Primary support arch frame and arch foot structure closely attached to and penetrating through existing tunnel and construction method of primary support arch frame and arch foot structure

Abstract

The invention discloses a primary supporting arch frame and arch foot structure closely attached to and penetrating through an existing tunnel and a construction method, and relates to the technical field of underground engineering construction.The primary supporting arch frame and arch foot structure comprises a plurality of sets of supporting assemblies arranged above the existing subway tunnel, and every two adjacent sets of supporting assemblies are connected through a mortise and tenon joint structure; an initial supporting profile steel frame is arranged above the multiple sets of supporting assemblies, profile steel arch feet are arranged at the bottom of the initial supporting profile steel frame, and the profile steel arch feet are connected with the supporting assemblies through cushion block connecting plates. According to the primary supporting arch frame and arch foot structure closely attached to the upper penetrating existing tunnel and the construction method, mounting and dismounting are convenient, repeated use can be achieved, the influence on the steel bar binding process is small, the primary supporting arch frame and arch foot structure is suitable for the situation that a newly-built upper penetrating tunnel second lining is closely attached to an existing tunnel primary supporting top plate structure through a shallow-buried excavation method, and the construction period can be effectively shortened.

Description

Technical Field

[0001] The invention relates to the technical field of underground engineering construction, and in particular to an initial arch frame arch foot structure and a construction method thereof which is closely attached to and passes through an existing tunnel. Background Art

[0002] With the large-scale construction of urban rail transit, new subway tunnels will inevitably pass through existing subway structures. Among them, close-fitting crossing construction is particularly critical and risky. In the construction of subway stations, shallow buried dark excavation is a common construction process. When it is necessary to closely pass through the existing subway tunnel structure, the primary support steel arch frame of the new station tunnel needs to be erected on the existing subway primary support structure. However, the stress redistribution caused by the excavation of the tunnel soil will cause the vertical steel arch frame to bear the vertical additional load from the upper strata. Since the arch foot section of the steel arch frame is narrow and sharp, stress concentration often occurs at the arch foot support point, which may cause damage to the primary support structure of the existing tunnel, and even destroy the waterproof layer of the existing tunnel, thereby causing water seepage problems in the existing tunnel. Therefore, effective measures are taken to disperse the stress concentration at the arch foot support point to avoid damage to the existing tunnel structure caused by the primary support arch frame of the new tunnel, and ensure the operation safety of the existing subway line.

[0003] At present, most of the research on close-fitting crossing of existing subway structures focuses on the settlement control of existing structures and the construction methods of close-fitting crossing. The relevant technical solutions are mainly aimed at close-fitting crossing under existing tunnels. However, there have been no public reports on the relevant technical solutions for close-fitting crossing over existing tunnels. Summary of the invention

[0004] The purpose of the present invention is to provide an arch foot structure and construction method for an initial support arch frame that fits closely over an existing tunnel, so as to solve the problems raised in the above-mentioned background technology, ensure the safety of the existing tunnel during the over-crossing construction process, and shorten the construction period.

[0005] To achieve the above-mentioned purpose, the present invention provides an arch foot structure of a primary support arch frame that closely passes through an existing tunnel, comprising a plurality of groups of support assemblies arranged above an existing subway tunnel, wherein two adjacent groups of the support assemblies are connected by a mortise and tenon structure; a primary support steel frame is arranged above the plurality of groups of the support assemblies, a steel arch foot is arranged at the bottom of the primary support steel frame, and the steel arch foot is connected to the support assembly through a pad connecting plate.

[0006] Preferably, the support assembly includes an embedded steel plate and a prefabricated plain concrete pad, the prefabricated plain concrete pad includes a front tenon, a middle load-bearing pad and a rear mortise, and the shape of the rear mortise is adapted to that of the front tenon; The embedded steel plate is embedded in the middle load-bearing pad, and the center of the embedded steel plate is aligned with the center of the middle load-bearing pad.

[0007] Preferably, the pad connecting plate is arranged above the embedded steel plate, an anchor bolt is anchored inside the middle load-bearing pad, one end of the anchor bolt passes through the embedded steel plate and the pad connecting plate and is fixed by a fixing member, and the pad connecting plate and the steel arch foot are fixedly connected.

[0008] Preferably, a locking foot anchor pipe connecting plate is provided above the pad connecting plate, the locking foot anchor pipe connecting plate is fixedly connected to the flange of the steel arch foot, and the width of the locking foot anchor pipe connecting plate is greater than the width of the flange.

[0009] Preferably, anchor pipe holes are symmetrically provided on the locking foot anchor pipe connecting plate, and locking foot anchor pipes are connected to the anchor pipe holes.

[0010] Preferably, the cross-sectional shape of the front tenon is set to be a dovetail shape or a superior arc shape.

[0011] A construction method for a primary arch support arch foot structure that closely passes through an existing tunnel comprises the following steps: Step S1, pre-embedded support components: after the excavation of the new tunnel is completed, pre-embedded support components on the upper part of the existing subway tunnel, the support components are arranged longitudinally along the new tunnel, and each prefabricated plain concrete pad corresponds to a primary support steel frame; Step S2, connecting the steel arch foot and the supporting assembly: pre-weld the locking foot anchor pipe connecting plate and the cushion block connecting plate to the corresponding positions of the steel arch foot, and when erecting the primary steel frame, install the locking foot anchor rod at the locking foot anchor pipe connecting plate, connect the steel arch foot and the supporting assembly through the pre-buried anchor bolts, and the cushion block connecting plate and the supporting assembly should be tightly connected; Step S3, dismantling the primary support steel frame and support assembly: before the secondary lining construction, dismantle the primary support steel frame within the secondary lining casting range, loosen the bolts at the connection between the steel arch foot and the support assembly, dismantle the support assembly, reuse it in the next cycle and repeat the above steps.

[0012] Therefore, the present invention adopts the above-mentioned primary support arch foot structure and construction method that closely fits the existing tunnel. The precast plain concrete pad can diffuse the relatively concentrated additional stress transmitted to the steel arch foot to a relatively large area, avoiding the damage of the existing tunnel structure and its waterproof layer caused by the stress concentration at the steel arch foot support point, thereby ensuring the safety of the existing tunnel during the overpass construction process; the precast plain concrete pad is prefabricated and assembled, which is convenient to install and disassemble, can be reused, and has little effect on the steel bar binding process. It is suitable for the situation where the secondary lining of a newly built overpass tunnel using the shallow buried and dark excavation method is closely fitted with the primary support top plate structure of the existing tunnel, and can effectively shorten the construction period.

[0013] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a construction schematic diagram of an embodiment of an arch foot structure of a primary support arch frame and a construction method for closely passing through an existing tunnel according to the present invention; Figure 2 It is an elevation view of an embodiment of an arch foot structure of a primary support arch frame and a construction method for closely passing through an existing tunnel according to the present invention; Figure 3 It is a top view of an embodiment of an arch foot structure and a construction method of a primary support arch frame that closely passes through an existing tunnel according to the present invention; Figure 4 It is an elevation view of a support assembly of an embodiment of an arch foot structure and a construction method of a primary support arch frame that closely passes through an existing tunnel according to the present invention; Figure 5 A top view of a support assembly of an embodiment of an arch foot structure and a construction method of a primary support arch frame that fits closely over an existing tunnel according to the present invention; Figure 6 It is a connection elevation view of two adjacent structures of an embodiment of a primary support arch frame arch foot structure and a construction method for closely passing through an existing tunnel according to the present invention; Figure 7 It is a top view of the connection of two adjacent structures of an embodiment of a primary support arch frame arch foot structure and a construction method for closely passing through an existing tunnel according to the present invention; Figure numerals: 1. existing subway tunnel; 2. supporting assembly; 3. primary support steel frame; 4. steel arch foot; 5. pad connection plate; 6. embedded steel plate; 7. prefabricated plain concrete pad; 71. front tenon; 72. middle load-bearing pad; 73. rear mortise; 8. anchor bolt; 9. locking foot anchor pipe connection plate; 10. anchor pipe hole; 11. locking foot anchor pipe. DETAILED DESCRIPTION

[0015] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0016] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0017] Example See also Figure 1-7 The present invention provides a primary support arch frame arch foot structure that closely passes through an existing tunnel, including multiple groups of support assemblies 2 arranged above an existing subway tunnel 1, and two adjacent groups of support assemblies 2 are connected by mortise and tenon structures; primary support steel frames 3 are arranged above the multiple groups of support assemblies 2, and steel arch feet 4 are arranged at the bottom of the primary support steel frames 3, and the steel arch feet 4 are connected to the support assemblies 2 through a pad connecting plate 5.

[0018] The support assembly 2 includes an embedded steel plate 6 and a prefabricated plain concrete pad 7. The prefabricated plain concrete pad 7 includes a front tenon 71, a middle load-bearing pad 72 and a rear mortise 73. The rear mortise 73 and the front tenon 71 are of the same shape and size. The cross-sectional shape of the front tenon 71 is set to be a dovetail shape or a superior arc shape. In this embodiment, a dovetail-shaped front tenon 71 is used. The embedded steel plate 6 is embedded in the middle load-bearing pad 72, and the center of the embedded steel plate 6 is aligned with the center of the middle load-bearing pad 72, and each side is parallel to each side of the middle load-bearing pad 72. Bolt holes are opened at the four corners of the embedded steel plate 6 for the anchor bolts 8 to pass through.

[0019] A pad connecting plate 5 is arranged above the embedded steel plate 6, and an anchor bolt 8 is anchored inside the middle load-bearing pad 72. One end of the anchor bolt 8 passes through the embedded steel plate 6 and the pad connecting plate 5 and is fixed by a fixing piece. The pad connecting plate 5 and the steel arch foot 4 are fixedly connected.

[0020] A locking foot anchor pipe connecting plate 9 is arranged above the pad connecting plate 5, and the locking foot anchor pipe connecting plate 9 is fixedly connected to the flange of the steel arch foot 4, and the width of the locking foot anchor pipe connecting plate 9 is greater than the width of the flange. Anchor pipe holes 10 are symmetrically opened on the locking foot anchor pipe connecting plate 9, and the anchor pipe holes 10 are connected to the locking foot anchor pipes 11.

[0021] like Figure 1 As shown in the figure, a certain underground excavation station project closely passes through the existing subway line mining section. The new station adopts the partial excavation method, dividing the entire section into 8 small pilot holes for excavation. The cross-section type of each small pilot hole is flat-top straight wall type. Since the design floor of the new station is closely fitted with the primary support at the top of the existing mining section, it is necessary to take protective measures for the top of the existing section during the construction of the primary support structure of the new tunnel to avoid the steel arch foot 4 of the primary support steel frame 3 from damaging the primary support structure and waterproof layer of the existing subway tunnel 1. At the same time, the impact of the protective measures taken on the top of the existing section on the binding of the secondary lining steel bars should be reduced to improve construction efficiency.

[0022] The support assembly 2, the steel arch foot 4 and the pad connection plate 5 are used for protection. The key dimensions of the above structure are as follows: Figure 4-Figure 5As shown, the length of the front tenon 71 is Ls, the length of the middle load-bearing pad 72 is Lc, the width of the middle load-bearing pad 72 is Wc, the height of the middle load-bearing pad 72 is Hc, the length of the embedded steel plate 6 is Lg, and the width of the embedded steel plate 6 is Wg. The key dimensions are determined as follows: ① The length of the embedded steel plate 6 should meet the following requirements: Lg ≥ Hh + 2·α·Hf. Among them, Hh is the height of the steel frame section, Hf is the weld heel size of the fillet weld connected to the steel plate, and α is a coefficient greater than 1.5; ② The width of the embedded steel plate 6 should meet the following requirements: Wg≥Wh+2·α·Hf. Among them, Wh is the cross-sectional width of the steel frame, and Hf is the weld heel size of the fillet weld connected to the steel plate; ③The length of the middle load-bearing pad 72 should meet the following requirements: a. Lc=Sg-Ls. Among them, Sg is the middle distance between adjacent steel frames, that is, the sum of the lengths of the middle load-bearing pad 72 and the front tenon 71 is the middle distance between adjacent primary support steel frames 3; b. Lc ≥ Lg + 2·α·Hg. Wherein, Hg is the thickness of the embedded steel plate 6; ④ The width of the middle load-bearing pad 72 should meet the following requirements: Wc ≥ Wg + 2·α·Hg; ⑤ The height of the middle load-bearing pad 72 should satisfy: Hc≥max(Lg, Wg), that is, it should not be less than the maximum size of the embedded steel plate 6.

[0023] According to the above description and the method for determining the key dimensions, a corresponding mold is generated to prefabricate the support assembly 2 .

[0024] The construction steps are as follows: Step S1, pre-embedded support components: after the excavation of the new tunnel is completed, pre-embedded support components on the upper part of the existing subway tunnel, the support components are arranged longitudinally along the new tunnel, and each prefabricated plain concrete pad corresponds to a primary support steel frame; Step S2, connecting the steel arch foot and the supporting assembly: pre-weld the locking foot anchor pipe connecting plate and the cushion block connecting plate to the corresponding positions of the steel arch foot, and when erecting the primary steel frame, install the locking foot anchor rod at the locking foot anchor pipe connecting plate, connect the steel arch foot and the supporting assembly through the pre-buried anchor bolts, and the cushion block connecting plate and the supporting assembly should be tightly connected; Step S3, dismantling the primary support steel frame and support assembly: before the secondary lining construction, dismantle the primary support steel frame within the secondary lining casting range, loosen the bolts at the connection between the steel arch foot and the support assembly, dismantle the support assembly, reuse it in the next cycle and repeat the above steps.

[0025] Therefore, the present invention adopts the above-mentioned primary support arch frame arch foot structure and construction method that closely fits the existing tunnel. It is convenient to install and disassemble, can be reused, has little impact on the steel bar binding process, is suitable for the situation where the secondary lining of a newly built tunnel through shallow buried tunnel excavation method is closely fitted with the primary support top plate structure of the existing tunnel, and can effectively shorten the construction period.

[0026] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A primary arch support arch foot structure that closely passes through an existing tunnel, characterized in that: It comprises a plurality of groups of supporting assemblies arranged above an existing subway tunnel, wherein two adjacent groups of the supporting assemblies are connected by a mortise and tenon structure; a primary support steel frame is arranged above the plurality of groups of the supporting assemblies, a steel arch foot is arranged at the bottom of the primary support steel frame, and the steel arch foot is connected to the supporting assemblies through a pad connecting plate.

2. The primary support arch foot structure for closely passing through an existing tunnel according to claim 1, characterized in that: The support assembly includes a pre-buried steel plate and a prefabricated plain concrete pad, wherein the prefabricated plain concrete pad includes a front tenon, a middle load-bearing pad and a rear mortise, and the shape of the rear mortise is adapted to that of the front tenon; The embedded steel plate is embedded in the middle load-bearing pad, and the center of the embedded steel plate is aligned with the center of the middle load-bearing pad.

3. The primary support arch foot structure for closely passing through an existing tunnel according to claim 2, characterized in that: The pad connection plate is arranged above the embedded steel plate, and an anchor bolt is anchored inside the middle load-bearing pad. One end of the anchor bolt passes through the embedded steel plate and the pad connection plate and is fixed by a fixing piece. The pad connection plate is fixedly connected to the steel arch foot.

4. The primary support arch foot structure for closely passing through an existing tunnel according to claim 3 is characterized in that: A locking foot anchor pipe connecting plate is arranged above the pad connecting plate, and the locking foot anchor pipe connecting plate is fixedly connected to the flange of the steel arch foot, and the width of the locking foot anchor pipe connecting plate is greater than the width of the flange.

5. The primary arch support arch foot structure for closely passing through an existing tunnel according to claim 4, characterized in that: The locking foot anchor pipe connecting plate is symmetrically provided with anchor pipe holes, and the locking foot anchor pipes are connected to the anchor pipe holes.

6. The primary support arch foot structure for closely passing through an existing tunnel according to claim 5, characterized in that: The cross-sectional shape of the front tenon is set to be a dovetail shape or a superior arc shape.

7. A construction method for a primary arch support arch foot structure that is close to and passes through an existing tunnel as described in any one of claims 1 to 6, characterized in that: The following steps are involved: Step S1, pre-embedded support components: after the excavation of the new tunnel is completed, pre-embedded support components on the upper part of the existing subway tunnel, the support components are arranged longitudinally along the new tunnel, and each prefabricated plain concrete pad corresponds to a primary support steel frame; Step S2, connecting the steel arch foot and the supporting assembly: pre-weld the locking foot anchor pipe connecting plate and the cushion block connecting plate to the corresponding positions of the steel arch foot, and when erecting the primary steel frame, install the locking foot anchor rod at the locking foot anchor pipe connecting plate, connect the steel arch foot and the supporting assembly through the pre-buried anchor bolts, and the cushion block connecting plate and the supporting assembly should be tightly connected; Step S3, dismantling the primary support steel frame and support assembly: before the secondary lining construction, dismantle the primary support steel frame within the secondary lining casting range, loosen the bolts at the connection between the steel arch foot and the support assembly, dismantle the support assembly, reuse it in the next cycle and repeat the above steps.

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