End reinforcement structure for reinforcement treatment of soil dissolving hole of shield tunnel

Abstract

The end reinforcing structure for reinforcing the soil dissolving hole of the shield tunnel comprises a drill hole, a sleeve valve pipe, a casing material layer and a pipe fixing and grout stopping layer, the sleeve valve pipe is layered up and down in a penetrating section of the soil dissolving hole layer, grouting is performed section by section from bottom to top, and the casing material layer in a corresponding area is permeated to fill the soil dissolving hole layer. And meanwhile, an external soil rock layer around the soil dissolving cave layer is solidified. According to the utility model, the advantages of sectionality, depth setting and repeated re-injection of a sleeve valve pipe grouting method are fully utilized, and the consolidation characteristic of slurry is utilized, so that the original filler in the hole body is cemented and compacted, the hydraulic connection between the hole body and external soil layers and rock stratums is cut off, the continuous development of corrosion and subsurface corrosion effects is avoided, and hidden dangers are eliminated.

Description

Technical Field

[0001] This utility model belongs to the field of shield tunneling technology, specifically relating to an end reinforcement structure for the reinforcement treatment of karst caves in shield tunnels. Background Technology

[0002] Currently, there are more and more large-diameter shield tunnels being constructed in China, and the geological strata encountered during excavation are becoming more diverse, involving a wider range of fields. For example, Guangzhou Baiyun Airport is located in the karst area of ​​Guangzhou Baiyun District, where karst development is strong and engineering geological conditions are complex. However, due to the special nature of the airport's operation, detailed investigations cannot be conducted in the early stages, and many exploration boreholes are missing, making it impossible to fully reveal the situation of karst caves. Geological exploration can only be carried out through later supplementary investigations. Moreover, the construction period is quite strict during the airport's non-stop construction. Therefore, it is necessary to adopt an efficient, fast, and reliable reinforcement treatment method to deal with the karst caves found within the influence range of the shield tunnel.

[0003] However, the following technical defects exist in the shield tunneling process:

[0004] 1) The appearance of karst caves can lead to a series of risks such as shield machine head loading, jamming, segment breakage and attitude loss, and surface subsidence and collapse, thereby reducing the safety and construction efficiency of shield tunneling in karst areas.

[0005] 2) The sleeve valve grouting method used to reinforce the karst cave can effectively consolidate and compact the area of ​​the karst cave, but it cannot effectively cut off the hydraulic connection between the cave and the external soil and rock layers. Therefore, there are still hidden dangers of dissolution and undercutting, which makes the reinforced structure unable to meet the needs of the tunnel boring machine. Utility Model Content

[0006] The technical problem to be solved by this utility model is to overcome the shortcomings of the existing technology and provide a brand-new end reinforcement structure for the reinforcement treatment of karst caves in shield tunnels.

[0007] To solve the above technical problems, the present invention adopts the following technical solution:

[0008] A shield tunnel end reinforcement structure for reinforcing karst caves is provided. The structure is laid out based on the burial depth of the top and bottom boundaries of the karst cave layer. The shield end reinforcement structure includes a sleeve valve pipe extending downwards from the ground and penetrating the entire karst cave layer. Specifically, multiple boreholes penetrating the karst cave layer are provided in the area of ​​the karst cave layer, each borehole forming a sleeve valve pipe. The top and bottom of each sleeve valve pipe penetrate the borehole, and the bottom end of the sleeve valve pipe is closed, forming a grouting hole in the circumferential direction. The shield end reinforcement structure also includes a casing material layer filling the space between the outer wall of the sleeve valve pipe and the inner wall of the borehole, and a grout-stopping layer located at the borehole opening. The sleeve valve pipe is layered vertically and horizontally within the penetrating section of the karst cave layer, and the casing material layer permeates into the corresponding area during grouting from bottom to top, filling the karst cave layer while simultaneously solidifying with the surrounding external soil and rock layers.

[0009] Preferably, the number of through-segments is based on the depth of the karst cave layer, and the formed through-segments need to cover the top and bottom of the karst cave layer. The resulting filling area can cover the entire karst cave layer and the adjacent external soil and rock layers, thereby improving the strength of the end reinforcement.

[0010] According to a specific embodiment and preferred aspect of this utility model, the grouting force formed by the penetrating section of the sleeve valve pipe gradually decreases from bottom to top. Based on the depth variation of the stratum, different grouting pressures are used to meet the permeability requirements.

[0011] According to another specific embodiment and preferred aspect of this utility model, the grouting holes in each through section are arranged in a spiral pattern along the length of the sleeve valve pipe and around the outer periphery of the sleeve valve pipe. This arrangement of grouting holes allows for more uniform and dense filling into the karst cavern layer.

[0012] In some specific implementations, the length of the area formed between the through sections of each pair of adjacent sleeve valves may be equal or unequal. For multiple sleeve valves, the layout of the areas formed by the through sections is designed to meet the filling needs under different working conditions. Generally, the areas formed by the through sections are not equal because the different pressures created are more conducive to grout penetration.

[0013] In some specific embodiments, the grouting holes between the through sections of every two adjacent sleeve valve tubes are aligned or staggered. Given multiple sleeve valve tubes, the distribution of the grouting holes generally maintains a relatively uniform and dense structure. Typically, the staggered distribution results in a better complementary grouting effect, especially when the areas formed by the through sections are not equal, where the grouting effect is optimal.

[0014] Preferably, each sleeve valve tube has a conical end cap formed at its end, and a protective head that can hook onto the end of the borehole is formed at the outer end of the conical end cap. The conical end cap facilitates the assembly of the sleeve valve tube, and the protective head further stabilizes the positioning of the sleeve valve tube.

[0015] In addition, the casing material layer is a clay-cement grout layer. This casing material layer is mainly used to prevent deformation, displacement, or damage to the sleeve valve grouting pipe during the grouting process, and to ensure that the cement grout passes through the sleeve valve grouting pipe. The casing material is required to have low shrinkage, high brittleness, and high early strength; the loss and diffusion coefficient of the casing material is taken as 1.3.

[0016] Preferably, the grout-stopping layer is formed on top of the casing material layer; generally, the water-cement ratio of the grout used is 1:1.5. A 1 / 2-inch galvanized pipe is inserted into the gap between the sleeve valve pipe and the hole wall to the top surface of the casing material (the top boundary of the reinforced tunnel). The prepared grout is injected from the 1 / 2-inch galvanized pipe until it comes out of the hole. After the grout surface at the hole sinks, it should be reinjected multiple times to ensure the grout-stopping effect.

[0017] Furthermore, the bottom of the borehole is located 20±5cm below the bottom of the karst cave layer.

[0018] In some specific embodiments, after grouting is completed, the sleeve valve pipe is cut off from the surface of the self-curing grout-stopping layer to form a port. The shield end reinforcement structure also includes a mortar sealing layer filled at the port. The reinforcement operation is convenient and does not require deep treatment of the sleeve valve pipe.

[0019] Due to the implementation of the above technical solution, this utility model has the following advantages compared with the prior art:

[0020] In existing shield tunneling processes, the presence of karst caves leads to a series of risks, including shield machine head jamming, segment breakage, loss of attitude control, and surface subsidence and collapse. These risks reduce the safety and efficiency of shield tunneling in karst areas. Furthermore, while the sleeve valve grouting method used for reinforcing karst caves effectively consolidates and densifies the area, it fails to effectively sever the hydraulic connection between the cave and the external soil and rock layers. Therefore, the risk of dissolution and undercutting remains, rendering the reinforced structure inadequate for shield tunneling requirements. This invention cleverly solves these shortcomings by providing an overall design for the shield tunneling end reinforcement structure. To address the various shortcomings of traditional tunnel boring machines (TBMs), this shield end reinforcement structure allows grouting to enter from the upper end of the sleeve valve pipe. The grout is then output from the lowest grouting hole to disrupt or penetrate the outer casing material layer, thereby filling the corresponding karst cave layer. Multiple grouting operations are then performed sequentially to ensure the grouting area covers the entire karst cave layer. Simultaneously, the grouting solidifies with the surrounding external soil and rock layers. Therefore, this invention fully utilizes the advantages of the sleeve valve pipe grouting method—segmented, fixed-depth, and multiple re-grouting—and leverages the consolidation characteristics of the grout to cement the original filling material within the cave, severing the hydraulic connection between the cave and the external soil and rock layers, preventing further dissolution and undercutting, and eliminating potential hazards. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the end reinforcement structure in this embodiment (first grouting);

[0022] Figure 2 This is a schematic diagram of the end reinforcement structure (second grouting) in this embodiment;

[0023] Figure 3 This is a schematic diagram of the end reinforcement structure in this embodiment (after grouting).

[0024] Among them: 1. Drilling; 2. Sleeve valve pipe; 3. Shell material layer; 4. Solid pipe grouting layer; 5. Conical head; 6. Protective head; 7. Port; 8. Mortar sealing layer; T, karst cave layer; B, external soil and rock layer. Detailed Implementation

[0025] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the present utility model will be described in detail below with reference to the accompanying drawings and specific embodiments. Many specific details are set forth in the following description to provide a full understanding of the present utility model. However, the present utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present utility model. Therefore, the present utility model is not limited to the specific embodiments disclosed below.

[0026] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0028] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0029] In utility models, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0030] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0031] like Figure 1 and Figure 2 As shown, the end reinforcement structure for the reinforcement treatment of karst caves in shield tunnels in this embodiment is laid out based on the burial depth of the top and bottom boundaries of the karst cave layer T. The shield end reinforcement structure includes multiple boreholes 1 that extend from the ground downwards and penetrate the entire karst cave layer T, sleeve valve pipes 2 distributed in each borehole 1 and penetrating the top and bottom of the borehole 1 respectively, a shell material layer 3 filling the space between the outer wall of the sleeve valve pipe 2 and the inner wall of the borehole 1, and a solid pipe grouting layer 4 located at the borehole opening.

[0032] In some specific embodiments, borehole 1 extends vertically downwards from the karst cavern T, with the bottom of borehole 1 located approximately 20 cm below the bottom of the karst cavern. Each sleeve valve pipe 2 has its bottom closed, forming a grouting hole circumferentially. The closed end of each sleeve valve pipe 2 is located below the bottom of borehole 1. The sleeve valve pipe 2 is layered vertically within the penetrating section of the karst cavern T, and grouting is performed segment by segment from bottom to top, with the corresponding area of ​​the casing material layer 3 filling the karst cavern T while simultaneously solidifying it with the surrounding external soil and rock layer B. The number of penetrating sections is determined based on the depth of the karst cavern T, and the formed penetrating sections need to cover both the top and bottom of the karst cavern T. This filling area can cover the entire karst cavern T and the adjacent external soil and rock layer B, thereby improving the strength of the end reinforcement.

[0033] In this example, each sleeve valve tube 2 has a conical end cap 5 at its bottom end, and a protective head 6 that can hook onto the borehole end is formed at the outer end of the conical end cap 5. The conical end cap 5 facilitates the assembly of the sleeve valve tube 2, and the protective head 6 further stabilizes the positioning of the sleeve valve tube 2. Simultaneously, the grouting force formed by the penetrating section of the sleeve valve tube 2 gradually decreases from bottom to top. Different grouting pressures are used based on the depth variations of the formation to meet the permeability requirements. The grouting holes in each penetrating section are arranged spirally along the length of the sleeve valve tube 2 around its outer periphery. This layout of grouting holes allows for more uniform and dense filling into the karst cavern layer. The length of the area formed between each pair of adjacent sleeve valve tubes 2 penetrating sections may be equal or unequal. For multiple sleeve valve tubes 2, the area layout formed by the penetrating sections meets the filling needs under different working conditions. Generally, the areas formed by the penetrating sections are not equal because the different pressures facilitate grouting permeability. The grouting holes between each pair of adjacent sleeve valve pipes 2 are aligned or staggered. Based on the multiple sleeve valve pipes 2, the distribution of the grouting holes can maintain relative uniformity and density. Generally, the complementary grouting effect formed by the staggered distribution is better, especially when the areas formed by the through sections are not equal, the grouting effect is optimal.

[0034] Layer 3 of the casing material is a clay-cement grout layer. This casing material layer is mainly used to prevent deformation, displacement, or damage to the sleeve valve grouting pipe during the grouting process, and to ensure that the cement grout passes through the sleeve valve grouting pipe. The casing material is required to have low shrinkage, high brittleness, and high early strength; the loss and diffusion coefficient of the casing material is taken as 1.3.

[0035] The grout-stopping layer 4 is formed on top of the casing material layer. Under normal circumstances, the water-cement ratio of the grout used is 1:1.5. A 1 / 4-inch galvanized pipe is inserted into the gap between the sleeve valve pipe and the hole wall to the top surface of the casing material (the top boundary of the reinforced tunnel). The prepared grout is injected from the 1 / 4-inch galvanized pipe until it comes out of the hole. After the grout surface at the hole sinks, it should be reinjected multiple times to ensure the grout-stopping effect.

[0036] Combination Figure 3 As shown, after grouting is completed, the sleeve valve pipe is cut off from the surface of the self-solidifying grout-stopping layer 4 to form port 7. The shield end reinforcement structure also includes a mortar sealing layer 8 filled in port 7. The reinforcement operation is convenient and does not require deep treatment of the sleeve valve pipe.

[0037] In addition, it should be noted that: the reinforcement treatment covers a 5m radius outside the shield tunnel structure, and all karst caves from the ground to the tunnel bottom must be treated; when the tunnel bottom is limestone, karst caves within 5m of the tunnel floor slab outside the 5m radius must be treated; when the tunnel bottom is a relatively stable aquitard (e.g., clay, silty clay), if the aquitard thickness is ≥5m, the karst below the tunnel bottom generally does not require treatment. If the aquitard thickness is <5m, and the thickness of the top slab of the uppermost karst cave is <5m or the thickness-to-span ratio is <1, then karst caves within 5m of the tunnel structure outside the 5m radius, below the rock surface, must be treated; when the tunnel bottom to the rock surface is a sand layer or there is no relatively stable aquitard, if the thickness of the top slab of the uppermost karst cave is ≥5m, the karst below the tunnel bottom generally does not require treatment. If the thickness of the top slab of the uppermost karst cave is <5m or the thickness-to-span ratio is <1, after extending the tunnel structure outwards by 5m, karst caves within 5m below the rock surface must be treated.

[0038] In summary, after adopting this shield tunnel end reinforcement structure, grouting enters from the upper end of the sleeve valve pipe, and the grout exits from the grouting hole at the lowest section to disrupt or penetrate the shell material layer, thereby completing the filling of the corresponding karst cave layer. Then, multiple grouting operations are performed sequentially to ensure the grouting area covers the entire karst cave layer. Simultaneously, the formed grout solidifies with the surrounding external soil and rock layers. Therefore, this invention fully utilizes the advantages of the sleeve valve pipe grouting method—segmented, fixed-depth, and multiple re-grouting—and leverages the consolidation characteristics of the grout to cement and compact the original filling material within the cave, severing the hydraulic connection between the cave and the external soil and rock layers, and preventing karst cave filling. The continued development of erosion and undercutting processes eliminates hidden dangers; on the other hand, the number of penetration sections is based on the depth of the karst cave layer, and the formed penetration sections need to cover the top and bottom of the karst cave layer. In this way, the filling area can cover the entire karst cave layer and the adjacent external soil and rock layers to improve the strength of the end reinforcement; thirdly, the grouting force formed by the penetration section of the sleeve valve pipe gradually decreases from bottom to top. Based on the changes in the depth of the strata, different grouting pressures are used to meet the permeability requirements. The grouting holes in each penetration section are spirally arranged along the length of the sleeve valve pipe and on the outer periphery of the sleeve valve pipe. Based on the layout of the grouting holes, it can be more uniform. The dense filling extends to the karst cavern layer. Simultaneously, based on multiple sleeve valve pipes, the regional layout formed by the through-section meets the filling needs under different working conditions. Generally, the regions formed by the through-section are not equal because the pressure varies, which is more conducive to grout penetration. Furthermore, based on the multiple sleeve valve pipes, the distribution of grouting holes maintains relative uniformity and density. Generally, the complementary grouting effect formed by the staggered distribution is better, especially under working conditions where the regions formed by the through-section are not equal, resulting in the best grouting effect. Fourthly, the conical end cap facilitates… The assembly of the sleeve valve pipe, with the assistance of the protective head, further stabilizes the positioning of the sleeve valve pipe; at the same time, the casing material layer is a clay cement slurry layer, which is mainly used to prevent the sleeve valve grouting pipe from deforming, displacing or being damaged during the grouting process, and to ensure that the cement slurry passes through the sleeve valve grouting pipe. The casing material is required to have low shrinkage, high brittleness, and high early strength. At the same time, the pipe-fixing and grout-stopping layer has a pipe-fixing and grout-stopping effect; fifthly, after the grouting is completed, the sleeve valve pipe is cut off from the surface of the pipe-fixing and grout-stopping layer to form a port. The shield end reinforcement structure also includes a mortar sealing layer filled at the port, which makes the reinforcement operation convenient and does not require deep treatment of the sleeve valve pipe.

[0039] The present utility model has been described in detail above, with the aim of enabling those skilled in the art to understand its contents and implement it. However, this description should not be construed as limiting the scope of protection of the present utility model. All equivalent changes or modifications made in accordance with the spirit and essence of the present utility model should be included within the scope of protection of the present utility model.

Claims

1. A shield tunnel loess cave reinforcement structure for reinforcing a loess cave, the shield tunnel loess cave reinforcement structure being arranged based on the top and bottom boundary depths of the loess cave layer, and the shield tunnel loess cave reinforcement structure comprising a sleeve valve pipe that penetrates the entire loess cave layer from the ground downward, characterized in that: A plurality of drill holes are arranged in the area where the soil cave layer is located, and sleeve valve pipes are formed in each drill hole. The top and bottom of each sleeve valve pipe penetrates the drill hole, and the bottom end of the sleeve valve pipe is closed and forms a grouting hole in the circumferential direction. The shield end reinforcement structure further includes a casing material layer filled between the outer wall of the sleeve valve pipe and the inner wall of the drill hole, and a pipe fixing and grout stopping layer located at the mouth of the drill hole. The sleeve valve pipe is layered on the through section of the soil cave layer, and the casing material layer in the corresponding area is filled into the soil cave layer by penetrating from bottom to top and segment by segment grouting, while being fixed with the surrounding soil and rock layer of the soil cave layer.

2. The end reinforcement structure for reinforcing karst caves in shield tunnels according to claim 1, characterized in that: The number of through sections is arranged based on the depth of the soil cave layer, and the formed through sections need to cover the top and bottom of the soil cave layer.

3. The ground treatment apparatus according to claim 1, wherein the ground treatment apparatus is a shield tunnel ground treatment apparatus. The grouting force formed by the through section of the sleeve valve pipe gradually decreases from bottom to top and segment by segment.

4. The ground treatment apparatus according to claim 1, wherein the ground treatment apparatus is a shield tunnel ground treatment apparatus. The grouting holes in each through section are arranged in a spiral along the length direction of the sleeve valve pipe and the outer periphery of the sleeve valve pipe.

5. The end reinforcement structure for reinforcing karst caves in shield tunnels according to claim 1, 2, 3, or 4, characterized in that: The length of the area formed between the through sections of each adjacent two sleeve valve pipes is equal or unequal.

6. The ground treatment apparatus according to claim 1 or 2 or 3 or 4, wherein the ground treatment apparatus is a shield tunnel soil cave reinforcement treatment apparatus. The grouting holes between the through sections of each adjacent two sleeve valve pipes are aligned or distributed in a staggered manner.

7. The ground treatment apparatus according to claim 1, wherein the ground treatment apparatus is a shield tunnel ground treatment apparatus. The end of each sleeve valve pipe forms a conical head, and a protection head capable of being hooked on the end of the drill hole is formed at the outer end of the conical head.

8. The ground treatment apparatus according to claim 1, wherein the ground treatment apparatus is a shield tunnel ground treatment apparatus. The casing material layer is a clay cement grout layer.

9. The ground treatment apparatus according to claim 1, wherein the ground treatment apparatus is a shield tunnel ground treatment apparatus. The pipe fixing and grout stopping layer is formed at the top of the casing material layer; and / or, the bottom of the drill hole is located 20±5 cm below the bottom of the soil cave layer.

10. The ground treatment apparatus according to claim 1, wherein the ground treatment apparatus is a shield tunnel ground treatment apparatus. After the grouting is completed, the sleeve valve pipe is cut off from the surface of the pipe fixing and grout stopping layer to form a port, and the shield end reinforcement structure further includes a mortar plugging layer filled in the port.

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