Tunnel supporting system and method for controlling upward floating of tunnel

Abstract

The invention relates to the technical field of rail traffic engineering, and discloses a tunnel supporting system and a method for controlling tunnel floating, the tunnel supporting system comprises a subway tunnel, the outer side of the subway tunnel is provided with a reinforcing soil body which is not in contact with the subway tunnel, and the top end of the reinforcing soil body is a soil layer to be excavated; a plurality of supporting piles are arranged on the left side and the right side of the reinforced soil body, every two adjacent supporting piles on the left side and the right side are fixedly connected through a plurality of supporting pieces, and a dragging pipe with one end penetrating and extending to the gap between the two supporting piles on the left side is arranged in the gap between the two supporting piles on the right side. The dragging pipe penetrates through the reinforced soil body and is located on the outer side of the subway tunnel, a plurality of grouting holes are formed in the dragging pipe, and according to the tunnel supporting system, the integrality of the soil body above the tunnel can be enhanced through grouting of the dragging pipe and the grouting holes, downward pressure can be provided, upward floating deformation of the tunnel is limited, and the safety of the tunnel is improved.

Description

Technical Field

[0001] The invention relates to the technical field of rail transportation engineering, and in particular to a method for controlling tunnel buoyancy. Background Art

[0002] There are often various construction projects above the operating subway tunnels, which require the excavation of part of the tunnel cover. As a result, the tunnel will partially float up, which may affect the speed of vehicles.

[0003] At present, there are two main methods to reduce the floating caused by excavation of overburden above the tunnel. One is to reinforce the soil layer above the tunnel with jet grouting piles or mixing piles when the proportion of excavated soil is very small, and the other is to reinforce the soil layer above the tunnel with jet grouting piles or mixing piles and set up concrete structure slabs for weight when the excavation of soil is large. However, when the proportion of soil to be excavated above the tunnel is very high and the soil is large, the above two methods are difficult to control the floating deformation of the tunnel below, and cannot ensure that the tunnel floats within the allowable range, which poses a major safety risk. Summary of the invention

[0004] The present invention provides a method for controlling tunnel buoyancy, which can effectively improve tunnel grouting efficiency, effectively control tunnel buoyancy deformation, and ensure tunnel safety.

[0005] The technical solution of the present invention to solve the above technical problems is as follows: A tunnel support system includes a subway tunnel, wherein a reinforced soil body not in contact with the subway tunnel is arranged on the outside of the subway tunnel, the top of the reinforced soil body is a soil layer to be excavated, a plurality of supporting piles are arranged on the left and right sides of the reinforced soil body, and two adjacent supporting piles on the left and right sides are fixedly connected by a plurality of supporting members, a dragging pipe with one end penetrating through and extending to the gap between the two supporting piles on the left is arranged in the gap between the two supporting piles on the right, the dragging pipe passes through the reinforced soil body and is located on the outside of the subway tunnel, and a plurality of grouting holes are opened on the dragging pipe.

[0006] Based on the above technical solution, the present invention can also be improved as follows.

[0007] Preferably, the distance between two adjacent support members is determined by the properties of the soil layer outside the foundation pit; when the soil layer is silt soil, the distance is denser, 3-5m, and when the soil layer is sandy soil or old clay soil, the distance is appropriately increased to 5-8m.

[0008] Preferably, the support member is a steel support or a concrete support.

[0009] Preferably, the distance between two adjacent grouting holes is appropriately adjusted according to the soil layer; the specific adjustment form is as follows, wherein for the sand layer, the spacing is sparse, the spacing is 500mm; for the silt clay soil, the spacing is dense, the spacing is 200mm; for other soil layers, the spacing is between 200mm-500mm.

[0010] A method for controlling tunnel buoyancy according to claim 1, wherein the specific implementation steps are: S1. First, determine the position of the support pile according to the construction drawings and design requirements, then use a drilling machine to drill holes at the pile positions, and then use a crane to place the steel cage in the hole. After the steel cage is placed, pour concrete; S2. Use jet grouting piles or mixing piles to reinforce the soil below the soil layer to be excavated to form a reinforced soil body; S3. Excavate the earthwork of the foundation pit on both sides symmetrically, and set up support members layer by layer according to the excavation depth; S4, until the bottom of the foundation pit is dug, directional drilling construction starts from the right foundation pit, and the grouting pipe is dragged through the reinforced soil to the left foundation pit; S5. After fixing both ends of the grouting pipe, the grouting operation is carried out. The grouting slurry enters the gap between the subway tunnel and the reinforced soil through several grouting holes. After the grouting slurry solidifies, the soil reinforcement is achieved. After confirming that the tunnel has not floated, the soil layer to be excavated is excavated.

[0011] Compared with the prior art, the technical solution of this application has the following beneficial technical effects: 1. The tunnel support system proposed in the present invention can strengthen the integrity of the soil above the tunnel through grouting of the drag pipe and grouting holes, and can provide downward pressure to limit the floating deformation of the tunnel and improve the safety of the tunnel.

[0012] 2. The method for controlling the buoyancy of a tunnel proposed in the present invention is very effective in controlling the buoyancy deformation of a tunnel when foundation pit excavation is required above an operating subway tunnel and part of the tunnel covering soil is removed. It can achieve precise control to avoid affecting the safety of the operating tunnel. It can also be used in the construction of some shallow buried tunnels, which can greatly increase the safety of the tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a cross-sectional view of the tunnel support system of the present invention; Figure 2 This is a longitudinal section view of the tunnel support system of the present invention.

[0014] In the figure: 1. subway tunnel; 2. reinforced soil; 3. soil layer to be removed; 4. support piles; 5. drag pipe; 6. support member; 7. grouting hole. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in 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. 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.

[0016] In the embodiment, Figure 1 and Figure 2 A tunnel support system is provided, comprising a subway tunnel 1, characterized in that: a reinforced soil body 2 not in contact with the subway tunnel 1 is arranged on the outside of the subway tunnel 1, the top of the reinforced soil body 2 is a soil layer 3 to be excavated, a plurality of supporting piles 4 are arranged on the left and right sides of the reinforced soil body 2, two adjacent supporting piles 4 on the left and right sides are fixedly connected by a plurality of supporting members 6, a dragging pipe 5 with one end penetrating through and extending to the gap between the two supporting piles 4 on the left is arranged in the gap between the two supporting piles 4 on the right, the dragging pipe 5 passes through the reinforced soil body 2 and is located on the outside of the subway tunnel 1, and a plurality of grouting holes 7 are opened on the dragging pipe 5.

[0017] The distance between two adjacent support members 6 is determined by the properties of the soil layer outside the foundation pit; when the soil layer is silt, the distance is denser, at 3-5m, and when the soil layer is sandy soil or old clay, the distance is appropriately increased to 5-8m. It should be clarified that under normal circumstances, when the foundation pit depth is less than 10m, there are generally two supports in the vertical direction, and the support members 6 are erected according to the above rules. When the foundation pit depth is 10m-15m, the number of supports in the vertical direction needs to be increased by at least one, generally one.

[0018] The support member 6 is a steel support or a concrete support.

[0019] The distance between two adjacent grouting holes 7 is appropriately adjusted according to the soil layer; the specific adjustment form is as follows, wherein for the sand layer, the spacing is sparse, the spacing is 500mm; for the silt clay soil, the spacing is dense, the spacing is 200mm; for other soil layers, the spacing is between 200mm-500mm, wherein the permeability of other soil layers is between the sand layer and the silt clay soil, so the spacing is between 200mm-500mm, and there are many types of other soil layers and they are common knowledge to technicians in this technical field, so they will not be elaborated here.

[0020] A method for controlling tunnel buoyancy, the specific implementation steps are: S1. First, determine the pile position of the support pile 4 according to the construction drawings and design requirements, and then use a drilling machine to drill holes at the pile positions. The hole depth and hole diameter must meet the design requirements. During the drilling process, mud must be injected to protect the wall to prevent the hole wall from collapsing. Then use a crane to place the steel cage in the hole. After the steel cage is placed, pour concrete; S2, using jet grouting piles or mixing piles to reinforce the soil below the soil layer 3 to be excavated, so as to form a reinforced soil body 2; S3, symmetrically excavate the earthwork of the foundation pit on both sides, and set up support members 6 layer by layer according to the excavation depth; S4, until the bottom of the foundation pit is dug, directional drilling construction is started from the right foundation pit, and the grouting pipe 5 is dragged through the reinforced soil 2 to the left foundation pit; S5. After fixing both ends of the grouting pipe 5, the grouting operation is carried out. The grouting slurry enters the gap between the subway tunnel 1 and the reinforced soil 2 through a plurality of grouting holes 7. After the grouting slurry solidifies, the soil is reinforced, the integrity of the soil above the tunnel is strengthened, and downward pressure is provided to control the deformation of the shield tunnel and prevent it from floating. After confirming that the tunnel has not floated, the soil layer 3 to be excavated is excavated.

[0021] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0022] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A tunnel support system, comprising a subway tunnel (1), characterized in that: A reinforced soil body (2) not in contact with the subway tunnel (1) is arranged outside the subway tunnel (1), the top of the reinforced soil body (2) is a soil layer (3) to be excavated, a plurality of support piles (4) are arranged on both sides of the reinforced soil body (2), two adjacent support piles (4) on the left and right sides are fixedly connected by a plurality of support members (6), a drag pipe (5) is arranged at one end penetrating through and extending to the gap between the two support piles (4) on the left, the drag pipe (5) passes through the reinforced soil body (2) and is located outside the subway tunnel (1), and a plurality of grouting holes (7) are opened on the drag pipe (5).

2. A method for controlling tunnel buoyancy according to claim 1, characterized in that: The distance between two adjacent support members (6) is determined by the properties of the soil layer outside the foundation pit; when the soil layer is silt soil, the distance is closer, 3-5m, and when the soil layer is sandy soil or old clay soil, the distance is appropriately increased, reaching 5-8m.

3. A method for controlling tunnel buoyancy according to claim 1, characterized in that: The support member (6) is a steel support or a concrete support.

4. A method for controlling tunnel buoyancy according to claim 1, characterized in that: The distance between two adjacent grouting holes (7) is appropriately adjusted according to the soil layer; the specific adjustment form is as follows, wherein for the sand layer, the spacing is sparse, the spacing is 500 mm; for the silt clay soil, the spacing is dense, the spacing is 200 mm; for other soil layers, the spacing is between 200 mm and 500 mm.

5. A method for controlling tunnel buoyancy according to claim 1, characterized in that: The specific implementation steps are: S1. First, determine the pile position of the support pile (4) according to the construction drawings and design requirements, then use a drilling machine to drill holes at the pile position, and then use a crane to place the steel cage in the hole. After the steel cage is placed, pour concrete; S2, using jet grouting piles or mixing piles to reinforce the soil below the soil layer (3) to be excavated, so as to form a reinforced soil body (2); S3, symmetrically excavate the earthwork of the foundation pit on both sides, and set up support members (6) layer by layer according to the excavation depth; S4, until the bottom of the foundation pit is dug, directional drilling construction is started from the right foundation pit, and the grouting pipe (5) is dragged through the reinforced soil (2) to the left foundation pit; S5. After fixing both ends of the grouting pipe (5), the grouting operation is performed. The grouting slurry enters the gap between the subway tunnel (1) and the reinforced soil (2) through a plurality of grouting holes (7). After the grouting slurry solidifies, the soil is reinforced. After confirming that the tunnel has not floated, the soil layer (3) to be excavated is excavated.

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