A construction method for a tunnel under a highway

Abstract

The invention relates to a construction method for a highway underpass tunnel, belonging to the technical field of tunnels and underground engineering. By firstly carrying out synchronous construction on two mutually non-adjacent side areas, and then taking tunnel construction in opposite directions on two adjacent single-flow direction areas, such an arrangement can ensure that in the process of constructing the double-flow direction area, the width of the tunnel groove excavated at the bottom of the double-flow direction area is relatively small, and the highway pavement located at the top of the tunnel can be effectively guaranteed not to collapse, thereby solving the problem that when the intersection angle between the tunnel and the highway is small, or even when the tunnel completely overlaps with a long section of the highway, the double-flow direction area of ​​the highway pavement is large, the traffic volume in the double-flow direction area of ​​the highway pavement is high, and when the bottom position of the double-flow direction area of ​​the highway pavement is constructed, the risk of collapse of the double-flow direction area of ​​the highway pavement is caused.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnels and underground engineering, and in particular relates to a construction method for an underpass tunnel of a highway. Background Art

[0002] The existing high-speed railway tunnels passing under the highway have the problems of smaller and smaller intersection angles and shallower tunnel depths. In addition, due to the large cross-section of the tunnel construction and the long construction period, the impact on the highway above is also increasing. In view of this situation, it is necessary to propose a construction method suitable for tunnels under highways.

[0003] For example, the invention patent with patent application publication number: CN104533426A discloses a tunnel construction method of ultra-shallow buried underpass of expressway with large span by cover-and-cut method, which closes part of the road surface of the expressway above the tunnel in different areas, and keeps vehicles passing normally on the unclosed road surface; constructs retaining structures on both sides of the tunnel main structure under the road surface of the closed area, and lays covers fixedly connected to the retaining structures on the road surface of the closed area, guides vehicles to the top surface of the covers, and restores traffic in the closed area; closes the road surface of the remaining areas under the expressway, constructs retaining structures and covers of corresponding parts, and lays covers on the entire road surface to restore traffic on the entire road surface; excavates foundation pit from the side under the protection of the retaining structures and covers; constructs the main structure of the tunnel from bottom to top in the foundation pit; and finally backfills the gap between the top of the tunnel main structure and the covers, thereby completing the tunnel construction.

[0004] Based on the search of patent application publication numbers and the shortcomings found therein:

[0005] In order to speed up the construction progress, the existing construction method for tunnels under highways is to first close the dual-flow area of ​​the highway pavement and then construct the bottom position of the dual-flow area on the highway pavement. In this setting, when the angle between the tunnel and the highway is small, or even when the tunnel completely overlaps with a long section of highway, there is a risk of collapse of the dual-flow area on the highway pavement due to the large area of ​​the dual-flow area on the highway pavement when constructing the bottom position of the dual-flow area on the highway pavement. Summary of the invention

[0006] In order to solve the problem that when the intersection angle between the tunnel and the highway is small, or even the tunnel completely overlaps with a long section of highway, the dual-flow area of ​​the highway pavement is large, the traffic volume in the dual-flow area of ​​the highway pavement is high, and construction is performed on the bottom position of the dual-flow area of ​​the highway pavement, which may cause the risk of collapse of the dual-flow area of ​​the highway pavement, the present invention provides a construction method for a highway underpass tunnel.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A construction method for a highway underpass tunnel comprises the following steps:

[0009] S1: Divide the highway road surface into three areas, namely, the dual-flow area across the center line of the highway and the side areas on both sides of the dual-flow area; first, the construction unit closes the side areas on the left and right sides, and the dual-flow area that is not closed allows vehicles to pass normally;

[0010] S2: The construction unit simultaneously carries out tunnel construction under the closed two side areas;

[0011] S3: After the tunnel construction is completed in the side area, the dual-flow area is divided into two adjacent single-flow areas. The construction unit closes the two single-flow areas and removes the closing equipment installed on the side area. At this time, the side area is open to vehicles for normal traffic.

[0012] S4: The construction unit carries out tunnel construction in two adjacent single-flow areas at the same time, and the tunnel construction directions in the two single-flow areas are opposite;

[0013] S5: After the tunnel construction under the two adjacent single-flow areas is completed, remove the closing equipment installed on the dual-flow area to complete the underpass tunnel construction of the expressway.

[0014] As a preferred technical solution of the present invention, the following steps are also included:

[0015] S21: a tunnel trench is excavated under the road surface of the highway in the closed area, and guard plate structures are respectively constructed and installed on both sides of the tunnel trench, and the guard plate structures are respectively vertically arranged to fit the left and right sides of the tunnel trench;

[0016] S22: a cover plate is horizontally arranged between the guard plate structures on both sides, and a top surface of the cover plate is arranged to fit the bottom surface of the highway in the closed area;

[0017] S23: The cover plate and the two guard plate structures together form a construction space, and a support assembly is also provided, wherein the support assembly is provided at the top of the construction space and is used to support the cover plate;

[0018] S24: constructing a tunnel structure at the bottom of the construction space, and after the tunnel structure is constructed, removing the support assembly, and pouring cement toward the top of the tunnel structure and the construction space to achieve sealing.

[0019] As a preferred technical solution of the present invention, the support assembly includes two groups of steel rope groups and a support unit, the support unit includes a support steel plate, the support steel plate is fitted on the bottom surface of the cover plate, the two groups of steel rope groups are symmetrically arranged at both ends of the support steel plate, the steel rope group includes a plurality of steel ropes, and the plurality of steel ropes are arranged at equal intervals along the length direction of the support steel plate, and the two ends of the steel ropes are respectively connected to one end of the support steel plate and the guard plate structure.

[0020] As a preferred technical solution of the present invention, the support assembly also includes a plurality of hydraulic unit groups, which are arranged at equal intervals along the length direction of the support steel plate between the support steel plate and the cover plate. The hydraulic unit group includes a plurality of hydraulic units, which are arranged at equal intervals along the width direction of the support steel plate between the support steel plate and the cover plate. The hydraulic unit includes a hydraulic rod with a retractable length, and the hydraulic rod is vertically connected to the cover plate and the support steel plate.

[0021] As a preferred technical solution of the present invention, the interior of the supporting steel plate is hollow, and the hydraulic rod includes a fixed rod and a telescopic rod with a hollow interior. The fixed rod is vertically arranged on the supporting steel plate, one end of the fixed rod is connected to the interior of the supporting steel plate, and the telescopic rod is slidably and sealedly arranged on the other end of the fixed rod.

[0022] As a preferred technical solution of the present invention, the hydraulic unit also includes a pressure relief valve, a support connecting rod, a support moving rod and a support spring. The support connecting rod is vertically arranged at the bottom of the support steel plate, the interior of the support connecting rod and the interior of the support steel plate are connected to each other, the support moving rod is slidably and sealedly arranged at the other end of the support connecting rod, the support spring is arranged in the support moving rod, the two ends of the support spring are respectively connected to the support moving rod and the support connecting rod, and the pressure relief valve is sealed at the connection between the support connecting rod and the support steel plate.

[0023] As a preferred technical solution of the present invention, the support unit also includes a one-way valve, and the support steel plate also includes an oil delivery port, which is connected to the interior of the support steel plate, and the one-way valve is sealed in the oil delivery port, and the support steel plate is filled with hydraulic oil through the oil delivery port.

[0024] As a preferred technical solution of the present invention, the hydraulic unit also includes a flexible block, which is arranged in the fixed rod. The flexible block will change due to the change in the oil pressure of the hydraulic oil. When the flexible block is deformed, the oil pressure of the hydraulic oil in the supporting steel plate is lower than the oil pressure of the hydraulic oil when the hydraulic oil in the supporting steel plate enters the supporting connecting rod through the pressure relief valve.

[0025] As a preferred technical solution of the present invention, the tunnel structure is a square block with a hollow interior. The axial direction of the tunnel structure is set along the length direction of the supporting steel plate. The tunnel structure is set at the bottom of the construction space. The tunnel structure is located at the bottom of the supporting assembly, and a number of supporting movable rods can lock or release their abutting relationship with the top of the tunnel structure.

[0026] As a preferred technical solution of the present invention, a plurality of construction spaces are provided, and the plurality of construction spaces are arranged at equal intervals along the construction direction of the tunnel, and the plurality of construction spaces are interconnected, and the cover plates and the guard plate structures in adjacent construction spaces are arranged in close contact with each other, and a plurality of support assemblies and the plurality of tunnel structures are provided, and the plurality of support assemblies and the plurality of tunnel structures are matched one-to-one with the plurality of construction spaces, and any of the support assemblies is arranged in the corresponding construction space, and two adjacent tunnel structures are arranged in close contact with each other.

[0027] The beneficial effects of the present invention are:

[0028] The present invention provides a method for constructing an underpass tunnel for a highway, by firstly carrying out synchronous construction on two non-adjacent side areas, and then taking tunnel construction in opposite directions on two adjacent single-flow areas. Such an arrangement can ensure that during the construction of the dual-flow area, the width of the tunnel trench excavated at the bottom of the dual-flow area is relatively small, which can effectively ensure that the highway pavement at the top of the tunnel will not collapse. This solves the problem that when the intersection angle between the tunnel and the highway is small, or even when the tunnel completely overlaps with a long section of highway, the dual-flow area of ​​the highway pavement is large, the traffic volume in the dual-flow area of ​​the highway pavement is high, and when construction is carried out at the bottom of the dual-flow area of ​​the highway pavement, there is a risk of collapse of the dual-flow area of ​​the highway pavement. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0030] Figure 1 A highway map of a highway underpass tunnel device according to the present invention;

[0031] Figure 2 It is an overall cross-sectional view of a highway underpass tunnel device of the present invention;

[0032] Figure 3 This is a cross-sectional view of a supporting steel plate of a highway underpass tunnel device of the present invention;

[0033] Figure 4This is a surface diagram of a supporting steel plate of a highway underpass tunnel device according to the present invention.

[0034] Description of main symbols

[0035] In the figure: 1. side area; 2. dual-flow area; 201. single-flow area; 3. guard plate structure; 4. cover plate; 5. steel rope; 6. support steel plate; 7. hydraulic rod; 701. fixed rod; 702. telescopic rod; 8. pressure relief valve; 9. support connecting rod; 10. support moving rod; 11. support spring; 12. one-way valve; 13. flexible block; 14. tunnel structure. DETAILED DESCRIPTION

[0036] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0037] See also Figure 1-4 This embodiment provides a construction method for a highway underpass tunnel, comprising the following steps:

[0038] S1: Divide the highway road surface into three areas, namely, the dual-flow area 2 across the center line of the highway and the side area 1 on both sides of the dual-flow area 2; first, the construction unit closes the side areas 1 on the left and right sides, and the dual-flow area 2 that is not closed allows vehicles to pass normally;

[0039] S2: The construction unit simultaneously carries out tunnel construction under the closed two side areas 1;

[0040] S3: After the tunnel construction is completed in the side area 1, the dual-flow area 2 is divided into two adjacent single-flow areas 201. The construction unit closes the two single-flow areas 201 and removes the closing equipment installed on the side area 1. At this time, the side area 1 is open to vehicles for normal traffic;

[0041] S4: The construction unit performs tunnel construction under two adjacent single-flow areas 201 at the same time, and the tunnel construction directions under the two single-flow areas 201 are opposite;

[0042] S5: After the tunnel construction under the two adjacent single-flow areas 201 is completed, the closed equipment set on the dual-flow area 2 is removed to complete the construction of the underpass tunnel of the expressway. This solution provides a construction method for an underpass tunnel of an expressway, by first synchronously constructing two non-adjacent side areas 1, and then taking tunnel construction in opposite directions for the two adjacent single-flow areas 201. Such a setting can ensure that during the construction of the dual-flow area 2, the width of the tunnel trench excavated at the bottom of the dual-flow area 2 is relatively small, which can effectively ensure that the road surface of the expressway located at the top of the tunnel will not collapse, and solve the problem that when the intersection angle between the tunnel and the expressway is small, or even when the tunnel completely overlaps with a long section of the expressway, due to the large area of ​​the dual-flow area 2 of the expressway pavement, there is a high traffic volume in the dual-flow area 2 of the expressway pavement, and when the bottom position of the dual-flow area 2 of the expressway pavement is constructed, there is a risk of collapse of the dual-flow area 2 of the expressway pavement.

[0043] It should be noted here that the expressway mentioned in this plan is a two-way road, and the road in either direction has two traffic lanes. The adjacent traffic lanes and the traffic lane areas with opposite vehicle travel directions are combined into a dual-flow area 2, and the two traffic lanes located next to the dual-flow area 2 are defined as side areas 1.

[0044] Furthermore, in S2 or S4, the following steps are also included:

[0045] S21: a tunnel trench is excavated under the highway road surface in the closed area, and guard plate structures 3 are respectively constructed and installed on both sides of the tunnel trench, and the guard plate structures 3 are respectively vertically arranged to fit the left and right sides of the tunnel trench;

[0046] S22: A cover plate 4 is horizontally arranged between the guard plate structures 3 on both sides, and the top surface of the cover plate 4 is arranged to fit the bottom surface of the highway in the closed area;

[0047] S23: The cover plate 4 and the two guard plate structures 3 together form a construction space, and a support assembly is also provided. The support assembly is provided at the top of the construction space for supporting the cover plate 4;

[0048] S24: constructing a tunnel structure 14 at the bottom of the construction space. After the tunnel structure 14 is constructed, removing the support components, and pouring cement toward the top of the tunnel structure 14 and the construction space to achieve sealing.

[0049] By providing the cover plate 4 and the guard plate structure 3, it is possible to ensure that not only the highway road surface will not collapse, but also the interior of the tunnel groove will not collapse, thereby ensuring the personal safety of construction workers and the driving safety of the highway road surface.

[0050] Specifically, the support assembly of the present scheme includes two groups of steel rope groups and a support unit. The support unit includes a support steel plate 6. The support steel plate 6 is fitted on the bottom surface of the cover plate 4. The two groups of steel rope groups are symmetrically arranged at both ends of the support steel plate 6. The steel rope group includes a plurality of steel ropes 5. The plurality of steel ropes 5 are arranged at equal intervals along the length direction of the support steel plate 6. The two ends of the steel ropes 5 are respectively connected to one end of the support steel plate 6 and the guard plate structure 3. Through the tension of the steel ropes 5, the force of the support steel plate 6 against the cover plate 4 can be ensured, thereby improving the supporting force of the cover plate 4 on the tunnel groove.

[0051] Furthermore, in order to improve the supporting force of the supporting steel plate 6 on the cover plate 4 in this scheme, the supporting assembly of this scheme also includes a plurality of hydraulic unit groups, and the plurality of hydraulic unit groups are arranged at equal intervals along the length direction of the supporting steel plate 6 between the supporting steel plate 6 and the cover plate 4. The hydraulic unit group includes a plurality of hydraulic units, and the plurality of hydraulic units are arranged at equal intervals along the width direction of the supporting steel plate 6 between the supporting steel plate 6 and the cover plate 4. The hydraulic unit includes a hydraulic rod 7 of telescopic length, and the hydraulic rod 7 is vertically connected to the cover plate 4 and the supporting steel plate 6. The hydraulic rod 7 is provided, and the function of the hydraulic rod 7 is to ensure the tension between the steel rope 5 connecting the supporting steel plate 6 and the guard plate structure 3 through its own telescopic structure, so as to improve the supporting force of the supporting steel plate 6 on the cover plate 4 through the hydraulic rod 7.

[0052] In order to ensure that the force exerted by each hydraulic rod 7 on the cover plate 4 is consistent, the interior of the support steel plate 6 of this solution is hollow, and the hydraulic rod 7 includes an internally hollow fixed rod 701 and a telescopic rod 702, the fixed rod 701 is vertically arranged on the support steel plate 6, one end of the interior of the fixed rod 701 is interconnected with the interior of the support steel plate 6, and the telescopic rod 702 is slidably and sealedly arranged at the other end of the fixed rod 701; in addition, the support unit of this solution also includes a one-way valve 12, and the support steel plate 6 also includes an oil delivery port, which is connected to the interior of the support steel plate 6, and the one-way valve 12 is sealed in the oil delivery port, and the support steel plate 6 is filled with hydraulic oil through the oil delivery port; by providing hydraulic oil, when the hydraulic oil is filled to the support When the cover plate 4 is in the steel plate 6, since the interior of the fixed rod 701 and the interior of the supporting steel plate 6 are interconnected, the telescopic rod 702 will extend out of the fixed rod 701 under the action of the hydraulic oil pressure, so that it can be matched with the bottom surface of the cover plate 4. Since the hydraulic oil has the same force on each telescopic rod 702, therefore, while ensuring that the cover plate 4 and the supporting steel plate 6 are parallel to each other, the force of each telescopic rod 702 on the cover plate 4 is consistent. Such an arrangement can further enhance the supporting force of the supporting steel plate 6 on the cover plate 4, which can not only ensure that the highway pavement will not collapse, but also ensure that the interior of the tunnel slot will not collapse, thereby ensuring the personal safety of construction workers and the driving safety of the highway pavement.

[0053] It should be noted that the hydraulic unit of the present scheme also includes a flexible block 13, which is arranged in the fixed rod 701. The flexible block 13 will change due to the change in the oil pressure of the hydraulic oil. By providing the flexible block 13, when the traffic volume on the highway is large, the corresponding highway area will vibrate, and the vibration will cause the cover plate 4 supporting the bottom of its area to vibrate, and then cause the telescopic rod 702 to vibrate following the vibration of the cover plate 4. Since the hydraulic oil pressure in the support steel plate 6 reaches a certain level, it cannot be compressed; therefore, it is necessary to provide a flexible block 13 in the fixed rod 701. When the telescopic rod 702 is compressed with a small displacement, the sealing space between the support steel plate 6 and the fixed rod 701 will become smaller, and the hydraulic oil pressure in the sealed space will increase. The increase in the hydraulic oil pressure will compress the space of the flexible block 13, and then the sealed space will restore its original volume, thereby ensuring that the hydraulic oil pressure in the support steel plate 6 is always consistent, and ensuring that the structure of the support steel plate 6 will not be deformed due to the increase in the hydraulic oil pressure.

[0054] In addition, the hydraulic unit of the present scheme also includes a pressure relief valve 8, a support connecting rod 9, a support moving rod 10 and a support spring 11. The support connecting rod 9 is vertically arranged at the bottom of the support steel plate 6, and the interior of the support connecting rod 9 and the interior of the support steel plate 6 are connected to each other. The support moving rod 10 is slidably sealed at the other end of the support connecting rod 9, and the support spring 11 is arranged in the support moving rod 10. The two ends of the support spring 11 are respectively connected to the support moving rod 10 and the support connecting rod 9. The pressure relief valve 8 is sealed at the connection between the support connecting rod 9 and the support steel plate 6. In the present scheme, by providing the support connecting rod 9 and the support moving rod 10, when a large shaking occurs in the highway area, it will cause a large displacement change of the cover plate 4. , which causes the telescopic amount of the telescopic rod 702 to change. According to the above embodiment, the flexible block 13 will be pressed to a situation where it cannot be deformed. If the telescopic rod 702 continues to shrink at this time, the excess hydraulic oil will flow into the supporting connecting rod 9 through the pressure relief valve 8, ensuring that the supporting steel plate 6 can still effectively support the cover plate 4, ensuring that the highway area will not collapse immediately, and leaving enough time for vehicles located in the highway area to evacuate. It is worth noting that the flexible block 13 of this scheme will change due to the change in the oil pressure of the hydraulic oil. When the flexible block 13 can be deformed, the oil pressure of the hydraulic oil in the supporting steel plate 6 is less than the oil pressure of the hydraulic oil when the hydraulic oil in the supporting steel plate 6 enters the supporting connecting rod 9 through the pressure relief valve 8.

[0055] In addition, the tunnel structure 14 of the present solution is a square block with a hollow interior. The axial direction of the tunnel structure 14 is arranged along the length direction of the supporting steel plate 6. The tunnel structure 14 is arranged at the bottom of the construction space. The tunnel structure 14 is located at the bottom of the supporting assembly. A number of supporting movable rods 10 can lock or release their abutting and matching relationship with the top of the tunnel structure 14. When the highway area collapses, in order to reduce the degree of collapse of the highway area, the supporting movable rods 10 will extend due to the force of the hydraulic oil and achieve an abutting and matching relationship with the top of the tunnel structure 14. Further, a supporting force is provided for the highway area, so that even if the highway area collapses, the severity of the collapse will be reduced; more importantly, since the supporting movable rods 10 did not have an abutting and matching relationship with the tunnel structure 14 when the highway area just collapsed, the tunnel structure 14 did not deform at the beginning and could still be used normally. Such a setting can ensure that when the highway area collapses, workers working in the tunnel structure 14 can be provided with time to escape.

[0056] Furthermore, a number of construction spaces are provided, and the construction spaces are arranged at equal intervals along the construction direction of the tunnel, and the construction spaces are interconnected, and the cover plates 4 and the guard plate structures 3 in adjacent construction spaces are arranged in close contact with each other, and a number of support assemblies and tunnel structures 14 are provided, and the support assemblies and the tunnel structures 14 are matched one-to-one with the construction spaces, and any support assembly is arranged in the corresponding construction space, and two adjacent tunnel structures 14 are arranged in close contact with each other.

[0057] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A construction method for a highway underpass tunnel, characterized in that: The following steps are involved: S1: Divide the highway road surface into three areas, namely, the dual-flow area across the center line of the highway and the side areas on both sides of the dual-flow area; first, the construction unit closes the side areas on the left and right sides, and the dual-flow area that is not closed allows vehicles to pass normally; S2: The construction unit simultaneously carries out tunnel construction under the closed two side areas; S3: After the tunnel construction is completed in the side area, the dual-flow area is divided into two adjacent single-flow areas. The construction unit closes the two single-flow areas and removes the closing equipment installed on the side area. At this time, the side area is open to vehicles for normal traffic. S4: The construction unit carries out tunnel construction in two adjacent single-flow areas at the same time, and the tunnel construction directions in the two single-flow areas are opposite; S5: After the tunnel construction under the two adjacent single-flow areas is completed, the closing equipment installed on the dual-flow area is removed to complete the construction of the underpass tunnel of the expressway; In S2 or S4, the following steps are further included: S21: a tunnel trench is excavated under the road surface of the highway in the closed area, and guard plate structures are respectively constructed and installed on both sides of the tunnel trench, and the guard plate structures are respectively vertically arranged to fit the left and right sides of the tunnel trench; S22: a cover plate is horizontally arranged between the guard plate structures on both sides, and the top surface of the cover plate is arranged to fit the bottom surface of the highway in the closed area; S23: The cover plate and the two guard plate structures together form a construction space, and a support assembly is also provided, wherein the support assembly is provided at the top of the construction space and is used to support the cover plate; S24: constructing a tunnel structure at the bottom of the construction space, and after the tunnel structure is constructed, removing the support assembly, and pouring cement toward the top of the tunnel structure and the construction space to achieve sealing; The support assembly includes two groups of steel ropes and a support unit. The support unit includes a support steel plate. The support steel plate is attached to the bottom surface of the cover plate. The two groups of steel ropes are symmetrically arranged at both ends of the support steel plate. The steel rope group includes a plurality of steel ropes. The plurality of steel ropes are arranged at equal intervals along the length direction of the support steel plate. The two ends of the steel ropes are connected to one end of the support steel plate and the guard plate structure respectively. The support assembly further comprises a plurality of hydraulic unit groups, which are arranged between the support steel plate and the cover plate at equal intervals along the length direction of the support steel plate, the hydraulic unit group comprises a plurality of hydraulic units, which are arranged between the support steel plate and the cover plate at equal intervals along the width direction of the support steel plate, the hydraulic unit comprises a hydraulic rod of telescopic length, and the hydraulic rod is vertically connected to the cover plate and the support steel plate; The hydraulic unit further comprises a pressure relief valve, a support connecting rod, a support moving rod and a support spring, wherein the support connecting rod is vertically arranged at the bottom of the support steel plate, the interior of the support connecting rod and the interior of the support steel plate are connected to each other, the support moving rod is slidably and sealedly arranged at the other end of the support connecting rod, the support spring is arranged in the support moving rod, the two ends of the support spring are respectively connected to the support moving rod and the support connecting rod, and the pressure relief valve is sealedly arranged at the connection between the support connecting rod and the support steel plate; The interior of the supporting steel plate is hollow, and the hydraulic rod includes a fixed rod and a telescopic rod with a hollow interior. The fixed rod is vertically arranged on the supporting steel plate, one end of the interior of the fixed rod is connected to the interior of the supporting steel plate, and the telescopic rod is slidably and sealedly arranged on the other end of the fixed rod; The hydraulic unit further comprises a flexible block, which is arranged in the fixed rod. The flexible block changes due to the change of the oil pressure of the hydraulic oil. When the flexible block is deformed, the oil pressure of the hydraulic oil in the support steel plate is less than the oil pressure of the hydraulic oil when the hydraulic oil in the support steel plate enters the support connecting rod through the pressure relief valve. The tunnel structure is a square block with a hollow interior. The axial direction of the tunnel structure is set along the length direction of the supporting steel plate. The tunnel structure is set at the bottom of the construction space. The tunnel structure is located at the bottom of the supporting assembly. Several supporting movable rods can lock or release their abutting relationship with the top of the tunnel structure.

2. The construction method of a highway underpass tunnel according to claim 1, characterized in that: The support unit further includes a one-way valve, and the support steel plate further includes an oil delivery port, which is communicated with the interior of the support steel plate. The one-way valve is sealed in the oil delivery port, and the support steel plate is filled with hydraulic oil through the oil delivery port.

3. The construction method of a highway underpass tunnel according to claim 1, characterized in that: A plurality of construction spaces are provided, and the plurality of construction spaces are arranged at equal intervals along the construction direction of the tunnel. The plurality of construction spaces are interconnected, and the cover plates and the guard plate structures in adjacent construction spaces are arranged in close contact with each other. A plurality of support assemblies and a plurality of tunnel structures are provided, and the plurality of support assemblies and the plurality of tunnel structures are matched one-to-one with the plurality of construction spaces. Any of the support assemblies is arranged in the corresponding construction space, and two adjacent tunnel structures are arranged in close contact with each other.

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