A split tunnel structure and construction method suitable for a small-clearance four-lane tunnel

Abstract

The present invention provides a split tunnel structure and construction method suitable for a narrow-spacing four-lane tunnel. The structure comprises two tunnels spaced a certain distance apart, each comprising a tunnel body and a plurality of concrete center columns spaced in the middle of the tunnel body along the tunnel's travel direction. The concrete center columns extend from the bottom of the tunnel body to the top. This invention can effectively reduce tunnel construction costs.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel engineering, and in particular to a split tunnel structure and a construction method suitable for a small-clearance four-lane tunnel. Background Art

[0002] my country is a mountainous country. With the rapid development of urbanization, resources at urban road nodes are becoming increasingly scarce in urban tunnel construction. Traditional split tunnel designs, especially under tunnel construction redline restrictions, struggle to meet the connectivity needs of urban infrastructure. This often requires the construction of a four-lane tunnel structure (eight lanes in both directions). Conventional four-lane tunnels often have spans exceeding 20 meters. Previous projects typically employed a construction method with two temporary, double-layered pilot tunnels on both sides, requiring extensive removal of temporary supports and resulting in significant engineering waste. Furthermore, since urban tunnels must accommodate pedestrian traffic, the presence of pedestrian passages further widens the tunnel span, increasing tunnel construction costs. Therefore, a new split tunnel structure suitable for close-spacing four-lane tunnels is urgently needed to effectively reduce tunnel construction costs. Summary of the Invention

[0003] The purpose of the present invention is to provide a split tunnel structure and construction method suitable for a small-clearance four-lane tunnel, so as to solve the problem of high cost of existing tunnel construction.

[0004] In order to solve the above technical problems, the present invention provides a split tunnel structure suitable for a small-clearance four-lane tunnel, comprising two tunnels with a small clear distance, wherein the tunnel includes a tunnel body and a plurality of concrete center columns located in the middle of the tunnel body and arranged in sequence along the direction of tunnel travel, wherein the concrete center columns extend from the bottom of the tunnel body to the top of the tunnel body.

[0005] Optionally, the tunnel further includes a connecting beam arranged on two adjacent concrete center columns.

[0006] Optionally, the tunnel further includes a middle partition plate arranged along the traveling direction of the tunnel and located on the concrete center column and the connecting beam.

[0007] Optionally, the middle partition divides the tunnel body into two layers, upper and lower layers.

[0008] Optionally, the tunnel body includes a rock and soil matrix with a travel channel, a primary lining arranged on the inner wall of the rock and soil matrix, and a secondary lining arranged on the inner wall of the primary lining, the concrete center column extends from the bottom of the primary lining through the secondary lining to the top of the primary lining, and the middle partition extends to the primary lining on both sides.

[0009] Optionally, the middle partition is ≥3m away from the top of the tunnel body.

[0010] Optionally, the concrete center column is a reinforced concrete center column or a steel tube concrete center column.

[0011] Optionally, adjacent concrete center columns are set at intervals of 4-6m.

[0012] Optionally, the tunnel body is symmetrically arranged about the concrete center column.

[0013] The present invention also provides a construction method for a divided tunnel structure suitable for a small-clearance four-lane tunnel, comprising: excavating the first of the two tunnels, including: excavating the soil layer on the first side of the upper step to form a first semi-arched channel on the first side of the upper step, applying a first primary lining and a first locking foot small guide tube on the top of the first semi-arched channel, applying a concrete center column on the side of the first semi-arched channel close to the second side, and connecting the upper part of the concrete center column to the first primary lining on the top of the semi-arched channel and extending downward to the bottom of the tunnel body, applying a first middle partition plate on the bottom of the first semi-arched channel to form a ring with the first primary lining, the concrete center column and the first middle partition plate, excavating the soil layer on the first side of the middle step to form a first middle-step channel on the first side of the middle step, and retaining the first middle-step channel at the bottom of the first middle-step channel. Core soil, the side of the first intermediate step channel close to the second side is a concrete center column, the side of the first intermediate step channel away from the second side is constructed with a second primary lining and a second locking foot small conduit, the top of the first intermediate step channel is a first intermediate partition, then, the first core soil is excavated, a temporary inverted arch is constructed at the bottom of the first intermediate step channel, so that the second primary lining, the first intermediate partition, the concrete center column and the temporary inverted arch form a ring, a connecting beam of the concrete center column is constructed, the soil layer on the first side of the lower step is excavated to form the first side of the lower step into the first lower step channel, the side of the first lower step channel close to the second side is a concrete center column, the side of the first lower step channel away from the second side is constructed with a third primary lining and a third locking foot small conduit, the top of the first lower step channel is a temporary inverted arch, and the bottom of the first lower step channel is constructed with a fourth primary lining, the third primary lining, The fourth primary lining, the concrete center column and the temporary inverted arch are surrounded by a ring, the soil layer on the second side of the upper step is excavated to form a second semi-arched channel on the second side of the upper step, the fifth primary lining and the fifth locking foot small guide tube are applied on the top of the second semi-arched channel, the side of the second semi-arched channel close to the first side is a concrete center column, and the second middle partition is applied at the bottom of the second semi-arched channel, so that the fifth primary lining, the concrete center column and the second middle partition are surrounded by a ring, the soil layer on the second side of the middle step is excavated to form a second middle step channel on the second side of the middle step, and the second core soil at the bottom of the second middle step channel is retained, the side of the second middle step channel close to the first side is a concrete center column, the side of the second middle step channel away from the first side is applied with the sixth primary lining and the sixth locking foot small guide tube, the top of the second middle step channel is the second middle partition, and then Then, excavate the second core soil, excavate the soil layer on the second side of the lower step to form a second lower step channel on the second side of the lower step, the side of the second lower step channel close to the first side is a concrete middle column, the side of the second lower step channel away from the second side is constructed with the seventh primary lining and the seventh lock foot small guide tube, the bottom of the second lower step channel is constructed with the eighth primary lining, the sixth primary lining, the seventh primary lining and the eighth primary lining, the second middle partition and the concrete middle column form a ring, a second lining inverted arch is constructed on the fourth primary lining and the eighth primary lining, and the inverted arch is backfilled with arch filling material, the first side wall second lining is constructed on the second primary lining and the third primary lining, the second side wall second lining is constructed on the sixth primary lining and the seventh primary lining, and finally the arch part second lining is constructed on the first primary lining and the fifth primary lining, and the temporary inverted arch is removed, wherein the first side is one of the left and right sides.The second side is the other of the left and right sides; the second of the two tunnels is excavated; wherein the structure after the construction of the first tunnel is symmetrical to the structure after the construction of the second tunnel.

[0014] The present invention provides a split tunnel structure and construction method suitable for a small-spacing four-lane tunnel, which has the following beneficial effects:

[0015] Since the split tunnel structure suitable for a small-clearance four-lane tunnel includes two tunnels, both tunnels are provided with concrete center columns, and the concrete center columns extend from the bottom of the tunnel body to the top of the tunnel body, so that the tunnel body can be supported by the center columns. The main span width can be reduced by dividing the span by the center columns. For example, for a conventional four-lane tunnel with a main span of 20m, the main span of the tunnel can be reduced to 12m, which can reduce the cost of the tunnel. In addition, the reduction in the main span width can reduce the area of ​​tunnel section excavation, which is more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 1 is a schematic structural diagram of a split tunnel structure applicable to a four-lane tunnel with a small clearance, according to an embodiment of the present invention;

[0017] Figure 2 2 is a schematic structural diagram of a single hole of a divided tunnel structure applicable to a four-lane tunnel with a small clearance, according to an embodiment of the present invention;

[0018] Figure 3 This is a structural diagram of a split tunnel structure suitable for a small-clearance four-lane tunnel during construction according to an embodiment of the present invention;

[0019] Figure 4 It is a structural schematic diagram of a single hole during the construction of a split tunnel structure suitable for a four-lane tunnel with a small clearance according to an embodiment of the present invention.

[0020] Description of reference numerals:

[0021] 100-tunnel; 112-primary lining; 113-secondary lining; 120-concrete center column; 130-connecting beam; 140-middle partition;

[0022] 201 - first semi-arched channel; 202 - first primary lining; 203 - first locking foot small conduit; 204 - first middle partition;

[0023] 205 - First intermediate step; 206 - First core soil; 207 - Second primary lining; 208 - Second locking foot small guide tube; 209 - Temporary invert;

[0024] 210 - first lower-step channel; 211 - third primary lining; 212 - third locking foot small guide tube; 213 - fourth primary lining;

[0025] 214 - second semi-arched passage; 215 - fifth primary lining; 216 - fifth locking foot small conduit; 217 - second middle partition;

[0026] 218 - Second intermediate passage; 219 - Second core soil; 220 - Sixth primary lining; 221 - Sixth locking foot small conduit;

[0027] 222 - Second lower step passage; 223 - Seventh primary lining; 224 - Seventh locking foot small guide tube; 225 - Eighth primary lining;

[0028] 226-Secondary lining of inverted arch; 227-Inverted arch filling; 228-Secondary lining of first side wall; 229-Secondary lining of second side wall; 230-Secondary lining of arch. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0031] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0032] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like indicate positions or locations based on the positions shown in the accompanying drawings, or the positions or locations in which the inventive product is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0033] Furthermore, terms such as "horizontal" and "vertical" do not necessarily mean that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0034] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0035] refer to Figure 1 and Figure 2 , Figure 1 1 is a schematic structural diagram of a split tunnel structure applicable to a small-clearance four-lane tunnel according to an embodiment of the present invention. Figure 2 : This is a structural schematic diagram of a single hole of a split tunnel structure suitable for a four-lane tunnel with a small clearance in an embodiment of the present invention. This embodiment provides a split tunnel structure suitable for a four-lane tunnel with a small clearance, including two tunnels 100 with a small clearance, wherein the tunnel 100 includes a tunnel body and a plurality of concrete center columns 120 located in the middle of the tunnel body and arranged in sequence along the direction of travel of the tunnel 100, wherein the concrete center columns 120 extend from the bottom of the tunnel body to the top of the tunnel body.

[0036] Since the split tunnel structure suitable for a small-clearance four-lane tunnel includes two tunnels 100, both tunnels 100 are provided with concrete center columns 120, and the concrete center columns 120 extend from the bottom of the tunnel body to the top of the tunnel body, so that the tunnel body can be supported by the center columns. The main span width can be reduced by dividing the span by the center columns. For example, for a conventional four-lane tunnel 100 with a main span of 20m, the main span of the tunnel 100 can be reduced to 12m, which can reduce the cost of the tunnel 100. In addition, the reduction in the main span width can reduce the area of ​​tunnel section excavation, which is more environmentally friendly.

[0037] Preferably, tunnel 100 also includes connecting beams 130 positioned between two adjacent concrete center columns 120. The center columns and connecting beams 130 form a spatial grid framework, enhancing the overall rigidity of tunnel 100. Furthermore, compared to conventional two-lane tunnels 100, tunnel 100 has better air permeability, as the center columns are spaced 4-6 meters apart, resulting in less stress for drivers.

[0038] Preferably, the tunnel 100 also includes a middle partition 140 arranged along the traveling direction of the tunnel 100 and located on the concrete center column 120 and the connecting beam 130. In this way, the middle partition 140 and the space of the tunnel body above the middle partition 140 can be used as an escape passage. Compared with the tunnel 100 in which the escape passage is set at the bottom of the tunnel body, the width of the main span of the tunnel 100 can be effectively reduced, thereby reducing the cost of the tunnel 100 and being more environmentally friendly. For example, for a conventional four-lane tunnel 100, the construction limit can be reduced by 2m.

[0039] Furthermore, the middle partition 140 divides the tunnel body into two layers, upper and lower layers.

[0040] The distance between the middle partition plate 140 and the top of the tunnel body is ≥3m to meet pedestrian needs and ensure mechanical operations.

[0041] Specifically, the tunnel body includes a rock and soil matrix with a travel passage, a primary lining 112 disposed on the inner wall of the rock and soil matrix, and a secondary lining 113 disposed on the inner wall of the primary lining 112. The concrete center column 120 extends from the bottom of the primary lining 112 through the secondary lining 113 to the top of the primary lining 112, and the center partition 140 extends laterally to both sides of the primary lining 112. The provision of the center column can effectively reduce the thickness of the secondary lining 113. For example, for a conventional four-lane tunnel 100, the thickness of the secondary lining 113 can be reduced from 70 cm to 45 cm.

[0042] Specifically, the concrete center column 120 may be a reinforced concrete center column or a steel tube concrete center column, or other concrete center columns, which is not limited in this embodiment.

[0043] Specifically, adjacent concrete center columns 120 are spaced 4-6 meters apart.

[0044] In this embodiment, the concrete center column 120 is constructed by cast-in-place piles.

[0045] The tunnel body is symmetrically arranged about the concrete center column 120 .

[0046] refer to Figure 3 and Figure 4 , Figure 3 This is a structural diagram of a split tunnel structure suitable for a small-clearance four-lane tunnel during construction according to an embodiment of the present invention. Figure 4 1 is a schematic diagram of a single tunnel structure during the construction of a split tunnel structure for a four-lane tunnel with a small clearance distance according to an embodiment of the present invention. This embodiment also provides a construction method for a split tunnel structure for a four-lane tunnel with a small clearance distance, including:

[0047] Excavation of the first of two tunnels 100, including:

[0048] Excavate the soil layer on the first side of the upper step to form a first semi-arched channel 201 on the first side of the upper step. Build a first primary lining 202 and a first locking foot small guide tube 203 on the top of the first semi-arched channel 201. Build a concrete center column 120 on the side of the first semi-arched channel 201. The concrete center column 120 is connected to the first primary lining 202 on the top of the semi-arched channel and extends downward to the bottom of the tunnel body. Build a first middle diaphragm 204 on the bottom of the first semi-arched channel 201 so that the first primary lining 202, the concrete center column 120, and the first middle diaphragm 204 form a ring.

[0049] The soil layer on the first side of the middle step is excavated to form a first middle step channel 205 on the first side of the middle step, and the first core soil 206 at the bottom of the first middle step channel 205 is retained. The side of the first middle step channel 205 close to the second side is a concrete middle column 120. The side of the first middle step channel 205 away from the second side is constructed with a second primary lining 207 and a second locking foot small guide tube 208. The top of the first middle step channel 205 is a first middle diaphragm 204. Afterwards, the first core soil 206 is excavated, and a temporary inverted arch 209 is constructed at the bottom of the first middle step channel 205, so that the second primary lining 207, the first middle diaphragm 204, the concrete middle column 120 and the temporary inverted arch 209 form a ring. The connecting beam 130 of the concrete middle column 120 is constructed.

[0050] The soil layer on the first side of the lower step is excavated to form a first lower step channel 210 on the first side of the lower step. The side of the first lower step channel 210 close to the second side is a concrete center column 120. The side of the first lower step channel 210 away from the second side is constructed with a third primary lining 211 and a third locking foot small guide tube 212. The top of the first lower step channel 210 is a temporary inverted arch 209. The bottom of the first lower step channel 210 is constructed with a fourth primary lining 213. The third primary lining 211, the fourth primary lining 213, the concrete center column 120, and the temporary inverted arch 209 form a ring.

[0051] The soil layer on the second side of the upper step is excavated to form a second semi-arched passage 214 on the second side of the upper step. A fifth primary lining 215 and a fifth locking foot small guide tube 216 are installed on the top of the second semi-arched passage 214. The side of the second semi-arched passage 214 close to the first side is a concrete center column 120. A second middle partition 217 is installed at the bottom of the second semi-arched passage 214, so that the fifth primary lining 215, the concrete center column 120 and the second middle partition 217 form a ring.

[0052] The soil layer on the second side of the middle step is excavated to form a second middle step channel 218 on the second side of the middle step, and a second core soil 219 is retained at the bottom of the second middle step channel 218. The side of the second middle step channel 218 close to the first side is a concrete center column 120. The side of the second middle step channel 218 away from the first side is constructed with a sixth primary lining 220 and a sixth locking foot small guide tube 221. The top of the second middle step channel 218 is a second middle partition 217. Afterwards, the second core soil 219 is excavated.

[0053] The soil layer on the second side of the lower step is excavated to form a second lower step channel 222 on the second side of the lower step. The side of the second lower step channel 222 close to the first side is a concrete center column 120. The side of the second lower step channel 222 away from the second side is constructed with a seventh primary lining 223 and a seventh locking foot small guide tube 224. The bottom of the second lower step channel 222 is constructed with an eighth primary lining 225. The sixth primary lining 220, the seventh primary lining 223, the eighth primary lining 225, the second middle partition plate 217, and the concrete center column 120 form a ring.

[0054] A secondary lining invert 226 is constructed on the fourth primary lining 213 and the eighth primary lining 225, and the invert filler 227 is backfilled on the invert. A first side wall secondary lining 228 is constructed on the second primary lining 207 and the third primary lining 211. A second side wall secondary lining 229 is constructed on the sixth primary lining 220 and the seventh primary lining 223. Finally, an arch secondary lining 230 is constructed on the first primary lining 202 and the fifth primary lining 215, and the temporary invert 209 is removed.

[0055] The first side is one of the left side and the right side, and the second side is the other of the left side and the right side;

[0056] excavation of the second of the two tunnels 100;

[0057] The structure of the first tunnel 100 after construction is symmetrical to the structure of the second tunnel 100 after construction.

[0058] In this embodiment, dual core soil retention reduces the exposed excavation surface and the amount of temporary support by 75%, thus reducing tunnel construction workload and being more environmentally friendly. A central column system replaces the traditional double-layered pilot tunnel, avoiding wasteful support removal and effectively lowering the cost of Tunnel 100. The timely installation of the first and second diaphragms, concrete central columns, and connecting beams, along with the core soil retention, significantly reduces the risk of landslides during construction. Furthermore, this embodiment utilizes a multi-part construction method that effectively minimizes the adverse disturbances caused by small clearances.

[0059] In this embodiment, the clearance of the upper step is no less than 3m at the highest point, ensuring that pedestrian functions are met. It can also effectively divide the tunnel 100 to reduce the peak bending moment of the tunnel 100, and facilitate the subsequent application of the second lining 113 with steel formwork.

[0060] The concrete center columns 120 are arranged at intervals of 4-6 meters.

[0061] The concrete center column 120 is constructed by cast-in-place piles.

[0062] The spacing of the temporary inverts 209 along the tunnel traveling direction is consistent with the spacing of the first primary lining 202 .

[0063] Among them, the clearance of the middle step is ≥4.5m to ensure mechanical construction.

[0064] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A construction method for a split tunnel structure suitable for a four-lane tunnel with a small clearance. The split tunnel structure comprises two tunnels with a small clearance. The tunnels include a tunnel body and a plurality of concrete center columns located in the middle of the tunnel body and spaced apart in the tunnel travel direction. The concrete center columns extend from the bottom of the tunnel body to the top of the tunnel body. The tunnel also includes a connecting beam provided between two adjacent concrete center columns. The tunnel also includes a middle diaphragm arranged along the tunnel travel direction and located on the concrete center column and the connecting beam, characterized in that: include: Excavation of the first of two tunnels, including: Excavate the soil layer on the first side of the upper step to form a first semi-arched passage on the first side of the upper step, apply the first primary lining and the first locking foot small guide tube on the top of the first semi-arched passage, apply a concrete center column on the side of the first semi-arched passage close to the second side, and connect the upper part of the concrete center column with the first primary lining on the top of the semi-arched passage and extend it down to the bottom of the tunnel body, apply the first middle diaphragm on the bottom of the first semi-arched passage, so that the first primary lining, the concrete center column and the first middle diaphragm form a ring. The soil layer on the first side of the middle step is excavated to form a first middle step channel on the first side of the middle step, and the first core soil at the bottom of the first middle step channel is retained. The side of the first middle step channel close to the second side is a concrete middle column, and the side of the first middle step channel away from the second side is constructed with a second primary lining and a second locking foot small guide tube. The top of the first middle step channel is the first middle partition. Afterwards, the first core soil is excavated, and a temporary inverted arch is constructed at the bottom of the first middle step channel, so that the second primary lining, the first middle partition, the concrete middle column and the temporary inverted arch form a ring, and a connecting beam of the concrete middle column is constructed. Excavate the soil layer on the first side of the lower step to form a first lower step channel on the first side of the lower step. The side of the first lower step channel close to the second side is a concrete center column. The side of the first lower step channel away from the second side is constructed with a third primary lining and a third locking foot small guide tube. The top of the first lower step channel is a temporary inverted arch. The bottom of the first lower step channel is constructed with a fourth primary lining. The third primary lining, the fourth primary lining, the concrete center column and the temporary inverted arch form a ring. Excavate the soil layer on the second side of the upper step to form a second semi-arched passage on the second side of the upper step. Apply the fifth primary lining and the fifth locking foot small guide tube on the top of the second semi-arched passage. The side of the second semi-arched passage close to the first side is a concrete center column. Apply the second middle partition at the bottom of the second semi-arched passage, so that the fifth primary lining, the concrete center column and the second middle partition form a ring. The soil layer on the second side of the middle step is excavated to form a second middle step channel on the second side of the middle step, and the second core soil at the bottom of the second middle step channel is retained. The side of the second middle step channel close to the first side is a concrete middle column, and the side of the second middle step channel away from the first side is constructed with the sixth primary lining and the sixth locking foot small guide tube. The top of the second middle step channel is the second middle partition. After that, the second core soil is excavated. Excavate the soil layer on the second side of the lower step to form a second lower step channel on the second side of the lower step. The side of the second lower step channel close to the first side is a concrete center column. The side of the second lower step channel away from the second side is constructed with a seventh primary lining and a seventh locking foot small guide tube. The bottom of the second lower step channel is constructed with an eighth primary lining. The sixth, seventh and eighth primary linings, the second middle partition and the concrete center column form a ring. Construct the secondary lining of the inverted arch on the fourth and eighth primary linings, and backfill the inverted arch with the inverted arch filling material. Construct the secondary lining of the first side wall on the second and third primary linings, construct the secondary lining of the second side wall on the sixth and seventh primary linings, and finally construct the secondary lining of the arch on the first and fifth primary linings. Remove the temporary inverted arch. The first side is one of the left side and the right side, and the second side is the other of the left side and the right side; excavation of the second of two tunnels; Among them, the structure after the construction of the first tunnel is symmetrical with the structure after the construction of the second tunnel.

2. The construction method for a divided tunnel structure suitable for a small clearance four-lane tunnel according to claim 1, characterized in that: The middle partition divides the tunnel body into two layers, an upper layer and an lower layer.

3. The construction method for a divided tunnel structure suitable for a small clearance four-lane tunnel according to claim 2, characterized in that: The tunnel body includes a rock and soil matrix with a travel channel, a primary lining arranged on the inner wall of the rock and soil matrix, and a secondary lining arranged on the inner wall of the primary lining. The concrete center column extends from the bottom of the primary lining through the secondary lining to the top of the primary lining, and the middle partition extends to the primary lining on both sides.

4. The construction method for a divided tunnel structure suitable for a small clearance four-lane tunnel according to claim 3, characterized in that: The distance between the middle partition and the top of the tunnel body is ≥3m.

5. The construction method of a divided tunnel structure applicable to a small clearance four-lane tunnel according to claim 1, characterized in that: The concrete center column is a reinforced concrete center column or a steel tube concrete center column.

6. The construction method of a divided tunnel structure applicable to a small clearance four-lane tunnel according to claim 1, characterized in that: Adjacent concrete columns are set at intervals of 4-6m.

7. The construction method of a divided tunnel structure applicable to a small clearance four-lane tunnel according to claim 1, characterized in that: The tunnel body is symmetrically arranged about the concrete center column.

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