircular pile are arranged on the top of the interlocking pile, and the second crown beam is rigidly connected to the top plate; a first crown beam is arranged on the top of the semicircular pile, and the first crown beam is provided with an embedded steel plate that docks the first steel support on the inner side of the foundation pit, and a retaining wall is arranged on the top of the first crown beam, and the retaining wall is raised above the ground. The present invention has the advantages of low traffic relief pressure, fast pipeline recovery speed, high foundation pit excavation efficiency, low construction risk, short construction period, and large tunnel space, and can be used for the design and construction of tunnel structures under busy roads adjacent to subways.

Description

Technical Field

[0001] The present invention relates to the technical field of urban tunnel engineering design and construction, and in particular to a semi-covered and excavated urban tunnel structure and construction method adjacent to a subway. Background Art

[0002] Urban tunnels typically run parallel to and beneath major urban roads, which may be flanked by subway stations and high-rise buildings. Construction methods commonly used for building urban tunnels along busy urban roads include open-cut, covered-cut, underground excavation, and semi-covered-cut methods.

[0003] Urban tunnels generally have large excavation spans. For example, the span of a one-way three-lane urban tunnel is generally not less than 15m. If the urban tunnel is constructed using the hidden excavation method, an arched roof must be installed. This results in a small thickness of cover soil. The properties of the soil layer near the roof are generally poor, and support measures such as pipe sheds and advance grouting need to be considered. However, these measures are costly and risky and are generally not adopted.

[0004] The open-cut method has simple construction procedures, spacious construction space, and high excavation and excavation efficiency, but it requires long-term road occupation. Some roads where urban tunnel foundation pits are located do not have the conditions for road closures and traffic detours, resulting in certain limitations of the open-cut method.

[0005] Although the covered excavation method occupies the road for a shorter time than the open excavation method, the foundation pit still needs to occupy the road in its entire section, and similar to the open excavation method, it also has limitations.

[0006] The foundation pit of the semi-covered method can be fenced in sections, occupying only half of the road at a time. The traffic relief pressure is less than that of the open-cut method and the covered-cut method. However, the temporary covering plate is generally located near the ground, and the pipelines cannot be moved back above the covering plate. The main structure construction can be completed before the soil is backfilled, the pipelines are moved back, and the temporary covering plate is removed. The number of traffic relief times and the amount of temporary engineering demolition are relatively large.

[0007] It can be seen that traditional design and construction methods have many disadvantages and limitations.

[0008] Solving the drawbacks and limitations of the above-mentioned traditional design and construction solutions requires technical innovation. The significance of solving the above problems lies in proposing an urban tunnel structure and construction method that can not only reduce the pressure of traffic diversion and pipeline relocation, but also improve excavation efficiency and shorten the construction period. Summary of the Invention

[0009] To overcome the problems existing in related technologies, the disclosed embodiments of the present invention provide a semi-covered, excavated urban tunnel structure and construction method adjacent to a subway station. This addresses numerous issues during construction of a busy urban road section adjacent to a subway excavation pit, including high traffic pressure, slow pipeline restoration, low excavation efficiency, high construction risks, and long construction periods. The technical solution is as follows:

[0010] The semi-covered urban tunnel structure adjacent to the subway is equipped with: grouting plates, pre-grouting pipes, and tracking grouting pipes. The grouting plates, pre-grouting pipes, and tracking grouting pipes are located around the subway piers and caps. Pre-grouting pipes are set in a single row, and tracking grouting pipes are set in double rows.

[0011] A second crown beam and a semicircular pile are set on the top of the interlocking pile, and the second crown beam is rigidly connected to the top plate; a first crown beam is set on the top of the semicircular pile, and an embedded steel plate for connecting to the first steel support is set on the inner side of the foundation pit of the first crown beam. A retaining wall is set on the top of the first crown beam, and the retaining wall is higher than the ground.

[0012] In one embodiment, the first steel support is an H-shaped steel support, and the first steel support is connected to the semicircular pile through an embedded steel plate and an H-shaped steel purlin;

[0013] A second steel support is provided on the lower side of the first steel support. The second steel support is a steel pipe support and is connected to the interlocking pile through a double-jointed I-steel purlin. The second steel support adopts an axial force servo system.

[0014] In one embodiment, a drainage well is provided at the lower end of the top plate. The drainage well is arranged in a plum blossom shape, avoiding the positions of temporary piles and pull-out piles and the second steel support. A water stop ring is provided at the bottom plate of the drainage well.

[0015] In one embodiment, the temporary pile column and pull-out pile is set below the top longitudinal beam, the temporary pile column part is above the bottom plate, and the pull-out pile part is below the bottom plate. The temporary pile column is cut off after the construction of the main structure of the tunnel is completed. The pull-out pile adopts a compound grouting method at the pile side and pile end, and the main force reinforcement at the top of the pull-out pile is anchored into the bottom plate.

[0016] In one embodiment, an L-shaped retaining wall is provided at the column position of the top plate, a top longitudinal beam is provided at the column position of the top plate, a vertical construction joint is provided near the top plate position for later construction, and a horizontal steel bar connector is provided at the construction joint position.

[0017] In one embodiment, holes for feeding holes and excavation holes are reserved in the top plate, tongue and groove are set around the holes, beams are set next to the tongue and groove, and the reserved holes are closed after the construction of the main structure of the tunnel is completed; a soil pile pool is set above the top plate, armpit corners are set at both ends of the top plate, inclined horizontal construction joints are set on the side walls near the armpit corners, and vertical steel bar connectors are set at the horizontal construction joints.

[0018] In one embodiment, post-cast holes are set at the temporary piles of the bottom plate and the middle plate, tongue and groove are set around the post-cast holes, and beams are set next to the tongue and groove. After the construction of the main structure of the tunnel is completed, the post-cast holes are sealed.

[0019] In one embodiment, both ends of the top plate are rigidly connected to the second crown beam at the top of the pile, and stress monitoring points are embedded in the connection position between the top plate and the column and in the middle position of the column.

[0020] Another object of the present invention is to provide a construction method for realizing the semi-covered and excavated urban tunnel structure adjacent to the subway. The construction method for the semi-covered and excavated urban tunnel structure adjacent to the subway comprises the following steps:

[0021] (1) Traffic diversion, pipeline relocation, and site leveling;

[0022] (2) Bury pre-grouting pipes and tracking grouting pipes in the vicinity of the subway structure and perform pre-grouting;

[0023] (3) Construction of the first phase half-width top slab foundation pit interlocking piles, steel sheet piles, temporary piles and anti-pullout piles, dewatering wells, crown beams, and steel supports;

[0024] (4) Deploy monitoring points and conduct monitoring at locations such as interlocking piles, columns, supports, the ground surface, surrounding subway buildings, and underground pipelines;

[0025] (5) Excavate and construct the first-phase half-roof slab and the L-shaped retaining wall on the roof, relocate the pipelines above the first-phase half-roof slab, backfill the soil, restore road traffic, and remove the steel sheet piles;

[0026] (6) Construct the foundation pit retaining piles and dewatering wells for the second phase half-width top slab, and excavate and construct the second phase half-width top slab;

[0027] (7) Continue to reduce water levels and monitor, gradually excavate and install the first and second steel supports, and determine whether to conduct track grouting on the subway based on the monitoring data;

[0028] (8) Excavate to the bottom of the pit, and construct the bottom plate, the side wall of the second negative floor, the middle plate, and the side wall of the first negative floor in sequence and remove the supports. Post-cast holes are set at the temporary concrete piles of the bottom plate and the middle plate;

[0029] (9) Remove the temporary piles between the top and bottom plates to seal the holes, demolish the retaining structures and retaining walls near the surface, relocate the pipelines above the second half of the top plate, backfill the soil, and restore road traffic.

[0030] In one embodiment, the retaining piles are bored cast-in-place piles with a diameter of 1200 mm and jet-jet piles for water-stopping curtains. The diameter of the temporary piles and pull-out piles is 1200 mm. The first and second steel supports are made of 1000×1000 reinforced concrete.

[0031] The present invention has the advantages of low traffic relief pressure, fast pipeline restoration, high foundation pit excavation efficiency, low construction risk, short construction period, and large tunnel space. It can be used for the design and construction of tunnel structures under busy roads adjacent to subways. The technical solutions provided by the embodiments disclosed in the present invention can have the following beneficial effects:

[0032] 1. Compared with the full-open-cut and full-cover excavation construction schemes, the present invention constructs the first-phase half-width roof slab first and then the second-phase half-width roof slab. The horizontal width of the foundation pit enclosure and the occupied road is 0.5 times that of the above-mentioned schemes. Problems such as road closures and detours that may be caused by the full-open-cut and full-cover excavation schemes will not occur. The road above the first-phase half-width cover excavation roof slab can be restored more quickly and pipelines can be relocated, which can greatly reduce the pressure of traffic diversion and pipeline relocation.

[0033] 2. Compared with the full cover excavation construction scheme, the reinforced concrete piles of the present invention change the stress state of the permanent cover plate construction stage from single span to double span. The bearing capacity of the retaining pile top of the semi-cover excavation scheme can be much reduced compared with the full cover excavation scheme. Therefore, the diameter of the retaining pile of the present invention is reduced by 0.2-0.3m compared with the full cover excavation scheme, and the steel content of the retaining pile is reduced by 20-30kg / m 3 , less engineering investment;

[0034] 3. Compared with the semi-blanket construction scheme, the roof of the present invention is a permanent and temporary combination structure. There is sufficient space above the roof for pipeline recovery. The pipeline recovery space is twice that of the semi-blanket scheme, which allows for rapid relocation of pipelines. There will be no problems in the semi-blanket scheme where the temporary cover cannot be relocated, the temporary cover needs to be broken off and re-enclosed and evacuated, and the permanent roof is installed last, resulting in a delay in relocating pipelines.

[0035] 4. The temporary columns of the present invention are reinforced concrete piles, i.e. bored cast-in-place piles, which have a compressive and flexural bearing capacity 3 to 4 times greater than that of hollow steel pipe columns of the same size and lattice columns of similar size. This allows the roof to bear a greater thickness of soil cover and is suitable for biased load conditions where half of the roof is backfilled with soil and the other half is not. The temporary columns are constructed in one go, which reduces the need for inserting lattice columns and steel pipe columns compared to other temporary columns, simplifying the process.

[0036] 5. The present invention buries deep pre-grouting pipes around existing subway pile foundations and caps, pre-grouting to the bottom of the foundation pit retaining piles, forming a closed water-stop curtain around the subway pile foundations and caps, thus preventing water loss and pile foundation settlement around the subway pile foundations caused by foundation pit construction;

[0037] 6. The tracking grouting of the present invention can be carried out multiple times and in sections, and whether to start the tracking grouting is determined based on the monitoring data, which is beneficial to saving project investment;

[0038] 7. The steel support of the present invention adopts an axial force servo system, which can protect surrounding buildings (structures) such as subways through active deformation control technology.

[0039] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0041] Figure 1 This is a flow chart of the construction method of a semi-covered and excavated urban tunnel structure adjacent to a subway provided by the present invention.

[0042] Figure 2 This is a cross-sectional view of a semi-covered and excavated urban tunnel structure adjacent to a subway provided by the present invention.

[0043] Figure 3 It is a cross-sectional view during the excavation of a first-phase half-width top plate foundation pit provided by the present invention.

[0044] Figure 4 It is a cross-sectional view of the first-phase half-width top plate foundation pit during backfilling provided by the present invention.

[0045] Figure 5 It is a cross-sectional view during the excavation of the second-phase half-width top plate foundation pit provided by the present invention.

[0046] Figure 6 It is a cross-sectional view during the period of backbuilding structure after foundation pit excavation is completed provided by the present invention.

[0047] Figure 7 It is a cross-sectional view of the tunnel main structure provided by the present invention during the completion of construction.

[0048] Figure 8 This is a plan view of the pre-buried grouting pipe around the subway pile foundation cap provided by the present invention;

[0049] Among them, a, front view; b, side view; c, cross-sectional view.

[0050] Figure 9 This is a cross-sectional diagram of the arrangement of monitoring points in subway sections, stations, and vertical elevators provided by the present invention;

[0051] Among them, a, front view; b, side view; c, vertical elevator structure diagram.

[0052] Figure 10 It is a schematic diagram of the method of reserving holes and sealing holes in the bottom plate and middle plate at temporary piles provided by the present invention.

[0053] Figure 11 It is the vertical displacement cloud diagram of the pile foundation provided by the present invention.

[0054] Figure 12 It is the lateral displacement cloud diagram of the pile foundation provided by the present invention.

[0055] Figure 13 This is the vertical displacement cloud map of the bridge deck and piers provided by the present invention.

[0056] Figure 14 This is the lateral displacement cloud map of the bridge deck and piers provided by the present invention.

[0057] Reference numerals:

[0058] 1. Grouting plate; 2. Pre-grouting pipe; 3. Tracking grouting pipe; 4. Interlocking pile; 5. Semi-circular pile; 6. Steel sheet pile; 7. Temporary pile column and pull-out pile; 8. Dewatering well; 9. First crown beam; 10. Second crown beam; 11. First steel support; 12. Top plate; 13. L-shaped retaining wall; 14. Second steel support; 15. Bottom plate; 16. First side wall; 17. Middle plate; 18. Second side wall; 19. Top longitudinal beam; 20. Post-cast holes; 21. Retaining wall. DETAILED DESCRIPTION

[0059] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0060] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly attached to the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used in the present invention are for illustrative purposes only and do not represent the only implementation methods.

[0061] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0062] A semi-covered and excavated urban tunnel structure adjacent to a subway comprises the following contents: a grouting plate 1, a pre-grouting pipe 2, and a tracking grouting pipe 3. The grouting plate 1, the pre-grouting pipe 2, and the tracking grouting pipe 3 are located adjacent to the subway piers and the surrounding areas. The pre-grouting pipes are arranged in a single row, and the tracking grouting pipes are arranged in double rows.

[0063] A second crown beam 10 and a semicircular pile 5 are set on the top of the interlocking pile, and the second crown beam 10 is rigidly connected to the top plate 12; a first crown beam 9 is set on the top of the semicircular pile 5, and the first crown beam 9 is provided with an embedded steel plate docking with the first steel support 11 on the inner side of the foundation pit, and a retaining wall 21 is set on the top of the first crown beam 9, and the retaining wall 21 is higher than the ground.

[0064] The first steel support 11 is an H-shaped steel support, which is connected to the semicircular pile 5 through a pre-buried steel plate and connected to the steel sheet pile 6 through an H-shaped steel purlin; the second steel support 14 is a steel pipe support, which is connected to the interlocking pile through a double-jointed I-shaped steel purlin, and the second steel support adopts an axial force servo system.

[0065] The dewatering well 8 is arranged in a plum blossom shape, avoiding the position of the temporary pile and anti-pulling pile 7 and the second steel support 14. A water stop ring is set at the bottom plate of the dewatering well;

[0066] Temporary piles and anti-pullout piles 7 are set below the top longitudinal beam 19. The temporary piles are above the bottom plate, and the anti-pullout piles are below the bottom plate. The temporary piles are removed after the construction of the main structure of the tunnel is completed. The anti-pullout piles are grouted at the pile side and pile end. The main force reinforcement at the top of the anti-pullout pile is anchored into the bottom plate.

[0067] In the early stage of construction, the top plate 12 is equipped with an L-shaped retaining wall 13 at the column position, which is higher than the ground and also serves as a crash barrier for restoring the road;

[0068] The top plate 12 of the early construction is provided with a top longitudinal beam at the column position, a vertical construction joint is provided near the position of the later construction top plate 12, and a horizontal steel bar connector is provided at the construction joint position;

[0069] In the later stage of construction, holes such as feeding holes and excavation holes are reserved in the top plate 12. Tongues and grooves are set around the holes, and beams are set beside the tongues and grooves. After the main structure of the tunnel is completed, the reserved holes are closed;

[0070] In the later stage of construction, a soil pile pool is set above the top plate; armpits are set at both ends of the top plate, inclined horizontal construction joints are set on the side walls near the armpits, and vertical steel bar connectors are set at the horizontal construction joints;

[0071] Post-cast holes 20 are set at the temporary piles of the bottom plate 15 and the middle plate 17. Tongues and grooves are set around the post-cast holes 20, and beams are set beside the tongues and grooves. The post-cast holes 20 are sealed after the construction of the main structure of the tunnel is completed.

[0072] Grouting plates 1, pre-grouting pipes 2 and tracking grouting pipes 3 are buried around existing subways and other buildings within the range of three times the foundation pit depth. The depth of the pre-grouting pipes is not less than the depth of the urban tunnel retaining piles, and the depth of the tracking grouting pipes is not less than the depth of the urban tunnel foundation pit.

[0073] Both ends of the top plate 12 are rigidly connected to the second crown beam 10 at the top of the pile, and stress monitoring points are embedded in the connection position between the top plate and the column and in the middle position of the column.

[0074] The columns are temporary reinforced concrete piles 7, which also serve as pull-out piles. A reinforced concrete top longitudinal beam is set on the top of the piles, and post-cast holes 20 are set on the bottom plate and the middle plate at the temporary piles. After the construction of the main structure of the tunnel is completed, the temporary piles are cut off and the post-cast holes 20 are sealed. The temporary piles and pull-out piles 7 adopt a compound post-grouting process on the pile side and pile end.

[0075] The tunnel has a double-deck, single-span structure. Both floors can be used as underground roads, or one floor can be used as an underground road and the other as an underground commercial street.

[0076] The interlocking piles 4, semicircular piles 5, temporary piles and pull-out piles 7, top plates 12, first steel supports 11, second steel supports 14, surface settlement, groundwater levels, surrounding subways and other buildings (structures), underground pipelines, etc. are monitored and measured, with 24-hour fully automatic monitoring of subway viaducts and tracks.

[0077] The excavated top plate is constructed in half widths horizontally. The retaining structure of the foundation pit of the excavated top plate in the early stage is semicircular piles 5 and steel sheet piles 6. The internal support is an H-shaped first steel support 11. The top plate is provided with an L-shaped retaining wall 13 at the column position. The pipeline is relocated above it, the soil is backfilled, and the traffic is restored. The L-shaped retaining wall 13 also serves as a crash barrier for restoring the road.

[0078] The interlocking piles close to the subway side are constructed using the full casing and full rotary process, while the interlocking piles 4 away from the subway side are constructed using rotary drilling.

[0079] The second steel support 14 adopts an axial force servo system and protects adjacent buildings such as subways through active deformation control technology.

[0080] Example 1:

[0081] The construction method of a semi-covered and cut-through urban tunnel structure adjacent to a subway station includes the following steps:

[0082] (1) Carry out traffic diversion, pipeline relocation, and site leveling;

[0083] (2) Bury grouting plates, pre-grouting pipes, and tracking grouting pipes close to the subway structure. 108 steel flower pipe, tracking grouting pipe uses sleeve valve pipe with an opening diameter of 110mm. Before the foundation pit is excavated, pre-grouting is carried out on the pile foundation cap adjacent to the subway. The grouting pipe plane layout is as follows: Figure 8 As shown;

[0084] (3) Construction of the first phase half-width top slab foundation pit interlocking piles, steel sheet piles, temporary piles and anti-pullout piles, dewatering wells, crown beams, and steel supports, such as Figure 3As shown, the foundation pit depth is 20 meters, the foundation pit width is 18 meters, and the minimum clear distance between the urban tunnel and the existing subway line elevated section pile cap is about 9 meters; the bite piles are meat-vegetarian bite piles with a pile diameter of 1000mm, the steel sheet pile model is PU400X170, and the length is 9 meters. The temporary pile column and pull-out pile has a pile diameter of 1000mm. The connection node between the pile column and the top plate is as follows Figure 10 As shown; the diameter of the drainage pipe well is 1.0m, the diameter of the well pipe is 0.6m, the drainage well enters the pit bottom and extends into the strongly weathered sandstone by not less than 3.0m, or extends into the medium or slightly weathered limestone by not less than 1.0m, the cap beam size is 500×1000mm, and the steel support is H-shaped steel HW400x400;

[0085] (4) Monitoring points shall be set up and monitored at interlocking piles, columns, supports, buildings (structures) on the ground and within the range of three times the depth of the foundation pit, underground pipelines, etc. The monitoring points of subway elevated sections, stations and vertical elevators shall be arranged as follows: Figure 9 As shown;

[0086] (5) Excavate and construct the first phase half-width top plate and L-shaped retaining wall on the top plate. The top plate thickness is 1200mm, and the L-shaped retaining wall thickness is 400mm with armpit angles. Relocate the pipelines above the first phase half-width top plate, backfill the soil, restore road traffic, and remove the steel sheet piles. Figure 4 As shown;

[0087] (6) Construction of the second phase half-width roof foundation pit interlocking piles and drainage wells. The interlocking piles are meat and vegetable interlocking piles with a pile diameter of 1000mm. The drainage pipe well has a hole diameter of 1.0m and a well pipe diameter of 0.6m. The drainage well enters the pit bottom and extends into the strongly weathered sandstone for not less than 3.0m, or into the medium or slightly weathered limestone for not less than 1.0m. Excavation and construction of the second phase half-width roof, the roof thickness of 1200mm, such as Figure 5 As shown;

[0088] (7) Continue to reduce water levels and monitor, gradually excavate and install the first and second steel supports. The diameter of the steel supports is 609 mm and the wall thickness is 16 mm. Active deformation control technology is used to determine whether to perform track grouting on the subway based on monitoring data.

[0089] (8) Excavate to the bottom of the pit and construct the bottom plate, the side wall of the second negative floor, the middle plate, and the side wall of the first negative floor in sequence. The tunnel structure span is 16m, the bottom plate thickness is 1300mm, the side wall thickness is 1200mm, and the middle plate thickness is 600mm. The supports are removed and post-cast holes are set at the temporary concrete piles of the bottom plate and the middle plate. The size of the post-cast holes is 1200×1200. Figure 6 As shown;

[0090] (9) Remove the temporary piles between the top and bottom plates, seal the post-casting holes, and the connection nodes between the temporary piles and the middle and bottom plates. Figure 10As shown in the figure, the retaining structure and retaining wall near the ground surface are demolished, the pipelines are moved back above the half-width roof of the second phase, the soil is backfilled, and the road traffic is restored. Figure 7 shown.

[0091] Example 2:

[0092] Compared with Example 1, the retaining piles in Example 2 use bored cast-in-place piles with a diameter of 1200 mm and a jet-jet pile water-stop curtain.

[0093] Example 3:

[0094] Compared with Example 1, the diameter of the temporary piles and pull-out piles in Example 3 is 1200 mm.

[0095] Example 4:

[0096] Compared with Example 1, the support in Example 4 adopts 1000×1000 reinforced concrete support.

[0097] Example 5:

[0098] Compared with Example 1, the tunnel structure in Example 5 has a span of 20m, a top plate thickness of 1300mm, a side wall thickness of 1300mm, a bottom plate thickness of 1400mm, and a middle plate thickness of 750mm.

[0099] Based on Example 1, a modified Moore-Coulomb constitutive relationship was used to simulate the impact of a partially covered, sequentially constructed urban tunnel excavation on an existing subway line viaduct. Snap-in piles were modeled using plate elements, using equivalent wall thickness. Piles and track structures were modeled using beam elements. Abutments, piers, and deck structures were modeled using solid elements. The model boundary was set to a distance no less than 2.5 times the excavation size, and displacement constraints were used as boundary conditions.

[0100] When the excavation of the urban tunnel foundation pit is completed, the numerical simulation calculation results of the displacement of the adjacent subway line viaduct bridge structure are as follows: Figures 11 to 14 show.

[0101] According to the results of finite element calculations, when the urban tunnel foundation pit is near the construction of a subway line viaduct, the maximum settlement of the existing subway line viaduct pile cap is 2.96mm, the maximum horizontal displacement is 2.70mm, the maximum settlement of the bridge deck is 3.08mm, the maximum horizontal deformation is 3.11mm, the longitudinal deformation difference of the single track is 0.4mm / 10m, and the lateral height difference is 0.5mm, which meets the relevant regulations, operational requirements and force requirements of the subway facility safety control indicators.

[0102] In summary, the present invention has the advantages of low traffic relief pressure, fast pipeline restoration speed, high foundation pit excavation efficiency, low construction risk, short construction period, and large tunnel space. At the same time, it can ensure the structural safety and operational safety of the elevated bridge of the adjacent subway line, and can be used for the design and construction of tunnel structures under busy roads adjacent to the subway.

[0103] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the disclosure disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the present disclosure being indicated by the appended claims.

[0104] It should be understood that the present disclosure is not limited to the exact structures described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure should be limited by the appended claims.

Claims

1. A construction method for a semi-covered and excavated urban tunnel structure adjacent to a subway, characterized by: The semi-covered urban tunnel structure adjacent to the subway is equipped with: grouting plates, pre-grouting pipes, and tracking grouting pipes. The grouting plates, pre-grouting pipes, and tracking grouting pipes are located around the subway piers and caps. Pre-grouting pipes are set in a single row, and tracking grouting pipes are set in double rows. A second crown beam and a semicircular pile are set on the top of the interlocking pile, and the second crown beam is rigidly connected to the top plate; a first crown beam is set on the top of the semicircular pile, and an embedded steel plate for docking with the first steel support is set on the inner side of the foundation pit of the first crown beam. A retaining wall is set on the top of the first crown beam, and the retaining wall is higher than the ground; The retaining piles are bored cast-in-place piles with a diameter of 1200mm and jet-jet piles for water-stop curtains. The diameter of temporary piles and anti-pullout piles is 1200mm. The first and second steel supports are made of 1000×1000 reinforced concrete. The construction method includes the following steps: (1) Traffic diversion, pipeline relocation, and site leveling; (2) Bury pre-grouting pipes and tracking grouting pipes in the vicinity of the subway structure and perform pre-grouting; (3) Construction of the first phase half-width top slab foundation pit interlocking piles, steel sheet piles, temporary piles and anti-pullout piles, dewatering wells, crown beams, and steel supports; (4) Deploy monitoring points and conduct monitoring at interlocking piles, columns, supports, ground surface, surrounding subway buildings, and underground pipelines; (5) Excavate and construct the first-phase half-roof slab and the L-shaped retaining wall on the roof, relocate the pipelines above the first-phase half-roof slab, backfill the soil, restore road traffic, and remove the steel sheet piles; (6) Construct the foundation pit retaining piles and dewatering wells for the second phase half-width top slab, and excavate and construct the second phase half-width top slab; (7) Continue to reduce water levels and monitor, gradually excavate and install the first and second steel supports, and determine whether to conduct track grouting on the subway based on the monitoring data; (8) Excavate to the bottom of the pit, and construct the bottom plate, the side wall of the second negative floor, the middle plate, and the side wall of the first negative floor in sequence and remove the supports. Post-cast holes are set at the temporary concrete piles of the bottom plate and the middle plate; (9) Remove the temporary piles between the top and bottom plates to seal the holes, demolish the retaining structures and retaining walls near the surface, relocate the pipelines above the second half of the top plate, backfill the soil, and restore road traffic.

2. The construction method of a semi-covered and excavated urban tunnel structure adjacent to a subway according to claim 1 is characterized in that: The first steel support is an H-shaped steel support, and the first steel support is connected to the semicircular pile through an embedded steel plate and an H-shaped steel purlin; A second steel support is provided on the lower side of the first steel support. The second steel support is a steel pipe support and is connected to the interlocking pile through a double-jointed I-steel purlin. The second steel support adopts an axial force servo system.

3. The construction method of a semi-covered and excavated urban tunnel structure adjacent to a subway according to claim 1 is characterized in that: A drainage well is provided at the lower end of the top plate. The drainage well is arranged in a plum blossom shape to avoid the positions of temporary piles and pull-out piles and the second steel support. A water stop ring is provided at the bottom plate of the drainage well.

4. The construction method of a semi-covered and excavated urban tunnel structure adjacent to a subway according to claim 3 is characterized in that: The temporary piles and pull-out piles are arranged below the top longitudinal beam. The temporary pile part is above the bottom plate, and the pull-out pile part is below the bottom plate. The temporary piles are cut off after the construction of the main structure of the tunnel is completed. The pull-out piles are grouted in a compound manner at the pile side and pile end, and the main load-bearing reinforcement at the top of the pull-out pile is anchored into the bottom plate.

5. The construction method of a semi-covered and excavated urban tunnel structure adjacent to a subway according to claim 3 is characterized in that: The top plate is provided with an L-shaped retaining wall at the column position, a top longitudinal beam is provided at the column position, a vertical construction joint is provided near the top plate position for later construction, and a horizontal steel bar connector is provided at the construction joint position.

6. The construction method of a semi-covered and excavated urban tunnel structure adjacent to a subway according to claim 5 is characterized in that: The top plate is provided with holes for feeding and excavation, with tongue and groove provided around the holes and beams provided beside the tongue and groove. The reserved holes are closed after the construction of the main structure of the tunnel is completed. A soil pile pool is provided above the top plate, armpit corners are provided at both ends of the top plate, an inclined horizontal construction joint is provided on the side wall near the armpit corner, and a vertical steel bar connector is provided at the horizontal construction joint.

7. The construction method of a semi-covered and excavated urban tunnel structure adjacent to a subway according to claim 3 is characterized in that: Post-cast holes are set at the temporary piles of the bottom plate and the middle plate, and tongue and groove are set around the post-cast holes, and beams are set next to the tongue and groove. After the construction of the main structure of the tunnel is completed, the post-cast holes are sealed.

8. The construction method of a semi-covered and excavated urban tunnel structure adjacent to a subway according to claim 5 is characterized in that: The two ends of the top plate are rigidly connected to the second crown beam on the top of the pile, and stress monitoring points are embedded in the connection position between the top plate and the column and in the middle position of the column.

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