A TBM tail structure for preventing deformation of a pipe segment

Abstract

A TBM tail structure for preventing segment deformation, comprising a tail shell, an original steel plate bundle assembly, prefabricated concrete pads and at least two additional steel plate bundle assemblies; an arc-shaped groove is formed in the lower part of the tail shell, and prefabricated concrete pads are arranged at the four corners of the arc-shaped groove to realize front vertical support of the bottom of the segment; the additional steel plate bundles are arranged along the axial direction of the tail shell at intervals and avoid the arc-shaped groove, each additional steel plate bundle is assembled by a positioning block, a fixed bottom plate, a steel plate bundle, a pressing plate and a countersunk screw; the positioning block is higher than the pressing plate to form a protection structure, and the top surface of the countersunk screw is not higher than the pressing plate to avoid scratching the segment. The present application solves the problems of segment falling, elliptical deformation and faulting of large-diameter TBM in soft and broken water-rich strata through bottom slot support and multi-channel steel plate bundle assembly structure, without the need for custom-made special segments, and has strong structural versatility, high forming control precision and is suitable for large-diameter double shield TBM long tunnel projects.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering and underground construction equipment technology, and in particular to a TBM tail structure for preventing segment deformation. Background Technology

[0002] The double-shield TBM has advantages such as strong adaptability to geological formations, simultaneous construction of tunneling and segment lining, and high overall construction efficiency. It is now widely used in long tunnel projects such as inter-basin water transfer, railways, highways, and urban underground spaces.

[0003] Existing large-diameter double-shield TBMs generally employ a closed cylindrical shell with a single steel plate bundle sealing structure at the shield tail. The original steel plate bundles can only prevent the leakage of gravel behind the shield wall and do not provide circumferential restraint for the tunnel segments. Due to the large weight of the tunnel segments and the heavy load from the surrounding rock, the slope at the lower 5-7 points of the shield tail is gentle, and the suspended section is long. Gravel filling and grouting are severely delayed, leaving the tunnel segments unrestrained the moment they exit the shield tail. This makes them highly susceptible to sagging, misalignment, elliptic deformation, and cracking, seriously affecting the forming quality and structural durability.

[0004] To address the aforementioned issues of segment sagging, misalignment, and elliptic deformation, small-diameter (3-7m) TBMs have adopted a scheme combining small slots at the bottom of the shield tail with precast segments and outriggers: two narrow slots are cut at the bottom of the shield tail, and precast concrete outriggers are installed at the bottom of the segments, allowing them to directly support the rock surface after exiting the shield tail. This scheme can, to some extent, suppress segment instability and deformation.

[0005] However, this scheme has significant drawbacks: First, it cannot withstand the self-weight of large-diameter tunnel segments with an excavation diameter of over 9m and the pressure of the surrounding rock, and problems such as segment sagging, misalignment, and elliptic deformation remain prominent; Second, it requires specially customized tunnel segments with concrete legs, resulting in high manufacturing costs for the matching molds, poor equipment versatility, and complex on-site construction organization, making it difficult to promote on a large scale; Third, it still uses a single-channel steel plate bundle sealing structure. only It acts as a buffer against gravel, but lacks circumferential flexible constraint capabilities, cannot limit the radial deformation of the tunnel segments, and has almost no control over sag, misalignment, or elliptic deformation.

[0006] In summary, existing shield tail structures cannot meet the high-precision forming requirements of tunnel segments in large-diameter, soft, fractured, and water-rich strata. The market urgently needs a new type of TBM shield tail structure to solve the above problems. Summary of the Invention

[0007] In order to solve the above-mentioned technical problems, the present invention provides a TBM shield tail structure for preventing segment deformation. This structure can overcome the defects of insufficient shield tail constraint, easy elliptic deformation of large-diameter segments, high cost of special support leg segments, and lack of deformation constraint capability of traditional steel plate bundles.

[0008] To achieve the above objectives, the present invention provides a TBM tail structure for preventing segment deformation, comprising a tail shell and an existing steel plate bundle assembly, wherein the existing steel plate bundle assembly is located at the end of the tail shell.

[0009] It also includes precast concrete spacers and at least two additional steel plate bundle assemblies;

[0010] The lower part of the shield tail shell is provided with an arc-shaped groove, and the precast concrete pads are respectively set at the four corners of the arc-shaped groove;

[0011] At least two additional steel plate bundle assemblies are axially spaced on the inner wall of the tail shield shell, and avoid the arc-shaped groove;

[0012] Each newly added steel plate bundle assembly includes a positioning block, a fixing base plate, a steel plate bundle, a pressure plate, and countersunk screws. The positioning block is welded and fixed to the inner wall of the shield tail shell. The fixing base plate is positioned and welded to the inner wall of the shield tail shell based on the positioning block. The steel plate bundle is installed on the fixing base plate by the pressure plate and countersunk screws. The top surface of the countersunk screw is not higher than the top surface of the pressure plate, and the top surface of the positioning block is not lower than the top surface of the pressure plate.

[0013] As a further improvement of the present invention, the circumferential central angle of the arc-shaped groove is 15° to 30°, the circumferential arc length is 1.5m to 2.5m, and the axial length is 1.5m to 2.5m.

[0014] As a further improvement of the present invention, the precast concrete pad has a length of 200mm to 300mm, a width of 150mm to 250mm, and a height of 70mm to 120mm.

[0015] As a further improvement of the present invention, the axial spacing between two adjacent newly added steel plate bundle assemblies is 200mm to 300mm; the axial spacing between the original steel plate bundle assembly and the adjacent newly added steel plate bundle assembly is 200mm to 300mm; the newly added steel plate bundle assembly covers a range of 200° to 280° circumferentially along the inner sidewall of the shield tail shell.

[0016] As a further improvement of the present invention, the steel plate bundle is composed of at least 4 layers of spring steel plates stacked in a staggered manner, and the dimensions of a single spring steel plate are 150mm to 200mm in length, 80mm to 120mm in width, and 0.8mm to 1.2mm in thickness.

[0017] As a further improvement of the present invention, the positioning block is made of Q690 high-strength steel plate, with a width of 30mm to 50mm and a height of 18mm to 24mm. The gap between the positioning block and the segment during subsequent construction is 20mm to 30mm, and it is at least 1mm higher than the top surface of the pressure plate.

[0018] As a further improvement of the present invention, the fixed base plate is made of Q355B steel plate, with a width of 20mm to 40mm and a height of 7mm to 15mm.

[0019] As a further improvement of the present invention, the circumferential central angle of the arc-shaped groove is 22°, the circumferential arc length is 1.7m, and the axial length is 2m; the precast concrete pad is 250mm long, 200mm wide, and the height is adjustable from 70mm to 120mm; the axial spacing between two adjacent newly added steel plate bundle assemblies is 250mm, the axial spacing between the newly added steel plate bundle assembly and the original steel plate bundle assembly is 250mm, and the newly added steel plate bundle assembly covers a 240° range along the inner sidewall of the shield tail shell; the steel plate bundle is composed of four layers of spring steel plates stacked in staggered layers, with each spring steel plate being 180mm long, 100mm wide, and 1mm thick; the positioning block is a Q690 high-strength steel plate, 40mm wide and 20mm high, the reserved gap between the positioning block and the segments during subsequent construction is 24.5mm, and the top surface of the positioning block is 5mm higher than the top surface of the pressure plate; the fixed base plate is a Q355B steel plate, 30mm wide and 10mm high.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. Solve the common problem of large-diameter tunnel segment sagging.

[0022] This invention features an arc-shaped groove at the bottom of the shield tail and four precast concrete pads at the corners, which forms vertical support at the bottom before assembling the tunnel segments. This eliminates the long suspended sections of the tunnel segments caused by the traditional closed shield tail, improves the filling density, and addresses the problems of segment drop and misalignment at the 5-7 point positions, significantly improving the tunnel forming quality.

[0023] 2. A pioneering dual-track replaceable steel plate bundle constraint system, achieving significant elliptic deformation control.

[0024] Compared to the traditional single-channel steel plate bundle that only has the function of material blocking, the present invention adds at least two new steel plate bundle components. The multiple steel plate bundle components form a continuous and adaptive circumferential flexible constraint system, which can uniformly absorb the deformation of the surrounding rock, limit the radial expansion of the tunnel segments, stably control the elliptical deformation of the tunnel segments within 3‰, and control the maximum misalignment between the rings within 5mm, thus meeting the high-precision forming specifications for large-diameter tunnels.

[0025] 3. High versatility, significantly reducing overall project costs.

[0026] This invention eliminates the need for custom-made special tunnel segments with concrete supports; existing standard universal tunnel segments can be used directly, saving the design and production costs of special tunnel segment molds and shortening the construction preparation cycle. The structural parameter range covers a variety of working conditions and can be adapted to double-shield TBMs with an excavation diameter of not less than 9m. It is especially suitable for various soft, broken, water-rich, high-stress long tunnels, and has strong versatility, low cost, and wide applicability.

[0027] 4. Built-in protective structure extends the service life of the steel plate bundle.

[0028] This invention features a positioning block that extends above the pressure plate to form a protective step. During the TBM step change process, the tunnel segment only contacts the positioning block and will not directly rub against the pressure plate and spring steel plate, thus preventing the pressure plate from falling off and the steel plate bundle from wearing out. The countersunk screws have their top surfaces lower than the pressure plate, preventing the screws from scratching the outer arc surface of the tunnel segment and reducing tunnel segment damage and rework.

[0029] 5. It can be disassembled and maintained inside the tunnel without affecting tunneling efficiency.

[0030] The overall structure can be modified and constructed inside the tunnel while the machine is stopped, with a short modification cycle. When the spring steel plate is worn or damaged, the steel plate bundle can be exposed by pushing the auxiliary thrust cylinder to the specified stroke. The countersunk screws and pressure plates can be directly disassembled to replace a single steel plate. There is no need to disassemble the entire TBM and carry out a large amount of planing and welding work. The normal tunneling rhythm is not interrupted, the construction efficiency is high, and the long-term operation and maintenance costs are lower.

[0031] 6. Improve the overall durability of the tunnel and reduce the risk of leakage.

[0032] Under the constraint of this structure, the segments are subjected to uniform stress, have small misalignment, and have tight joint sealing, which can effectively reduce the risk of later leakage, cracking, and structural damage, extend the overall service life of the tunnel, and have outstanding economic, social and environmental benefits. Attached Figure Description

[0033] Figure 1 This is a schematic elevation view of the shield tail structure described in this invention;

[0034] Figure 2 for Figure 1 Schematic diagram of the AA section;

[0035] Figure 3 Schematic diagram of the newly added steel plate bundle assembly;

[0036] Marking description: 1. Shield tail shell, 2. Arc groove, 3. Pad block, 4. Existing steel plate bundle assembly, 5. Newly added steel plate bundle assembly, 51. Positioning block, 52. Fixed base plate, 53. Steel plate bundle, 54. Pressure plate, 55. Countersunk screw. Detailed Implementation

[0037] The present invention will be further described below with reference to specific embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0038] The tunnel in a certain section of the Guangdong Water Resources Allocation Project in the Beibu Gulf is 10.021km long, with a maximum burial depth of 186m and an excavation diameter of Φ9.23m. It is constructed using a double-shield TBM. The strata are mainly metamorphic sandstone, microschist, and migmatite, traversing 8 small faults and 2 large faults. The faults are fractured, poorly cemented, and prone to water inrush and collapse. The starting section is a 472m long, 600m radius small curve with Class V soft rock.

[0039] During the initial tunneling phase, it was observed that the bottom 6 o'clock position of the tunnel lining segments did not show significant sagging. However, during TBM step changes, the shield tail swayed by 25 mm, causing frequent hard scraping between the shield and the tunnel lining segments. In severe cases, this resulted in cracks and damage to the outer arc surface of the segments. Simultaneously, due to the irregular swaying of the shield tail during step changes, the segment gap fluctuated between 20 and 35 mm, significantly increasing the difficulty of segment selection and assembly, and reducing assembly efficiency by 40%. During the process of the tunnel lining segments exiting the shield tail and moving to the 5th ring, especially in the bottom 5-7 o'clock area, regular elliptic deformation, misalignment, and longitudinal joint opening problems occurred. The maximum lateral elliptic deformation rate reached 5.1‰, the maximum misalignment exceeded 22.95 mm, and the maximum longitudinal joint opening reached 16 mm. The elliptic deformation of the tunnel lining segments within the shield tail affected the roundness and flatness of the next ring segment assembly, creating a vicious cycle of "elliptic deformation-misalignment-assembly deviation."

[0040] Based on the above problems, the shield tail structure was modified as follows:

[0041] like Figure 1-3 As shown, an arc-shaped groove 2 with a central angle of 22° is opened circumferentially at the lower part of the shield tail shell 1, with a circumferential arc length of 1.7m and an axial length of 2m; precast concrete pads 3 are arranged at the four corners of the arc-shaped groove 2. The size of the pads 3 is 250mm×200mm. The height of the pads 3 is dynamically adjusted on site according to the gap between the previous ring segment and the rock layer and the thickness of the loose slag, and is selected in the range of 70-120mm. Before assembling the segments, the loose slag in the groove is cleaned. After the pads 3 are in place, gravel is blown in until it is flush with the shield shell to form continuous vertical support and eliminate the bottom of the segments being suspended.

[0042] The original steel plate bundle assembly 4 is set at the end of the shield tail shell. Based on the original steel plate bundle assembly 4 at the end of the shield tail, two new steel plate bundle assemblies 5 are set at 250mm intervals along the inner wall of the shield tail shell 1. The two sets of new steel plate bundle assemblies 5 cover the 240° area of ​​the lower part of the shield tail in a circumferential manner, and avoid the arc-shaped groove 2 to prevent the support pad 3 from interfering with the steel plate bundle 53.

[0043] Each newly added steel plate bundle assembly 5 includes a positioning block 51, a fixing base plate 52, a steel plate bundle 53, a pressure plate 54, and countersunk screws 55.

[0044] Because the inner wall of the tail shield shell 1 is smooth, the steel plate bundle 53 cannot be directly fixed to the inner wall. Therefore, a positioning block 51 needs to be welded to the inner wall of the tail shield shell 1. The main function of the positioning block 51 is to provide positioning. At the same time, the positioning block 51 is higher than the pressure plate 54, which can effectively prevent the segments from rubbing against the pressure plate 54 during the step change, thus preventing the pressure plate 54 and the steel plate bundle 53 from falling off and failing. It plays an effective protective role. The positioning block 51 is made of Q690 high-strength steel plate and is welded and fixed to the inner wall of the tail shield shell 1. It is 40mm wide and 20mm high, with a 24.5mm gap reserved with the segments during subsequent construction. The top surface of the positioning block 51 is 445mm higher than the pressure plate 545mm, forming a protective step.

[0045] The fixed base plate 52 is used as the mounting base for the steel plate bundle 53. It is made of Q355B steel plate and is fixed to the inner wall of the shield tail shell 1 by positioning and welding based on the positioning block 51. It is 30mm wide and 10mm high.

[0046] The steel plate bundle 53 is installed on the fixed base plate 52 via pressure plate 54 and countersunk screws 55. The steel plate bundle 53 is composed of four layers of high-strength spring steel plates stacked in a staggered manner. The staggered arrangement between layers balances rigidity and elastic deformation capacity, achieving "flexible constraint." During installation, overlapping of adjacent spring steel plates should be avoided. This is mainly achieved through staggered installation and tightening of the spring steel plates, effectively preventing the spring steel plate blades from falling off and being damaged if individual pressure plate 54 bolts fall off. Each spring steel plate is 180mm long, 100mm wide, and 1mm thick, requiring a total of 1440 plates. The pressure plate 54 is used to tighten and fix the steel plate bundle 53. Countersunk screws are tightened onto the pressure plate 54, with the top surface of the countersunk screws 55 not exceeding the top surface of the pressure plate 54, and the top surface of the pressure plate 54 not exceeding the top surface of the positioning block 51.

[0047] The above-mentioned tail shield structure modification has been completed.

[0048] When the steel plate bundle 53 is damaged, the entire shield tail 5 ring segment can be tied and fixed together. After the auxiliary thrust cylinder is pushed to the specified stroke, the steel plate bundle assembly 5 will be exposed. First, remove the countersunk bolts 55 and pressure plate 54, and then replace the damaged spring steel plate to restore the function of the shield tail steel plate bundle 53.

[0049] After the modification, the double-shield TBM has accumulated a tunneling length of over 2km, with no further significant ellipticity, misalignment, leakage, or corner damage. The shield tail sway amplitude is controlled within 15mm, the shield tail gap is evenly distributed, the segment selection and assembly are smooth, and the flared end and initial misalignment are completely eliminated. The ellipticity of the segments after exiting the shield tail is stably controlled within 3‰, the maximum misalignment at the bottom 5 / 7 points is reduced to within 5mm, the longitudinal flared end and tension gap are eliminated, and the segment forming quality meets the design and specification requirements. This verifies that the invention is technologically advanced, highly reliable, practical, and has great promotional value.

[0050] Compared to the small-slot design of small-diameter TBMs (3~7m), this structure increases the slot at the shield tail. This design does not require a specific segment mold with outriggers, allowing for flexible placement of precast concrete pads at position 3 and facilitating bottom gravel filling. It successfully solves the problem of insufficient and incomplete gravel filling at positions 5~7 at the bottom in traditional large-diameter TBMs with no open shield tail. This saves on segment production costs, improves construction convenience, and enhances the fullness of the bottom gravel filling. It successfully solves the common quality problem of segment dropping under adverse geological conditions such as weak and fractured surrounding rock. Meanwhile, the traditional TBM tail shield only uses a single steel plate bundle 53 design, which mainly serves to prevent gravel leakage. However, with the development of large-diameter tunnels, the self-weight of the segments is increasing, and the gravel filling is relatively delayed. The lack of support and constraint at the tail shield makes it very easy for the segments to detach and misalign. By adding two steel plate bundles 53, the elliptic deformation of the segments during the process of detaching from the tail shield can be effectively prevented, greatly improving the segment forming quality. This is of great significance for the reliability and durability of tunnel segments.

[0051] In other embodiments, the circumferential central angle of the arc-shaped groove 2 is 15°–30°, the circumferential arc length is 1.5m–2.5m, and the axial length is 1.5m–2.5m. The precast concrete pad block 3 has a length of 200mm–300mm, a width of 150mm–250mm, and a height of 70mm–120mm. The axial distance between two adjacent newly added steel plate bundle assemblies 5 is 200mm–300mm; the axial distance between the original steel plate bundle assembly 4 and the adjacent newly added steel plate bundle assembly 5 is 200mm–300mm; the newly added steel plate bundle assembly 5 covers a circumferential range of 200°–280° along the inner sidewall of the shield tail shell 1. The dimensions of a single spring steel plate are 150mm–200mm in length, 80mm–120mm in width, and 0.8mm–1.2mm in thickness. The positioning block 51 is 30mm-50mm wide and 18mm-24mm high, with a 20mm-30mm gap reserved between it and the segments during subsequent construction, and protrudes at least 1mm above the top surface of the pressure plate 54. The fixing base plate 52 is 20mm-40mm wide and 7mm-15mm high.

[0052] The above-described embodiments are merely illustrative of the present invention. Any equivalent embodiments made by those skilled in the art, without departing from the scope of the technical features disclosed in the present invention, using partial modifications or alterations to the technical content disclosed in the present invention, shall still fall within the scope of the technical features of the present invention.

Claims

1. A TBM tail shield structure for preventing segment deformation, comprising a tail shield shell and an existing steel plate bundle assembly, wherein the existing steel plate bundle assembly is disposed at the end of the tail shield shell, characterized in that: It also includes precast concrete spacers and at least two additional steel plate bundle assemblies; The lower part of the shield tail shell is provided with an arc-shaped groove, and the precast concrete pads are respectively set at the four corners of the arc-shaped groove; At least two additional steel plate bundle assemblies are axially spaced on the inner wall of the tail shield shell, and avoid the arc-shaped groove; Each newly added steel plate bundle assembly includes a positioning block, a fixing base plate, a steel plate bundle, a pressure plate, and countersunk screws. The positioning block is welded and fixed to the inner wall of the shield tail shell. The fixing base plate is positioned and welded to the inner wall of the shield tail shell based on the positioning block. The steel plate bundle is installed on the fixing base plate by the pressure plate and countersunk screws. The top surface of the countersunk screw is not higher than the top surface of the pressure plate, and the top surface of the positioning block is not lower than the top surface of the pressure plate.

2. The TBM tail shield structure for preventing segment deformation according to claim 1, characterized in that: The circumferential central angle of the arc-shaped groove is 15° to 30°, the circumferential arc length is 1.5m to 2.5m, and the axial length is 1.5m to 2.5m.

3. A TBM tail shield structure for preventing segment deformation according to claim 1, characterized in that: The precast concrete pad has a length of 200mm to 300mm, a width of 150mm to 250mm, and a height of 70mm to 120mm.

4. A TBM tail shield structure for preventing segment deformation according to claim 1, characterized in that: The axial spacing between two adjacent newly added steel plate bundle assemblies is 200mm to 300mm; the axial spacing between the original steel plate bundle assembly and the adjacent newly added steel plate bundle assembly is 200mm to 300mm; the newly added steel plate bundle assembly covers a range of 200° to 280° circumferentially along the inner sidewall of the shield tail shell.

5. A TBM tail shield structure for preventing segment deformation according to claim 1, characterized in that: The steel plate bundle is composed of at least 4 layers of spring steel plates stacked in a staggered manner, with each spring steel plate having a length of 150mm to 200mm, a width of 80mm to 120mm, and a thickness of 0.8mm to 1.2mm.

6. A TBM tail shield structure for preventing segment deformation according to claim 1, characterized in that: The positioning block is made of Q690 high-strength steel plate, with a width of 30mm to 50mm and a height of 18mm to 24mm. The gap between it and the segment during subsequent construction is 20mm to 30mm, and it protrudes at least 1mm above the top surface of the pressure plate.

7. A TBM tail shield structure for preventing segment deformation according to claim 1, characterized in that: The fixed base plate is made of Q355B steel plate, with a width of 20mm to 40mm and a height of 7mm to 15mm.

8. The TBM tail shield structure for preventing segment deformation according to claim 1, characterized in that: The arc-shaped groove has a circumferential central angle of 22°, a circumferential arc length of 1.7m, and an axial length of 2m; the precast concrete pad is 250mm long, 200mm wide, and its height is adjustable from 70mm to 120mm; the axial spacing between two adjacent newly added steel plate bundle assemblies is 250mm, the axial spacing between the newly added steel plate bundle assembly and the original steel plate bundle assembly is 250mm, and the newly added steel plate bundle assembly covers a 240° range along the inner wall of the shield tail shell; the steel plate bundle is composed of four layers of spring steel plates stacked in staggered layers, with each spring steel plate being 180mm long, 100mm wide, and 1mm thick; the positioning block is made of Q690 high-strength steel plate, 40mm wide and 20mm high, with a 24.5mm gap reserved between the positioning block and the segments during subsequent construction, and the top surface of the positioning block protruding 5mm above the top surface of the pressure plate; the fixed base plate is made of Q355B steel plate, 30mm wide and 10mm high.

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