Multi-directionally deformable tunnel lining component and method of construction

Abstract

This application relates to the field of tunnel engineering technology, and provides a multi-directional deformation-compatible connecting tunnel support structure component and its construction method. The multi-directional deformation-compatible connecting tunnel support structure component includes a multi-directionally movable columnar crown-shaped truss component and foamed concrete. The truss component is columnar in shape and is positioned between the tunnel inner wall and the surrounding rock. It includes multiple sets of movable truss rods, each set of rods bent into multiple crown shapes. The multiple sets of movable truss rods are arranged sequentially along the length of the tunnel. Adjacent sets of movable truss rods are connected by telescopic joints. Hinged interfaces are provided at both ends of the truss component; one end of the hinged interface connects to the truss component, and the other end is hinged to the tunnel inner wall. Foamed concrete fills the space between the tunnel inner wall and the surrounding rock, encasing the truss component within this space. The structure of this application embodiment can protect the integrity of the overall tunnel structure through multi-directional deformation and pre-set damage locations.

Description

Technical Field

[0001] This application relates to the field of tunnel engineering technology, specifically to a connecting tunnel support structure component and construction method applicable to multi-directional deformation. Background Technology

[0002] As the core structure of underground transportation engineering, the structural safety of tunnels is particularly important when facing earthquakes, geological fault activity, or uneven ground settlement. The geological conditions at the locations of fault-crossing tunnels are complex, and compared to other types of tunnels, they are at extremely high risk of severe damage. Therefore, continuously improving the overall stability and durability of fault-crossing tunnel structures has become a key task in the field of transportation tunnel construction.

[0003] Related Technology 1 discloses a novel multi-stage seismic isolation structure for tunnels traversing active fault zones. This structure involves sequentially installing a seismic isolation structure at the tunnel entrance and a seismic isolation structure along the fractured zone within the tunnel body. Each of these structures comprises multiple sub-structures, and each sub-structure employs a multi-stage seismic isolation layer design on the tunnel cross-section. Related Technology 1 reduces overall tunnel damage through multi-stage energy dissipation and vibration reduction, while also reserving areas for slippage displacement. However, this method disturbs the surrounding rock during construction, reducing its stability and potentially leading to collapses, endangering construction safety, and impacting the tunnel's future use.

[0004] Related Technology 2 discloses a tunnel vibration-damping lining structure and its application method. The overall structure consists of a lining body, movable connectors, compensating components, and multiple energy-absorbing bodies. A buffer gap is reserved between two adjacent lining bodies. The movable connectors are concentrically and movably disposed at the ends of the lining bodies, allowing the lining bodies and movable connectors to rotate radially relative to each other. The compensating components are slidably disposed between two adjacent movable connectors along the tunnel axis, allowing the lining bodies and compensating components to move axially relative to each other. Multiple energy-absorbing bodies are circumferentially distributed within the buffer gap, and their two ends are movably connected to the sidewalls of adjacent lining body sections. Related Technology 2, by setting movable connectors, allows radial rotation between the lining bodies, giving the lining structure a certain degree of flexibility to adapt to impact forces in different directions. Although Related Technology 2 can reduce vibration and resist displacement by setting damping materials, its vibration reduction and isolation effect is constrained by various factors such as seismic waves and geological conditions, making it difficult to function stably.

[0005] The inventors of this application have discovered through research that there is relatively little research on performance-enhancing components for tunnel joints. How to provide a support structure component for tunnel joints that can be adapted to multi-directional deformation and can protect the integrity of the overall tunnel structure is a technical problem that needs to be solved in this field. Summary of the Invention

[0006] In view of this, the embodiments of this application provide a connecting tunnel support structure component and construction method that can be adapted to multi-directional deformation, which can protect the integrity of the overall tunnel structure through multi-directional deformation and preset damage locations.

[0007] To achieve the above objectives, this application adopts the following technical solution:

[0008] In a first aspect, embodiments of this application provide a connecting tunnel support structure component that can be adapted to multi-directional deformation, including a multi-directional movable columnar crown truss component and foamed concrete;

[0009] The multi-directional movable columnar crown truss component is columnar in shape and is installed between the tunnel inner wall and the surrounding rock. The multi-directional movable columnar crown truss component includes multiple sets of movable truss rods, each set of movable truss rods being bent into multiple crown shapes and is overall columnar, with adjacent crown shapes pointing in opposite directions along the columnar axis. The multiple sets of movable truss rods are arranged sequentially along the length of the tunnel and are all installed between the tunnel inner wall and the surrounding rock. Adjacent sets of movable truss rods are connected by multiple telescopic joints. Each set of movable truss rods has hinged interfaces at both ends, with one end hinged to the movable truss rod and the other end hinged to the tunnel inner wall.

[0010] The foamed concrete fills the space between the tunnel inner wall and the surrounding rock, and the multi-directional movable columnar crown truss component is wrapped between the tunnel inner wall and the surrounding rock.

[0011] Based on the first aspect, in some embodiments, the material of the multi-directional movable columnar crown truss component is high-ductility, low-yield-point steel, which has an elastic modulus of 160MPa-225MPa, a yield strength ratio of 0.6-0.8, and a yield strength ≥800MPa.

[0012] Based on the first aspect, in some embodiments, each group of truss movable rods has multiple movable nodes, and each movable node is provided with an auxiliary reinforcing component for reinforcing the movable node, the auxiliary reinforcing component being fixed to the movable node by bolts.

[0013] Based on the first aspect, in some embodiments, each set of truss movable rods includes multiple sections of steel bars, multiple bolts, and multiple auxiliary reinforcement components, which are EPDM rubber washers or springs; a section of steel bar is provided between two adjacent movable nodes in each set of truss movable rods, and the two sections of steel bars are connected by bolts, with rubber washers or springs passing through the screw and placed between the two sections of steel bars to form the crown shape; the connection part between the two sections of steel bars is the movable node.

[0014] Based on the first aspect, in some embodiments, a hinge base is pre-embedded on the outer side of the tunnel inner wall at a position corresponding to the hinge interface, the two ends of the hinge interface are fixed on the hinge base, and the middle part of the hinge interface is hinged to the truss movable rod.

[0015] Based on the first aspect, in some embodiments, the hinge interface is U-shaped, each hinge interface corresponds to two hinge bases, the two ends of the U-shape are respectively fixed on the two corresponding hinge bases, and the middle part of the U-shape is hinged to the truss movable rod.

[0016] Secondly, embodiments of this application provide a construction method for a connecting tunnel support structure component applicable to multi-directional deformation, the construction method comprising:

[0017] The multi-directional movable columnar crown truss component is installed around the outer side of the tunnel inner wall, and the hinged interface of the truss movable rod is hinged to the hinged base pre-embedded in the tunnel inner wall.

[0018] Temporary formwork was erected on both sides of the tunnel, so that the multi-directional movable columnar crown truss components were located in the pouring space enclosed by the temporary formwork and the inner wall of the tunnel;

[0019] Foamed concrete is poured into the pouring space in layers, so that the multi-directional movable columnar crown truss component is completely covered by foamed concrete; wherein, the foamed concrete is poured in multiple layers, each layer being ≤300 mm thick, and a vibrating device is used to vibrate each layer of foamed concrete during layer pouring to remove air bubbles from the foamed concrete.

[0020] After the foamed concrete has initially set, the temporary formwork is removed, and the curing time for the initially set foamed concrete is preset.

[0021] Based on the second aspect, in some embodiments, when using a vibrating device to vibrate each layer of foamed concrete during layered pouring, the vibration spacing is ≤50cm and the single-point vibration time is 20 to 30 seconds.

[0022] Based on the second aspect, in some embodiments, a deformation compensation space of 3cm-5cm is reserved between the multi-directional movable columnar crown truss component and the inner wall of the tunnel.

[0023] Based on the second aspect, in some embodiments, the construction method further includes:

[0024] Clean the outer surface of the tunnel inner wall to ensure it is flat and free of debris;

[0025] The outer surface of the tunnel inner wall is sandblasted to achieve a roughness Ra≥50μm.

[0026] The advantages of the embodiments of this application compared to the prior art include:

[0027] In this embodiment, foamed concrete has the characteristics of lower strength than commonly used concrete and is prone to cracking and damage under greater stress. This embodiment utilizes this characteristic to set the location of the foamed concrete as the pre-failure location. When the tunnel main structure is affected by earthquakes, the foamed concrete will absorb most of the stress energy and release energy through cracking and damage, causing the damage to concentrate at the preset failure location, preventing or reducing the degree of damage to the tunnel main structure, thereby ensuring the integrity of the tunnel column structure.

[0028] Moreover, the multi-directional movable columnar crown truss component has the characteristics of being compressible, expandable, and deformable in multiple directions. The embodiments of this application utilize this characteristic to buffer and dissipate external force energy through the contraction and expansion deformation of the multi-directional movable columnar crown truss component.

[0029] Therefore, it can be seen that the embodiments of this application protect the integrity of the overall tunnel structure through multi-directional deformation and preset damage locations. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A schematic diagram of a connecting tunnel support structure component suitable for multi-directional deformation, provided in an embodiment of this application;

[0032] Figure 2 A three-dimensional structural schematic diagram of a multi-directional movable columnar crown truss component provided in an embodiment of this application;

[0033] Figure 3 for Figure 2 The main view;

[0034] Figure 4 for Figure 3 The right view;

[0035] Figure 5 A schematic diagram of a set of truss movable members provided in an embodiment of this application;

[0036] Figure 6 A schematic diagram illustrating the connection between the truss movable rod, the hinged interface, and the junction base provided in an embodiment of this application;

[0037] Figure 7This is a schematic diagram of the structure of an active node provided in an embodiment of this application;

[0038] Figure 8 This is a schematic flowchart illustrating the construction method for a multi-directionally deformable connecting tunnel support structure component provided in an embodiment of this application. Detailed Implementation

[0039] The present application will be described more clearly below with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the function of the present application, but do not limit the present application in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application. These all fall within the protection scope of the present application.

[0040] To make the objectives, technical solutions, and advantages of this application clearer, the following description will be provided in conjunction with the accompanying drawings and specific embodiments.

[0041] See Figures 1 to 5 The multi-directional deformation-adaptable connecting tunnel support structure component provided in this application embodiment includes a multi-directional movable columnar crown truss component 30 and foamed concrete 40.

[0042] The multi-directional movable columnar crown truss component 30 is columnar in shape and is positioned between the tunnel inner wall 10 and the surrounding rock 20. The multi-directional movable columnar crown truss component 30 includes multiple sets of movable truss rods 31. Each set of movable truss rods 31 is bent into multiple crown shapes and is columnar in shape, with adjacent crown shapes pointing in opposite directions along the columnar axis. The multiple sets of movable truss rods 31 are arranged sequentially along the length of the tunnel and are all positioned between the tunnel inner wall 10 and the surrounding rock 20; adjacent sets of movable truss rods 31 are connected by multiple telescopic joints 32. The multi-directional movable columnar crown truss component 30 has hinged interfaces 50 at both ends. One end of the hinged interface 50 is connected to the multi-directional movable columnar crown truss component 30, and the other end is hinged to the tunnel inner wall 10.

[0043] Foamed concrete 40 is filled between the tunnel inner wall 10 and the surrounding rock 20, and multi-directional movable columnar crown truss component 30 is encased between the tunnel inner wall 10 and the surrounding rock 20.

[0044] The working principle of the multi-directional movable columnar crown-shaped truss component 30 is explained below. The curvature at the crown position of the truss movable rod 31 changes with the stress it receives: increased radial inward stress increases the curvature at the crown position, achieving a contraction effect in the radial direction; conversely, increased radial outward stress decreases the curvature at the crown position, achieving an expansion effect in the radial direction. Multiple sets of truss telescopic rods 31 are connected by telescopic joints 32. The curvature near the telescopic joints 32 changes with the stress received: increased axial inward stress increases the curvature near the telescopic joints 32, achieving a contraction effect in the axial direction; conversely, increased axial outward stress decreases the curvature near the telescopic joints 32, achieving an expansion effect in the axial direction. Therefore, the aforementioned multi-directional movable columnar crown-shaped truss component 30 can deform radially and / or axially when subjected to external stress, achieving a contraction / expansion effect in the radial and / or axial direction, thereby preventing or mitigating damage to the tunnel inner wall caused by external stress. The aforementioned radial and axial directions are determined based on the columnar shape of the multi-directional movable columnar crown truss component 30 as a whole.

[0045] like Figure 5 As shown, the truss movable rod 31 is columnar in shape and is fitted onto the outer side of the tunnel inner wall 10, with a certain gap between it and the tunnel inner wall 10. The truss movable rod 31 is bent into multiple crown shapes, closed at both ends, with adjacent crown shapes pointing in opposite directions along the columnar axis. Similar to a wavy line, connecting the two ends of the wavy line to form a column, the crests and troughs of the wavy line are the aforementioned crown shapes.

[0046] For example, the multi-directional movable columnar crown truss component 30 has hinge interfaces 50 at both ends. Specifically, in the multi-set truss telescopic rods 31 of the multi-directional movable columnar crown truss component 30, the two sets of truss telescopic rods 31 located at both ends are provided with hinge interfaces 50. For example, the two sets of truss telescopic rods 31 located at both ends (e.g.) Figure 5 and Figure 6 As shown, a hinged interface 50 is provided at the crown-shaped position near the outer side.

[0047] In some embodiments, the multi-directional movable columnar crown truss component 30 can be made of high-ductility, low-yield-point steel. This high-ductility, low-yield-point steel has an elastic modulus of 160 MPa-225 MPa, a yield strength ratio of 0.6-0.8, and a yield strength ≥800 MPa. If the yield strength ratio is too high, the steel lacks sufficient plasticity and is prone to fracture, leading to stress concentration and poor seismic resistance; if the yield strength ratio is too low, the steel has insufficient load-bearing capacity and low yield strength.

[0048] In this embodiment of the application, each set of truss movable rods 31 may have multiple movable nodes, and each movable node is provided with an auxiliary reinforcement component for reinforcing the movable node. The auxiliary reinforcement component can be fixed to the movable node with bolts.

[0049] In this embodiment, adding auxiliary reinforcing components to the movable node strengthens it, which greatly improves the tensile and compressive strength and elastic deformation resistance of the truss movable member 31, enhances its fatigue resistance and shear resistance, and increases its service life. The movable node corresponds to a fatigue-prone position of the truss movable member 31, specifically the position of the crown-shaped top of the truss movable member 31; one crown-shaped top corresponds to one movable node.

[0050] Specifically, each set of truss movable members 31 may include multiple steel bars, multiple bolts, and multiple auxiliary reinforcing components. These auxiliary reinforcing components are EPDM rubber washers or springs. A steel bar is installed between two adjacent movable nodes in each set of truss movable members 31, and the two steel bars are connected by bolts to form the aforementioned crown shape. The connection point between the two steel bars is the movable node. After these multiple steel bars are connected together, they form a shape as described above. Figure 5 The shape shown. See also Figure 7 Two sections of reinforcing bars 311 are connected together by bolts 312, and an auxiliary reinforcing component 313, which is a rubber washer or a spring, is provided between the two sections of reinforcing bars 311. The rubber washer or spring passes through the bolt and is placed between the two sections of reinforcing bars 311 to prevent the connecting ends of the two sections of reinforcing bars 311 from directly contacting each other.

[0051] like Figure 4 As shown, in some embodiments, a hinge base 11 is pre-embedded on the outer side of the tunnel inner wall 10 at a position corresponding to the hinge interface 50. The two ends of the hinge interface 50 are fixed on the hinge base 11, and the middle part of the hinge interface 50 is hinged to the truss movable rod 31.

[0052] For example, the hinge base 11 can be a steel plate, and bolt holes can be provided on the hinge base 11 to more firmly fix the hinge base 11 to the inner wall 10 of the tunnel by bolts. One end of each hinge interface 50 can correspond to one hinge base 11.

[0053] For example, see Figure 3 The hinge interface 50 can be U-shaped, and each hinge interface 50 corresponds to two hinge bases 11. The two ends of the U-shape are fixed on the corresponding two hinge bases 11, and the middle part of the U-shape is hinged to the truss movable rod 31.

[0054] In this embodiment, the foamed concrete 40 has a density greater than 2200 kg / m³, a tensile strength of 1.0 MPa to 1.2 MPa, and an elastic modulus of 1.5 GPa to 5 GPa. The foamed concrete 40 uses a water-cement ratio of 0.53:1, and 0.2%-0.3% sodium lignin xanthate by weight of the cement is added as a water-reducing agent.

[0055] This foamed concrete uses 42.5 grade silicate cement as the matrix, with 30% fly ash added to improve crack resistance. A protein-based foaming agent, diluted 1:35, is used to prepare closed-cell foam with an average pore size of 0.3 mm using a high-pressure foaming machine. The water-cement ratio is strictly controlled at 0.53:1, and 0.25% sodium lignin xanthate water-reducing agent is added to achieve a slump of 180 mm for pumping. Mixing is performed for 3 minutes at 240 rpm using a twin-shaft planetary mixer to ensure the foam volume ratio remains stable at 35%-40%. After final setting, it forms a honeycomb structure with a density of 2200 kg / m³ and an elastic modulus of 3.2 GPa. Under shear stress, the internal microporous structure of the foamed concrete preferentially undergoes directional crushing, and combined with a tensile strength of 1.1 MPa, it achieves controllable cracking and can absorb seismic energy.

[0056] Therefore, foamed concrete has characteristics such as low density, low strength, numerous internal pores, and susceptibility to cracking. Consequently, it will crack and be damaged under significant seismic stress. Furthermore, foamed concrete has a certain water absorption rate, which shortens its service life. Therefore, adding water-reducing agents during the foamed concrete preparation process can reduce its water absorption rate and improve its impermeability, extending its service life under normal conditions and preventing rust and corrosion of the multi-directional movable columnar crown truss components 30.

[0057] In some embodiments, considering the balance between range of motion and stability, the rotation angle of the movable node can be set to ±15°; considering displacement compensation requirements and structural size limitations, the stroke of the telescopic joint 32 can be set to ±50mm. Additionally, the EPDM rubber washer can have a Shore hardness of 80A, and the spring can be a disc spring with a stiffness coefficient of 50N / mm-80N / mm.

[0058] In this embodiment, foamed concrete has the characteristics of lower strength than commonly used concrete and is prone to cracking and damage under greater stress. This embodiment utilizes this characteristic to set the location of the foamed concrete as the pre-failure location. When the tunnel main structure is affected by earthquakes, the foamed concrete will absorb most of the stress energy and release energy through cracking and damage, causing the damage to concentrate at the preset failure location, preventing or reducing the degree of damage to the tunnel main structure, thereby ensuring the integrity of the tunnel column structure.

[0059] Furthermore, the multi-directional movable columnar crown truss component is compressible, expandable, and deformable in multiple directions. This embodiment utilizes this characteristic to buffer and dissipate external force energy through the contraction and expansion deformation of the multi-directional movable columnar crown truss component. Additionally, after the earthquake subsides, the truss structure itself possesses a certain degree of elasticity, allowing it to recover to some extent after the external force disappears, thus continuing to provide support for the tunnel.

[0060] Based on the above-mentioned connecting tunnel support structure components that can be adapted to multi-directional deformation, this application embodiment also provides a construction method for connecting tunnel support structure components that can be adapted to multi-directional deformation.

[0061] See Figure 8 The construction method for the multi-directional deformation-compatible connecting tunnel support structure component may include steps 801 to 805, as detailed below:

[0062] Step 801: Embed a hinge base at a predetermined position on the inner wall of the tunnel and fix the hinge base in the inner wall of the tunnel.

[0063] The articulated base can be made of steel plate and may have bolt holes, which are used to secure the articulated base firmly to the tunnel wall. For example, a torque wrench can be used to tighten the bolts to a torque value of 10 kN·m-15 kN·m.

[0064] Excessive torque results in overly rigid components that cannot absorb energy; insufficient torque leads to inadequate rigidity and tightness, making them prone to misalignment. The torque value indirectly reflects the axial preload of the bolts. A setting range of 10kN·m-15kN·m ensures that the preload of all bolts is evenly distributed, avoiding local overload or insufficient preload.

[0065] Specifically, a lower limit of 10 kN·m ensures sufficient preload. The torque value directly determines the bolt preload, which is calculated using the torque-preload formula T = K × F × d, where T is the torque, F is the preload, d is the nominal bolt diameter, and K is the torque coefficient. This lower limit ensures that the bolted connection maintains sufficient clamping force under working loads, preventing loosening, slippage, or vibration failure due to insufficient preload. Furthermore, it can counteract the effects of external loads. If axial tensile or shear forces exist during operation, sufficient preload ensures a tight fit between the mating surfaces, preventing relative displacement of components.

[0066] An upper limit of 15 kN·m prevents bolt overload failure. Exceeding the yield strength or tensile strength of the bolt material can lead to plastic deformation (elongation) or breakage. This upper limit ensures the torque does not exceed the bolt's safe operating range, preventing bolt breakage, thread stripping, or crushing by connecting parts due to excessive preload. Furthermore, considering fluctuations in the coefficient of friction, the actual preload of the torque wrench is affected by the friction coefficient of the threaded pair and the supporting surface (e.g., lubrication status, surface roughness). The upper limit provides a safety margin to prevent the actual preload from exceeding the bolt's load-bearing capacity due to a decrease in the coefficient of friction (e.g., after applying lubricant).

[0067] Step 802: The multi-directional movable columnar crown truss component is installed around the outer side of the tunnel inner wall, and the hinged interface of the truss movable rod is hinged to the hinged base pre-embedded in the tunnel inner wall.

[0068] For example, each set of truss movable members can be sequentially fitted onto the outer side of the tunnel inner wall, with hinged interfaces located at the crown-shaped positions on the outer sides of the two sets of truss movable members at both ends. The hinged interfaces are aligned with hinged bases pre-embedded in the tunnel inner wall to adjust the position of each set of truss movable members. Then, the hinged interfaces are hinged to the hinged bases pre-embedded in the tunnel inner wall.

[0069] Optionally, after step 802, the construction method further includes: installing EPDM rubber washers or springs at the movable nodes of each group of truss movable members to reinforce the movable nodes. The EPDM rubber washers or springs can be fixed to the movable nodes of each group of truss movable members using bolts.

[0070] For example, the Shore A hardness of the EPDM rubber washer can be 80A, and the spring can be a disc spring with a stiffness coefficient of 50N / mm-80N / mm. The EPDM rubber washer or spring can be fixed to the moving node of each truss moving rod by tightening the bolts with a preload of 20kN-30kN using a torque wrench.

[0071] In this embodiment, a deformation compensation space of 3cm-5cm should be reserved between the multi-directional movable columnar crown truss component and the inner wall of the tunnel.

[0072] Step 803: Temporary templates are erected on both sides of the tunnel so that the multi-directional movable columnar crown truss components are located in the casting space enclosed by the temporary templates, the tunnel wall and the surrounding rock.

[0073] Foamed concrete shrinks to a certain extent during the solidification process. To compensate for the shrinkage, a 3‰ pre-camber can be set on the temporary formwork. This way, after the foamed concrete solidifies and shrinks, the surface of the foamed concrete will be relatively flat and will not be sunken.

[0074] During the setting process, foamed concrete undergoes drying shrinkage and chemical shrinkage due to moisture evaporation and the hydration reaction of cementitious materials. Because of its porous structure, the shrinkage rate of foamed concrete may be slightly higher than that of ordinary concrete. However, through experimental testing (such as linear shrinkage tests under standard curing conditions), its average linear shrinkage rate can be measured to be approximately 0.3% (i.e., 3‰). Setting the pre-camber to the same proportion as the shrinkage rate (3‰) essentially counteracts the depressions caused by shrinkage through "reverse pre-deformation," resulting in a smooth final surface.

[0075] Step 804: Foamed concrete is poured in layers into the pouring space so that the multi-directional movable columnar crown truss component is completely covered by foamed concrete.

[0076] The foamed concrete can be poured in multiple layers (e.g., 3 layers), with each layer having a thickness of ≤300 mm. When pouring the foamed concrete in layers, a vibrating device is used to vibrate each layer of foamed concrete to remove air bubbles from the foamed concrete.

[0077] For example, a pouring hole can be opened in the inner wall of the tunnel, through which foamed concrete is poured into the pouring space. The vibrating equipment can be an immersion vibrator, which is inserted into the pouring space through the pouring hole to vibrate each layer of foamed concrete.

[0078] The effective range of vibratory compaction equipment is limited (typically, the effective depth of a vibrator is about 300-500mm). A layer thickness of ≤300mm ensures that the vibration force is evenly distributed throughout the entire pour, preventing air bubbles from being trapped in the lower layers due to excessively thick pours. If a single pour is too thick, the lower layers of concrete may form an "air bubble trap" due to insufficient vibration force, leading to localized looseness and uneven strength. Layered pouring ensures that each layer of concrete is within the optimal effective range of the vibratory compaction equipment, guaranteeing the full expulsion of excess air from the foamed concrete and improving material density and integrity.

[0079] In addition, when using a vibrating device to vibrate each layer of foamed concrete, the vibration spacing should be 30cm-50cm, and the vibration time at a single point can be 20 to 30 seconds.

[0080] The effective range of vibratory compaction equipment is limited, typically with a single-point vibration radius of approximately 20-25 cm. Therefore, to ensure complete coverage without blind spots, the relatively low fluidity of foamed concrete necessitates a vibration spacing of ≤50 cm. If the spacing exceeds 50 cm, the areas of action of adjacent vibration points cannot overlap, potentially leading to missed areas in the middle, resulting in defects such as honeycomb and voids, affecting the concrete's density and integrity. Furthermore, a reasonable vibration spacing ensures even distribution of vibration force, preventing localized over- or under-vibration. If the spacing is too close (<30 cm), adjacent air bubbles in the foamed concrete may rupture and fuse, damaging the bubble structure; if the spacing is too far (>50 cm), insufficient vibration may cause air bubble aggregation or concrete particle accumulation, affecting strength and durability.

[0081] Excessive single-point vibration time (>30 seconds) in foamed concrete may cause air bubbles to burst (especially with high-powered vibrating equipment), compromising its lightweight properties and potentially causing aggregate separation from cement paste, affecting material uniformity. Conversely, insufficient single-point vibration time (<20 seconds) fails to adequately expel excess air from the foamed concrete. A single-point vibration time of 20-30 seconds strikes a balance between expelling excess air and protecting effective air bubbles, ensuring that the foamed concrete particles tightly encapsulate the air bubbles without compromising their stability.

[0082] Based on the completeness of the scheme, the preparation process of foamed concrete slurry is described below.

[0083] Foamed concrete is a lightweight porous material containing numerous closed pores, formed by uniformly introducing foam into a cementitious slurry and then hydrating and hardening it. The core raw materials include cementitious materials, aggregates, foaming agents, foam stabilizers, and water. Cementitious materials include silicate cement, and additional active admixtures such as fly ash, silica fume, and slag powder may be added.

[0084] First, the raw materials are processed, including: passing the cement and admixtures through an 80-mesh sieve to remove lumps and ensure uniform fineness; drying the aggregates in advance (moisture content <1%); and diluting the foaming agent with water (e.g., 1 kg of foaming agent concentrate to 30 kg-50 kg of water).

[0085] Next, foam is prepared using a foam generator (high-pressure air type / mechanical stirring type). The diluted foaming liquid is added to the generator, and compressed air is introduced or high-speed stirring is used to generate foam (foam density 815 kg / m³, bubble diameter ≥ 80% with a proportion of 0.21 mm). The air flow rate of the foam generator is 510 m³ / h, and the stirring speed is 800 rpm–1500 rpm. The prepared foam must be used within 30 minutes to avoid defoaming (a foam stabilizer solution can also be added to improve stability).

[0086] Next, the cement slurry is mixed. First stage (dry mixing): Cement, admixtures, and aggregates are added to the mixer and mixed at low speed for 1 minute (50-80 rpm) until homogeneous. Second stage (wet mixing): Water and admixtures (water-reducing agent / early strength agent, etc.) are added and mixed at medium speed for 2-3 minutes (100-150 rpm) until the slurry is free of lumps and has uniform fluidity (slump 180mm-220mm, adjusted according to the molding method).

[0087] Next, the cement paste and foam are mixed. The foam is added to the cement paste in multiple batches, stirring at low speed for 30-60 seconds (≤50 rpm) after each addition, using a "tumbling + swirling" method to ensure uniform foam dispersion. The foam volume should account for 60%-80% of the total mixture volume. The density of the foamed concrete can be controlled by adjusting the amount of foam; for example, when the density of the foamed concrete is 600 kg / m³, the foam volume is approximately three times the volume of the cement paste. This yields the foamed concrete paste.

[0088] Before pouring the foamed concrete slurry into the pouring space, coat the inner wall of the pouring space with a release agent (such as a mixture of engine oil and diesel oil at a ratio of 1:3), or lay a polyethylene film on the inner wall of the pouring space to prevent sticking. Then, pour the foamed concrete slurry into the pouring space in layers through the pouring holes. For instructions on how to pour the foamed concrete slurry into the pouring space, please refer to the aforementioned content; it will not be repeated here.

[0089] Optionally, before step 804, the construction method further includes: cleaning the outer surface of the tunnel inner wall to ensure that the outer surface of the tunnel inner wall is flat and free of debris; and sandblasting the outer surface of the tunnel inner wall to make the roughness Ra of the outer surface of the tunnel inner wall ≥ 50 μm.

[0090] When subsequent sealing material filling or other connection treatments are performed, a roughness Ra≥50μm provides a larger surface area, allowing the sealing or connecting material to better interlock and bond with the joint surface. This ensures the sealing and firmness of the connection, effectively preventing leakage, deformation, and other problems during tunnel use. Appropriate roughness can increase the coefficient of friction between two joint surfaces, better resisting relative sliding when the tunnel is subjected to external forces such as earthquakes or ground movement, thus improving the stability and safety of the tunnel structure.

[0091] If the roughness is less than 50μm, the outer surface of the tunnel inner wall is relatively smooth, and the adhesion between the foamed concrete and the outer surface may be insufficient. During long-term use, the foamed concrete may detach or fail, leading to gaps between the outer surface of the tunnel inner wall and the foamed concrete. This affects the tunnel's waterproofing performance and structural stability. A smoother interface is also less conducive to forming an effective seal, allowing water, air, and other media to easily enter the tunnel through these gaps, causing corrosion and damage to the tunnel's facilities. It also affects the tunnel's functionality and safety.

[0092] Step 805: After the foamed concrete has initially set, remove the temporary formwork and set a preset curing time for the initially set foamed concrete.

[0093] For example, permeable geotextile can be covered on the initially set foamed concrete, and a curing agent can be sprayed on it. It should then be cured for at least 7 days in a constant temperature and humidity environment of 20±2℃ and ≥95%. The solidified foamed concrete has a density greater than 2200 kg / m³, a tensile strength of 1.0 MPa to 1.2 MPa, and an elastic modulus of 1.5 GPa to 5 GPa.

[0094] The above construction methods are applicable to tunnel projects under complex geological conditions such as active fault zones and soft soil settlement areas, and have both structural safety and construction controllability.

[0095] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A connecting tunnel support structure component applicable to multi-directional deformation, characterized in that, Includes multi-directional movable columnar crown truss components and foamed concrete; The multi-directional movable columnar crown truss component is columnar in shape and is installed between the tunnel inner wall and the surrounding rock. The multi-directional movable columnar crown truss component includes multiple sets of movable truss rods, each set of rods being bent into multiple crown shapes and overall columnar in shape, with adjacent crown shapes pointing in opposite directions along the columnar axis. The multiple sets of movable truss rods are arranged sequentially along the length of the tunnel and are all installed between the tunnel inner wall and the surrounding rock. Adjacent sets of movable truss rods are connected by multiple telescopic joints. The multi-directional movable columnar crown truss component has hinged interfaces at both ends; one end of the hinged interface is connected to the multi-directional movable columnar crown truss component, and the other end is hinged to the tunnel inner wall. The foamed concrete fills the space between the tunnel inner wall and the surrounding rock, and the multi-directional movable columnar crown truss component is wrapped between the tunnel inner wall and the surrounding rock.

2. The multi-directional deformation-adaptive connecting tunnel support structure component according to claim 1, characterized in that, The multi-directional movable columnar crown truss component is made of high-ductility, low-yield-point steel with an elastic modulus of 160MPa-225MPa, a yield strength ratio of 0.6-0.8, and a yield strength ≥800MPa.

3. The multi-directional deformation-adaptable connecting tunnel support structure component according to claim 2, characterized in that, Each set of truss movable members has multiple movable nodes, and each movable node is provided with an auxiliary reinforcement component for reinforcing the movable node. The auxiliary reinforcement component is fixed to the movable node by bolts.

4. The multi-directional deformation-adaptable connecting tunnel support structure component according to claim 3, characterized in that, Each set of truss movable members includes multiple steel bars, multiple bolts, and multiple auxiliary reinforcement components, which are EPDM rubber washers or springs; a steel bar is set between two adjacent movable nodes in each set of truss movable members, and the two steel bars are connected by bolts. The rubber washer or spring passes through the bolt and is set between the two steel bars to form the crown shape; the connection part between the two steel bars is the movable node.

5. The multi-directional deformation-adaptable connecting tunnel support structure component according to claim 4, characterized in that, A hinge base is pre-embedded on the outer side of the tunnel inner wall at a position corresponding to the hinge interface. Both ends of the hinge interface are fixed on the hinge base, and the middle part of the hinge interface is hinged to the truss movable rod.

6. The multi-directional deformation-adaptable connecting tunnel support structure component according to claim 5, characterized in that, The hinge interface is U-shaped, with each hinge interface corresponding to two hinge bases. The two ends of the U-shape are fixed on the corresponding two hinge bases, and the middle part of the U-shape is hinged to the truss movable rod.

7. A construction method for a multi-directional deformation-compatible connecting tunnel support structure component according to claim 6, characterized in that, The construction method includes: A hinge base is pre-embedded at a predetermined position on the inner wall of the tunnel, and the hinge base is fixed in the inner wall of the tunnel. The multi-directional movable columnar crown truss component is installed around the outer side of the tunnel inner wall, and the hinged interface of the truss movable rod is hinged to the hinged base pre-embedded in the tunnel inner wall. Temporary formwork was erected on both sides of the tunnel, so that the multi-directional movable columnar crown truss components were located in the casting space enclosed by the temporary formwork, the tunnel wall and the surrounding rock; Foamed concrete is poured into the pouring space in layers, so that the multi-directional movable columnar crown truss component is completely covered by foamed concrete; wherein, the foamed concrete is poured in multiple layers, each layer being ≤300mm thick, and a vibrating device is used to vibrate each layer of foamed concrete during layer pouring to remove air bubbles in the foamed concrete. After the foamed concrete has initially set, the temporary formwork is removed, and the curing time for the initially set foamed concrete is preset.

8. The construction method for the multi-directional deformation-compatible connecting tunnel support structure component according to claim 7, characterized in that, When using a vibratory compactor to compact each layer of foamed concrete during layered pouring, the compaction spacing should be ≤50cm, and the compaction time at a single point should be 20 to 30 seconds.

9. The construction method for the multi-directional deformation-compatible connecting tunnel support structure component according to claim 7, characterized in that, A 3cm-5cm deformation compensation space is reserved between the multi-directional movable columnar crown truss component and the tunnel inner wall.

10. The construction method for the multi-directional deformation-compatible connecting tunnel support structure component according to claim 7, characterized in that, Before the foamed concrete is poured in layers into the pouring space, so that the multi-directional movable columnar crown truss component is completely covered by the foamed concrete, the construction method further includes: Clean the outer surface of the tunnel inner wall to ensure it is flat and free of debris; The outer surface of the tunnel inner wall is sandblasted to achieve a roughness Ra≥50μm.

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