A protective structure and support method for an existing tunnel structure in a sandy and gravel stratum

Abstract

The present invention discloses a protective structure and support method for an existing tunnel structure in a gravel stratum. A steel support layer is installed on the inner wall of the corresponding protection section of the tunnel. The inner sidewall of the support layer is supported by multiple support frames. The two corresponding ends of a single support frame extend to the bottom of the tunnel and are fixed. Multiple extrusion devices are provided between the single support frame and the support layer to press the support layer against the sidewall and top of the tunnel. The extrusion devices are fixed to the support frame. After the support layer is installed, the extrusion device performs multi-point extrusion on the support layer so that the support layer is tightly attached to the inner sidewall of the tunnel. The support layer is a steel structure layer with the characteristics of elastic contraction. On the one hand, it can improve the support strength, and on the other hand, it can contract under vibration to absorb vibration energy. The installation method is installation during splicing and is reusable.

Description

Technical Field

[0001] The present invention belongs to the technical field of engineering construction, and in particular relates to a protective structure and a supporting method for an existing tunnel structure in a sand and gravel stratum. Background Art

[0002] In urban areas, the construction of new subway tunnels crossing existing operational subway lines is a typical proximity operation. Since subway tunnels are large-scale transportation systems, typically consisting of two-track tunnels, their importance and the stringent requirements for deformation control are self-evident. Construction of the existing tunnel creates a primary disturbance to the soil, while the close-proximity crossing of the new tunnel creates a secondary disturbance, exacerbating deformation of the surrounding rock mass and altering the stress state and pattern of the existing tunnel. Without specific countermeasures, adverse effects on the existing subway tunnel can easily occur, such as a reduction in the structural load-bearing capacity or even damage, and excessive deformation that intrudes into the clearance.

[0003] The primary challenge faced during the construction of shield tunnels through existing subway tunnels is the impact of construction on the existing tunnel. There are three control standards for new tunnels passing under existing tunnels: first, the safety and normal operation of the overlying existing tunnel must be ensured; second, the safety and normal operation of the new tunnel must be ensured, specifically, deformation of the new tunnel must meet limit requirements, meaning excessive deformation cannot occur; and third, the impact of the new tunnel on the surrounding environment must be met, such as ground subsidence requirements. Existing tunnels carry large volumes of high-frequency rail transit and have become a preferred choice for commuters, placing very high demands on deformation control. When a shield tunnel passes through an existing operating tunnel, the accumulation of multiple disturbances can exacerbate deformation in the existing tunnel. Reasonable control methods and measures can effectively mitigate the negative impact of the crossing on the operating tunnel.

[0004] From the perspective of control methods and targets, control measures can be broadly categorized into three types: strengthening existing tunnels, soil reinforcement, and support and partition methods. The existing tunnel must be supported while also ensuring the proper operation of the subway. Therefore, sufficient support strength is required, while also mitigating the impact of vibrations generated by the shield machine during construction. Vibration can easily cause cracks between shield segments to widen, leading to structural instability. Summary of the Invention

[0005] The purpose of the present invention is to provide a protective structure and support method for existing tunnel structures in sand and gravel formations, so as to reduce the impact of vibration generated by the shield machine during construction. Vibration can easily cause cracks between shield segments to become larger, resulting in structural instability.

[0006] To solve the above technical problems, the present invention is achieved through the following technical solutions:

[0007] A protective structure for an existing tunnel structure in a gravel stratum, wherein a steel support layer is installed on the inner wall of the corresponding protection section of the tunnel, the outer wall of the support layer abuts against the side wall and top of the supporting tunnel, the support layer extends along the length of the tunnel, and the support layer has shrinkage elasticity;

[0008] The inner side wall of the support layer is supported by a plurality of support frames;

[0009] Multiple support frames are arranged along the length of the tunnel, a single support frame extends along the cross-sectional curve of the supporting layer, and the two corresponding ends of the single support frame extend to the bottom of the tunnel and are fixed;

[0010] A plurality of extrusion devices are provided between a single support frame and the support layer for pressing the support layer against the side walls and top of the tunnel. The extrusion devices are arranged extending along the length direction of the support frame.

[0011] Furthermore, the supporting layer is a steel plate, and the surface of the steel plate has a regular arc-shaped transition surface.

[0012] The supporting layer is a steel plate with a corrugated transition corresponding to the tunnel cross-section. Rubber columns are installed in the corrugated grooves on the side of the steel plate that abuts the tunnel. The rubber columns are circular and extend along the length of the grooves. After being squeezed and deformed, they contact the inner wall of the tunnel and the steel plate corrugated grooves.

[0013] A pressing roller is installed in the corrugated groove on the other side of the tunnel where the steel plate is adjacent to. The pressing roller is hollow, and one side of the pressing roller is arc-shaped for abutting against the inner wall of the corrugated groove, while the other side of the pressing roller is flat, which is used to cooperate with the extrusion device to extrude and transmit the force to the steel plate.

[0014] The extrusion device includes a screw rod, and the support frame has a screw hole for the corresponding screw rod to pass through. One end of the screw rod contacts the plane side of the pressing roller, and the other end is fixed with a rod sleeve for rotation.

[0015] The pressing roller is provided with a through hole at the end portion corresponding to the screw rod, and the position of the through hole is a blind hole support portion for the screw rod end portion to be inserted and rotated together.

[0016] Furthermore, the end of the support frame is provided with a pad, and the pad is provided with a through hole for bolts to pass through and be fixed to the bottom of the tunnel.

[0017] A method for supporting an existing tunnel structure protection structure in a sandy and gravel stratum, using an existing tunnel structure protection structure in a sandy and gravel stratum, comprises the following steps:

[0018] (1) Using data research, theoretical analysis, numerical calculation, and on-site measurement to determine the length and range of the support points, cut the steel plate used for the support layer to match the length range of the support points, and cut the rubber columns to match the length range of the support points;

[0019] (2) Install the rubber column in the corresponding corrugated groove of the steel plate and perform preliminary fixation with glue. After the rubber column is initially fixed to all the corrugated grooves, the supporting layer is installed as a whole on the inner wall of the tunnel support point, and a temporary wooden beam is used to support the steel plate of the supporting layer and the bottom of the tunnel;

[0020] (3) Install the support frame, install the support frame in sequence, and control the spacing between the support frames to be 1-2m. Then fix the bottom of the support frame to the bottom of the tunnel, insert the pressing roller, align the blind hole corresponding to the pressing roller with the screw hole, and then install the screw rod. The screw rod passes through the thread in the corresponding screw hole and is limited to the blind hole of the pressing roller;

[0021] (4) Insert the steel bar into the rod sleeve and rotate it, so that the tightening process of the screw acts on the pressing roller, which presses the support layer through the pressing roller, so that the support layer is close to the inner wall of the tunnel, and the steel plate and rubber column are deformed. Finally, the temporary wooden beam support is removed to complete the process.

[0022] The present invention has the following beneficial effects: the extrusion device is fixed to the support frame. After the support layer is installed, the support layer is extruded at multiple points by the extrusion device so that the support layer is tightly attached to the inner wall of the tunnel. The support layer is a steel structure layer and has the characteristics of elastic shrinkage. On the one hand, it can improve the support strength, and at the same time it can shrink under vibration and absorb vibration energy. The installation method is installation during splicing, which has the function of easy disassembly and installation. It can be installed for different existing tunnel construction points and can be reused. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments.

[0024] Figure 1 : Schematic diagram of the structure of the present invention and the tunnel separation structure.

[0025] Figure 2 : Schematic diagram of the coordination structure of the support layer and the support frame of the present invention.

[0026] Figure 3 : Schematic diagram of the support frame and pressing roller installation structure of the present invention.

[0027] Figure 4 : Schematic diagram of the complete assembly structure of the present invention.

[0028] In the accompanying drawings, the components represented by the respective reference numerals are listed as follows: supporting layer 1 , supporting frame 2 , rubber column 4 , pressing roller 3 , screw rod 5 , screw hole 21 , rod sleeve 51 , and pad 22 . DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0030] like Figure 1-4 As shown: a protective structure for an existing tunnel structure in a gravel stratum, a steel structure support layer 1 is installed on the inner wall of the corresponding protection section tunnel, the outer wall of the support layer 1 is in contact with the side wall and top of the supporting tunnel, the support layer 1 extends along the length of the tunnel, and the support layer 1 has shrinkage elasticity; subway tunnels are generally arched in design, with vertical side walls, an arc-shaped top, a horizontal bottom section, a central extension section of the bottom for rails and concrete sleepers, and a recessed section, and a construction road extending toward the center at the bottom of the side wall, which is poured with concrete and is also used to fix the end of the support frame.

[0031] The inner side wall of the supporting layer 1 is supported by a plurality of support frames 2; there is at least one support frame, which is evenly and equidistantly arranged.

[0032] Multiple support frames 2 extend along the length of the tunnel. Each support frame 2 follows the cross-sectional curve of the support layer 1, with its two corresponding ends extending to the tunnel bottom and fixed. The cross-sectional shape of the support layer is identical to that of the tunnel sidewalls and roof, and the corresponding support frames have the same structure, ensuring sufficient contact and support. The support frames are steel columns with a rectangular tubular cross-section, featuring vertical sections on both sides and a curved section at the top.

[0033] A plurality of extrusion devices are provided between a single support frame 2 and the support layer 1 for pressing the support layer 1 against the side walls and top of the tunnel. The extrusion devices are arranged extending along the length direction of the support frame 2 .

[0034] The extrusion device is fixed to the support frame. After the support layer is installed, the support layer is extruded at multiple points through the extrusion device so that the support layer is close to the inner wall of the tunnel. The support layer is a steel structure layer with the characteristics of elastic shrinkage. On the one hand, it can improve the support strength, and at the same time it can shrink under vibration and absorb vibration energy. The installation method is installation during splicing, which has the function of easy disassembly and installation. It can be installed at different existing tunnel construction points and can be reused.

[0035] The supporting layer 1 is a steel plate, the surface of which has a regular arc-shaped transition surface. After being bent into the shape of the tunnel inner wall, the steel plate itself has compressible elasticity.

[0036] Support layer 1 is a steel plate with a corrugated transition corresponding to the tunnel cross-section. This sinusoidal shape provides regularity and elasticity, absorbing vibration energy. When tunnel construction is close together, the shield machine passes near an existing tunnel, causing the corresponding segments to vibrate violently. This is when the steel plate against the segments comes into play. The corrugated transition surface of the steel plate absorbs vibration energy, causing it to stretch in both directions. This stretching and rebound releases vibration energy, reducing the effect of the intense vibration being transmitted to the segments.

[0037] A rubber column 4 is installed in the corrugated groove on the side of the steel plate that abuts the tunnel. This circular column 4 extends along the length of the groove. After being squeezed and deformed, it contacts the inner wall of the tunnel and the steel plate corrugated groove. It fills the gaps in the steel plate corrugated groove, ensuring that the steel plate fully contacts the tunnel inner wall. The rubber column acts as an auxiliary filler and has better elastic shrinkage properties.

[0038] A pressing roller 3 is installed in the corrugated groove on the other side of the steel plate, corresponding to the side against which the tunnel is abutting. This roller is hollow, with one side curved to abut against the inner wall of the corrugated groove. The other side is flat, cooperating with the extrusion device to apply force and transmit the force to the steel plate. The pressing roller is hollow and has a slightly arc-shaped circular cross-section. It cooperates with the extrusion device, allowing the extrusion end of the extrusion device to fully exert force on the corrugated groove of the steel plate, solving the problem of unstable force on the corrugated surface of the steel plate.

[0039] The extrusion device includes a screw 5. The support frame 2 has a screw hole 21 for the corresponding screw 5 to pass through. One end of the screw 5 contacts the flat side of the pressing roller 3, and the other end is fixed with a rod sleeve 51 for rotation. The rod body passes through the rod sleeve to rotate the screw. With the cooperation of the screw hole, the pressure roller transmits force to squeeze the steel plate, making the steel plate close to the interior of the tunnel.

[0040] The pressing roller 3 is provided with a through hole at the end portion corresponding to the screw 5 , and the position of the through hole is a blind hole support portion for the screw 5 end portion to be inserted and rotated together.

[0041] The end of the support frame 2 is provided with a pad 22, and the pad 22 is provided with a through hole for bolts to pass through and be fixed to the bottom of the tunnel.

[0042] A method for supporting a protective structure of an existing tunnel structure in a sandy and gravel stratum comprises the following steps:

[0043] (1) Using data research, theoretical analysis, numerical calculation, and on-site measurement to determine the length and range of the support points, cut the steel plate used for the support layer to match the length range of the support points, and cut the rubber columns to match the length range of the support points;

[0044] (2) Install the rubber column in the corresponding corrugated groove of the steel plate and perform preliminary fixation with glue. After the rubber column is initially fixed to all the corrugated grooves, the supporting layer is installed as a whole on the inner wall of the tunnel support point, and a temporary wooden beam is used to support the steel plate of the supporting layer and the bottom of the tunnel;

[0045] (3) Install the support frame, install the support frame in sequence, and control the spacing between the support frames to be 1-2m. Then fix the bottom of the support frame to the bottom of the tunnel, insert the pressing roller, align the blind hole corresponding to the pressing roller with the screw hole, and then install the screw rod. The screw rod passes through the thread in the corresponding screw hole and is limited to the blind hole of the pressing roller;

[0046] (4) Insert the steel bar into the rod sleeve and rotate it, so that the tightening process of the screw acts on the pressing roller, which presses the support layer through the pressing roller, so that the support layer is close to the inner wall of the tunnel, and the steel plate and rubber column are deformed. Finally, the temporary wooden beam support is removed to complete the process.

[0047] This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can better understand and utilize the present invention.

Claims

1. A protective structure for an existing tunnel structure in a sandy and gravel stratum, characterized by: A steel structure support layer (1) is installed on the inner wall of the corresponding protection section tunnel, the outer side wall of the support layer (1) is in contact with the side wall and top of the supporting tunnel, the support layer (1) extends along the length direction of the tunnel, and the support layer (1) has shrinkage elasticity; The inner side wall of the support layer (1) is supported by a plurality of support frames (2); A plurality of support frames (2) are arranged and extended along the length direction of the tunnel, a single support frame (2) extends along the cross-sectional curve of the support layer (1), and two corresponding ends of the single support frame (2) extend to the bottom of the tunnel and are fixed; A plurality of extrusion devices are provided between a single support frame (2) and the support layer (1), for pressing the support layer (1) against the tunnel sidewall and top, and the extrusion devices are arranged extending along the length direction of the support frame (2); The supporting layer (1) is a steel plate, the surface of the steel plate has a regular arc-shaped transition surface, and the steel plate has a corrugated transition corresponding to the tunnel cross section; A rubber column (4) is installed in the corrugated groove on one side of the steel plate that is close to the tunnel. The rubber column (4) is circular and extends along the length direction of the corrugated groove. After being squeezed and deformed, the rubber column (4) contacts the inner wall of the tunnel and the corrugated groove of the steel plate. A pressing roller (3) is installed in the corrugated groove on the other side of the tunnel corresponding to the steel plate, and the pressing roller (3) is hollow. One side of the pressing roller (3) is arc-shaped for contacting with the inner wall of the corrugated groove, and the other side of the pressing roller (3) is flat and is used to cooperate with the extrusion device to perform extrusion force and transmit the force to the steel plate; The extrusion device includes a screw (5), the support frame (2) has a screw hole (21) for the corresponding screw (5) to pass through, one end of the screw (5) abuts against the flat side of the pressing roller (3), and the other end is fixed with a rod sleeve (51) for rotation; The end of the support frame (2) is provided with a pad (22), and the pad (22) is provided with a through hole for bolts to pass through and be fixed to the bottom of the tunnel.

2. The protective structure for an existing tunnel structure in a sandy and gravel stratum according to claim 1, characterized in that: The pressing roller (3) is provided with a perforation at the end portion corresponding to the screw rod (5), and the position of the perforation is a blind hole support portion for the screw rod (5) end portion to be inserted and rotated together.

3. A method for supporting an existing tunnel structure protection structure in a sandy and gravel stratum, using the existing tunnel structure protection structure in a sandy and gravel stratum as claimed in claim 2, characterized in that: It includes the following steps: (1) Use data research, theoretical analysis, numerical calculation, and on-site measurement to determine the length and range of the support points, cut the steel plate used for the support layer to match the length range of the support points, and cut the rubber columns to match the length range of the support points; (2) Install the rubber column in the corresponding corrugated groove of the steel plate and fix it preliminarily with glue. After the rubber column is preliminarily fixed in the corrugated groove, install the supporting layer as a whole on the inner wall of the tunnel support point. The steel plate serving as the supporting layer is supported by temporary wooden beams between the tunnel bottom. (3) Install the support frame, install the support frame in sequence, and control the spacing between the support frames to be 1-2m. Then fix the bottom of the support frame to the bottom of the tunnel, insert the pressing roller, align the blind hole corresponding to the pressing roller with the screw hole, and then install the screw rod. The screw rod passes through the thread in the corresponding screw hole and is limited to the blind hole of the pressing roller; (4) Insert the steel bar into the rod sleeve and rotate it, so that the tightening process of the screw acts on the pressing roller, which presses the support layer so that the support layer is close to the inner wall of the tunnel. The steel plate and rubber column are deformed, and finally the temporary wooden beam support is removed to complete the process.

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