Method for cutter head to escape from large-diameter boulder stratum during shield tunneling

Abstract

The application discloses a cutter head escape method based on large-diameter boulder stratum shield crossing, and aims to solve the problem that the cutter head is difficult to escape safely when the shield crossing rich-water large-diameter boulder stratum is blocked. In the application, the hollow support steel pipe pile row drilled in front of the blocked cutter head can effectively support the earth of the tunnel face in front of the cutter head, so that the shield machine can be smoothly opened at normal pressure, and the large-diameter boulders between the support steel pipe pile row and the cutter head panel can be safely and efficiently removed after the opening, thereby solving the problem of cutter head blocking caused by large-diameter boulders. The hollow sleeve steel pipe piles drilled concentrically along the existing isolation piles can remove the existing isolation piles on one hand, thereby solving the problem that the existing isolation piles slide downward after being disturbed by the cutter head and cause the cutter head to be blocked; on the other hand, the sleeve steel pipe piles can remove the isolation piles and part of the soil above the cutter head, thereby avoiding the problem that the cutter head is blocked due to the fact that the rich-water large-diameter boulder stratum is loose and cannot bear the large earth pressure above the cutter head.

Description

Technical Field

[0001] This invention application relates to the field of shield tunneling technology, specifically to a method for cutterhead detachment during shield tunneling through large-diameter boulder strata. Background Technology

[0002] The shield tunneling method is a method of constructing tunnels by cutting and excavating. It utilizes the advancement of shield machinery in the strata, and the shield shell and segments support the surrounding rock to prevent tunnel collapse. At the same time, cutting devices are used to excavate the soil in front of the excavation face, and the soil is transported out of the tunnel by excavation machinery. Jacks are used to press and tighten the soil at the rear, and precast concrete segments are assembled to form the tunnel structure.

[0003] Due to the complex geological structure and the differences in geological characteristics between different strata, tunnel boring machines (TBMs) face significant risks when traversing unstable strata with large-diameter boulders and abundant water. In such strata, the TBM needs to open its chamber for cutterhead replacement after each period of excavation. In particular, because the strata with large-diameter boulders and abundant water have poor self-stability, it is necessary to install isolation piles and dewatering wells on the ground for reinforcement before opening the chamber to replace the cutterheads. However, during tunneling, the TBM relies on the face in front of the cutterhead to provide reaction force for the cutterheads. In the strata with large-diameter boulders and abundant water, when the cutterheads come into contact with the boulders, the boulders fall off as the cutterheads rotate, and cannot be properly broken up by the cutterheads. The large boulders that fall off roll forward with the TBM, accumulating at the location of the isolation piles, which can easily cause the cutterhead to get stuck.

[0004] In addition, after the isolation pile is cut as the tunnel boring machine advances, it will slide down to a certain extent due to the disturbance of the cutterhead. As a result, the sliding end of the isolation pile will interfere with the tunnel boring machine, exacerbating the problem of cutterhead jamming.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the background technology of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] In view of at least one of the above technical problems, this disclosure provides a method for cutterhead detachment in shield tunneling through large-diameter boulder strata, aiming to solve the problem of shield tunneling encountering cutterhead obstruction and difficulty in safely detaching itself when crossing water-rich large-diameter boulder strata.

[0007] According to one aspect of this disclosure, a method for cutterhead detachment in shield tunneling through large-diameter boulder strata is provided, comprising the following steps: (1) A row of hollow support steel pipe piles is drilled at least 20cm in front of the trapped cutterhead; the bottom wall of the support steel pipe piles is provided with a number of filter holes. (2) Obtain the top elevation of the cutterhead and the corresponding ground elevation above the top of the cutterhead based on the current geological report of the tunnel boring machine. Drill hollow steel pipe piles concentrically to the corresponding position of the cutterhead at the existing isolation piles. (3) The shield machine is opened under normal pressure, and large-diameter boulders are manually removed from the chamber and between the support steel pipe piles and the cutterhead panel; (4) Start the tunnel boring machine and confirm that the cutterhead is rotating normally. Remove each set of steel pipe piles and each support steel pipe pile in sequence at the ground. The tunnel boring machine is freed from its predicament.

[0008] In some embodiments of this disclosure, in step (1), the bottom end face of the support steel pipe pile is at least 2m lower than the bottom of the cutterhead, and the range of the filter holes begins at the position corresponding to the top of the cutterhead of the support steel pipe pile and ends at the bottom of the support steel pipe pile.

[0009] In some embodiments of this disclosure, in step (1), the supporting steel pipe pile is provided with a filter screen within the range of the filter holes.

[0010] In some embodiments of this disclosure, in step (1), water pumps for drawing water to the ground are respectively installed at the bottom of each support steel pipe pile.

[0011] In some embodiments of this disclosure, in step (2), a distance of 20cm to 30cm is left between the bottom of the steel pipe pile and the cutterhead.

[0012] In some embodiments of this disclosure, in step (3), after the chamber is opened, the residual isolation pile between the bottom of the steel pipe pile and the cutterhead is broken by manual labor in the soil chamber.

[0013] In some embodiments of this disclosure, in step (4), a vibratory hammer and a hydraulic jack are used to sequentially remove the casing steel pipe pile and the support steel pipe pile, while clay backfilling is carried out at the same time.

[0014] One or more technical solutions provided in the embodiments of this application have at least one of the following technical effects or advantages: 1. The hollow support steel pipe pile row drilled in front of the cutterhead can effectively support the soil coming from the face in front of the cutterhead, ensuring that the tunnel boring machine can open the chamber smoothly under normal pressure. After opening the chamber, it can safely and efficiently remove large-diameter boulders between the support steel pipe pile row and the cutterhead panel, solving the problem of large-diameter boulders blocking the cutterhead.

[0015] 2. Hollow-core steel pipe piles, drilled concentrically along the existing isolation piles, can remove the existing isolation piles, solving the problem of the existing isolation piles sliding down and causing jamming on the cutterhead after being disturbed by the cutterhead. On the other hand, the installation of the steel pipe piles can remove the isolation piles and part of the soil above the cutterhead, thereby reducing the pressure on the isolation piles and soil layers above the cutterhead. This avoids the problem of the cutterhead getting stuck due to the looseness of the water-rich, large-diameter boulder strata being unable to withstand the large soil pressure above the cutterhead.

[0016] 3. Hollow support steel pipe piles are equipped with water filter holes within the cutterhead area and from below the cutterhead to the pile bottom. This allows the support steel pipe piles to be used as dewatering wells, thereby avoiding the adverse effects of groundwater on the shield machine's opening and boulder removal operations. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the shield machine cutterhead jamming state in one embodiment of this application.

[0018] Figure 2 This is a schematic diagram of the layout of hollow support steel pipe piles in one embodiment of this application.

[0019] Figure 3 This is a schematic diagram of the hollow steel pipe structure of the supporting steel pipe pile in one embodiment of this application.

[0020] In the above figures, 1 is the cutterhead, 2 is the existing isolation pile, 3 is the hollow support steel pipe pile, and 31 is a partially hollow steel pipe. Detailed Implementation

[0021] To better understand the technical solution of this application, the above technical solution will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] When a tunnel boring machine (TBM) passes through a water-rich, large-diameter boulder stratum, the poor self-stability of this stratum prevents the cutterhead from effectively cutting and breaking the large-diameter boulders at the face. This causes the boulders to detach and roll forward with the cutterhead. After traveling a certain distance through this stratum, the TBM needs to open its tunnel for cutter replacement. To improve the stability of the water-rich, large-diameter boulder stratum and avoid affecting the TBM's tunnel opening operation, current solutions generally involve drilling isolation piles in front of the cutterhead to stabilize the stratum. After the cutterhead replacement is completed, the TBM continues tunneling. However, at this point, detached boulders rolling to the isolation pile location can easily cause boulder accumulation, leading to cutterhead jamming. Even if the TBM can effectively cut the isolation pile, the pile itself is at risk of sliding due to the disturbance caused by the cutterhead. (See [link to relevant documentation]). Figure 1 The sliding and sinking isolation pile 2 and the shield machine cutterhead 1 have positional interference, which increases the possibility that the isolation pile will block the cutterhead.

[0023] Therefore, this example discloses a method for cutterhead detachment during shield tunneling through large-diameter boulder strata, which includes the following steps: (1) Drill a row of hollow support steel pipe piles at least 20cm in front of the trapped cutterhead; the bottom wall of the support steel pipe piles is provided with a number of filter holes.

[0024] Considering the poor self-stability of water-rich, large-diameter boulder strata, it is not feasible to directly perform tunnel boring machine (TBM) operations to clear and remove the stuck boulders. Therefore, see [reference needed]. Figure 2 A row of support steel pipe piles is drilled at least 20cm in front of the trapped cutterhead to effectively support the soil layer at the face in front of the cutterhead. Specifically, in this embodiment, the row of support steel pipe piles is drilled parallel to the cutterhead panel at a position 20cm in front of the cutterhead. To ensure reliable support for the soil layer at the face in front of the cutterhead, adjacent support steel pipe piles are tightly tangential to avoid problems such as excessive spacing between adjacent support steel pipe piles leading to soil leakage from the gap.

[0025] In this embodiment, a rotary drilling rig is specifically used for drilling the support steel pipe piles. Before construction, the excavation mileage and position coordinates of the cutterhead are measured and laid out to determine the drilling points for the support steel pipe piles on the ground. Then, the rotary drilling rig is used to drill at the corresponding laid-out points. In this example, after drilling 3m, a steel casing is placed at the pile hole opening. The steel casing is coaxially set with the pile body. Drilling continues, and the vibratory hammer is started to lower and extend the hollow steel pipe piles. In this example, the support steel pipe piles are installed in a skip-pile manner, specifically, the odd-numbered piles are installed first, followed by the even-numbered piles. In other embodiments, the support steel pipe piles are drilled sequentially, thereby realizing the drilling of the support steel pipe pile row and stabilizing the face in front of the cutterhead.

[0026] Furthermore, in this embodiment, considering that the stratum where the tunnel boring machine is trapped is a water-rich stratum with well-developed groundwater, to avoid the adverse effects of water on the tunnel boring machine's opening and escape, hollow steel pipe piles are specifically used for the support steel pipe piles in this embodiment. Thus, the hollow support steel pipe piles not only stabilize the stratum at the face in front of the cutterhead but also serve as dewatering wells, avoiding the need for additional dewatering well drilling, saving construction costs and time, and preventing excessive disturbance to the unstable, water-rich, large-diameter boulder stratum. Specifically, in this embodiment, see... Figure 3 The hollow steel pipe is made of 2cm thick steel plate. To realize the function of the dewatering well, several filter holes are arrayed on the pipe wall. In this example, the filter holes have a rectangular structure outline of 1cm×10cm. In other embodiments, the filter holes are arranged in a quincunx pattern, thereby ensuring that external water can enter the hollow support steel pipe pile to the maximum extent and reduce the adverse effects of water on the cutterhead detachment.

[0027] To ensure the water collection function of the dewatering well, the drilling depth of the supporting steel pipe piles is such that the bottom end face of the supporting steel pipe pile is at least 2m below the bottom of the cutterhead. In this embodiment, the bottom of the supporting steel pipe pile is 2.5m below the bottom of the cutterhead, with 50cm reserved for future expansion. Furthermore, the filter holes on the surface of the hollow steel pipe begin at the position corresponding to the top of the cutterhead and end at the bottom of the supporting steel pipe pile. This ensures that the filter holes effectively cover the entire corresponding area of ​​the cutterhead, thereby avoiding the adverse effects of water-rich strata on the shield tunneling. Water enters the pipe body through the array of filter holes on the surface of the hollow steel pipe, achieving water collection. Considering that the water contains impurities such as gravel and soil, which will settle and accumulate at the bottom of the hollow support steel pipe pile after entering the pile, thus affecting the effect of the dewatering well, in this embodiment, a filter screen is installed on the hollow steel pipe part of the support steel pipe pile corresponding to the filter holes, so as to achieve the effect of filtering impurities in the water. The filter screen is made of 60-mesh nylon cloth. In other embodiments, the filter screen is made of wire mesh or window screen.

[0028] In addition, each hollow support steel pipe pile is equipped with a water pump to pump the groundwater collected inside the pile to the surface, thereby preventing water from accumulating inside the pile and overflowing into the cutterhead area, which would affect the cutterhead detachment operation.

[0029] (2) Obtain the top elevation of the cutterhead and the corresponding ground elevation above the top of the cutterhead based on the current geological report of the tunnel boring machine. Drill hollow steel pipe piles concentrically to the corresponding position of the cutterhead at the existing isolation piles.

[0030] Because existing isolation piles may slide down after being cut by the cutterhead during excavation, causing positional interference between the cutterhead and the sliding pile head, resulting in cutterhead jamming. To solve the problem of interference from existing isolation piles to the cutterhead, in this embodiment, hollow steel pipe piles are drilled concentrically at each isolation pile location, thereby removing the isolation piles and resolving the jamming problem.

[0031] Specifically, firstly, based on the current tunneling mileage and location coordinates of the tunnel boring machine, the elevation of the top of the cutterhead and the corresponding ground elevation directly above the top of the cutterhead are determined. The difference between these two elevations is then used to determine the length of the existing isolation piles within the stratum, and based on this, the drilling depth for the casing steel pipe piles is determined. In this example, a rotary drilling rig is used to drill for the casing steel pipe piles. Considering that the isolation piles on both sides of the cutterhead have little or no obstruction effect on the cutterhead, the existing isolation piles above the cutterhead are removed in this example.

[0032] To prevent damage to the cutterhead upon contact with the rotary drilling rig, a 20cm gap is maintained between the bottom of the steel pipe pile and the top of the cutterhead in this example. In other embodiments, a gap of 20cm to 30cm is maintained between the bottom of the steel pipe pile and the top of the cutterhead. This ensures a safe distance between the rotary drilling rig bit and the cutterhead. The remaining portion of the existing isolation pile is manually removed after the tunnel boring machine (TBM) opens its chamber.

[0033] In addition, in this embodiment, considering the curvature of the cutterhead, in order to reduce the amount of measurement work, a safety distance of 20cm to 30cm is left between the bottom of each steel pipe pile and the horizontal plane where the top of the cutterhead is located. That is, the top of the cutterhead is used as the judgment base point, thereby avoiding the introduction of too much measurement and calculation process due to the curvature of the cutterhead, and at the same time avoiding the impact of measurement and calculation errors on safe construction.

[0034] In this embodiment, hollow steel pipe piles are used for the casing steel pipe piles. Thus, on the one hand, the existing isolation piles concentric with the pile body are removed by drilling the casing steel pipe piles; on the other hand, since the existing isolation piles and part of the soil are removed by the rotary drilling of the casing steel pipe piles, the pressure on the isolation piles and soil layers above the cutterhead is reduced. This avoids the risk of the cutterhead getting stuck due to the large soil pressure from above on the water-rich, large-diameter boulder strata with poor self-stability. This achieves the effect of decompression of the cutterhead and is conducive to the shield machine getting out of trouble.

[0035] (3) The shield machine is opened under normal pressure, and large-diameter boulders are manually removed from the chamber and between the support steel pipe piles and the cutterhead panel.

[0036] After the hollow support steel pipe piles in front of the cutterhead, which also serve as dewatering wells, and the hollow casing steel pipe piles above the cutterhead are completed, the shield machine will be opened under normal pressure. Large-diameter boulders will be removed from the shield machine's soil chamber and between the cutterhead panel and the support steel pipe piles using tools such as pneumatic picks and shovels, with manual assistance. Existing isolation piles remaining above the cutterhead will also be broken up, thus resolving the problem of large-diameter boulders and existing isolation piles obstructing the cutterhead.

[0037] (4) Start the tunnel boring machine and confirm that the cutterhead is rotating normally. Remove each set of steel pipe piles and each support steel pipe pile in sequence at the ground. The tunnel boring machine is freed from its predicament.

[0038] After clearing the large-diameter boulders in front of the cutterhead and the existing isolation piles above it, the tunnel boring machine (TBM) is started to confirm whether the cutterhead is rotating normally, thus determining whether the cutterhead is freed from its entrapment. Once the cutterhead is freed, vibratory hammers and hydraulic jacks are used to remove the various casing steel pipe piles and support steel pipe piles at the ground level, with clay backfilling along the removal edges. After all steel pipe piles have been removed, the TBM begins tunneling, thus completing the cutterhead freeing operation in the water-rich, large-diameter boulder strata.

[0039] Although some preferred embodiments of this invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0040] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of its inventive concept. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for cutterhead detachment during shield tunneling through large-diameter boulder strata, characterized in that, Includes the following steps: (1) A row of hollow support steel pipe piles is drilled at least 20cm in front of the trapped cutterhead; the bottom wall of the support steel pipe piles is provided with a number of filter holes. (2) Obtain the top elevation of the cutterhead and the corresponding ground elevation above the top of the cutterhead based on the current geological report of the tunnel boring machine. Drill hollow steel pipe piles concentrically to the corresponding position of the cutterhead at the existing isolation piles. (3) The shield machine is opened under normal pressure, and large-diameter boulders in the chamber and between the support steel pipe piles and the cutterhead panel are manually removed; (4) Start the tunnel boring machine and confirm that the cutterhead is rotating normally. Remove each set of steel pipe piles and each support steel pipe pile in sequence at the ground. The tunnel boring machine is freed from its predicament.

2. The method for freeing the cutterhead from obstruction according to claim 1, characterized in that, In step (1), the bottom end face of the support steel pipe pile is at least 2m lower than the bottom of the cutterhead, and the range of the filter holes begins at the position corresponding to the top of the cutterhead of the support steel pipe pile and ends at the bottom of the support steel pipe pile.

3. The method for freeing the cutter head from obstruction according to claim 2, characterized in that, In step (1), the supporting steel pipe pile is provided with a filter screen within the range of the filter holes.

4. The method for freeing the cutterhead from obstruction according to claim 1, characterized in that, In step (1), water pumps for drawing water to the ground are installed at the bottom of each support steel pipe pile.

5. The method for unblocking the cutterhead according to claim 1, characterized in that, In step (2), a distance of 20cm to 30cm is left between the bottom of the steel pipe pile and the cutter head.

6. The method for freeing the cutterhead from obstruction according to claim 5, characterized in that, In step (3), after the chamber is opened, the remaining isolation pile between the bottom of the steel pipe pile and the cutterhead is broken by manual labor in the soil chamber.

7. The method for freeing the cutterhead from obstruction according to claim 1, characterized in that, In step (4), a vibratory hammer and a hydraulic jack are used to remove the casing steel pipe pile and the support steel pipe pile in sequence, while clay backfilling is carried out at the same time.

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