Joining tunnel supporting structure component applicable to multidirectional deformation and construction method

Abstract

The invention is suitable for the technical field of tunnel engineering, and provides a tunnel supporting structure joining component suitable for multidirectional deformation and a construction method. The joined tunnel supporting structure component applicable to multi-directional deformation comprises a multi-directional movable columnar crown-shaped truss component and foamed concrete, the whole truss component is columnar, is arranged between the inner wall of a tunnel and surrounding rock, and comprises a plurality of groups of truss movable rods, and each group of truss movable rods are bent into a plurality of crown shapes; the truss movable rods are sequentially arranged in the length direction of the tunnel. Every two adjacent groups of truss movable rods are connected through a telescopic joint; one end of each hinge joint is connected with the corresponding truss part, and the other end of each hinge joint is hinged to the inner wall of the tunnel; the space between the tunnel inner wall and the surrounding rock is filled with the foamed concrete, and the truss component is wrapped between the tunnel inner wall and the surrounding rock. According to the embodiment of the invention, the integrity of the overall structure of the tunnel can be protected through multi-directional deformation and the preset damage position.

Description

Technical Field

[0001] The present application relates to the technical field of tunnel engineering, and particularly relates to a connecting tunnel support structure component applicable to multi-directional deformation and a construction method thereof. Background Art

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

[0003] A new type of multi-level seismic isolation and vibration reduction structure for tunnels crossing active fault zones is disclosed in Related Art One. A portal seismic isolation and vibration reduction structure and a seismic isolation and vibration reduction structure for the broken zone of the tunnel body are sequentially arranged longitudinally in the tunnel. The portal seismic isolation and vibration reduction structure and the seismic isolation and vibration reduction structure for the broken zone of the tunnel body each include multiple sub-structures, and each sub-structure adopts a multi-level seismic isolation layer design in the tunnel cross-section. Related Art One reduces the damage suffered by the overall tunnel through the method of multi-level energy dissipation and vibration reduction and reserves a dislocation displacement activity area. However, this method will disturb the surrounding rock during construction, reduce its stability, easily cause collapses, endanger construction safety, and also affect the later use of the tunnel.

[0004] A tunnel shock-absorbing lining structure and its usage method are disclosed in Related Art Two. The overall structure is composed of a lining main body, a movable connecting piece, a compensating piece and multiple energy-absorbing bodies. A buffer gap is reserved between two adjacent lining main bodies; the movable connecting piece is concentrically and movably arranged at the end of the lining main body, so that the lining main body and the movable connecting piece can perform relative rotation in the radial direction; the compensating piece is slidably arranged along the tunnel axis between two adjacent movable connecting pieces, so that the lining main body and the compensating piece can perform relative displacement in the axial direction; multiple energy-absorbing bodies are circumferentially distributed in the buffer gap, and both ends of the energy-absorbing body are movably connected to the side walls of the cross-sections of adjacent lining main bodies respectively. Related Art Two can make the lining main bodies perform radial rotation through the setting of the movable connecting piece, so that the lining structure has a certain flexibility to adapt to impact forces in different directions. Although Related Art Two can perform shock absorption and anti-displacement through the setting of shock-absorbing materials, its shock isolation effect is restricted by various factors such as seismic waves and geological conditions and is difficult to play a stable role.

[0005] The inventors of the present application have found through research that: the research on performance enhancement components at the tunnel connection part is relatively less. How to provide a tunnel connection part support structure component that is applicable to multi-directional deformation and can protect the integrity of the overall tunnel structure is a technical problem to be solved in this field. Summary of the Invention

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

[0007] In order to achieve the above objectives, this application adopts the following technical solutions: In a first aspect, an embodiment of the present application provides a connecting tunnel support structure component applicable to multi-directional deformation, including a multi-directional movable columnar crown truss component and foamed concrete; The multi-directionally movable columnar crown-shaped truss component is columnar in shape as a whole and is arranged between the inner wall of the tunnel and the surrounding rock; the multi-directionally movable columnar crown-shaped truss component includes multiple groups of truss movable rods, each group of truss movable rods is bent into multiple crowns and is columnar in shape as a whole, and two adjacent crowns point in opposite directions in the axial direction of the column; the multiple groups of truss movable rods are arranged in sequence along the length direction of the tunnel and are all arranged between the inner wall of the tunnel and the surrounding rock; two adjacent groups of truss movable rods are connected by multiple telescopic joints; both ends of each group of truss movable rods are provided with hinged interfaces, one end of the hinged interface is hinged to the truss movable rod and the other end is hinged to the inner wall of the tunnel; The foamed concrete is filled between the inner wall of the tunnel and the surrounding rock, and the multi-directionally movable columnar crown-shaped truss components are covered between the inner wall of the tunnel and the surrounding rock.

[0008] Based on the first aspect, in some embodiments, the material of the multi-directionally movable columnar crown-shaped truss component is high-ductility and low-yield point steel, the elastic modulus of the high-ductility and low-yield point steel is 160MPa-225MPa, the yield strength ratio is 0.6-0.8, and the yield strength is ≥800MPa.

[0009] Based on the first aspect, in some embodiments, each group of truss movable rods has a plurality of movable nodes, and each movable node is provided with an auxiliary reinforcement component for reinforcing the movable node, and the auxiliary reinforcement component is fixed at the movable node by bolts.

[0010] Based on the first aspect, in some embodiments, each group of truss movable rods includes multiple sections of steel bars, multiple bolts and multiple auxiliary reinforcement components, and the auxiliary reinforcement components are EPDM rubber washers or springs; a section of steel bars is arranged between two adjacent movable nodes in each group of truss movable rods, and the two sections of steel bars are connected by bolts, and the rubber washers or springs are arranged between the two sections of steel bars through screws to form the crown shape; the connecting part between the two sections of steel bars is the movable node.

[0011] Based on the first aspect, in some embodiments, a hinge base is pre-buried at a position corresponding to the hinge interface on the outer side surface of the inner wall of the tunnel, 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.

[0012] Based on the first aspect, in some embodiments, the hinge interface is concave-shaped, and each hinge interface corresponds to two hinge bases. The two ends of the concave shape are respectively fixed on the corresponding two hinge bases, and the middle part of the concave shape is hinged to the truss movable rod.

[0013] In a second aspect, an embodiment of the present application provides a construction method for a connecting tunnel support structure component applicable to multi-directional deformation. The construction method includes: Circularly install the multi-directionally movable columnar crown-shaped truss component on the outer side of the inner wall of the tunnel, and hinge the hinge interface of the truss movable rod to the hinge base embedded in the inner wall of the tunnel; Erect temporary formworks on both sides of the tunnel so that the multi-directionally movable columnar crown-shaped truss component is located in the pouring space surrounded by the temporary formwork and the inner wall of the tunnel; Pour foamed concrete into the pouring space in layers so that the multi-directionally movable columnar crown-shaped truss component is completely covered by the foamed concrete; wherein, the foamed concrete is poured in multiple layers, and the thickness of each layer is ≤ 300 mm, and a vibrating device is used to vibrate each layer of foamed concrete during the layered pouring to discharge the air bubbles in the foamed concrete; After the foamed concrete begins to set, remove the temporary formwork and cure the initially set foamed concrete for a preset time.

[0014] Based on the second aspect, in some embodiments, when using a vibrating device to vibrate each layer of foamed concrete during the layered pouring, the vibration spacing is ≤ 50 cm, and the single-point vibration time is 20 seconds to 30 seconds.

[0015] Based on the second aspect, in some embodiments, a deformation compensation space of 3 cm - 5 cm is reserved between the multi-directionally movable columnar crown-shaped truss component and the inner wall of the tunnel.

[0016] Based on the second aspect, in some embodiments, the construction method further includes: Clean the outer side of the inner wall of the tunnel to ensure that the outer side of the inner wall of the tunnel is flat and free of debris; Perform sandblasting treatment on the outer side of the inner wall of the tunnel so that the roughness Ra of the outer side of the inner wall of the tunnel is ≥ 50 μm.

[0017] The beneficial effects of the embodiments of the present application compared with the prior art include: In the embodiments of the present application, foamed concrete has the characteristics that its strength is lower than that of common concrete, and it is prone to cracking and damage under large stresses. The embodiments of the present application utilize this characteristic to set the position where the foamed concrete is located as a pre-damage position. When the main structure of the tunnel is affected by seismic motion, the foamed concrete will absorb most of the stress energy and release energy by means of cracking and damage, causing the damage to concentrate at the preset damage position, preventing the main structure of the tunnel from being damaged or reducing the degree of damage to the main structure of the tunnel, thereby ensuring the integrity of the tunnel column structure.

[0018] Moreover, the multi-directionally movable columnar crown-shaped truss member has the characteristics of being compressible, expandable, and deformable in multiple directions. The embodiments of the present application utilize this characteristic to buffer and consume external force energy through the contraction and expansion deformation of the multi-directionally movable columnar crown-shaped truss member.

[0019] It can be seen that the embodiments of the present application protect the integrity of the overall tunnel structure through multi-directional deformation and preset damage positions. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0021] Figure 1 Structural schematic diagram of the adaptable multi-directional deformation connecting tunnel support structure member provided by the embodiment of the present application; Figure 2 Stereoscopic structural schematic diagram of the multi-directionally movable columnar crown-shaped truss member provided by the embodiment of the present application; Figure 3 For Figure 2 front view; Figure 4 For Figure 3 right view; Figure 5 Structural schematic diagram of a group of truss movable rods provided by the embodiment of the present application; Figure 6 Connection schematic diagram between the truss movable rod, the articulated interface and the connection base provided by the embodiment of the present application; Figure 7 Structural schematic diagram of the movable node provided by the embodiment of the present application; Figure 8 Flow schematic diagram of the construction method of the adaptable multi-directional deformation connecting tunnel support structure member provided by the embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present application will be described more clearly in conjunction with specific embodiments below. The following 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 form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made. These all belong to the protection scope of the present application.

[0023] To make the purpose, technical solutions and advantages of the present application clearer, the following will be described through specific embodiments in conjunction with the accompanying drawings.

[0024] See Figures 1 to 5 , the connective tunnel support structure component applicable to multi-directional deformation provided in the embodiment of the present application includes a multi-directionally movable columnar crown-shaped truss component 30 and foamed concrete 40.

[0025] The multi-directionally movable columnar crown-shaped truss component 30 is columnar as a whole and is arranged between the tunnel inner wall 10 and the surrounding rock 20. The multi-directionally movable columnar crown-shaped truss component 30 includes multiple groups of truss movable rods 31. Each group of truss movable rods 31 is bent into multiple crown shapes and is columnar as a whole. The adjacent two crown shapes point in opposite directions along the axial direction of the column. The multiple groups of truss movable rods 31 are arranged in sequence along the length direction of the tunnel and are all arranged between the tunnel inner wall 10 and the surrounding rock 20; the adjacent two groups of truss movable rods 31 are connected by multiple telescopic joints 32. Hinge interfaces 50 are arranged at both ends of the multi-directionally movable columnar crown-shaped truss component 30. One end of the hinge interface 50 is connected to the multi-directionally movable columnar crown-shaped truss component 30, and the other end is hinged to the tunnel inner wall 10.

[0026] The foamed concrete 40 is filled between the tunnel inner wall 10 and the surrounding rock 20, and the multi-directionally movable columnar crown-shaped truss component 30 is wrapped between the tunnel inner wall 10 and the surrounding rock 20.

[0027] The working principle of the multi-directionally movable columnar crown-shaped truss component 30 will be described below. The curvature at the crown-shaped position of the truss movable rod 31 changes with the change of the stress it receives: an increase in the radially inward stress makes the curvature at the crown-shaped position larger, so as to achieve the effect of shrinking in the radial direction; on the contrary, an increase in the radially outward stress makes the curvature at the crown-shaped position smaller, so as to achieve the effect of expanding in the radial direction. Multiple groups of truss telescopic rods 31 are connected through telescopic joints 32, and the curvature near the position of the telescopic joint 32 changes with the change of the stress it receives: an increase in the axially inward stress makes the curvature near the position of the telescopic joint 32 larger, so as to achieve the effect of shrinking in the axial direction; on the contrary, an increase in the axially outward stress makes the curvature near the position of the telescopic joint 32 smaller, so as to achieve the effect of expanding in the axial direction. Therefore, when the above-mentioned multi-directionally movable columnar crown-shaped truss component 30 is subjected to external stress, it can deform in the radial and / or axial directions, achieving the effect of shrinking / expanding in the radial and / or axial directions to prevent or mitigate the damage of the tunnel inner wall caused by external stress. Among them, the above-mentioned radial and axial directions are determined based on the columnar shape of the overall multi-directionally movable columnar crown-shaped truss component 30.

[0028] As Figure 5 shown, the truss movable rod 31 is integrally columnar, sleeved on the outer side of the tunnel inner wall 10, and there is a certain gap between it and the tunnel inner wall 10. The truss movable rod 31 is bent into multiple crown shapes, with the head and tail closed, and the adjacent two crown shapes point in opposite directions in the axial direction of the column. Similar to a wavy line, the two ends of the wavy line are connected to form a column, and the wave crests and wave troughs of the wavy line are the above-mentioned crown shapes.

[0029] Exemplarily, hinge interfaces 50 are provided at both ends of the multi-directionally movable columnar crown-shaped truss component 30. Specifically, it can be: among the multiple groups of truss telescopic rods 31 of the multi-directionally movable columnar crown-shaped truss component 30, hinge interfaces 50 are provided on the two groups of truss telescopic rods 31 located at both ends. For example, it can be that hinge interfaces 50 are provided at the crown-shaped positions near the outer sides of the two groups of truss telescopic rods 31 located at both ends (as Figure 5 and Figure 6 shown).

[0030] In some embodiments, the material of the multi-directionally movable columnar crown-shaped truss component 30 can be high-ductility low-yield-point steel. The elastic modulus of this high-ductility low-yield-point steel is 160 MPa - 225 MPa, the yield ratio is 0.6 - 0.8, and the yield strength ≥ 800 MPa. Among them, if the yield ratio is too high, the steel has insufficient plasticity, is prone to fracture, has stress concentration, and poor seismic resistance; if the yield ratio is too low, the steel has insufficient bearing capacity and low yield strength.

[0031] In the embodiment of the present application, each group 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, and the auxiliary reinforcement component may be fixed at the movable node by bolts.

[0032] In the embodiment of the present application, auxiliary reinforcement components are added to the active nodes to reinforce the active nodes, which can greatly improve the tensile pressure and elastic deformation effect of the truss active rod 31, enhance the fatigue resistance and shear resistance of the truss active rod 31, and improve the service life. Among them, the active node corresponds to the fatigue-prone position of the truss active rod 31, that is, the position of the crown top of the truss active rod 31, and one crown top corresponds to one active node.

[0033] Specifically, each group of truss movable rods 31 may include multiple sections of steel bars, multiple bolts and multiple auxiliary reinforcement components, the auxiliary reinforcement components are EPDM rubber washers or springs, and a section of steel bars is arranged between two adjacent movable nodes in each group of truss movable rods 31. The two sections of steel bars are connected by bolts to form the above-mentioned crown shape, and the connection between the two sections of steel bars is the movable node. The multiple sections of steel bars are connected together to form a Figure 5 See the shape shown. Figure 7 The two sections of steel bars 311 are connected together by bolts 312, and an auxiliary reinforcement component 313 is arranged between the two sections of steel bars 311. The auxiliary reinforcement component 313 is a rubber washer or a spring. The rubber washer or spring passes through the screw and is arranged between the two sections of steel bars 311 to prevent the connection ends of the two sections of steel bars 311 from directly contacting each other.

[0034] like Figure 4 As shown, in some embodiments, an articulated base 11 is pre-buried at a position corresponding to the articulated interface 50 on the outer side surface of the tunnel inner wall 10 , both ends of the articulated interface 50 are fixed on the articulated base 11 , and the middle part of the articulated interface 50 is hinged to the truss movable rod 31 .

[0035] For example, the hinge base 11 may be a steel plate, and bolt holes may be provided on the hinge base 11, so that the hinge base 11 can be more firmly fixed to the tunnel inner wall 10 by bolts. One end of each hinge interface 50 may correspond to one hinge base 11.

[0036] For an example, see Figure 3 The articulated interface 50 may be in a concave shape, each articulated interface 50 corresponds to two articulated bases 11 , the two ends of the concave shape are respectively fixed on the corresponding two articulated bases 11 , and the middle part of the concave shape is hinged to the truss movable rod 31 .

[0037] In the embodiments of the present application, the density of the foamed concrete 40 is greater than 2200 kg / m³, the tensile strength is 1.0 MPa to 1.2 MPa, and the elastic modulus is 1.5 GPa to 5 GPa. Among them, the water-cement ratio selected for the foamed concrete 40 is 0.53:1, and sodium lignosulfonate accounting for 0.2% - 0.3% of the cement mass is added as a water reducer.

[0038] This foamed concrete uses 42.5-grade portland cement as the matrix, incorporates 30% fly ash to improve crack resistance, uses a protein-based foaming agent diluted by 1:35 and prepares closed-cell foam with an average pore diameter of 0.3 mm through a high-pressure foaming machine. The water-cement ratio is strictly controlled at 0.53:1 and 0.25% sodium lignosulfonate water reducer is added to make the slump of the fresh concrete reach 180 mm to meet the pumping requirements. It is mixed for 3 minutes at a speed of 240 r / min by a twin-shaft planetary mixer to ensure that the foam volume ratio is stable at 35% - 40%. After final setting, a honeycomb structure with a density of 2200 kg / m³ and an elastic modulus of 3.2 GPa is formed. When the foamed concrete is under shear stress, the internal microporous structure preferentially undergoes directional crushing, and together with the tensile strength of 1.1 MPa, it realizes controllable cracking and can absorb seismic energy.

[0039] It can be seen that the foamed concrete has characteristics such as low density, low strength, many internal pores, and easy fragmentation. Therefore, when affected by large seismic stresses, the foamed concrete will crack and be damaged. At the same time, the foamed concrete has a certain water absorption rate, which will shorten its service life. Therefore, by adding a water reducer during the preparation of the foamed concrete, the water absorption rate of the foamed concrete can be reduced and its impermeability can be improved, which can extend the service life of the foamed concrete under normal circumstances and can prevent the multi-directionally movable columnar crown-shaped truss member 30 from rusting and corroding.

[0040] In some embodiments, considering the balance relationship between the movement range and stability, the rotation angle of the movable node can be set to ±15°; considering the displacement compensation requirements and the limitations of the structural dimensions, the stroke of the telescopic joint 32 can be set to ±50 mm. In addition, the Shore hardness of the ethylene propylene diene monomer rubber gasket can be 80A, the spring can be a disc spring, and the stiffness coefficient can be 50 N / mm - 80 N / mm.

[0041] In the embodiments of the present application, the foamed concrete has the characteristics that its strength is lower than that of common concrete and it is prone to cracking and damage under large stresses. The embodiments of the present application utilize this characteristic to set the position where the foamed concrete is located as a pre-destruction position. When the tunnel main structure is affected by seismic motion, the foamed concrete will absorb most of the stress energy and release energy by cracking and damage, making the damage concentrated at the preset destruction position, preventing the tunnel main structure from being damaged or reducing the degree of damage to the tunnel main structure, thereby ensuring the integrity of the tunnel column structure.

[0042] Moreover, the multi-directionally movable columnar crown truss member has the characteristics of being compressible, expandable, and deformable in multiple directions. In the embodiments of the present application, this characteristic is utilized to buffer and consume external force energy through the contraction and expansion deformation of the multi-directionally movable columnar crown truss member. In addition, after the ground motion disappears, since the truss structure itself has a certain elasticity, it can recover to a certain extent after the external force disappears, thereby continuing to support the tunnel.

[0043] Based on the above-mentioned connecting tunnel support structure member applicable to multi-directional deformation, the embodiments of the present application further provide a construction method for the connecting tunnel support structure member applicable to multi-directional deformation.

[0044] See Figure 8 , the construction method of the connecting tunnel support structure member applicable to multi-directional deformation may include steps 801 to 805, which are described in detail as follows: Step 801, embed a hinge base at a preset position on the inner wall of the tunnel and fix the hinge base in the inner wall of the tunnel.

[0045] Among them, the hinge base can be a steel plate, and bolt holes can be provided on the hinge base. The hinge base is fixed more firmly in the inner wall of the tunnel through bolts. For example, a torque wrench can be used to lock the bolts with a torque value of 10 kN·m - 15 kN·m.

[0046] If the torque is too large, the rigidity of the component is too strong and it cannot absorb energy; if the torque is too small, the stiffness is insufficient and the tightness is insufficient, which is likely to cause dislocation. The torque value indirectly reflects the axial pre-tightening force of the bolt. The setting range of 10 kN·m - 15 kN·m ensures that the pre-tightening forces of all bolts are evenly distributed, avoiding local overload or insufficient pre-tightening.

[0047] Specifically, the lower limit value of 10 kN·m can ensure sufficient pre-tightening force. The torque value directly determines the pre-tightening force of the bolt. The pre-tightening force is calculated through the torque-pre-tightening force formula T = K×F×d, where T is the torque, F is the pre-tightening force, d is the nominal diameter of the bolt, and K is the torque coefficient. The lower limit value ensures that the bolt connection maintains sufficient clamping force under the working load, preventing connection loosening, slipping, or vibration failure caused by insufficient pre-tightening force. Moreover, it can also offset the influence of external loads. If there is axial tension or shear force during operation, sufficient pre-tightening force can keep the joint surface in close contact, avoiding relative displacement of components.

[0048] The upper limit value of 15 kN·m can prevent the bolt from overloading and failing. Exceeding the yield strength or tensile strength of the bolt material will cause plastic deformation (elongation) or fracture of the bolt. The upper limit value ensures that the torque does not exceed the safe working range of the bolt, avoiding bolt fracture, thread slipping, or crushing of the connected parts due to excessive pre-tightening force. Additionally, considering the fluctuation of the friction coefficient, the actual pre-tightening force of the torque wrench is affected by the friction coefficients of the thread pair and the supporting surface (such as lubrication state, surface roughness). The upper limit value reserves a safety margin to prevent the actual pre-tightening force from exceeding the bolt's load-bearing capacity due to a decrease in the friction coefficient (such as after applying lubricant).

[0049] Step 802: Install the multi-directionally movable columnar crown-shaped truss component around the outer side of the tunnel inner wall, and hinge the hinge interface of the truss movable rod with the hinge base embedded in the tunnel inner wall.

[0050] For example, each group of truss movable rods can be sequentially sleeved on the outer side of the tunnel inner wall. Hinge interfaces are provided at the crown-shaped positions on the outer sides of the two groups of truss movable rods at both ends. Align the hinge interfaces with the hinge bases embedded in the tunnel inner wall to adjust the positions of each group of truss movable rods. Then, hinge the hinge interfaces with the hinge bases embedded in the tunnel inner wall.

[0051] Optionally, after step 802, the construction method further includes: setting ethylene propylene diene monomer (EPDM) rubber gaskets or springs at the movable joints of each group of truss movable rods for strengthening the movable joints. Among them, the EPDM rubber gaskets or springs can be fixed at the movable joints of each group of truss movable rods through bolts.

[0052] For example, the Shore hardness of the EPDM rubber gasket can be 80A, the spring can be a disc spring, and the stiffness coefficient of the disc spring can be 50 N / mm - 80 N / mm. A torque wrench can be used to tighten the bolts with a pre-tightening force of 20 kN - 30 kN to fix the EPDM rubber gaskets or springs at the movable joints of each group of truss movable rods.

[0053] In the embodiment of the present application, a deformation compensation space of 3 cm - 5 cm should be reserved between the multi-directionally movable columnar crown-shaped truss component and the tunnel inner wall.

[0054] Step 803: Erect temporary formworks on both sides of the tunnel so that the multi-directionally movable columnar crown-shaped truss component is located in the pouring space enclosed by the temporary formworks, the tunnel inner wall, and the surrounding rock.

[0055] Among them, the foamed concrete will shrink to a certain extent during the solidification process. To compensate for the influence of shrinkage, a 3‰ camber can be set for the temporary formwork. In this way, after the foamed concrete solidifies and shrinks, the surface of the foamed concrete will be relatively flat without depression.

[0056] During the solidification process, foamed concrete will undergo drying shrinkage and chemical shrinkage due to water evaporation, hydration reactions of cementitious materials, etc. Due to its porous structure, the shrinkage rate of foamed concrete may be slightly higher than that of ordinary concrete. However, through experimental tests (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‰). The pre-camber is set at the same ratio as the shrinkage rate (3‰). Essentially, it offsets the depression caused by shrinkage through "reverse preset deformation" to make the final surface flat.

[0057] Step 804, pour the foamed concrete into the pouring space in layers so that the multi-directionally movable columnar crown-shaped truss members are completely covered by the foamed concrete.

[0058] Among them, the foamed concrete can be poured in multiple layers (such as 3 layers), with the thickness of each layer ≤ 300 mm. And when pouring the foamed concrete in layers, a vibrating device is used to vibrate each layer of foamed concrete to discharge the air bubbles in the foamed concrete.

[0059] Exemplarily, a pouring hole can be opened on the inner wall of the tunnel, and the foamed concrete is poured into the pouring space through this pouring hole. The vibrating device can be an inserted vibrating device, and the vibrating device is inserted into the pouring space through this pouring hole to vibrate each layer of foamed concrete.

[0060] The action range of the vibrating device is limited (usually the effective action depth of the vibrating rod is about 300 - 500 mm). A thickness of each layer ≤ 300 mm can ensure that the vibrating force is evenly transmitted to the entire pouring layer, avoiding the inability to discharge the air bubbles in the lower layer due to excessive single pouring thickness. If the single pouring is too thick, the lower-layer concrete may form a "bubble retention layer" due to insufficient vibrating force, resulting in local looseness and uneven strength. Pouring in layers makes each layer of concrete within the optimal action range of the vibrating device, ensuring that the excess air in the foamed concrete is fully discharged, and improving the material density and integrity.

[0061] In addition, when using the vibrating device to vibrate each layer of foamed concrete, the vibrating spacing is 30 cm - 50 cm, and the single-point vibrating time can be 20 seconds to 30 seconds.

[0062] The effective action range of the vibrating equipment is limited. Generally, the influence radius of single-point vibration is about 20 cm - 25 cm. Therefore, to ensure that there is no blind area in the vibration coverage, since the fluidity of the foamed concrete is relatively low, the vibration spacing is set to ≤ 50 cm. If the vibration spacing is greater than 50 cm, the action areas of adjacent vibration points cannot overlap, which may cause vibration omission in the middle area, forming defects such as honeycombs and holes, affecting the compactness and integrity of the concrete. In addition, a reasonable vibration spacing can make the vibration force evenly transmitted, avoiding local over-vibration or under-vibration. If the vibration spacing is too close (< 30 cm), it may cause the adjacent bubbles in the foamed concrete to rupture and fuse, destroying the bubble structure; if the vibration spacing is too far (> 50 cm), it may cause bubbles to aggregate or concrete particles to accumulate due to insufficient vibration, affecting the strength and durability.

[0063] If the single-point vibration time of the foamed concrete is too long (> 30 seconds), it may cause bubbles to rupture (especially when the power of the vibrating equipment is relatively high), which will destroy the lightweight characteristics of the foamed concrete and may also cause the separation of the aggregate and cement paste in the foamed concrete, affecting the material uniformity. And if the single-point vibration time is too short (< 20 seconds), the excess air in the foamed concrete cannot be fully discharged. The single-point vibration time is set to 20 seconds - 30 seconds, which is the balance time between "discharging excess air" and "protecting effective bubbles", which can not only make the foamed concrete particles tightly wrap the bubbles, but also not damage the bubble stability.

[0064] Based on the integrity of the scheme, the preparation process of the foamed concrete slurry is introduced below.

[0065] Foamed concrete is a lightweight porous material formed by uniformly introducing foam into a cement-based slurry and undergoing hydration and hardening, containing a large number of closed pores. The core raw materials include cementitious materials, aggregates, foaming agents, foam stabilizers and water. The cementitious materials include Portland cement, and active admixtures such as fly ash, silica fume, and slag powder can be added.

[0066] 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 (water content < 1%); diluting the foaming agent with water (for example, 1 kg of foaming agent stock solution is diluted with 30 kg - 50 kg of water).

[0067] Then, a foam machine (high-pressure air type / mechanical stirring type) is used to prepare foam. The diluted foaming liquid is added to the foam machine, and compressed air is introduced or high-speed stirring is carried out to generate foam (foam density 815 kg / m³, the proportion of bubbles with a diameter of 0.21 mm ≥ 80%). The air flow rate of the foam machine is 510 m³ / h, and the stirring speed is 800 rpm - 1500 rpm. The prepared foam needs to be used within 30 minutes to avoid defoaming (or a foam stabilizer solution can be dropped to improve stability).

[0068] After that, the cement paste is stirred. The first stage (dry mixing): Put cement, admixture, and aggregate into the mixer and stir at a low speed for 1 minute (rotation speed 50 - 80 rpm) until evenly mixed. The second stage (wet mixing): Add water and admixtures (such as water reducer / early strength agent, etc.), and stir at a medium speed for 23 minutes (rotation speed 100 - 150 rpm) until the paste has no lumps and uniform fluidity (slump 180 mm - 220 mm, adjusted according to the forming method).

[0069] After that, the cement paste is mixed with foam. Add the foam to the cement paste in multiple times. After each addition of foam, stir at a low speed for 30 seconds - 60 seconds (rotation speed ≤ 50 rpm), and adopt the method of "turning and swirling" to ensure that the foam is evenly dispersed. Among them, the volume of the foam accounts for 60% - 80% of the total volume of the mixture. In addition, 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 volume of the foam is about 3 times that of the cement paste volume). Thus, the paste of the foamed concrete is obtained.

[0070] Before pouring the paste of the foamed concrete into the pouring space, first coat the inner wall of the pouring space with a release agent (such as a mixture of machine oil and diesel oil, mixing ratio 1:3), or lay a polyethylene film on the inner wall of the pouring space to avoid sticking to the mold. After that, pour the paste of the foamed concrete into the pouring space in layers through the pouring hole. How to pour the paste of the foamed concrete into the pouring space, please refer to the relevant content above and will not be elaborated here.

[0071] Optionally, before step 804, this construction method further includes: cleaning the outer side of the tunnel inner wall to ensure that the outer side of the tunnel inner wall is flat and free of debris; performing sandblasting treatment on the outer side of the tunnel inner wall so that the roughness Ra of the outer side of the tunnel inner wall ≥ 50 μm.

[0072] When filling with sealing materials or performing other connection treatments subsequently, a roughness Ra ≥ 50 μm can provide a larger surface area, enabling the sealing material or connection material to better bite and bond with the joint surface, thereby ensuring the sealing and firmness of the connection and effectively preventing problems such as leakage and deformation of the tunnel during use. Appropriate roughness can increase the friction coefficient between the two joint surfaces. When the tunnel is subjected to external forces such as earthquakes and ground movements, it can better resist relative sliding and improve the stability and safety of the tunnel structure.

[0073] If the roughness is lower than 50 μm, the outer side of the tunnel inner wall is relatively smooth, and the bonding force between the foamed concrete and the outer side may be insufficient. During long-term use, the foamed concrete may fall off or fail, resulting in gaps between the outer side of the tunnel inner wall and the foamed concrete, affecting the waterproof performance and structural stability of the tunnel. A relatively smooth joint surface is not conducive to forming an effective seal, and it is easy for media such as water and air to enter the tunnel interior through the gaps in the joint surface, causing corrosion and damage to the facilities inside the tunnel, and at the same time affecting the use function and safety of the tunnel.

[0074] Step 805: After the foamed concrete begins to set, remove the temporary formwork and cure the initially set foamed concrete for a preset time.

[0075] For example, a permeable geotextile can be covered on the initially set foamed concrete, and a curing agent can be sprayed, and it is cured for at least 7 days in a constant temperature and humidity environment with a temperature of 20 ± 2 °C and a humidity of ≥ 95%. The density of the solidified foamed concrete 40 is greater than 2200 kg / m³, the tensile strength is 1.0 MPa to 1.2 MPa, and the elastic modulus is 1.5 GPa to 5 GPa.

[0076] The above construction method is applicable to tunnel projects under complex geological conditions such as active fault zones and soft soil settlement areas, and has both structural safety and construction controllability.

[0077] The above-described embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements 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 in the protection scope of the present invention.

Claims

1. A tunnel support structure component applicable to multi-directional deformation, characterized in that: It includes multi-directional movable column-shaped crown truss components and foamed concrete; The multi-directionally movable columnar crown-shaped truss component is columnar in shape as a whole and is arranged between the inner wall of the tunnel and the surrounding rock; the multi-directionally movable columnar crown-shaped truss component includes multiple groups of truss movable rods, each group of truss movable rods is bent into multiple crowns and is columnar in shape as a whole, and two adjacent crowns point in opposite directions in the axial direction of the column; the multiple groups of truss movable rods are arranged in sequence along the length direction of the tunnel and are all arranged between the inner wall of the tunnel and the surrounding rock; two adjacent groups of truss movable rods are connected by multiple telescopic joints; both ends of the multi-directionally movable columnar crown-shaped truss component are provided with hinged interfaces, one end of the hinged interface is connected to the multi-directionally movable columnar crown-shaped truss component, and the other end is hinged to the inner wall of the tunnel; The foamed concrete is filled between the inner wall of the tunnel and the surrounding rock, and the multi-directionally movable columnar crown-shaped truss components are covered between the inner wall of the tunnel and the surrounding rock.

2. The multi-directionally deformable connecting tunnel support structure component according to claim 1 is characterized in that: The multi-directionally movable columnar crown-shaped truss component is made of high-ductility low-yield point steel, the elastic modulus of which is 160MPa-225MPa, the yield strength ratio is 0.6-0.8, and the yield strength is ≥800MPa.

3. The connecting tunnel support structure component applicable to multi-directional deformation according to claim 1 is characterized in that: Each group of truss movable rods has a plurality of movable nodes, and each movable node is provided with an auxiliary reinforcement component for reinforcing the movable node, and the auxiliary reinforcement component is fixed at the movable node by bolts.

4. The connecting tunnel support structure component applicable to multi-directional deformation according to claim 3 is characterized in that: Each group of truss movable rods includes multiple sections of steel bars, multiple bolts and multiple auxiliary reinforcement components, and the auxiliary reinforcement components are EPDM rubber washers or springs; a section of steel bars is arranged between two adjacent movable nodes in each group of truss movable rods, and the two sections of steel bars are connected by bolts. The rubber washers or springs are arranged between the two sections of steel bars through screws to form the crown shape; the connecting part between the two sections of steel bars is the movable node.

5. The connecting tunnel support structure component applicable to multi-directional deformation according to claim 1 is characterized in that: A hinge base is pre-buried at a position corresponding to the hinge interface on the outer side surface of the tunnel inner wall, 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.

6. The connecting tunnel support structure component applicable to multi-directional deformation according to claim 5 is characterized in that: The hinged interface is in a concave shape, each hinged interface corresponds to two hinged bases, the two ends of the concave shape are respectively fixed on the corresponding two hinged bases, and the middle part of the concave shape is hinged to the truss movable rod.

7. A construction method for connecting tunnel support structure components applicable to multi-directional deformation, characterized in that: The construction method comprises: Embedding a hinged base at a preset position on the inner wall of the tunnel, and fixing the hinged base in the inner wall of the tunnel; The multi-directionally movable columnar crown truss components are 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-buried in the tunnel inner wall; Temporary formwork is set up on both sides of the tunnel so that the multi-directionally movable columnar crown truss components are located in the casting space surrounded by the temporary formwork, the inner wall of the tunnel and the surrounding rock; The foamed concrete is poured into the pouring space in layers, so that the multi-directionally movable columnar crown-shaped truss components are completely covered by the foamed concrete; wherein the foamed concrete is poured in multiple layers, each layer having a thickness of ≤300 mm, and each layer of the foamed concrete is vibrated using a vibrating device during the layered pouring to discharge bubbles in the foamed concrete; After the initial setting of the foamed concrete, the temporary formwork is removed and the initial setting foamed concrete is cured for a preset time.

8. The construction method of the connecting tunnel support structure component applicable to multi-directional deformation according to claim 7 is characterized in that: When using vibrating equipment to vibrate each layer of foamed concrete during layered pouring, the vibration interval is ≤50cm, and the single-point vibration time is 20 seconds to 30 seconds.

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

10. The construction method of the connecting tunnel support structure component applicable to multi-directional deformation according to claim 7, characterized in that: The construction method also includes: Clean the outer side of the tunnel inner wall to ensure that it is flat and free of debris; The outer side surface of the inner wall of the tunnel is sandblasted so that the roughness Ra of the outer side surface of the inner wall of the tunnel is ≥50 μm.

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