Self-adaptive formwork assembly for wet spraying of concrete and wet spraying operation method of self-adaptive formwork assembly

Abstract

The invention discloses a self-adaptive formwork assembly for wet spraying of concrete, which comprises a movable connecting mechanism and a flexible formwork, and the movable connecting mechanism is mounted at one end of the flexible formwork and is used for connecting a spray head of a wet spraying trolley; the flexible formwork can generate elastic deformation through bending, so that the end, away from the movable connecting mechanism, of the flexible formwork is pressed on the steel arch support, the flexible formwork is bent to generate elastic deformation, and therefore the steel arch support, the flexible formwork and the sprayed face of the tunnel surrounding rock jointly define a dynamic spraying cavity. The movable connecting mechanism is a spherical hinge or a universal joint, so that when one end of the flexible formwork presses the steel arch support, the posture of the spray head is adjusted through a controller of the wet spraying trolley to spray concrete into the dynamic spraying cavity. According to the invention, spraying conditions can be improved, concrete resilience can be reduced, concrete compactness and bonding quality can be improved, material loss can be greatly reduced, continuous forming of concrete can be realized, and uniform thickness, flat surface and dense interior of a spraying layer can be ensured.

Description

Technical Field

[0001] This invention belongs to the field of tunnel construction technology, and more specifically, relates to an adaptive formwork assembly for wet sprayed concrete and a wet spraying operation method thereof. Background Technology

[0002] In modern tunnel construction, steel arch support is an important support method widely used in the initial support stage of tunnels. Steel arch support forms a stable support structure by installing steel arches in the surrounding rock, preventing rock collapse and ensuring construction safety. In the steel arch support system, spraying concrete into the gap between the steel arch support and the surrounding rock to form a combined support system is a key step in ensuring the stability of the tunnel structure and construction quality. Although this technology has been widely used in tunnel construction, traditional shotcrete construction methods still face many unresolved technical challenges, seriously affecting construction efficiency, quality, and the construction environment.

[0003] First, material waste has always been a major challenge in traditional shotcrete construction. During wet shotcrete operations, due to the considerable distance between the nozzle and the tunnel surrounding rock, the high-speed concrete jet impacts the sprayed surface. Concrete particles often detach from the sprayed surface due to insufficient adhesion, or rebound and splashing occur. This not only leads to a significant waste of concrete materials but also substantially increases construction costs. According to statistics, the overall material loss rate in traditional shotcrete construction is often as high as 30% or even higher. This means that for every 100 cubic meters of concrete sprayed, more than 30 cubic meters fail to adhere effectively to the sprayed surface, resulting in enormous resource waste.

[0004] Secondly, low construction quality and efficiency are also prominent problems faced by traditional shotcrete construction methods. Due to the uneven distribution of concrete jets and the existence of rebound, traditional shotcrete methods are difficult to achieve a full spray in one go, often requiring repeated re-spraying operations. This repeated re-spraying not only increases the construction process and prolongs the construction period, but also results in an uneven concrete surface and inconsistent thickness after spraying, seriously affecting the integrity and stability of the tunnel support structure. In addition, to ensure that the thickness of the shotcrete layer meets the design requirements, construction workers often need to perform a lot of manual cleaning and trimming work, which not only increases labor intensity but also seriously affects the construction progress.

[0005] Furthermore, the harsh construction environment is a significant drawback of traditional shotcrete construction methods. During spraying, the high-speed impact of the concrete jet on the sprayed surface generates a large amount of splashed material and dust. This dust and material not only severely deteriorates the working environment inside the tunnel, reduces visibility, and increases the labor intensity and health risks for construction workers, but may also lead to occupational diseases. In addition, the pervasive dust can impair the vision of construction workers, reducing construction safety and efficiency. To improve the construction environment, additional ventilation and dust removal measures are usually required, which not only increases construction costs but may also cause some pollution to the surrounding environment.

[0006] Besides the aforementioned problems, traditional shotcrete construction methods also have other technical limitations. For example, during the spraying process, the high-speed impact of the concrete jet makes it difficult to effectively guarantee the bonding quality between the concrete and the sprayed surface. Concrete rebound and spalling not only lead to material waste but also result in insufficient interlocking force between the concrete layer and the surrounding rock, affecting the overall load-bearing capacity of the support structure. Furthermore, traditional spraying methods struggle to precisely control the thickness of the sprayed layer, leading to uneven thickness and potential instances of excessively thick or thin layers. Excessively thick layers increase material costs and construction difficulty, while excessively thin layers fail to meet design load requirements, compromising tunnel safety. Summary of the Invention

[0007] In view of the above-mentioned defects or improvement needs of the prior art, the present invention provides an adaptive template component for wet sprayed concrete and a wet spraying operation method thereof, which can improve spraying conditions, reduce concrete rebound, improve concrete density and bonding quality, significantly reduce material loss, realize continuous molding of concrete, and ensure uniform thickness, smooth surface and dense interior of the sprayed layer.

[0008] To achieve the above objectives, according to one aspect of the present invention, an adaptive formwork assembly for wet-mix shotcrete is provided, comprising a movable connection mechanism and a flexible formwork, wherein: The movable connecting mechanism is installed at one end of the flexible template for connecting the nozzle of the wet spraying trolley; The flexible template is a template that can be bent to produce elastic deformation, so that the end of the flexible template away from the movable connection mechanism is pressed against the steel arch support to make the flexible template bend and produce elastic deformation, thereby making the steel arch support, the flexible template and the sprayed surface of the tunnel surrounding rock together form a dynamic spraying cavity. The movable connection mechanism is a ball joint or universal joint, which allows the attitude of the nozzle to be adjusted by the controller of the wet spraying trolley to spray concrete into the dynamic spraying chamber when the steel arch support is pressed at one end of the flexible template.

[0009] Preferably, the flexible template includes a template body, a reinforcing frame, and an anti-adhesion working surface, wherein: The main body of the template is made of polyurethane or rubber; The reinforcing skeleton is embedded in the part of the template body that comes into contact with the concrete. The reinforcing skeleton is made of aramid fiber mesh or carbon fiber prepreg. The side of the template body that comes into contact with the concrete is an anti-adhesion working surface, which is made of sintered Teflon coating or replaceable composite polyethylene film.

[0010] Preferably, the side of the template body away from the concrete is provided with a number of reinforcing ribs, which are parallel to each other, and each of the reinforcing ribs is integrally formed with the template body and extends in a direction parallel to the side edge of the template body; Along the middle of the template body towards both sides, the length of the reinforcing ribs gradually decreases, so that these reinforcing ribs are distributed in a rhomboid area.

[0011] Preferably, the Shore hardness of the portion of the template body in which the reinforcing skeleton is embedded is 60HD~75HD, and the elastic modulus is 150Mpa~300Mpa. The Shore hardness of the part of the template body that comes into contact with the steel arch support is 40HA~60HA, and the elastic modulus is 5MPa~15MPa.

[0012] Preferably, the template body has a load-bearing part for receiving concrete and two edge contact parts for contacting the steel arch support. Each edge contact part is respectively located on one side of the load-bearing part. The width of the template body is B, the width W1 of the load-bearing part is 0.7B~0.8B, and the width W2 of each edge contact part is 0.12B~0.15B. The width directions of the flexible template, the load-bearing part and the edge contact parts are all horizontal, and W1+2W2=B.

[0013] Preferably, the components of the edge contact portion are as follows: 100 parts of polyurethane prepolymer; 5-8 parts of nano-silica reinforced filler; 10-15 parts of lubricant, wherein the lubricant is selected from molybdenum disulfide or polytetrafluoroethylene.

[0014] Preferably, the portion of the flexible template that comes into contact with the steel arch support has an edge contact portion; Along the direction from the middle of the template body to the side edge, the thickness of the edge contact portion gradually decreases to reduce bending stiffness, thereby achieving adaptive fitting between the flexible template and the steel arch support.

[0015] Preferably, the edge contact portion is integrally formed with a labyrinth-shaped protrusion to achieve a sealed fit between the flexible template and the steel arch support.

[0016] Preferably, the flexible template is fitted with strain gauge sensors at the part where it is used to fit against the steel arch support, in order to obtain the pressure applied by the steel arch support to the flexible template.

[0017] According to another aspect of the present invention, a method for wet spraying concrete using the adaptive formwork assembly for wet sprayed concrete is also provided, comprising the following steps: S1. The movable connecting mechanism is detachably connected to the nozzle of the wet spraying trolley; S2. The mechanical arm of the wet spraying trolley drives the flexible template to move, so that the tail end of the flexible template presses against the side of the adjacent two steel arch supports away from the tunnel surrounding rock, and the tail end of the flexible template contacts the tunnel floor, so that the steel arch support, the flexible template and the sprayed surface of the tunnel surrounding rock together form a dynamic spraying chamber. S3. The controller of the wet spraying trolley adjusts the attitude of the nozzle so that the nozzle points to the bottom of the dynamic spraying chamber and the distance between the nozzle and the sprayed surface of the tunnel surrounding rock does not exceed 0.3m. S4. The concrete is sprayed into the dynamic spraying chamber at a spraying pressure of 0.1Mpa-0.2Mpa, wherein the initial setting time of the concrete is not greater than 5min and the final setting time is not greater than 10min. S5. Before the initial setting of the concrete, the mechanical arm of the wet spraying trolley drives the flexible template to climb along the steel arch support by installing the nozzle on the mechanical arm, and the tail end of the flexible template scrapes the plastic concrete during the climbing process. S6. Repeat steps S3 to S5 until concrete is sprayed onto the tunnel roof as well, then one spraying cycle is complete.

[0018] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1) The adaptive template assembly for wet-mix shotcrete of this invention, consisting of a flexible template, a steel arch support, and the sprayed surface of the tunnel surrounding rock, forms a dynamic spraying chamber. This structural feature alters the energy dissipation mechanism of the concrete jet. Within the dynamic spraying chamber, the high-speed sprayed concrete jet is no longer directly exposed in an open space but is constrained within a relatively closed geometric space. This physical constraint makes the kinetic energy conversion of the concrete on the sprayed surface more concentrated, reducing the loss of kinetic energy to ineffective spaces. Due to the lateral and rearward sealing of the chamber, the rebound path of the concrete flow after impacting the sprayed surface is blocked by the flexible template, forcing the rebounding material to undergo secondary or multiple impacts and re-attach within the chamber. This rebound and re-attachment mechanism significantly improves the initial adhesion rate of concrete to the surrounding rock and steel arch support.

[0019] 2) The adaptive formwork assembly for wet shotcrete of the present invention utilizes the flexible formwork's own elastic deformation capability to dynamically adjust according to the actual curvature and spacing of the steel arch support. This adaptability ensures that the edges of the formwork are always tightly pressed against the back of the steel arch support, adapting to installation deviations or irregular geometric shapes of the steel arch support. The elastic restoring force generated by the flexible formwork is converted into sealing pressure on the steel arch support. This sealing state effectively prevents cement slurry and fine aggregate from overflowing or leaking from the gap between the formwork and the arch during high-pressure shotcreting, ensuring the integrity of the shotcreting chamber.

[0020] 3) The adaptive formwork assembly for wet-mixed shotcrete of this invention features a movable connection mechanism that grants the nozzle independent degrees of freedom relative to the flexible formwork. While the steel arch support at the end of the formwork is clamped to maintain the chamber shape, the operator or controller can freely adjust the incident angle of the nozzle. This design allows the concrete jet to be directed at all dead corners at the bottom of the chamber at an optimal incident angle. Due to the presence of ball joints or universal joints, the nozzle can be adjusted to any posture within the conical envelope range. This means that within a fixed formwork stroke, full coverage of the internal space of the dynamic shotcrete chamber can be achieved, effectively avoiding the problem of incomplete support caused by shotcrete dead corners.

[0021] 4) The adaptive template assembly for wet-mixed shotcrete of this invention features a flexible template that can limit the sprayed concrete, allowing for precise physical definition of the concrete layer thickness. This replaces the traditional method of relying on experience to determine thickness, ensuring uniform support thickness and height across the entire tunnel cross-section, meeting design load requirements. The dynamic spraying chamber supports a continuous filling process from bottom to top. Within the confined space, the concrete achieves dense accumulation under the combined effects of gravity and spraying force, filling the gaps between the steel arch support and the surrounding rock. The concrete and steel arch support form a unified support structure, significantly enhancing the load-bearing capacity of the initial support structure.

[0022] 5) The adaptive template component for wet sprayed concrete of the present invention confines most of the dust and fine particles within the quasi-closed space of the dynamic spraying chamber, which greatly reduces the diffusion of dust to the entire cross section of the tunnel and can improve the construction environment inside the tunnel.

[0023] 6) The adaptive template assembly for wet shotcrete of the present invention, through high-pressure spraying within the confined space of the dynamic spraying chamber, enhances the interlocking force between concrete and surrounding rock, and between concrete and steel arch support. In particular, for the encapsulation of the steel arch support, due to the presence of chamber pressure, the concrete can tightly wrap around each flange of the arch, eliminating the risk of voids behind the arch. Attached Figure Description

[0024] Figure 1This is a side view of the nozzle on the adaptive template assembly for wet shotcrete of the present invention spraying onto the sprayed surface of the surrounding rock of a tunnel. Figure 2 This is a front view of the adaptive formwork assembly for wet shotcrete of the present invention when it is tightly attached to two steel arch supports; Figure 3 This is a three-dimensional schematic diagram of the adaptive formwork assembly for wet sprayed concrete of the present invention when it is tightly attached to two steel arch supports; Figure 4 This is the front view of the flexible template in this invention; Figure 5 This is a process flow diagram of the method of the present invention.

[0025] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1. Movable connection mechanism; 2. Flexible template; 3. Sprayer head; 4. Steel arch support; 21. Load-bearing part; 22. Edge contact part; 5. Sprayed surface; 6. Concrete; 7. Reinforcing ribs. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Reference Figures 1-4 An adaptive formwork assembly for wet-mix shotcrete includes a movable connection mechanism 1 and a flexible formwork 2, wherein: The movable connecting mechanism 1 is installed at one end of the flexible template 2 for connecting the nozzle 3 of the wet spraying trolley; The flexible template 2 is a template that can be bent to produce elastic deformation, so that the end of the flexible template 2 away from the movable connection mechanism 1 is pressed against the steel arch support 4 to make the flexible template 2 bend and produce elastic deformation, thereby making the steel arch support 4, the flexible template 2 and the sprayed surface 5 of the tunnel surrounding rock together form a dynamic spraying cavity. The movable connection mechanism 1 is a ball joint or universal joint, so that when the steel arch support 4 is pressed against one end of the flexible template 2, the attitude of the nozzle 3 is adjusted by the controller of the wet spraying trolley to spray concrete 6 into the dynamic spraying chamber.

[0028] The adaptive formwork assembly for wet shotcrete of the present invention achieves highly unified technical effects in ensuring construction quality, improving production efficiency, reducing material loss, and improving the working environment through the organic synergy of technical features such as physical constraints, elastic adaptation, multi-degree-of-freedom adjustment, and sliding forming. This lays a solid technical foundation for the intelligent and standardized construction of tunnel engineering.

[0029] Furthermore, the flexible template 2 includes a template body, a reinforcing frame, and an anti-adhesion working surface, wherein: The main body of the template is made of polyurethane or rubber; The template body is used to embed the reinforcing skeleton in the part that comes into contact with the concrete 6. The reinforcing skeleton is made of aramid fiber mesh or carbon fiber prepreg. The side of the template body that comes into contact with the concrete 6 is an anti-adhesion working surface, which is made of sintered Teflon coating or replaceable composite polyethylene film.

[0030] Polyurethane and rubber have excellent elastic recovery properties, which allows the formwork body to undergo large deformations when subjected to the compressive load of the wet spraying trolley robotic arm to adapt to the irregular arrangement of the steel arch support 4, and to quickly return to its original shape after the external force is removed, ensuring the geometric stability of the device in multi-cycle construction.

[0031] In a wet-sprayed tunnel environment, the formwork body must frequently withstand the lateral impact of high-speed concrete jets and the sliding friction between it and the steel arch support. Materials such as polyurethane have extremely high tear strength and abrasion resistance, which can effectively resist the impact of concrete and extend the physical life of the device under extreme working conditions.

[0032] By embedding aramid fiber mesh or carbon fiber prepreg within the formwork body, a composite reinforcement structure similar to reinforced concrete (6) is constructed. High-performance fibers (aramid or carbon fiber) possess extremely high tensile strength and extremely low elongation. This reinforcement skeleton effectively withstands the lateral earth pressure generated by wet-sprayed concrete, preventing excessive outward bulging deformation of the formwork body under pressure, thereby precisely controlling the uniformity of the support layer thickness. Compared to metal reinforcement materials, aramid and carbon fiber significantly reduce the self-weight of the formwork body while providing the same strength, reducing the load requirements on the end effector of the robotic arm. Simultaneously, this mesh-like or fabric-like skeleton does not impair the bending capacity of the formwork body in the normal direction, ensuring the technical characteristics of the formwork body being both rigid and flexible. By optimizing the fiber laying direction, the formwork body can exhibit good flexibility in the climbing direction and extremely high bending stiffness in the span direction across the two steel arch supports (4), thereby optimizing the mechanical boundary conditions of the dynamic spraying chamber.

[0033] Teflon or polyethylene film has an extremely low coefficient of friction and strong hydrophobicity. During the sliding ascent of the formwork body along the steel arch support 4, this anti-adhesion surface significantly reduces the shear force between the formwork body and the plastic concrete 6, preventing tearing or strain on the concrete surface caused by adhesion, and ensuring a smooth and even surface after molding. The anti-adhesion properties also prevent residual grout from forming scale on the formwork surface, significantly reducing labor costs and downtime for cleaning the formwork during construction breaks, thus ensuring continuous construction.

[0034] Furthermore, the side of the template body away from the concrete 6 is provided with several reinforcing ribs 7. These reinforcing ribs 7 are parallel to each other, and each reinforcing rib 7 is integrally formed with the template body and extends in a direction parallel to the side edge of the template body. After the side edge of the template body is bent, a part of it will press against the steel arch support 4.

[0035] The reinforcing ribs 7 are positioned slightly off-center from the bottom of the flexible template 2 to minimize their impact on the bending of the flexible template 2.

[0036] Because of the reinforcing ribs 7, when the concrete 6 applies pressure to the formwork body, the pressure of the concrete can be quickly and evenly transmitted to the reinforcing ribs 7 on the back through the main body material, and is borne by the entire load-bearing system, thus improving the load-bearing efficiency of the structure.

[0037] Along the middle of the template body towards both sides, the length of the reinforcing ribs 7 gradually decreases, so that these reinforcing ribs 7 are distributed in a rhomboid area.

[0038] This gradually varying length arrangement creates a non-uniform stiffness field in the formwork body. The central reinforcing rib 7 is the longest, providing the greatest structural stiffness and effectively bearing the gravity of the concrete 6 in the center of the dynamic spraying chamber and the impact load of the spraying, preventing excessive bulging or unstable deformation at the center of the formwork body.

[0039] As the length of the reinforcing rib 7 gradually decreases towards the side edge of the template body, this effectively reduces the bending stiffness of the template body edge area. This mechanical characteristic of being rigid inside and flexible outside makes the template body edge more prone to elastic deformation under the action of clamping force, thus enabling it to more sensitively capture and conform to the surface undulations or installation deviations of the steel arch support 4, significantly enhancing the adaptive sealing effect of the edge.

[0040] The rhomboid distribution avoids abrupt changes in stiffness. During the sliding process, the formwork body is subjected to dynamic lateral pressure from the concrete 6. The rhomboid arrangement of the reinforcing ribs 7 enables the stress to be smoothly transmitted and diffused from the center to the edge, reducing stress concentration and thus improving the fatigue resistance of the formwork body.

[0041] Furthermore, the Shore hardness of the portion of the template body in which the reinforcing skeleton is embedded is 60HD~75HD, and the elastic modulus is 150Mpa~300Mpa. The Shore hardness of the part of the template body that comes into contact with the steel arch support 4 is 40HA~60HA, and the elastic modulus is 5MPa~15MPa.

[0042] The portion of the formwork body with embedded reinforcing skeleton possesses high Shore hardness (60HD~75HD) and elastic modulus (150MPa~300MPa). Within this hardness and modulus range, the central region of the formwork body exhibits the mechanical properties of a high-strength elastomer, effectively resisting the enormous lateral impact force from high-pressure shotcrete. This ensures the stability of the cross-sectional geometry of the dynamic spraying chamber during concrete accumulation, preventing excessive deflection in the center of the formwork body from exceeding design standards for the support layer thickness, thus achieving precise control over material consumption. The high elastic modulus ensures that the formwork body can rapidly convert localized point loads into surface loads and uniformly transfer them to the internally nested aramid or carbon fiber reinforcing skeleton. This synergistic mechanical effect maximizes the tensile strength of the reinforcing material, enhancing the overall structural robustness of the formwork body.

[0043] The portion in contact with the steel arch support 4 has a low Shore hardness (40HA~60HA) and elastic modulus (5MPa~15MPa). The low Shore hardness gives the edges of the formwork body a soft rubber-like physical property. Under the clamping force applied by the robotic arm, the edge material can undergo significant local elastic deformation, which can fill the tiny unevenness on the surface of the steel arch support 4 caused by corrosion, processing errors, or installation deviations. The ultra-low elastic modulus of 5MPa~15MPa means that minimal pressure can induce sufficient strain, ensuring a continuous and tight seal between the edges of the formwork body and the steel arch support 4. This physically eliminates the possibility of leakage or runoff of the highly fluid plastic concrete 6 at the bottom of the dynamic spraying chamber, guaranteeing the density and construction quality of the interface between the steel arch support 4 and the concrete 6.

[0044] By limiting the hardness range to two different orders of magnitude, HD and HA, the physical boundary between the rigid support zone and the soft sealing zone is scientifically defined. This precise quantitative limitation allows the stress to achieve a reasonable gradient transition within the material when the template body undergoes bending deformation, effectively preventing material tearing or delamination caused by sudden stress changes at the rigid-flexible interface.

[0045] By precisely defining the differences in mechanical parameters (Shore hardness, elastic modulus) of different parts of the template body, a highly efficient synergy between stable shape control of the stress-bearing part and flexible sealing of the contact part is achieved at the technical level. This technical solution not only improves the physical reliability of the dynamic spraying chamber, but also ensures the forming quality and equipment durability of wet spraying operations under complex tunnel conditions from the perspective of material mechanics.

[0046] Furthermore, the template body has a load-bearing portion 21 for receiving concrete 6 and two edge contact portions 22 for contacting the steel arch support 4. Each edge contact portion 22 is respectively disposed on one side of the load-bearing portion 21. The width of the template body is B, the width W1 of the load-bearing portion 21 is 0.7B~0.8B, and the width W2 of each edge contact portion 22 is 0.12B~0.15B, and W1+2W2=B. The width directions of the flexible template 2, the load-bearing portion 21, and the edge contact portions 22 are consistent and all are horizontal.

[0047] The aforementioned width ratio ensures that the main body of the dynamic spraying chamber has a sufficiently wide load-bearing surface. During wet spraying, this width distribution covers most of the gaps between adjacent steel arch supports 4, ensuring that the vast majority of the sprayed concrete 6 is stably confined within the load-bearing area 21, thereby efficiently forming a dense support layer. Setting 70% to 80% of the area as the load-bearing area 21 prevents the main formwork from having a large load-bearing area and causing overall instability when subjected to the lateral pressure of the high-pressure concrete 6, thus ensuring that the geometry of the internal space of the spraying chamber is highly controlled.

[0048] In tunnel construction, the installation of the steel arch support 4 often involves a certain spacing deviation. The 10%–15% width proportion of the edge contact portion 22 provides ample physical overlap space for the formwork body and the steel arch support 4. This design ensures that even with slight lateral displacement during the movement of the robotic arm, the edge contact portion 22 maintains tight contact with the back of the steel arch support 4. Because there is an edge contact portion 22 on each side, the formwork body forms a symmetrical mechanical structure when compressed. When the wet spraying trolley applies clamping force, this symmetry prevents the formwork body from twisting or tilting, ensuring a high degree of sealing of the dynamic spraying chamber in both horizontal and vertical directions.

[0049] Furthermore, the components of the edge contact portion 22 are as follows: 100 parts of polyurethane prepolymer; 5-8 parts of nano-silica reinforced filler; 10-15 parts of lubricant, wherein the lubricant is selected from molybdenum disulfide or polytetrafluoroethylene.

[0050] Polyurethane possesses excellent molecular structure tunability, forming a highly elastic matrix that allows the edge contact portion 22 to undergo sufficient elastic deformation when subjected to the clamping force of the wet spraying trolley's robotic arm. This allows it to tightly wrap around the surface of the steel arch support 4 and its installation deviations, acting like a sealing gasket, thus creating a zero-gap dynamic spraying cavity boundary. During continuous wet spraying in the tunnel, the formwork body needs to continuously ascend along the steel arch support 4. The extremely high resilience of polyurethane ensures that the edge contact portion 22 can quickly return to its original sealing shape after passing through local protrusions such as the connecting plate of the steel arch support 4, guaranteeing the continuity of the sealing effect during long-distance sliding.

[0051] Nanoscale silica particles possess an extremely large specific surface area, enabling them to form strong physical / chemical bonding points with polyurethane molecular chains. This significantly enhances the tensile and tear strength of the edge contact portion 22 without substantially increasing the material's hardness (maintaining its flexibility). This ensures that the edge material will not peel or tear due to burrs or sharp protrusions when sliding on the complex surface of the steel arch support 4. The introduction of nanoscale silica filler improves the thermal stability of the composite material, preventing material softening and instability caused by frictional heat during continuous construction operations, thereby maintaining a constant geometric dimension of the edge contact portion 22 within the dynamic spraying chamber.

[0052] Molybdenum disulfide and polytetrafluoroethylene (PTFE) are high-performance solid lubricants. Introducing them into the polyurethane matrix endows the edge contact portion 22 with self-lubricating properties, significantly reducing the sliding friction resistance between the template body and the steel arch support 4. The low-friction interface effectively reduces mechanical wear during sliding. This not only reduces the drive power consumption of the robotic arm but also prevents surface ablation or scratches caused by high-intensity friction, significantly extending the service life of the template body.

[0053] The presence of lubricant further reduces the surface energy of the material.

[0054] The ratio of 5-8 parts nanofiller to 10-15 parts lubricant was precisely calculated to achieve a balance between strength and friction reduction. 100 parts polyurethane prepolymer served as a carrier to uniformly encapsulate the reinforcing and lubricating components, forming a functional composite that is macroscopically flexible, microscopically tough, and has an extremely smooth surface.

[0055] The aforementioned material formulation directly supports the follow-up climbing and continuous molding process. The high-performance edge contact part 22 ensures that the template body can be pressed tightly (no grout leakage) and move smoothly (no jamming) during rapid sliding, thereby achieving the technical goal of one-time continuous full filling and improving the overall integrity of the support structure.

[0056] In summary, by precisely formulating specific chemical components, the challenges of sealing stability, wear resistance, and smooth movement of the flexible formwork 2 under dynamic sliding and high-pressure spraying conditions have been solved from a materials science perspective. This technical solution provides a solid material foundation for the automated and continuous construction of wet-sprayed concrete in tunnels, and has significant economic and technical benefits.

[0057] Furthermore, along the direction from the middle of the template body to the side edge, the thickness of the edge contact portion gradually decreases to reduce the bending stiffness, thereby achieving adaptive fitting between the template body and the steel arch support 4.

[0058] According to the principles of mechanics of materials, bending stiffness is positively correlated with the cube of thickness. Through the wedge-shaped thinning design, the edge of the guide wing has extremely high physical flexibility. When the wet spraying trolley's robotic arm pushes the flexible template 2 against the steel arch support 4, this extremely thin edge can produce significant elastic deformation with minimal contact force, thus tightly wrapping around the surface of the steel arch support 4.

[0059] Thanks to the high sensitivity resulting from the gradual thickness change, the guide vanes can automatically fill and conform to the minute irregularities, rust spots, or machining tolerances on the surface of the steel arch support, achieving true self-adaptive fit. This fit is not merely a matter of macroscopic proximity, but also a tight interlocking of microscopic interfaces.

[0060] After the edge contact portion is pressed tightly against the steel arch support 4 to form a dynamic spraying chamber, the spraying pressure of the concrete 6 inside the chamber acts on the inner surface of the wedge-shaped wing. Due to the thinness and low stiffness of the edge, the internal pressure presses the edge contact portion more tightly against the back of the steel arch support 4. This pressure-assisted sealing mechanism ensures that no grout leakage or overflow occurs at the edge of the dynamic spraying chamber at lower spraying pressures.

[0061] The wedge-shaped structure allows the contact area to dynamically increase with the clamping force. As the robotic arm increases pressure, thicker guide vanes participate in the contact, thus providing multiple redundancies of sealing protection in the complex high-pressure jetting environment of tunnels.

[0062] Furthermore, the edge contact portion is integrally formed with a labyrinth-shaped protrusion to achieve a sealed fit between the flexible template 2 and the steel arch support 4.

[0063] During wet spraying, the highly fluid concrete slurry, if attempting to seep out from the contact interface, must sequentially pass through multiple narrow channels and expansion chambers formed by labyrinthine protrusions. As the slurry passes through these protrusions, it generates intense eddies accompanied by significant local pressure losses, thus dissipating the kinetic energy and pressure of the slurry within an extremely short path, completely eliminating slurry leakage and runoff from a physical perspective. The labyrinthine protrusions form multiple continuous sealing teeth. Even if the first layer of protrusions experiences minor gaps due to the extremely uneven surface of the steel arch support, the subsequent continuous protrusion structure still provides redundant sealing, ensuring the absolute sealing integrity of the dynamic spraying chamber boundary.

[0064] The raised structures typically have small cross-sectional dimensions, which makes them more prone to localized elastic deformation when subjected to the clamping force of a robotic arm than flat surfaces. These tiny protrusions can penetrate like elastic teeth into the microscopic pits, rust, or machining textures on the surface of the steel arch support, achieving a deeper level of interfacial engagement.

[0065] Furthermore, the flexible template 2 is equipped with strain gauge sensors at the part where it is attached to the steel arch support 4, in order to obtain the pressure applied by the steel arch support 4 to the flexible template 2.

[0066] The strain gauge sensor is embedded in the flexible template 2 and is installed in a recessed manner. It does not directly contact the steel arch support 4, which can effectively protect the strain gauge sensor and prevent the strain gauge sensor from being damaged by friction between the strain gauge sensor and the steel arch support 4.

[0067] Strain gauge sensors can convert the physical contact state between the edge of the flexible template 2 and the steel arch support 4 into precise electrical signals. This allows operators or control systems to monitor the sealing tightness of the dynamic spraying chamber edge in real time, ensuring that the clamping force is maintained above the critical value sufficient to prevent leakage of concrete grout 6. During the process of the robotic arm driving the flexible template 2 to climb along the steel arch support 4, the pressure detected by the strain gauge sensor will fluctuate due to potential surface undulations or changes in the installation angle of the steel arch support 4. The control system can fine-tune the output thrust of the robotic arm in real time based on these fluctuations, thereby maintaining a constant contact pressure throughout the climbing path. When the strain gauge sensor detects uneven pressure on both sides of the flexible template 2, it indicates that the flexible template 2 may have deflected. At this time, the controller of the wet spraying trolley can use this feedback to dynamically adjust the movable connection mechanism 1 or the posture of the robotic arm to ensure that the flexible template 2 always maintains the optimal alignment and force distribution.

[0068] The template body is made of elastic materials such as polyurethane or rubber. Sensors can monitor pressure in real time to prevent the template body from undergoing excessive elastic deformation due to excessive downward pressure from the robotic arm. By maintaining the optimal and necessary minimum sealing pressure, strain gauge sensors help reduce ineffective friction at the edge contact points 22 of the template body during continuous sliding. This not only reduces the wear rate of the material but also reduces the mechanical impact on the surface of the steel arch support 4, significantly extending the service life of the entire adaptive template assembly.

[0069] Reference Figure 5 According to another aspect of the present invention, a method for wet spraying concrete using the adaptive formwork assembly for wet spraying concrete is also provided, comprising the following steps: S1. The movable connecting mechanism 1 is detachably connected to the nozzle of the wet spraying trolley. In addition, the cylinder body of the drive cylinder can be hinged to the mechanical arm of the wet spraying trolley. The output shaft of the drive cylinder is hinged to a stop bar. The stop bar is fixedly installed at the bottom of the flexible template 2. When the flexible template 2 climbs upward, the output shaft of the drive cylinder can extend and retract to support the bottom of the flexible template 2 through the stop bar and restrict the position of the bottom of the flexible template 2, so that the flexible template 2 can maintain a bent state.

[0070] S2. The mechanical arm of the wet spraying trolley drives the flexible template 2 to move, so that the tail end of the flexible template 2 presses against the side of the two adjacent steel arch support 4 away from the tunnel surrounding rock, and the tail end of the flexible template 2 contacts the tunnel floor, so that the steel arch support 4, the flexible template 2 and the sprayed surface 5 of the tunnel surrounding rock together form a dynamic spraying chamber. S3. The controller of the wet spraying trolley adjusts the attitude of the nozzle 3 so that the nozzle 3 points to the bottom of the dynamic spraying chamber. The angle between the center line of the nozzle 3 and the horizontal plane can be set at 30°~60°, and the distance between the nozzle 3 and the sprayed surface 5 of the tunnel surrounding rock does not exceed 0.3m. S4. The concrete 6 is sprayed into the dynamic spraying chamber at a spraying pressure of 0.1Mpa-0.2Mpa, wherein the initial setting time of the concrete 6 is not greater than 5min and the final setting time is not greater than 10min. S5. Before the initial setting of the concrete 6, the mechanical arm of the wet spraying trolley drives the flexible template 2 to climb along the steel arch support 4 through the nozzle 3 installed on the mechanical arm, and the tail end of the flexible template 2 scrapes the plastic concrete 6 during the climbing process; by precisely controlling the movement trajectory of the mechanical arm of the wet spraying trolley, the flexible template 2 can be precisely driven to climb along the steel arch support 4 and the bending degree of the flexible template 2 can be maintained.

[0071] S6. Repeat steps S3 to S5 until concrete 6 is also sprayed on the tunnel top, then one spraying cycle is complete.

[0072] Steps S1 to S6 can then be repeated until all remaining sprayable surfaces 5 are coated.

[0073] Steps S1 and S2 integrated the template assembly with the wet spraying trolley and initially established the work boundary. By pressing the tail end of the flexible template 2 against two adjacent steel arch supports 4 and contacting the tunnel floor, this method creates a quasi-closed dynamic spraying chamber between the sprayed surface 5 of the surrounding rock, the steel arch supports 4, and the flexible template 2. This feature ensures that the concrete 6 is subjected to strict physical constraint in the initial stage of spraying, effectively suppressing radial splashing of the concrete 6 stream after impacting the sprayed surface 5. Efficient kinetic energy conversion and enhanced adhesion: Within the confined chamber, the impact energy of the concrete 6 particles is converted more into compaction energy than rebound kinetic energy. This physical environment enables the concrete 6 to achieve better filling and interlocking within the narrow gap behind the steel arch supports 4, significantly improving the bonding quality of the initial support.

[0074] Steps S3 and S4 precisely define the attitude and spraying pressure of nozzle 3. The controller adjusts the attitude of nozzle 3 to point towards the bottom of the chamber, ensuring that concrete 6 accumulates from the deepest part of the dynamic spraying chamber. This bottom-up filling method utilizes the dual compression of the material's own weight and the spraying force to ensure no voids remain inside the support layer. Low energy consumption and high utilization rate: Using a lower spraying pressure of 0.1MPa-0.2MPa, compared to the spraying pressure of traditional wet-mixed concrete construction, the air pressure is reduced by 20%-40%. Combined with the constraint of the dynamic spraying chamber, this significantly reduces the rebound loss of concrete 6. This low-pressure spraying mode not only saves compressed air energy but also protects the flexible template 2 and its sealing structure due to its smaller impact force, improving the overall system's operational stability.

[0075] The limitation on the initial and final setting times of concrete 6 in step S4 is a crucial prerequisite for the climbing operation in step S5. The extremely short setting time ensures that concrete 6 quickly acquires its initial strength after being sprayed into the chamber, enabling it to resist the impact of subsequent spraying and its own weight-based collapse. This provides a reliable physical support boundary for the smooth upward climbing of the flexible formwork 2.

[0076] In step S5, the flexible template 2 climbs with the robotic arm, and its tail end scrapes and smooths the concrete 6, which is still in a plastic state, in real time. The sliding flexible template 2 completes the filling, compaction, and smoothing processes in one go, eliminating the unevenness of the support surface in traditional processes and ensuring the uniformity of the sprayed layer thickness.

[0077] Step S6 achieves continuous operation from the bottom of the sidewall to the top of the tunnel by repeating S3-S5 in a loop.

[0078] The above construction method integrates the spraying and leveling of concrete 6 into a continuous mechanical cycle. This highly integrated operation mode eliminates the non-productive time of repeated spraying and manual cleaning of oversprayed waste, greatly shortening the cycle time of a single support operation. The integrity of the full-section support is enhanced: due to continuous spraying, there are no obvious cold joints or construction joints between the concrete 6 layers. This continuously formed support structure, together with the steel arch support 4, forms a truly integrated support system, significantly improving the initial support strength and safety reserve of the tunnel under complex geological conditions.

[0079] In traditional wet spraying processes, the nozzle 3 is relatively far from the sprayed surface 5, and the concrete stream 6 is prone to energy loss and radial splashing in the high-speed, open space. This invention shortens the spraying distance to no more than 0.3m. Close-range spraying ensures that the concrete stream 6 is no longer directly exposed to the open space, but is instead confined within a dynamic spraying chamber composed of a flexible template 2, steel arch support 4, and surrounding rock. This physical constraint reduces the loss of kinetic energy to ineffective spaces, allowing more impact energy to be converted into compaction energy. Due to the close distance and enclosed space, the rebound path of the concrete stream 6 after impacting the sprayed surface 5 is blocked by the flexible template 2. This forces the rebounding material to undergo secondary or multiple impacts and re-attach within the chamber, significantly improving the initial adhesion rate. Combined with the movable connection mechanism 1 (ball joint or universal joint), the nozzle 3 can flexibly adjust the incident angle at extremely close distances, ensuring that the concrete 6 accurately fills the narrow gaps and dead corners behind the steel arch, eliminating the risk of detachment due to incomplete support.

[0080] Traditional spraying relies on high-pressure air delivery, and the enormous impact force often causes severe rebound of the concrete 6. This invention uses a low pressure of 0.1MPa-0.2MPa, which reduces the air pressure by 20% to 40% compared to traditional construction methods. The lower spraying speed reduces the violent impact of concrete 6 particles on the sprayed surface 5, minimizing rebound losses caused by excessive impact force and allowing the concrete 6 to adhere more firmly to the sprayed surface 5.

[0081] With concrete 6 having an initial setting time of no more than 5 minutes and a final setting time of no more than 10 minutes, low-pressure close-range spraying ensures that the material can quickly gain initial strength to support its own weight load without collapsing. As the flexible formwork 2 climbs upward, its tail end scrapes and smooths the uncured plastic concrete 6 in real time. This sliding flexible formwork 2 physically confines the concrete 6 within the cavity, ensuring not only uniform thickness but also preventing overall collapse during thick-thickness spraying through the supporting effect of the flexible formwork 2.

[0082] Because the spraying process is mainly completed within a closed dynamic spraying chamber, and the spraying pressure is significantly reduced, the concentration of dust in the air is fundamentally reduced. This improves the working environment inside the tunnel, enhances visibility at the construction site, and improves the health and safety of personnel. The entire process is driven by the wet spraying trolley's robotic arm and controller, reducing the need for high-intensity manual operations, lowering the risks of working at heights, and realizing the transformation of tunnel construction towards intelligence and safety.

[0083] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An adaptive formwork assembly for wet shotcrete, characterized in that, Includes a movable connection mechanism and a flexible template, wherein: The movable connecting mechanism is installed at one end of the flexible template for connecting the nozzle of the wet spraying trolley; The flexible template is a template that can be bent to produce elastic deformation, so that the end of the flexible template away from the movable connection mechanism is pressed against the steel arch support to make the flexible template bend and produce elastic deformation, thereby making the steel arch support, the flexible template and the sprayed surface of the tunnel surrounding rock together form a dynamic spraying cavity. The movable connection mechanism is a ball joint or universal joint, which allows the attitude of the nozzle to be adjusted by the controller of the wet spraying trolley to spray concrete into the dynamic spraying chamber when the steel arch support is pressed at one end of the flexible template.

2. The adaptive formwork assembly for wet-mixed shotcrete according to claim 1, characterized in that, The flexible template includes a template body, a reinforcing frame, and an anti-adhesion working surface, wherein: The main body of the template is made of polyurethane or rubber; The reinforcing skeleton is embedded in the part of the template body that comes into contact with the concrete. The reinforcing skeleton is made of aramid fiber mesh or carbon fiber prepreg. The side of the template body that comes into contact with the concrete is an anti-adhesion working surface, which is made of sintered Teflon coating or replaceable composite polyethylene film.

3. The adaptive formwork assembly for wet-mixed shotcrete according to claim 2, characterized in that, The template body has several reinforcing ribs on the side away from the concrete. These reinforcing ribs are parallel to each other, and each reinforcing rib is integrally formed with the template body and extends in a direction parallel to the side edge of the template body. Along the middle of the template body towards both sides, the length of the reinforcing ribs gradually decreases, so that these reinforcing ribs are distributed in a rhomboid area.

4. The adaptive formwork assembly for wet-mixed shotcrete according to claim 2, characterized in that, The Shore hardness of the portion of the template body into which the reinforcing skeleton is embedded is 60HD~75HD, and the elastic modulus is 150Mpa~300Mpa. The Shore hardness of the part of the template body that comes into contact with the steel arch support is 40HA~60HA, and the elastic modulus is 5MPa~15MPa.

5. The adaptive formwork assembly for wet-mixed shotcrete according to claim 2, characterized in that, The template body has a load-bearing part for receiving concrete and two edge contact parts for contacting the steel arch support. Each edge contact part is located on one side of the load-bearing part. The width of the template body is B, the width W1 of the load-bearing part is 0.7B~0.8B, and the width W2 of each edge contact part is 0.12B~0.15B. The width directions of the flexible template, the load-bearing part and the edge contact parts are all horizontal, and W1+2W2=B.

6. The adaptive formwork assembly for wet-mixed shotcrete according to claim 5, characterized in that, The components of the edge contact portion are as follows: 100 parts of polyurethane prepolymer; 5-8 parts of nano-silica reinforced filler; 10-15 parts of lubricant, wherein the lubricant is selected from molybdenum disulfide or polytetrafluoroethylene.

7. The adaptive formwork assembly for wet-mix shotcrete according to claim 5, characterized in that, Along the direction from the middle of the template body to the side edge, the thickness of the edge contact portion gradually decreases to reduce bending stiffness, thereby achieving adaptive fitting between the flexible template and the steel arch support.

8. The adaptive formwork assembly for wet-mixed shotcrete according to claim 1, characterized in that, The edge contact portion is integrally formed with a labyrinth-shaped protrusion to achieve a sealed fit between the flexible template and the steel arch support.

9. The adaptive formwork assembly for wet-mixed shotcrete according to claim 1, characterized in that, The flexible template is fitted with strain gauge sensors at the parts that are close to the steel arch support to obtain the pressure applied by the steel arch support to the flexible template.

10. A wet spraying operation method for the adaptive formwork assembly for wet sprayed concrete as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1. The movable connecting mechanism is detachably connected to the nozzle of the wet spraying trolley; S2. The mechanical arm of the wet spraying trolley drives the flexible template to move, so that the tail end of the flexible template presses against the side of the adjacent two steel arch supports away from the tunnel surrounding rock, and the tail end of the flexible template contacts the tunnel floor, so that the steel arch support, the flexible template and the sprayed surface of the tunnel surrounding rock together form a dynamic spraying chamber. S3. The controller of the wet spraying trolley adjusts the attitude of the nozzle so that the nozzle points to the bottom of the dynamic spraying chamber and the distance between the nozzle and the sprayed surface of the tunnel surrounding rock does not exceed 0.3m. S4. The concrete is sprayed into the dynamic spraying chamber at a spraying pressure of 0.1Mpa-0.2Mpa, wherein the initial setting time of the concrete is not greater than 5min and the final setting time is not greater than 10min. S5. Before the initial setting of the concrete, the mechanical arm of the wet spraying trolley drives the flexible template to climb along the steel arch support by installing the nozzle on the mechanical arm, and the tail end of the flexible template scrapes the plastic concrete during the climbing process. S6. Repeat steps S3 to S5 until concrete is sprayed onto the tunnel roof as well, then one spraying cycle is complete.

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