Double-shield TBM (Tunnel Boring Machine) starting cavern arc-shaped gripper shoe concrete foundation and construction method

Abstract

The invention provides a double-shield TBM starting cavern arc-shaped supporting shoe concrete foundation and a construction method. The double-shield TBM starting cavern arc-shaped supporting shoe concrete foundation comprises a starting cavern and an arc-shaped concrete foundation body. The width or the diameter of the cross section of the starting cavern is larger than the effective diameter of a supporting shoe of the supporting shield. The arc-shaped concrete foundations are arranged on the two side walls of a starting cavern, and the inner arc faces of the arc-shaped concrete foundations form arc-shaped supporting faces which are matched with the effective diameter of a supporting shoe of a supporting shield and the direction where the supporting shoe is located. The scheme has the advantages that the arc-shaped concrete foundations are arranged on the two sides of the wall of the starting cavern to provide effective support for the TBM supporting shoe, and smooth starting of the TBM is guaranteed.

Description

Technical Field

[0001] The invention relates to the field of tunnel launch hole construction, and in particular to a double-shield TBM launch cavern arc-shaped support shoe concrete foundation and a construction method. Background Art

[0002] In recent years, full-face TBM tunnel boring machines have played a pivotal role in underground engineering excavation. Full-face TBMs can be divided into three types according to their support forms: open-type, single-shield and double-shield. Open-type TBMs are generally suitable for excavation construction in hard rock formations; single-shield TBMs are often used for construction in soft rock formations and unstable formations with high groundwater levels; double-shield TBMs, also known as telescopic shield TBMs, have strong excavation construction in hard and soft rock formations and are widely used in tunnel construction. They can also effectively ensure the safety and efficiency of construction when there are many mountain faults and complex geology.

[0003] Among them, the double shield TBM can integrate tunnel excavation, soil transportation, and lining grouting in the field of tunnel construction, realize one-time hole formation, efficiently utilize tunnel space, and achieve the goal of safe, efficient, and fast construction operations. Under specific geological conditions, the double shield TBM can effectively solve the problems of rock instability and water inflow, and its structural form and characteristics are superior to other types of tunnel boring machines, so it is favored by more and more construction units.

[0004] The TBM launch chamber is generally constructed by manual drilling and blasting, and its net internal space size must be larger than the diameter of the TBM shield. TBM launch is an indispensable key link in tunnel construction. The net cross-sectional size of the launch chamber after construction determines whether the TBM launch can be successfully implemented. Since the launch chamber has a gate-shaped cross-section and the TBM support shield has a circular cross-section, the support boots cannot reach the wall of the launch chamber after being extended, providing sufficient reaction force for the TBM launch, which makes it difficult to meet the TBM launch requirements and ensure its safe and smooth launch.

[0005] As far as the existing technology is concerned, there is no safe, efficient and convenient method to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to address the deficiencies in the prior art and thereby provide a double-shield TBM starting cavern arc-shaped concrete foundation and construction method, which are arranged on both sides of the starting cavern wall to provide effective support for TBM support shoes and ensure the smooth start of the TBM.

[0007] In order to achieve the above-mentioned object, the technical solution adopted by the present invention is: a double shield TBM starting cavern arc-shaped support shoe concrete foundation, comprising a starting cavern and an arc-shaped concrete foundation; The cross-sectional width or diameter of the starting cavern is greater than the effective diameter of the support shield shoe; The arc-shaped concrete foundation is arranged on the two side walls of the starting cavern, and the inner arc surface of the arc-shaped concrete foundation forms an arc-shaped supporting surface, which is adapted to the effective diameter of the support shoe of the support shield and the position of the support shoe.

[0008] Preferably, the starting hole is a gate-shaped cross-section.

[0009] Preferably, the arc-shaped concrete foundation includes a skeleton system consisting of a steel mesh, anchor steel bars and an arc-shaped steel plate, and concrete integrally cast based on the skeleton system.

[0010] A double shield TBM starting cavern arc support shoe concrete construction method comprises the following steps: Step 1) Construction of the starting cavern floor cushion: Clean the bottom plate of the starting cavern to expose the original rock. According to the design drawing elevation, measure and place points for the thickness of the bottom plate concrete. Mark the elevation of the concrete surface on both sides of the cave wall to make the slope of the bottom plate cushion layer fit the design slope. Pour concrete into the bottom plate cushion layer to the design thickness. Step 2) Measurement, positioning and installation of curved concrete foundation anchor steel bars: Use steel pipes to build a working platform, and measure and place anchor steel bars of the arc-shaped concrete foundation on the cave walls on both sides of the starting cave according to the design drawings. The anchor steel bars are set perpendicular to the cave walls and exposed to a set length. Step 3) Installation of steel mesh: After the anchor steel bars are installed, lay the steel mesh, the installation position should be ≥12cm away from the concrete surface, weld the steel mesh and anchor steel bars, and fix the overlapped area of ​​the steel mesh by tying and spot welding; Step 4) Template processing and installation: The template includes a top template, a bottom template and a side template. The top template and the bottom template are made of wood, and the side template is made of steel. The steel template is in an arc shape as a whole. According to the design drawings, the template installation position is measured on both sides of the starting cavern wall. The side template needs to be installed perpendicular to the longitudinal axis of the starting cavern and welded to the anchor steel bar for reinforcement. The bottom template and top template are installed after the side template is installed. After the installation, the reinforcement is installed. After the size is checked, proceed to the next step. Step 5) Spray anchor construction: Steel fiber concrete is used as the anchor material, and the anchor construction is carried out by using a concrete spraying machine. The spraying concrete is carried out from bottom to top according to the principle of segmentation, slices and layers. The spraying angle is always kept vertical to the sprayed surface. The thickness of a single spraying is controlled below 5cm, and the length of each segment does not exceed 6m. Step 6) Concrete finishing, grinding and curing: After the shotcrete construction is completed, before the concrete begins to set, the inner arc surface of the concrete foundation is ground and finished in sections. After the concrete is poured, it is watered and maintained according to the design requirements. After the set time and indicators, the bottom and top wooden formworks are removed to complete the construction.

[0011] Preferably, in step 2), the anchoring steel bar points in the same longitudinal direction remain parallel to the longitudinal axis of the tunnel; and the same vertical anchoring steel bar points remain perpendicular to the longitudinal axis of the tunnel.

[0012] Preferably, in step 3), the overlap length of the steel mesh is set according to 1-2 grids, and the connections between the steel meshes, the connections between the steel meshes and the anchoring steel bars, and the connections between the steel meshes and the steel nails are all fixed by welding.

[0013] Preferably, in step 4), the top template and the bottom template form acute angles with the transverse axis of the tunnel respectively.

[0014] Preferably, the net width of the starting tunnel is ≥5980 mm, with a gate-shaped cross-section, and the cross-section of the support shield is circular with a diameter ≥5230 mm.

[0015] Preferably, the inner arc radius of the side template is ≥2715mm.

[0016] Preferably, the side formwork comprises a plurality of horizontally spliced ​​steel formworks, and the number of the top formwork and the bottom formwork is at least two.

[0017] Compared with the prior art, the present invention has outstanding substantial features and significant progress. Specifically, the present invention is mainly used to solve the TBM starting problem. Since the starting cavern is usually a gate-shaped cross-section, while the cross-section of the support shield is circular, and since the net width of the starting cavern is larger than the diameter of the support shield, the TBM support boots cannot touch the walls on both sides of the starting cavern after being extended, resulting in a poor starting of the TBM. The present application constructs an arc-shaped concrete foundation on the walls on both sides of the TBM starting cavern, so that the double-shield TBM support boots can better support the cavern walls after being extended, thereby avoiding the phenomenon of poor starting of the TBM due to insufficient starting thrust.

[0018] The arc-shaped concrete foundation is constructed by hanging mesh spray anchor. The entire arc surface can be manufactured on-site according to demand, so that it can better fit the outer diameter of the TBM support shield. After the TBM support shoe is extended, it can fit the arc section tightly.

[0019] This method is universal and can be applied to the starting support problems of various TBM starting tunnels, which is conducive to its promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the concrete foundation of the arc-shaped support shoe of the launching cavern of the double-shield TBM in the present invention.

[0021] Figure 2 It is a longitudinal cross-sectional view of the concrete foundation of the arc-shaped support shoe of the starting cavern of the double-shield TBM in the present invention.

[0022] Figure 3 It is a schematic diagram of the concrete foundation of the arc-shaped support shoe of the starting cavern of the double-shield TBM in the present invention.

[0023] Figure 4 This is an angle diagram of the curved support shoe concrete foundation of the double shield TBM starting cavern.

[0024] Figure 5 This is the steel mesh diagram of the concrete foundation of the curved support shoe of the starting cavern of the double shield TBM.

[0025] Figure 6 It is one of the on-site schematic diagrams of the arc-shaped support shoe concrete method for the launching cavern of a double-shield TBM.

[0026] Figure 7 This is the second on-site construction drawing of the arc-shaped support shoe concrete method for the starting cavern of the double-shield TBM.

[0027] In the figure: 1. Launch chamber; 2. Concrete foundation; 3. Support shield; 4. Support boots. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described in detail below through specific implementation methods.

[0029] like Figure 1-Figure 5 As shown, a double-shield TBM starting cavern arc-shaped support shoe concrete foundation includes a starting cavern 1 and an arc-shaped concrete foundation 2.

[0030] The cross-sectional width or diameter of the starting cavern is larger than the effective diameter of the support shield's support shoe. In the present embodiment, the cross-sectional shape of the starting cavern is gate-shaped with a net width of 5980 mm, while the support shield 3 has a circular cross-sectional shape with a diameter of 5320 mm. This results in the TBM support shoe 4 being unable to touch the side wall of the starting cavern after being extended when the support shield is launched using the support shoe, and thus unable to provide additional reaction force for the TBM launch. Therefore, an arc-shaped concrete foundation is added in the present embodiment to solve this problem.

[0031] The arc-shaped concrete foundation 2 is arranged on the two side walls of the starting cavern 1, and the inner arc surface of the arc-shaped concrete foundation 2 forms an arc-shaped supporting surface, which is compatible with the effective diameter of the support shoe of the support shield and the orientation of the support shoe. Specifically, in this embodiment, the arc-shaped concrete foundation 2 includes a skeleton system composed of a steel mesh, anchor steel bars and an arc-shaped steel plate, and a concrete structure integrally cast based on the skeleton system. The specific construction process is described by the following construction method.

[0032] like Figure 1-Figure 7As shown, a double-shield TBM starting cavern arc-shaped support shoe concrete construction method, in this embodiment, the materials used for construction are mainly φ25mm steel bars, C30 sprayed anchor concrete, φ6mm steel mesh, 6mm thick arc-shaped steel plates, 15mm thick wooden formwork, 10cm×5cm square wood, φ48×3.5mm rack pipes and top supports.

[0033] Implement it by following these steps: Step 1) Construction of the starting cavern floor cushion: In this embodiment, the TBM starting cavern is 10m long. Before the support shoe concrete construction, the bottom plate construction should be carried out first, and the accumulated water, slag, etc. in the bottom plate casting area should be cleaned until the original appearance of the rock is exposed. According to the elevation requirements of the design drawings, the thickness of the bottom plate concrete is measured and placed, and the elevation of the bottom plate concrete surface is marked on both sides of the cave wall to make the slope of the bottom plate cushion layer fit the design slope. Finally, C30 concrete can be used to cast the bottom plate cushion layer with a casting thickness of 10cm.

[0034] Step 2) Measurement, positioning and installation of curved concrete foundation anchor steel bars: Use φ48×3.5mm steel pipes to build the working platform to ensure that the connections between the steel pipes are tight. Then, according to the design drawings, measure and place the anchor steel bars of the support shoe concrete foundation on the walls on both sides of the starting cavern. The axial spacing along the tunnel is 1.5m, and the circumferential spacing is 580mm, 580mm, 580mm, and 550mm from top to bottom. The anchor steel bars are φ25mm threaded steel bars, each 1m long. The anchor steel bars are installed perpendicular to the cavern wall, and the exposed length is preferably 20 to 30cm. The anchor steel bar points in the same longitudinal direction should be parallel to the longitudinal axis of the tunnel; the same vertical anchor steel bar points should be perpendicular to the longitudinal axis of the tunnel.

[0035] Step 3) Installation of steel mesh: After the anchoring steel bar is installed, the φ6mm steel mesh can be laid. The installation position is 12cm away from the concrete surface. The steel mesh and the anchoring steel bar are welded and fixed to prevent the mesh from deformation or displacement during the spraying process. The concrete foundation of the starting cavern support shoe adopts a single-layer mesh spraying concrete protection surface. The φ6mm steel mesh is tied and woven according to 200×200. The nodes are tied firmly with wire. The steel mesh is woven in sections. The overlap length of the sections shall not be less than 300mm. The overlap is tied with wire twice and then spot welded. The binding and welding length of the steel bars are strictly constructed according to the design and specifications.

[0036] Among them, the steel bar must be tested and qualified before use, and it must be rust-free before use. It is made in pieces outside the hole, and the overlap length is 1 to 2 meshes during installation. When laying the steel mesh, it must be installed straight, and the connection between the steel mesh and the steel mesh, and the connection between the steel mesh and the steel nails are welded together to prevent the steel mesh from shaking during spraying.

[0037] Step 4) Template processing and installation: The templates are divided into top templates, bottom templates, and side templates. The top and bottom templates are made of 1.5cm thick wooden templates, both 10m long, and 287mm and 536mm wide respectively. The side template steel template has an arc-shaped section and is processed with a 10mm thick steel plate. The inner arc radius is 2715mm. The outer side of the steel template is cut according to the actual shape of the cave wall on site to facilitate the steel template to better fit the cave wall. According to the requirements of the design drawings, 2 top and bottom templates are processed and manufactured respectively, and 10 arc-shaped steel templates are processed and manufactured.

[0038] According to the requirements of the design drawings, the template installation position is measured on the cave walls on both sides of the starting cavern. The lateral steel template is installed every 3.3m, and a total of 5 templates are installed on one side, and the left and right sides are supported. When installing the side template, it must be perpendicular to the longitudinal axis of the starting cavern, and welded and reinforced with anchor steel bars to prevent the template from deformation or displacement during the spraying process. The template and top template are installed after the side template is installed. During installation, it should be noted that the template angle should be consistent with the design drawings. After the installation is completed, the support is installed at the bottom of the bottom template to prevent the template from running; after the top template is installed, the tie bars are installed to prevent deformation during the spraying of concrete.

[0039] After the template is installed, the measurement engineer will check the diameter of the curved side of the side template to see if it meets the technical requirement of 2.715m. After confirmation, the template will be reinforced again and the edge will be sealed. After the size check is completed, proceed to the next step.

[0040] Among them, the steel mold is processed and manufactured strictly according to the design drawings, and the steel is corrected before cutting to ensure its processing accuracy; the radius of the inner arc of the steel mold is controlled to 2715mm, so as to better fit the arc surface of the TBM support shield; the steel mold should be kept perpendicular to the longitudinal axis of the tunnel during installation, and the top and bottom wooden molds should be at an angle of 29° and 23° to the transverse axis of the tunnel respectively according to the requirements of the drawings. At the same time, all templates are reinforced to prevent displacement or deformation of the template during the spraying process.

[0041] Step 5) Spray anchor construction: After the concrete spraying machine is installed and debugged, install a vibrating screen on the hopper to prevent oversized aggregate from entering the spraying machine. Use high-pressure water to wash the base surface. If there is a part that cannot be washed with water, use high-pressure wind to clean the rock surface. Bury the spraying layer thickness mark nails to check whether the spraying machine is working normally. A spraying test is required before formal construction. Concrete spraying can be carried out after everything is normal.

[0042] Use C30 steel fiber concrete as the spray anchor material. Turn on the metering pump before spraying concrete. After starting, pay attention to the wind pressure. The initial wind pressure reaches 0.5MPa before starting the operation, and adjust the wind pressure according to the nozzle discharge situation. General working wind pressure: 0.2Mpa. If the wind pressure is too small, the coarse aggregate will not be able to enter the mortar layer and fall off. Excessive wind pressure will increase the rebound amount. It can be controlled according to the size of the concrete rebound and the strength of the surface wet and easy to adhere. The spray pressure is adjusted in time according to the information fed back by the spray instrument.

[0043] The spraying of concrete should be carried out in sections, slices and layers from bottom to top. The nozzle should be basically vertical to the sprayed surface and the distance should be kept at 0.6 to 1.8 meters. The thickness of one spraying should be controlled below 5 cm and the length of each section should not exceed 6 meters.

[0044] During the spraying operation, loose materials such as floating soil and rebound objects on the sprayed surface should be carefully removed and blown clean with high-pressure air. The wind pressure and water pressure of the sprayer should be adjusted to prevent the concrete joints from being unsolid. The sprayed concrete should cover all the steel bars, and there should be no dry spots or slippage in the sprayed layer.

[0045] Step 6) Concrete finishing, grinding and curing: After the anchoring is completed, before the initial setting of the concrete, 3.5m long 10#C steel is used to grind and finish the inner arc surface of the arc steel formwork in sections. It is strictly forbidden to hit the formwork with gravity when finishing. After the concrete is poured, it is timely sprinkled with water for maintenance. The bottom wooden formwork can be removed only after the strength is guaranteed to be non-deformed and non-settled.

[0046] This scheme was tested in the Polihali Water Tunnel (PTT) project in Lesotho. The tunnel is about 38 km long and transports water from the Polihali Dam to the Katse Reservoir. The total length of TBM excavation is 34 km, and two double-shield TBMs are used to excavate in opposite directions, with a single unit excavating 17 km. The net width of the starting cavern is 5980 mm, which is a gate-shaped section; the support shield section is circular with a diameter of 5230 mm. Since the net width of the starting cavern is larger than the diameter of the TBM support shield, the support boots cannot touch the cavern wall after being extended, providing sufficient thrust for the TBM to start. Therefore, this method is used to construct an arc-shaped concrete foundation on the cavern walls on both sides of the starting cavern so that the support boots can have a good force-bearing surface after being extended. The present invention does not require too much construction resources, is simple and convenient to manufacture, and has a high degree of fit with the TBM support boots.

[0047] Finally, it should be noted that: The above describes in detail the preferred implementation of this patent, but this patent is not limited to the above implementation. Various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of this patent.

Claims

1. A double shield TBM starting cavern arc-shaped support shoe concrete foundation, characterized by: Includes launch chamber and curved concrete foundation; The cross-sectional width or diameter of the starting cavern is greater than the effective diameter of the support shield shoe; The arc-shaped concrete foundation is arranged on the two side walls of the starting cavern, and the inner arc surface of the arc-shaped concrete foundation forms an arc-shaped supporting surface, which is adapted to the effective diameter of the support shoe of the support shield and the position of the support shoe.

2. The double shield TBM launching chamber arc-shaped support shoe concrete foundation according to claim 1 is characterized in that: The starting tunnel is a gate-shaped section.

3. The double shield TBM launching chamber arc-shaped support shoe concrete foundation according to claim 1 is characterized in that: The arc-shaped concrete foundation includes a skeleton system consisting of a steel mesh, anchor steel bars and an arc-shaped steel plate, and concrete integrally cast based on the skeleton system.

4. A double shield TBM starting cavern arc support shoe concrete construction method, characterized in that: The following steps are involved: Step 1) Construction of the starting cavern floor cushion: Clean the bottom plate of the starting cavern to expose the original rock. According to the design drawing elevation, measure and place points for the thickness of the bottom plate concrete. Mark the elevation of the concrete surface on both sides of the cave wall to make the slope of the bottom plate cushion layer fit the design slope. Pour concrete into the bottom plate cushion layer to the design thickness. Step 2) Measurement, positioning and installation of curved concrete foundation anchor steel bars: Use steel pipes to build a working platform, and measure and place anchor steel bars of the arc-shaped concrete foundation on the cave walls on both sides of the starting cave according to the design drawings. The anchor steel bars are set perpendicular to the cave walls and exposed to a set length. Step 3) Installation of steel mesh: After the anchor steel bars are installed, lay the steel mesh, the installation position should be ≥12cm away from the concrete surface, weld the steel mesh and anchor steel bars, and fix the overlapped area of ​​the steel mesh by tying and spot welding; Step 4) Template processing and installation: The template includes a top template, a bottom template and a side template. The top template and the bottom template are made of wood, and the side template is made of steel. The steel template is in an arc shape as a whole. According to the design drawings, the template installation position is measured on both sides of the starting cavern wall. The side template needs to be installed perpendicular to the longitudinal axis of the starting cavern and welded to the anchor steel bar for reinforcement. The bottom template and top template are installed after the side template is installed. After the installation, the reinforcement is installed. After the size is checked, proceed to the next step. Step 5) Spray anchor construction: Steel fiber concrete is used as the anchor material, and the anchor construction is carried out by using a concrete spraying machine. The spraying concrete is carried out from bottom to top according to the principle of segmentation, slices and layers. The spraying angle is always kept vertical to the sprayed surface. The thickness of a single spraying is controlled below 5cm, and the length of each segment does not exceed 6m. Step 6) Concrete finishing, grinding and curing: After the shotcrete construction is completed, before the concrete begins to set, the inner arc surface of the concrete foundation is ground and finished in sections. After the concrete is poured, it is watered and maintained according to the design requirements. After the set time and indicators, the bottom and top wooden formworks are removed to complete the construction.

5. The method for constructing double shield TBM starting cavern arc-shaped support shoe concrete according to claim 4 is characterized in that: In step 2), the anchor steel bar points in the same longitudinal direction remain parallel to the longitudinal axis of the tunnel; the same vertical anchor steel bar points remain perpendicular to the longitudinal axis of the tunnel.

6. The method for constructing double shield TBM starting cavern arc-shaped support shoe concrete according to claim 4, characterized in that: In step 3), the overlap length of the steel mesh is set according to 1-2 grids, and the connections between the steel meshes, the steel meshes and the anchor steel bars, and the steel meshes and the steel nails are all fixed by welding.

7. The method for constructing double shield TBM starting cavern arc-shaped support shoe concrete according to claim 4, characterized in that: In step 4), the top formwork and the bottom formwork are respectively formed at acute angles with the transverse axis of the tunnel.

8. The method for constructing double shield TBM starting cavern arc-shaped support shoe concrete according to claim 4, characterized in that: The net width of the starting tunnel is ≥5980mm, with a gate-shaped cross-section; the support shield cross-section is circular with a diameter ≥5230mm.

9. The method for constructing double shield TBM starting cavern arc-shaped support shoe concrete according to claim 4, characterized in that: The inner arc radius of the side template is ≥2715mm.

10. The method for constructing double shield TBM starting cavern arc-shaped support shoe concrete according to claim 4, characterized in that: The side formwork comprises a plurality of horizontally spliced ​​steel formworks, and the number of the top formwork and the bottom formwork is at least two.

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