Shallow groove supporting type for narrow roadway permeable stratum and construction method

Abstract

The invention discloses a strip-shaped shallow foundation pit supporting type for a narrow roadway permeable stratum and a construction method, and belongs to the technical field of foundation pit construction of pipeline engineering. Comprising a first supporting frame and a second supporting frame which are symmetrically arranged. Each supporting frame comprises a plurality of supporting steel plates which are connected in sequence; u-shaped locking openings are formed in the two ends of the supporting steel plate; the adjacent supporting steel plates are connected through U-shaped locking openings. T-shaped stiffening ribs are arranged on the side faces of the supporting steel plates. Grouting holes are formed in the T-shaped stiffening ribs; brackets are welded on the side surfaces of the T-shaped stiffening ribs; a waist beam is arranged above the bracket; a transverse support is arranged on the side surface of the waist beam; the first supporting frame and the second supporting frame are fixedly connected through a cross brace; the waterless operation environment in the groove foundation pit is guaranteed, the influence of foundation pit operation in the narrow roadway on surrounding buildings and structures is reduced, and the problem that a traditional supporting structure is not suitable for construction of the narrow roadway of the permeable stratum is solved.

Description

Technical Field

[0001] The invention discloses a belt-shaped shallow foundation pit support type and a construction method for narrow tunnel permeable strata, belonging to the technical field of pipeline engineering foundation pit construction. Background Art

[0002] The foundation pits involved in pipeline projects for water pollution and water environment improvement projects are characterized by small burial depth, narrow and long plane distribution, and trench shape. For newly built or rebuilt pipelines in urban villages and community lanes, the pipeline trench foundation pits connecting pollution sources are all shallow foundation pits with a depth of no more than 2.0m. Due to the space limitations of the lanes, the buildings and structures on both sides and their foundations are close to the foundation pits. When encountering permeable strata, support construction is difficult. Commonly used support forms either cause large structural disturbances to the buildings and structures on both sides, or have poor water-stopping properties. There is currently no support form that is highly applicable and economical for shallow trench foundation pits in permeable strata in narrow lanes.

[0003] Existing foundation pit support technology has been deeply studied on large foundation pits. The mainstream support forms include cast-in-place piles, SMW method piles, cement soil walls and combinations with anchor rods and anchor cables. Due to the limitations of construction space, cost and construction period, they are not suitable for shallow trench support construction in narrow lanes. Common trench support forms in municipal engineering include steel sheet piles, channel steels, and plate braces. Steel sheet piles have good water-stopping properties but occupy a large space and have strong construction vibrations, which can easily cause vibration damage to surrounding buildings; channel steel support is highly flexible and easy to construct, but it does not stop water and is not suitable for permeable strata; plate brace support is to use wooden boards as temporary support measures, first excavate the foundation pit to the designed elevation and then set the supporting wooden boards, that is, excavate first and then support, with high safety risks and a small applicable depth range.

[0004] The existing support technology construction method in narrow tunnels has a great impact on buildings, and the water-stopping property of the support structure in the permeable stratum affects the safe operation in the trench. At present, it is necessary to propose a support form with strong applicability and high economy for the shallow trench support in the permeable stratum of narrow tunnels. Summary of the invention

[0005] The purpose of the present invention is to provide a belt-shaped shallow foundation pit support type and construction method suitable for permeable strata, so as to solve the problem that traditional support structures are not suitable for construction in narrow tunnels of permeable strata.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a strip-shaped shallow foundation pit support type for permeable strata in narrow tunnels, comprising a first support frame and a second support frame symmetrically arranged; the support frames each include a plurality of support steel plates connected in sequence; both ends of the support steel plates are provided with U-shaped locking openings; adjacent support steel plates are connected by U-shaped locking openings; T-shaped stiffening ribs are provided on the sides of the support steel plates; grouting holes are provided inside the T-shaped stiffening ribs; corbels are welded on the sides of the T-shaped stiffening ribs; a waist beam is provided above the corbels; a cross brace is provided on the sides of the waist beam; the first support frame and the second support frame are fixedly connected by a cross brace.

[0007] Preferably, rubber lubrication pads are provided on both sides of the U-shaped lock opening.

[0008] Preferably, the width of the rubber lubrication pad is equal to the locking depth of the U-shaped locking mouth, and the length is equal to the height of the supporting steel plate.

[0009] Preferably, the curling radius of the U-shaped locking mouth is not less than the thickness of the supporting steel plate; the locking mouth width of the U-shaped locking mouth is not less than the thickness of the supporting steel plate and the thickness of the rubber lubrication pad.

[0010] Preferably, an expansion waterproof rubber strip is provided at the U-shaped bottom of the U-shaped lock.

[0011] Preferably, a lubricating release agent is provided on the surface of the U-shaped lock.

[0012] Preferably, a grouting hose is provided in the grouting hole, and the upper end of the grouting hose is connected to the grouting equipment.

[0013] Preferably, the grouting hose is a rubber hose, the diameter of which is smaller than the diameter of the grouting hole.

[0014] Preferably, the bottom of the T-shaped stiffening rib is an inclined surface, and the slope of the inclined surface is 1:5.

[0015] In a second aspect, the present invention provides a construction method for a belt-shaped shallow foundation pit support type for a narrow tunnel permeable stratum, which specifically comprises the following steps: S1. Install a rubber lubricating pad on the inside of the U-shaped lock, apply a lubricating isolating agent on the surface, insert a grouting hose into the grouting hole, and inject water or air to confirm that the grouting pipeline is unobstructed; S2. Use pile driving equipment to drive the first support steel plate to the side of the foundation pit in a low-hammer and dense-hammer manner. The hammering point is located at the top enlarged head of the T-shaped stiffening rib. Protect the grouting hose during hammering. S3, repeat S1-S2 to process other supporting steel plates until both sides of the foundation pit are provided with supporting steel plates connected in sequence and a complete excavation trench section is formed; adjacent supporting steel plates are butt-jointed with U-shaped locks; S4. Grouting equipment: The grouting pipe is connected to the upper end of the grouting hose, and the curing agent is injected in sections to form a reinforcement body in the soil layer at the bottom of the foundation pit, and then clean water is injected to form a non-solidified area; S5. Excavate the soil layer in the foundation pit to the bottom of the support type, weld the corbels on the surface of the T-shaped stiffening ribs, and set up the waist beam and the cross brace fixedly connected to it above the corbels; after the work in the foundation pit is completed and backfilled, the waist beam and cross brace are removed, and the support steel plates are pulled out piece by piece; S6. Move the pulled out supporting steel plate to the next excavation trench section and repeat S1 to S5 until the foundation pit is completely constructed.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention combines the support steel plate with the water stop and grouting system, and utilizes the U-shaped lock of the support steel plate and the grouting holes in the stiffening rib to grout the bottom of the foundation pit to isolate the groundwater, thereby ensuring a waterless working environment in the trench foundation pit. The support steel plate occupies a small area and is constructed by a low-hammer dense impact method, thereby reducing the impact of foundation pit operations in narrow lanes on surrounding buildings and structures, and solving the problem that traditional support structures are not suitable for construction in narrow lanes in permeable strata. The support steel plate of the present invention can be reused, and compared with traditional large-scale foundation pit support methods such as cast-in-place piles, SMW construction piles and cement soil walls, the construction speed is fast and the economy is strong. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 It is a schematic diagram of the support frame structure of the present invention; Figure 2 It is a schematic diagram of the supporting steel plate structure of the present invention; Figure 3 It is a schematic diagram of the U-shaped lock of the present invention; Figure 4 It is a structural schematic diagram of adjacent U-shaped locks connected in the present invention; Figure 5 The present invention is a cross-sectional view of a belt-shaped shallow foundation pit support type for narrow tunnel permeable strata.

[0019] Among them: 1-support steel plate; 2-T-shaped stiffening rib; 3-U-shaped lock; 4-grouting hole; 5-corbel; 6-cross brace; 7-waist beam; 8-grouting hose; 9-rubber lubrication pad; 10-expansion waterstop strip; 11-grouting equipment; 12-reinforcement body; 13-non-solidification area. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, 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 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 here can be arranged and designed in various different configurations.

[0021] 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 claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] 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, further definition and explanation thereof is not required in subsequent drawings.

[0023] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0024] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0025] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings: The first object of the present invention is to provide a belt-shaped shallow foundation pit support type for narrow tunnel permeable strata, comprising a first support frame and a second support frame symmetrically arranged; Figure 1 and Figure 2 As shown, the support frames include a number of support steel plates 1 connected in sequence; U-shaped locks 3 are provided at both ends of the support steel plates 1; adjacent support steel plates 1 are connected by U-shaped locks 3; T-shaped stiffening ribs 2 are provided on the sides of the support steel plates 1; grouting holes 4 are provided inside the T-shaped stiffening ribs 2; corbels 5 are welded on the sides of the T-shaped stiffening ribs 2; a waist beam 7 is provided above the corbel 5; a cross brace 6 is provided on the side of the waist beam 7; the first support frame and the second support frame are fixedly connected by the cross brace 6.

[0027] The present invention forms a stable and strong support system by symmetrically arranged first and second support frames and fixedly connected between them through a cross brace 6. This structure can effectively resist the pressure from the surrounding strata and the scouring of water flow in a narrow and permeable tunnel environment, ensuring the stability of the foundation pit. At the same time, the U-shaped locks 3 arranged at both ends of the support steel plate 1 enable adjacent support steel plates 1 to be tightly and conveniently connected together, which not only ensures the continuity of the support, but also facilitates on-site installation and disassembly. This connection method has strong adaptability and can be adjusted according to actual engineering needs. The grouting holes 4 arranged inside the T-shaped stiffening rib 2 allow grouting operations to be carried out. By injecting slurry into the grouting holes 4, the bonding force between the support type and the surrounding strata can be enhanced, thereby improving the support effect. The design of the T-shaped stiffening rib 2 and the corbel 6 not only increases the rigidity of the support steel plate, but also provides additional bearing capacity. The waist beam 6 and the cross brace 7 arranged above the corbel further enhance the overall stability of the support structure, so that the support type can bear a larger load. The design of the entire support type takes into account the convenience of construction. Components such as the support steel plate 1, T-shaped stiffening rib 2, corbel 5, waist beam 6 and cross brace 7 can all be produced in a standardized manner. The on-site assembly is simple and quick, which reduces the difficulty and cost of construction.

[0028] like Figure 3 and Figure 4As shown, rubber lubrication pads 9 are provided on both sides of the U-shaped lock 3. And the width of the rubber lubrication pad 9 is equal to the lock depth of the U-shaped lock 3, and the length is equal to the height of the supporting steel plate 1. The width of the rubber lubrication pad 9 is equal to the lock depth of the U-shaped lock 3, ensuring that both sides of the lock can be fully covered by the rubber lubrication pad 9. It not only provides a uniform lubrication effect, but also enhances the sealing of the lock, effectively preventing moisture, soil and other impurities from penetrating into the support structure through the lock, and further improves the waterproof performance and durability of the support structure. The length of the rubber lubrication pad 9 is equal to the height of the supporting steel plate 1, so that when the supporting steel plates are connected, the locks within the entire height range can be lubricated and supported, which helps to reduce stress concentration at the connection and enhance the connection stability between the supporting steel plates 1. When subjected to external forces, the support structure can better maintain integrity and stability, and reduce the risk of deformation and displacement.

[0029] The curling radius of the U-shaped lock 3 is not less than the thickness of the supporting steel plate 1, so that the edge of the lock is fully strengthened, which helps to resist the direct impact of external forces on the lock, reduce the deformation and damage of the lock edge, and thus enhance the overall strength of the support structure. The lock width of the U-shaped lock 3 is not less than the thickness of the supporting steel plate 1 and the thickness of the rubber lubrication pad 9, ensuring that the supporting steel plates 1 can form a tight and stable fit when connected by the U-shaped lock 3. At the same time, the rubber lubrication pad 9 can fully fill the gap between the lock and the supporting steel plate 1, provide the necessary lubrication and sealing effects, and prevent the lock from loosening or failing due to excessive gaps. Due to the strengthening of the lock edge and the optimization of the lock width, the connection between the supporting steel plates is more reliable, which helps to reduce stress concentration at the connection and improve the shear strength and bending strength of the connection. In a complex geological environment, this reliable connection can ensure that the support structure maintains integrity and stability when subjected to various external forces.

[0030] The U-shaped bottom of the U-shaped lock 3 is provided with an expansion waterproof rubber strip 10. The expansion waterproof rubber strip 10 can expand after encountering water, and fits tightly between the bottom of the U-shaped lock 3 and the supporting steel plate 1, forming an effective waterproof barrier, which can effectively prevent groundwater from penetrating into the supporting structure through the lock gap, maintain a dry environment inside the foundation pit, and avoid the adverse effects of moisture on the supporting materials and soil stability.

[0031] The surface of the U-shaped lock 3 is provided with a lubricating release agent. During the installation and removal of the support steel plate 1, the friction resistance between the U-shaped lock 3 will affect the construction efficiency and the stability of the support structure. The lubricating release agent can significantly reduce this friction resistance, making the connection of the support steel plate smoother and improving the construction efficiency. At the same time, the lubricating release agent can also form a protective film on the surface of the lock, reducing the wear and scratches of the lock during installation and use, maintaining the flatness and precision of the lock, and extending the service life of the lock.

[0032] A grouting hose 8 is provided in the grouting hole 4, and the upper end of the grouting hose 8 is connected to the grouting equipment 11. The grouting hose 8 can transport the slurry in the grouting equipment 11 to the grouting hole 4, ensuring that the slurry is evenly distributed and filled into the gap between the support steel plate 1 and the stratum, improving the accuracy and efficiency of grouting, and helping to form a more compact and stable support structure. At the same time, the operator can adjust the position of the grouting hose and the grouting speed according to actual needs to ensure that the slurry can fully penetrate into every corner between the support steel plate 1 and the stratum, thereby improving the overall strength and stability of the support structure.

[0033] The grouting hose 8 is a rubber hose, and its diameter is smaller than the diameter of the grouting hole 4, which helps to reduce the pressure loss during the grouting process. At the same time, in a complex geological environment, the support structure needs to withstand various external forces and geological changes. The softness and bendability of the grouting hose 8 enable it to adapt to such complex geological conditions, ensuring that the slurry can be evenly distributed and filled into each gap between the support steel plate 1 and the stratum, thereby improving the adaptability and stability of the support structure.

[0034] The bottom of the T-shaped stiffening rib 2 is an inclined surface with a slope of 1:5, so that the grouting hose 8 can reach the stratum more smoothly.

[0035] In a second aspect, the present invention provides a construction method for a belt-shaped shallow foundation pit support type for a narrow tunnel permeable stratum, which specifically comprises the following steps: S1, excavate the trench foundation pit guide ditch, place the foundation pit edge line according to the designed trench foundation pit edge line position, cut the road surface and groove it, and remove the surface hard road surface structure to expose the soil layer under the road; set the rubber lubricating pad 9 on the inner side of the U-shaped lock 3, apply the lubricating release agent on the surface, the lubricating release agent can be a polyurethane lubricating release agent or an epoxy resin lubricating release agent, insert the grouting hose 8 into the grouting hole 4, and inject water or air to confirm that the grouting pipeline is unobstructed; S2. Use piling equipment to drive the first supporting steel plate 1 to the side of the foundation pit in a low-hammer and dense-strike manner. The hammering point is located at the top enlarged head of the T-shaped stiffening rib 2, and the grouting hose 8 is protected during hammering. The supporting steel plate 1 adopts a straight shape, and the piling equipment is driven into the soil in a low-hammer and dense-strike manner during construction. Compared with the trench foundation pit steel sheet pile support method, it occupies less space and has less vibration impact, ensuring the feasibility of foundation pit support in narrow tunnels.

[0036] S3, repeat S1-S2 to process other supporting steel plates 1, until both sides of the foundation pit are provided with supporting steel plates 1 connected in sequence and a complete excavation trench section is formed; adjacent supporting steel plates 1 are butt-jointed with U-shaped locks 3; the length of one complete excavation trench section is 5-10m; S4, such as Figure 5As shown, the grouting pipe of the grouting equipment 11 is connected to the upper end of the grouting hose 8, and the curing agent is injected in sections to form a reinforcement body 12 in the soil layer at the bottom of the foundation pit, and then clean water is injected to form a non-solidified area 13; wherein the curing agent can be selected from cement slurry or cement-water-glass double liquid slurry according to the permeability of the soil layer and the flow degree of groundwater, and the grouting process can adopt compaction grouting, the grouting pressure is 0.5-1.0MPa, and the slurry diffusion radius is 1.0m. After reaching the designed grouting volume, the curing agent is stopped, and clean water is injected to form a non-solidified area 13 to clean the grouting pipeline to prevent the pipeline from agglomerating. The clean water injection volume is 1.5-2 times the volume of the grouting hole 4; S5, the soil layer at the bottom of the foundation pit is reinforced with a body 12 to form strength, the soil layer in the foundation pit is excavated to the bottom of the support pattern (preferably 0.5m below), a corbel 5 is welded on the surface of the T-shaped stiffening rib 2, and a waist beam 7 and a cross brace 6 fixedly connected to the corbel 5 are erected above the corbel 5; after the operation in the foundation pit is completed and backfilled (preferably backfilled to 0.5m below), the waist beam 7 and the cross brace 6 are removed, and the support steel plate 1 is pulled out in blocks; S6, move the pulled out support steel plate 1 to the next excavation trench section and repeat S1 to S5 until the foundation pit is completely constructed. The number of turnovers of the support steel plate 1 is determined by its own deformation degree, and the recommended number of turnovers is 25 times.

[0037] The method of the present invention forms a stable and reliable support structure through the cooperation of the U-shaped lock 3 and the rubber lubricating pad 9, as well as the setting of the reinforcement body 12 and the non-solidified area 13 formed by grouting. This support structure can not only resist the influence of stratum pressure and groundwater, but also effectively prevent the dislocation and deformation between the supporting steel plates 1, ensuring the safety and stability of the foundation pit. The connection between the supporting steel plates 1 is completely watertight by the expansion waterproof rubber strip 10; the grouting in the foundation pit is performed by the grouting hole 4 and the grouting hose 8, and the reinforcement body 12 formed on both sides of the groove foundation pit closes the bottom of the foundation pit, so that the bottom of the pit is completely watertight. Compared with ordinary support plates and channel steel supports, the U-shaped lock 3 of the supporting steel plate 1 and the grouting at the bottom of the foundation pit isolate the groundwater in the foundation pit, forming a waterless working pit space, ensuring the quality requirements and safety of the pipeline operation in the pit, and solving the problem that the traditional support structure is not suitable for the construction of narrow tunnels in permeable strata.

[0038] This method is suitable for foundation pit support under complex geological conditions such as narrow tunnels and permeable strata, and by adjusting the size of the support steel plate 1, the design of the T-shaped stiffening rib 2, and the grouting parameters, it can flexibly adapt to different geological conditions and engineering requirements, thereby improving the flexibility and adaptability of the support construction.

[0039] Example A belt-shaped shallow foundation pit support type for permeable strata in narrow tunnels, comprising a first support frame and a second support frame symmetrically arranged; the support frames each comprise a plurality of support steel plates 1 connected in sequence; the support steel plates 1 have a thickness of not less than 10 mm, a width of 800 mm to 1000 mm, a height of not less than 2.5 m, and are made of Q235 carbon structural steel.

[0040] Both ends of the support steel plate 1 are provided with U-shaped locks 3; adjacent support steel plates 1 are connected by U-shaped locks 3; rubber lubricating pads 9 are provided on both sides of the U-shaped locks 3. The curling radius of the U-shaped lock 3 is not less than the thickness of the support steel plate 1, the lock depth is not less than 20mm, and the lock width is not less than the thickness of the support steel plate 1 and the thickness of the rubber lubricating pad 9. The thickness of the rubber lubricating pad 9 is not less than 3mm, the width is the same as the lock depth of the U-shaped lock 3, the length is the same as the height of the support steel plate 1, and it is fixed on both sides of the U-shaped lock 3, and the side facing the air is smooth and has good elasticity.

[0041] The side of the supporting steel plate 1 is provided with a T-shaped stiffening rib 2; the enlarged head height of the T-shaped stiffening rib 2 is not less than 30 mm, the rib height perpendicular to the plate surface of the supporting steel plate 1 is not less than 50 mm, the rib width is not less than 100 mm, the length is the same as the height of the supporting steel plate 1, the bottom slope is 1:5, the spacing between the T-shaped stiffening ribs 2 is 0.5 m, and each supporting steel plate 1 contains 2 T-shaped stiffening ribs 2.

[0042] The T-shaped stiffening rib 2 is provided with a grouting hole 4; the bottom of the T-shaped stiffening rib 2 is an inclined surface with a slope of 1:5. The diameter of the grouting hole 4 is not less than 10 mm, the lower turning section is located in the middle of the inclined surface of the T-shaped stiffening rib 2, the hole opening direction is perpendicular to the inclined surface, and the inner wall of the hole is smooth.

[0043] A corbel 5 is welded on the side of the T-shaped stiffening rib 2; the corbel 5 is welded 20 to 50 cm below the top of the T-shaped stiffening rib 2, which is determined by the depth of the foundation pit and the required working space in the pit.

[0044] A waist beam 7 is arranged above the corbel 5 ; a cross brace 6 is arranged on the side of the waist beam 7 ; and the first supporting frame and the second supporting frame are fixedly connected by the cross brace 6 .

[0045] The U-shaped bottom of the U-shaped lock 3 is provided with an expansion waterproof strip 10, and the surface of the U-shaped lock 3 is provided with a lubricating release agent. The expansion waterproof strip 10 has a size that satisfies the curling range of the U-shaped lock 3 and has the property of swelling when exposed to water.

[0046] A grouting hose 8 is provided in the grouting hole 4, and the upper end of the grouting hose 8 is connected to the grouting equipment 11. The grouting hose 8 is a rubber hose, and its diameter is smaller than the diameter of the grouting hole 4, and can be inserted into or pulled out of the grouting hole 4.

[0047] The supporting steel plate 1, T-shaped stiffening rib 2, U-shaped locking mouth 3 and grouting hole 4 are an integrated structure; the sizes of the corbel 5, cross brace 6 and waist beam 7 are determined by calculation based on the actual stratum and the corresponding foundation pit depth, and common steel sizes are selected based on the requirements of deformation and structural stability.

[0048] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A belt-shaped shallow foundation pit support type for narrow tunnel permeable strata, characterized in that: The invention comprises a first support frame and a second support frame which are symmetrically arranged; the support frames each comprise a plurality of support steel plates (1) connected in sequence; both ends of the support steel plates (1) are provided with U-shaped locking openings (3); adjacent support steel plates (1) are connected via the U-shaped locking openings (3); T-shaped stiffening ribs (2) are provided on the side of the support steel plates (1); grouting holes (4) are provided inside the T-shaped stiffening ribs (2); a corbel (5) is welded on the side of the T-shaped stiffening rib (2); a waist beam (7) is provided above the corbel (5); a cross brace (6) is provided on the side of the waist beam (7); the first support frame and the second support frame are fixedly connected via the cross brace (6).

2. A belt-shaped shallow foundation pit support type for narrow tunnel permeable strata according to claim 1, characterized in that: Rubber lubrication pads (9) are provided on both sides of the interior of the U-shaped locking opening (3).

3. A belt-shaped shallow foundation pit support type for narrow tunnel permeable strata according to claim 2, characterized in that: The width of the rubber lubrication pad (9) is equal to the locking depth of the U-shaped locking opening (3), and the length is equal to the height of the supporting steel plate (1).

4. A belt-shaped shallow foundation pit support type for narrow tunnel permeable strata according to claim 2, characterized in that: The curling radius of the U-shaped locking opening (3) is not less than the thickness of the supporting steel plate (1); and the locking width of the U-shaped locking opening (3) is not less than the thickness of the supporting steel plate (1) and the thickness of the rubber lubrication pad (9).

5. The strip-shaped shallow foundation pit support type for narrow tunnel permeable strata according to claim 1 is characterized in that: The U-shaped bottom of the U-shaped locking opening (3) is provided with an expansion waterproof rubber strip (10).

6. A belt-shaped shallow foundation pit support type for narrow tunnel permeable strata according to claim 1, characterized in that: A lubricating release agent is provided on the surface of the U-shaped lock (3).

7. The strip-shaped shallow foundation pit support type for narrow tunnel permeable strata according to claim 1 is characterized in that: A grouting hose (8) is provided in the grouting hole (4), and the upper end of the grouting hose (8) is connected to the grouting equipment (11).

8. A belt-shaped shallow foundation pit support type for narrow tunnel permeable strata according to claim 7, characterized in that: The grouting hose (8) is a rubber hose, and its diameter is smaller than the diameter of the grouting hole (4).

9. The belt-shaped shallow foundation pit support type for narrow tunnel permeable strata according to claim 1 is characterized in that: The bottom of the T-shaped stiffening rib (2) is an inclined surface, and the slope of the inclined surface is 1:

5.

10. A construction method for a belt-shaped shallow foundation pit support type in a narrow tunnel permeable stratum according to claim 1, characterized in that: The specific steps include: S1. Place a rubber lubricating pad (9) on the inner side of the U-shaped lock (3), apply a lubricating isolating agent on the surface, insert a grouting hose (8) into the grouting hole (4), and inject water or air to confirm that the grouting pipeline is unobstructed; S2. Use a pile driving device to drive the first support steel plate (1) to the side of the foundation pit in a low-hammer and dense-hammer manner, with the hammering point located at the top enlarged head of the T-shaped stiffening rib (2), and protect the grouting hose (8) during the hammering; S3, repeating S1 to S2 to process other supporting steel plates (1) until both sides of the foundation pit are provided with supporting steel plates (1) connected in sequence and a complete excavation trench section is formed; adjacent supporting steel plates (1) are butt-jointed with U-shaped locks (3); S4, the grouting pipe of the grouting equipment (11) is connected to the upper end of the grouting hose (8), and the curing agent is injected in sections to form a reinforcement body (12) in the soil layer at the bottom of the foundation pit, and then clean water is injected to form a non-cured area (13); S5, excavating the soil layer in the foundation pit to the bottom of the support pattern, welding the bracket (5) on the surface of the T-shaped stiffening rib (2), and setting up the waist beam (7) and the cross brace (6) fixedly connected to the bracket (5) above the bracket (5); after the operation in the foundation pit is completed and backfilled, the waist beam (7) and the cross brace (6) are removed, and the support steel plate (1) is pulled out piece by piece; S6. Move the pulled-out supporting steel plate (1) to the next excavated trench section and repeat S1 to S5 until the foundation pit is completely constructed.

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