Underground structure wall formwork support assembly

Abstract

The utility model relates to a kind of underground structure wall formwork supporting assembly, belong to building formwork supporting technical field.Aiming at the problems of unreliable support, easy to leak paste and difficult to adjust and reuse of existing post-cast strip formwork support, a supporting assembly including a plurality of pairs of flange and nylon bushing embedded sleeve, vertical pad strip, long circular hole pressing channel steel, adjustable double-end screw rod and sealing rubber strip is provided, the embedded sleeve and pressing channel steel are connected by screw rod and fastened using nut, reliable pressing and sealing of formwork are realized, and it is mainly used for supporting and plugging of formwork in underground structure post-cast strip construction.

Description

Technical Field

[0001] This utility model relates to the field of building formwork support technology. More specifically, this utility model relates to a formwork support component for underground structural walls. Background Technology

[0002] In the construction of post-cast strips in underground structures, the reliability of the formwork support structure directly affects the concrete forming quality, waterproofing performance, and construction efficiency. Currently, common support methods often employ temporary measures such as timber bracing or welded steel reinforcement. These methods have the following problems: First, the arrangement of support points is often sparse, making it difficult to evenly cover the entire formwork surface. This causes the central area of ​​the formwork to easily bulge and deform under the lateral pressure of the concrete, thus affecting the surface flatness of the structural wall. The reason for this is that traditional supports rely on on-site cutting and fixing, lacking overall pre-setting and standardized installation nodes, resulting in excessively large support spacing and uneven stress.

[0003] Secondly, insufficient sealing performance can easily lead to grout leakage. The contact edges between the formwork and the existing concrete wall usually lack an effective sealing structure. Relying solely on manual filling or temporary sealing with ordinary rubber strips is insufficient to adapt to the microscopic unevenness of the wall surface. Under pouring pressure, cement grout can easily seep out from the gaps, which not only affects the appearance quality but may also weaken the waterproof performance of the joints.

[0004] Third, traditional supports are mostly for single use, non-adjustable, and difficult to reuse. For example, while welded steel bar supports have a certain rigidity, they cannot be fine-tuned according to actual construction errors, and they need to be removed by cutting after concrete pouring, which not only damages the components but also increases material waste and labor costs. Although timber supports are slightly more adjustable, their rigidity and durability are limited, they are prone to deformation in damp underground environments, and their reuse rate is low.

[0005] Furthermore, the existing support structure is inadequate in preventing loosening and resisting vibration. Particularly during concrete pouring, frequent vibrations cause ordinary bolted connections to loosen, leading to support failure. Attempts to improve the situation by adding washers or double nuts have been made, but these methods have proven insufficient to effectively resist long-term vibration.

[0006] These problems not only affect construction quality but also lead to resource waste and project delays. Therefore, it is necessary to propose a new type of support component that can ensure support rigidity and sealing while being adjustable, reusable, and vibration-resistant and anti-loosening, thereby meeting the complex requirements of post-cast strip construction in underground structures. Utility Model Content

[0007] One object of this invention is to solve at least the problems described above and to provide at least the advantages that will be explained later.

[0008] To achieve these objectives and other advantages according to the present invention, a formwork support assembly for an underground structural wall is provided, the support assembly comprising: Multiple pairs of pre-embedded sleeves are pre-embedded in the concrete walls on both sides of the post-cast strip, and a flange is provided at one end inside the concrete. Nylon bushings are embedded in the pre-embedded sleeves. Multiple vertical pads are spaced apart and placed on the outside of the template, between each pair of pre-embedded sleeves; Multiple clamping channel steels are arranged at vertical intervals. Each clamping channel steel is clamped to the outside of multiple vertical pads. Both ends of the clamping channel steel are provided with elongated holes, and the length direction of the elongated holes is vertical. Multiple pairs of adjustable double-ended screws are provided. Each adjustable double-ended screw includes a first external thread section and a second external thread section with opposite directions of rotation at both ends, and an adjusting sleeve threadedly connected to the first and second external thread sections. The first external thread section is screwed into a nylon bushing. The second external thread section passes through the elongated hole of the template and the clamping channel steel in sequence, and a fixed nut is screwed onto one end of the second external thread section on the clamping channel steel. A flat washer and an elastic washer are placed between the nut and the clamping channel steel. The adjusting sleeve is provided with at least two anti-loosening pins, which penetrate the adjusting sleeve radially and abut against the first and second external thread sections respectively. A sealing strip is provided at the edge of the template that contacts the concrete wall.

[0009] Preferably, the anti-loosening pin is an internal hexagon set screw with a tapered tip at its end, which is tightly embedded in the threaded grooves of the first external thread section and the second external thread section. A reserve nut is provided at the connection between the first external thread section and the internal thread of the pre-embedded sleeve. After the first external thread section is screwed into place, the reserve nut is tightened to make it press against the outer end face of the pre-embedded sleeve.

[0010] Preferably, an elastic pad is provided between the flange of the clamping channel steel and the vertical pad, and the thickness of the elastic pad is 3-5mm.

[0011] Preferably, the outer end of the pre-embedded sleeve is provided with a temporary sealing structure, which includes a plastic protective cap that is threaded to the outer end of the pre-embedded sleeve; and multiple through-holes for overflow are opened on the flange, and a water-swellable sealing ring is embedded around the inner end face of the pre-embedded sleeve.

[0012] Preferably, a metal reinforcing sleeve is embedded in the inner wall of the elongated hole at both ends of the clamping channel steel. The metal reinforcing sleeve is made of stainless steel. The axial length of the metal reinforcing sleeve is the same as the thickness of the clamping channel steel. Both ends of the metal reinforcing sleeve are turned outward to form annular flanges. The outer diameter of the annular flanges is larger than the diameter of the elongated hole. The annular flanges are fixedly connected to the inner and outer surfaces of the clamping channel steel by spot welding.

[0013] Preferably, the sealing strip on the edge of the template has an integrally formed strip-shaped protrusion on the side near the inner side of the template, and a strip-shaped groove matching the strip-shaped protrusion is opened at the corresponding position of the template, with the strip-shaped protrusion being overfitted into the strip-shaped groove; The sealing strip has 3-4 serrated sealing lips extending along the length of the sealing strip on the side away from the template, with a height of 1-2mm for each serrated sealing lip.

[0014] Preferably, the nut on the second external thread section is provided with an anti-loosening cover plate on the side away from the clamping channel steel. The anti-loosening cover plate has a through hole in the center that is compatible with the second external thread section. The edge of the anti-loosening cover plate extends toward the clamping channel steel to form an annular retaining edge. The inner wall of the annular retaining edge is interference-fitted with the outer circumferential surface of the nut on the second external thread section. The flat gasket has an annular groove on the side facing the elastic gasket, and the elastic gasket has an annular protrusion on the side facing the flat gasket that matches the annular groove. The annular protrusion is interference-fitted into the annular groove.

[0015] Preferably, the outer circumferential surface of the nylon bushing is provided with at least two annular bosses spaced axially, and the inner circumferential surface of the embedded sleeve is provided with an annular groove that matches the annular bosses, with the annular bosses interference-fitted into the annular grooves; and the end of the nylon bushing facing the interior of the concrete wall is provided with a radially extending limiting flange, which abuts against the inner end face of the flange of the embedded sleeve, and the limiting flange and the flange are fixedly connected by at least two countersunk screws.

[0016] Preferably, the inner surface of the template facing the post-cast strip is provided with multiple reinforcing ribs spaced laterally. These ribs extend vertically, have an isosceles trapezoidal cross-section, and their thickness gradually decreases from the inner surface of the template outwards. Each reinforcing rib extends to the upper and lower edges of the template, and the ribs and template are integrally formed.

[0017] This utility model has at least the following beneficial effects: First, this invention significantly enhances the anchoring reliability of the sleeves in the concrete by setting flanges in multiple pairs of sleeves pre-embedded in the concrete wall, avoiding the problem of insufficient pull-out resistance of traditional pre-embedded parts, and providing a stable load-bearing foundation for the entire support structure. The nylon bushings embedded in the pre-embedded sleeves provide a corrosion-resistant, highly wear-resistant, and low-friction coefficient threaded connection interface for the adjustable double-ended screw, not only extending its service life but also ensuring the smoothness of repeated screw insertion and removal, improving the reusability of the component. By setting a combination of vertical pads and clamping channel steel, and opening vertical elongated holes at both ends of the channel steel, the support points of the formwork are more evenly and densely distributed, and vertical fine-tuning is allowed during installation, effectively overcoming construction errors, ensuring that the formwork can tightly fit the surface of the post-pouring strip, evenly resisting the lateral pressure of the concrete, and greatly reducing the risk of formwork bulging and deformation. The adjustable double-ended screw has an adjusting sleeve in the middle, which, together with the anti-loosening pin, allows the screw length to be precisely adjusted as needed, thereby achieving precise control of the template clamping force. The anti-loosening pin radially abuts against the threaded rod, effectively limiting the rotation of the adjusting sleeve under vibration, providing initial anti-loosening protection, and enhancing the dynamic stability of the support structure.

[0018] Secondly, this utility model, by setting a threaded plastic protective cap at the outer end, actively prevents the intrusion of impurities such as cement slurry during the construction phase, ensuring the cleanliness and functional integrity of the nylon bushing inside the embedded sleeve. The overflow hole on the flange allows cement slurry to flow through during concrete pouring and form a riveted solidification structure, transforming simple friction bonding into mechanical riveting, greatly enhancing the pull-out resistance and load-bearing reliability of the embedded sleeve. The water-swellable sealing ring embedded around the inner end face generates expansion pressure upon contact with water, passively sealing the microscopic gaps between the flange and the concrete, completely preventing cement slurry penetration. These three elements work synergistically to ensure the functional reliability and durability of the embedded sleeve from three dimensions: anti-fouling, enhanced bonding, and sealing.

[0019] Third, this utility model, by adding an anti-loosening cover plate, whose annular flange is interference-fitted with the outer circumference of the nut, generates a strong clamping force on the hexagonal surface of the nut, forming a direct physical constraint barrier. This greatly increases the torque required for the nut to rotate independently and effectively suppresses the tendency to loosen under vibration. The flat washer and the elastic washer, through the interference fit of the annular groove and the convex ridge, ensure that they always maintain precise alignment and tight fit under pressure and vibration, so that the elastic force of the elastic washer can be evenly and effectively applied to the entire contact surface. This dual anti-loosening structure, combining "physical constraint" and "optimized fit," significantly improves the anti-loosening reliability of the nut under long-term dynamic loads.

[0020] Fourth, this utility model achieves an interference fit between the annular boss on the nylon bushing and the annular groove in the pre-embedded sleeve, thereby restricting the circumferential rotation and axial movement of the nylon bushing and solving the stability defect of easy displacement caused by interference fit alone. The added limiting flange is rigidly connected to the flange of the pre-embedded sleeve through countersunk screws, forming a dual fixing mechanism of "interlocking positioning + screw locking". This ensures the absolute positional stability of the nylon bushing under long-term stress or vibration, providing a solid and durable threaded connection foundation for the screw, fundamentally eliminating the risk of support failure caused by bushing displacement, and the countersunk screw setting does not affect the screw screw screwing in.

[0021] Other advantages, objectives and features of this invention will be partly apparent from the following description, and partly understood by those skilled in the art through study and practice of this invention. Attached Figure Description

[0022] Figure 1 This is a side view of one of the technical solutions of this utility model.

[0023] Figure 2 This is a detailed drawing of the pre-embedded sleeve for one of the technical solutions of this utility model.

[0024] Figure 3 This is a detailed view of an adjustable double-ended screw, which is one of the technical solutions of this utility model.

[0025] Figure 4 This is a detailed drawing of the clamping channel steel according to one of the technical solutions of this utility model.

[0026] The following are the reference numerals in the instruction manual: 1. Vertical pad strip; 2. Embedded sleeve; 3. Adjustable double-ended screw; 4. Nut; 5. Clamping channel steel; 6. Template; 7. Concrete wall; 8. Nylon bushing; 9. Flange; 10. Oblong hole; 11. First external thread section; 12. Second external thread section; 13. Adjusting sleeve. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to examples, so that those skilled in the art can implement it based on the description.

[0028] It should be noted that, unless otherwise specified, the experimental methods described in the following implementation plan are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified.

[0029] In existing technologies, temporary measures such as timber bracing or welded steel bars are often used to support the formwork of post-cast strips in underground structures. These support points are sparse and cannot effectively resist the lateral pressure of concrete, easily leading to formwork bulging and grout leakage, affecting the flatness and waterproofing performance of the structural wall surface. Although welded steel bar supports have high rigidity, they are not adjustable, cannot accommodate construction errors, and are difficult to dismantle, often requiring cutting and destruction, and cannot be reused, increasing material and labor costs.

[0030] like Figures 1-4 As shown, this utility model provides an embodiment of a formwork support assembly for an underground structural wall. The support assembly includes multiple pairs of pre-embedded sleeves 2 embedded in the concrete walls 7 on both sides of the post-cast strip. Flanges 9 are provided inside the pre-embedded sleeves to enhance anchoring, and nylon bushings 8 are embedded inside. Multiple vertical pads 1 are spaced apart on the outer side of the formwork 6, with a center-to-center spacing controlled between 200-300mm, significantly improving the support density. A clamping channel steel 5 is laterally pressed against the outer side of the vertical pads, with vertically elongated holes 10 at both ends to allow for slight height adjustments during installation. One end of an adjustable double-ended screw 3 is screwed into the nylon bushing of the pre-embedded sleeve, and the other end passes through the elongated holes of the formwork and the clamping channel steel in sequence, and is tightened by a nut 4. A flat washer and an elastic washer are provided between the nut and the clamping channel steel to enhance anti-loosening performance. The adjustable double-ended screw has an adjusting sleeve 13 in the middle, with anti-slip texture or polygonal holes on its outer surface, and a pair of operating handles symmetrically welded on it, facilitating torque adjustment by construction personnel to achieve precise control of the template clamping force. Specifically, the adjustable double-ended screw includes a first external thread section 11 and a second external thread section 12 with opposite turns at both ends, and an adjusting sleeve 13 threadedly connected to the first and second external thread sections. The first external thread section is screwed into a nylon bushing, and the second external thread section passes through the template and the elongated hole of the clamping channel steel in sequence. A fixed nut is screwed onto one end of the second external thread section on the clamping channel steel. A flat washer and an elastic washer are placed between the nut and the clamping channel steel. The adjusting sleeve has at least two anti-loosening pins, which penetrate the adjusting sleeve radially and abut against the first and second external thread sections respectively. Compared with existing technologies, this invention not only significantly improves support rigidity and reliability, but also achieves a high degree of adjustability and reusability. All major components are detachable and reusable, greatly reducing overall construction costs. Meanwhile, the sealing strips at the contact edges between the formwork and the concrete wall effectively prevent grout leakage, further ensuring construction quality and structural performance.

[0031] The construction method of the underground structural wall formwork support assembly provided by this utility model begins with the pre-embedding work. After the reinforcement of the concrete wall on both sides of the post-pouring strip is tied, the pre-embedded sleeve is precisely positioned according to the set spacing and pre-fixed to the reinforcement skeleton. One end of this pre-embedded sleeve is equipped with a flange, which allows it to be firmly anchored in the wall during concrete pouring, forming a reliable load-bearing base. The nylon bushing embedded inside the sleeve provides a corrosion-resistant, highly wear-resistant, and low-friction coefficient internal thread interface for the subsequent adjustable double-ended screw.

[0032] Formwork support work can only be carried out after the main concrete on both sides of the post-pouring strip has reached the design strength. During construction, the formwork is first positioned tightly against the inner surface of the post-pouring strip, and vertical spacers are laid at intervals along the outer side, with the center-to-center spacing strictly controlled within the range of 200-300mm. This spacing arrangement greatly increases the support point density of the formwork. Then, the clamping channel steel is horizontally pressed over all the vertical spacers, and the elongated holes at both ends provide the necessary vertical installation adjustment margin. Next, one end of the adjustable double-ended screw is screwed into the pre-embedded nylon bushing, and the other end is passed through the corresponding holes on the formwork and the elongated holes on the clamping channel steel in sequence. Finally, a flat washer and an elastic washer are fitted onto the end of the screw, and the nut is tightened to complete the initial installation.

[0033] This invention allows for precise adjustment of the effective length of the screw by rotating the adjusting sleeve, thereby applying a uniform and controllable clamping force to the template and ensuring that the template does not shift or deform under the lateral pressure of the concrete. The operating handle welded to the adjusting sleeve greatly reduces the torque required for adjustment, making operation labor-saving and convenient. Sealing strips at the contact edges between the template and the existing concrete wall form the first flexible sealing barrier, effectively compensating for microscopic unevenness of the contact surface and blocking the leakage path of cement slurry. All components are designed as prefabricated and detachable connections. After the concrete is poured and reaches its strength, simply loosen the nut and remove the double-ended screw to easily remove the channel steel, spacer strip, and template. All parts (including the nylon bushing inside the pre-embedded sleeve) can be cleaned and reused in the next construction section, achieving full reuse and eliminating destructive traditional processes such as welding and cutting, fundamentally improving construction efficiency and reducing material waste costs.

[0034] In another embodiment of this invention, the anti-loosening mechanism for adjustable screw components used for template support is typically quite simple. Common practices include using ordinary turnbuckles with pins, or drilling through holes in the adjusting sleeve and inserting ordinary cylindrical pins. The ordinary cylindrical pins have line contact with the threaded rod, making it impossible for them to effectively engage with the threaded grooves. Under continuous vibration, relative slippage can easily occur, leading to loosening. Furthermore, the adjusting sleeves are often smooth cylindrical in shape, requiring extremely high torque to rotate them when the screw is under load, making operation extremely difficult and often requiring tools such as pipe wrenches, which can damage components and hinder precise control.

[0035] This embodiment specifically strengthens the adjustment and anti-loosening mechanism of the adjustable double-ended screw. The anti-loosening pin is a hexagonal set screw with a tapered tip. During assembly, a hexagonal wrench is used to screw the set screw into the radial threaded hole of the adjusting sleeve, ensuring its tapered tip is tightly embedded in the threaded grooves of the first external thread section 11 and the second external thread section 12 of the adjustable double-ended screw. This point-to-point embedding method creates significant local contact stress, resulting in a strong mechanical interlocking effect that effectively resists vibrations caused by concrete pouring impacts and prevents relative rotation between the adjusting sleeve and the threaded rod.

[0036] To further enhance reliability, this embodiment includes a reserve nut at the connection between the first external thread section and the nylon bushing of the pre-embedded sleeve. After the first external thread section of the adjustable double-ended screw is screwed into the nylon bushing to a predetermined depth, the operator uses a wrench to tighten the reserve nut, ensuring its end face firmly presses against the outer end face of the pre-embedded sleeve. This effectively adds a strong axial locking force to the screw's engagement section, forming a second mechanical barrier to prevent the screw from loosening.

[0037] At the same time, the ease of adjustment has been fundamentally improved. The outer surface of the adjusting sleeve is not a smooth cylinder, but is machined with anti-slip textures or has polygonal holes directly cut in it for inserting a wrench. More importantly, a pair of operating handles are symmetrically welded to the outer circumference of the adjusting sleeve. These operating handles provide the construction personnel with sufficient leverage, allowing them to precisely fine-tune the length of the screw even when it is initially tensioned, by rotating the handles with relatively little effort, thereby achieving precise and convenient control of the template clamping force.

[0038] In another embodiment of this invention, the clamping channel steel directly contacts the vertical pad strip. The rigid channel steel flange and the relatively soft wooden pad strip form a hard contact with a limited contact area. When tightening the nut of the adjustable double-ended screw, the enormous clamping force is concentrated on the vertical pad strip through the ridge line of the channel steel flange, easily causing dents or even localized crushing of the pad strip surface. This point-like or linear force distribution not only damages the pad strip but also results in extremely uneven clamping force on the formwork. The central area of ​​the formwork, due to insufficient pressure, is prone to bulging and deformation under the lateral pressure of the concrete, affecting the flatness of the wall surface.

[0039] This embodiment fundamentally improves the stress state by adding an elastic pad between the flange of the clamping channel steel and the vertical pad. The elastic pad is made of a high-molecular elastic material such as rubber or polyurethane, and its thickness is controlled between 3-5 mm. When installing the clamping channel steel, first place the cut elastic pad between the channel steel flange and the vertical pad, and then tighten the screws.

[0040] The flexible, elastic pad undergoes compression deformation under pressure. This deformation process allows it to fully adhere to the surface of the rigid channel steel flange and wooden pad, transforming the original line contact into a large-area surface contact, significantly increasing the effective bearing area. This increased contact area directly leads to a reduction in pressure, effectively preventing the risk of the vertical pad being crushed. Secondly, because the compression deformation of the elastic pad automatically compensates for microscopic unevenness in the contact surface, it absorbs and redistributes the concentrated clamping force applied by the adjustable double-ended screw, converting it into a uniformly distributed load acting along the entire length of the vertical pad. This uniformly distributed load is then evenly transmitted to the formwork through the vertical pad, ensuring consistent stress across all areas of the formwork and greatly reducing the possibility of formwork deformation due to uneven pressure.

[0041] This implementation method has a simple structure. The elastic pad not only protects the vertical pads and extends their service life, but more importantly, it ensures the final pouring quality and surface flatness of the underground structural wall by making the template bear the force evenly.

[0042] In another embodiment of this invention, the embedded sleeve is typically anchored to the concrete via its end flange. However, during concrete pouring, the highly fluid cement slurry, under pressure, easily seeps into the sleeve through the interface gap between the flange and the concrete. The embedded sleeve contains a precision nylon bushing; once the cement slurry seeps in and hardens, it completely blocks or deforms the internal threads of the nylon bushing, making it impossible to screw in the adjustable double-ended bolt during subsequent construction, thus rendering the entire embedded structure ineffective. Furthermore, the bond between the smooth flange surface and the concrete is primarily based on friction, with limited pull-out resistance, posing a risk of being pulled out under significant tensile forces.

[0043] This embodiment features a temporary sealing structure at the outer port of the embedded sleeve. This temporary sealing structure is a plastic protective cap that engages with the threaded outer port of the embedded sleeve. Throughout the construction phase before concrete pouring, this protective cap is tightly screwed onto the outer port of the embedded sleeve, acting like a reliable guardian to actively prevent cement slurry, mortar, or other debris from intruding into and contaminating the internal threads of the nylon bushing, thus ensuring the cleanliness and functional integrity of the embedded sleeve's interior.

[0044] To fundamentally enhance the mechanical bond between the embedded sleeve and the concrete, this embodiment incorporates multiple overflow holes penetrating the thickness of the flange. During concrete pouring, cement slurry flows through these overflow holes, forming a concrete rivet-like solidification structure on the other side of the flange. This transforms a simple planar friction bond into a highly efficient mechanical riveting bond, significantly enhancing the embedded sleeve's pull-out resistance and load-bearing reliability.

[0045] To address the seepage channel of the microscopic gaps at the interface between the flange and the concrete, this embodiment pre-embeds a water-swellable sealing ring around the inner end face of the embedded sleeve. During concrete pouring, when water comes into contact with this sealing ring, it rapidly expands, generating significant expansion pressure. This pressure tightly presses against the interface between the embedded sleeve and the concrete, forming a dynamic, adaptive, passive sealing ring that completely blocks the path of cement slurry seeping into the embedded sleeve along this interface.

[0046] This implementation method, through the synergistic effect of the plastic protective cap, the flange with overflow hole, and the water-swellable sealing ring, solves the three major technical problems of anti-fouling, anchoring, and sealing of the pre-embedded sleeve from three dimensions: construction process protection, permanent structural integration, and dynamic gap sealing, ensuring its functional reliability and durability throughout the entire construction life cycle.

[0047] In another embodiment of this invention, the elongated holes at both ends of the clamping channel steel are formed by direct punching or cutting, with the hole walls being the same material as the channel steel itself. During concrete pouring, the clamping channel steel bears the enormous axial clamping force transmitted by the adjustable double-ended screw and the lateral impact force of the concrete. The edges of the elongated holes, especially their ends, become significant stress concentration points. Under continuous and vibratory loads, stress cycles repeatedly at these points, easily leading to fatigue of the channel steel material and the initiation of micro-cracks. These cracks gradually propagate, potentially causing the clamping channel steel to fracture at the elongated holes. Once the clamping channel steel fails, its clamping effect on the formwork is immediately lost, leading to formwork bulging or even bursting, causing serious engineering quality and safety accidents.

[0048] This embodiment fundamentally strengthens the weak point of the elongated hole. An independent metal reinforcing sleeve is embedded in the inner wall of the elongated hole of the clamping channel steel. This metal reinforcing sleeve is preferably made of high-strength, corrosion-resistant stainless steel, and its axial length is completely consistent with the web thickness of the clamping channel steel.

[0049] The two ends of the metal reinforcing sleeve are flanged outwards, forming annular flanges. The outer diameter of these annular flanges is set to be larger than the diameter of the oblong hole. During installation, after the metal reinforcing sleeve is inserted into the oblong hole from one side, the annular flanges at both ends will respectively adhere to the inner and outer surfaces of the clamping channel steel. Subsequently, the annular flanges are firmly fixed to the inner and outer surfaces of the clamping channel steel through spot welding. This achieves multiple reinforcement effects. First, the rigid metal reinforcing sleeve directly replaces the original channel steel hole wall to withstand the extrusion and shear forces of the adjustable double-ended screw, and its higher strength fundamentally avoids the extrusion deformation and wear of the hole wall. Second, and most importantly, through the large-area welding of the annular flanges at both ends to the surface of the clamping channel steel, the metal reinforcing sleeve and the clamping channel steel are combined into an integral load-bearing structure. The load is effectively transferred from the clamping channel steel to the metal reinforcing sleeve and distributed through its overall structure, thereby completely eliminating the sharp stress concentration phenomenon at the edge of the original oblong hole. This significantly improves the fatigue resistance and overall load-bearing capacity of the clamping channel steel at the elongated hole, ensuring the long-term reliability and safety of the entire template support structure under harsh working conditions.

[0050] In another embodiment of this invention, the sealing strips installed on the edges of the template are typically only adhered with adhesive or placed directly on the contact surface. During template installation, positioning, and tightening of the adjustable double-ended bolts, the sealing strips are easily displaced or even completely detached due to friction or impact, causing their preset sealing function to fail. Furthermore, the contact surface between the traditional sealing strip and the concrete wall is a simple plane. However, the surface of the poured concrete wall inevitably has microscopic unevenness, air bubbles, and other defects. A hard, flat contact surface is difficult to adapt to such irregular surfaces, and there will always be unsealed micro-gaps, forming channels for cement grout leakage, which cannot meet the high standards of waterproofing required in underground engineering.

[0051] In this embodiment, a continuous strip-shaped protrusion is integrally molded on the side of the sealing strip closest to the inner side of the template. Correspondingly, a strip-shaped groove, perfectly matching the shape and size of the protrusion, is precisely machined at the corresponding position on the edge of the template. During installation, the strip-shaped protrusion of the sealing strip is forcefully embedded into the strip-shaped groove of the template using an interference fit. This mechanically interlocking fixing method provides an extremely strong constraint on the sealing strip, preventing displacement or detachment during any subsequent construction operations, fundamentally solving the problem of fixing reliability.

[0052] To enhance sealing performance, this embodiment incorporates a multi-layered sealing lip structure on the side of the sealing strip furthest from the formwork (i.e., the working surface in contact with the concrete wall). Specifically, it features three to four continuous, parallel, serrated sealing lips with a height of 1-2 mm. These serrated sealing lips extend along the entire length of the sealing strip. Once the formwork is installed and tightened, these soft, elastic serrated sealing lips preferentially contact the concrete wall surface. Under pressure, each sealing lip independently undergoes elastic deformation, perfectly filling and conforming to the microscopic depressions and pores on the concrete surface. This multi-layered fine-line contact design generates greater contact pressure compared to traditional wide-surface contact, and even if a sealing lip fails to completely seal due to defects, adjacent sealing lips provide redundant sealing protection, thereby greatly improving the reliability and effectiveness of the seal and completely eliminating grout leakage.

[0053] In another embodiment of this invention, the anti-loosening measures for the nut are limited to placing a flat washer and an elastic washer between the nut and the clamping channel steel. Under pressure, the single elastic washer, due to its own elastic deformation and the microscopic unevenness of its contact surface, is prone to localized poor fit and uneven stress distribution between the washer and the nut and clamping channel steel surfaces, thus weakening its anti-loosening effect. More importantly, this arrangement provides no additional physical constraint on the nut itself, relying solely on the friction between the threads and the elastic rebound force of the washer to prevent loosening. Under the continuous high-frequency vibration during the pouring of the post-cast concrete, the nut is highly susceptible to slight, gradual rotational loosening. This slight loosening gradually leads to a decrease in the preload of the adjustable double-ended screw, causing gaps in the formwork support, ultimately resulting in grout leakage or formwork bulging, severely affecting the construction quality of the underground structural wall.

[0054] This embodiment provides a dual anti-loosening mechanism, in which an anti-loosening cover plate is added to the side of the nut on the second external thread section away from the clamping channel steel. The anti-loosening cover plate has a through hole at its center for the second external thread section to pass through, and its edge extends towards the clamping channel steel to form an annular retaining edge. The inner diameter of this annular retaining edge is precisely machined to be slightly smaller than the circumscribed circle diameter of the nut, so that when the anti-loosening cover plate is fitted and tightened, the inner wall of its annular retaining edge forms an interference fit with the outer circumferential surface of the nut. This interference fit generates a strong clamping force on the hexagonal face of the nut, forming a direct and rigid physical constraint barrier, greatly increasing the torque required for the nut to rotate autonomously, thereby effectively suppressing its tendency to loosen under vibration.

[0055] To further optimize the anti-loosening performance of the gasket assembly, this embodiment improves the fit between the flat gasket and the elastic gasket. A ring-shaped groove is machined into the side of the flat gasket facing the elastic gasket. Correspondingly, a ring-shaped protrusion matching the shape and size of the aforementioned ring groove is provided on the side of the elastic gasket facing the flat gasket. During assembly, the ring-shaped protrusion of the elastic gasket is tightly embedded into the ring-shaped groove of the flat gasket with an interference fit. This fitting structure ensures that the flat gasket and the elastic gasket maintain precise alignment and tight contact under pressure and vibration, preventing relative displacement or misalignment between them. This allows the elastic force of the elastic gasket to act evenly and effectively across the entire contact surface, fully utilizing its anti-loosening and buffering function.

[0056] Therefore, this embodiment combines the physical constraints provided by the anti-loosening cover plate with the uniform elastic force provided by the optimized fitting of the gasket group to construct a dual anti-loosening structure that integrates active constraint and passive buffering. This significantly improves the anti-loosening reliability of the nut under long-term dynamic loads and completely solves the problem of template support failure caused by slight loosening of the nut.

[0057] In another embodiment of this invention, the nylon bushing inside the embedded sleeve is typically installed using a simple interference fit. When the adjustable double-ended screw is screwed in or out, the significant friction between the screw thread and the internal thread of the nylon bushing generates a torque that causes the nylon bushing to rotate. The static friction generated by the interference fit alone is often insufficient to resist this torque, causing the nylon bushing to rotate circumferentially (circumferential displacement) within the embedded sleeve. Furthermore, after prolonged exposure to the axial tensile force or vibration load of the screw, the nylon bushing is also prone to gradually loosening and being pulled out of the embedded sleeve axially (axial displacement). Both circumferential rotation and axial dislodgement disrupt the normal fit between the adjustable double-ended screw and the internal thread of the nylon bushing, leading to loose thread engagement or even complete failure, thereby severely weakening the load-bearing stability and reliability of the entire support assembly.

[0058] This embodiment completely solves the displacement problem of the nylon bushing through a dual fixing mechanism. First, at least two annular bosses are spaced axially at intervals on the outer circumferential surface of the nylon bushing. Correspondingly, annular grooves, perfectly corresponding to the shape and position of these annular bosses, are precisely machined on the inner circumferential surface of the pre-embedded sleeve. During assembly, pressure is applied to press the nylon bushing into the pre-embedded sleeve, causing the annular bosses to interference fit into the annular grooves of the pre-embedded sleeve. This boss-groove fitting structure mechanically restricts both circumferential rotation and axial movement of the nylon bushing relative to the pre-embedded sleeve, providing a strong and reliable first layer of constraint.

[0059] To further ensure a foolproof solution, this embodiment also includes a second layer of fixing structure. A radially outward-extending limiting flange is installed at the end of the nylon bushing facing inwards towards the concrete wall. Once the nylon bushing is in place, this limiting flange will tightly abut against the inner end face of the flange inside the embedded sleeve. Subsequently, at least two countersunk screws are used, passing through the flange from the outside of the embedded sleeve flange and screwed into the limiting flange of the nylon bushing, rigidly connecting and fixing the two together. The countersunk screws ensure that the screw heads do not protrude from the flange surface, thus not affecting the screwing-in operation of the adjustable double-ended screw.

[0060] This modular structure allows the nylon bushing to achieve precise positioning and initial fixation through the interference fit of the "annular boss-annular groove," and is then completely locked in place by the rigid connection of the "limiting flange-countersunk screw." It simultaneously resists circumferential torque and axial pull-out force, ensuring the absolute positional stability of the nylon bushing within the embedded sleeve. This provides an extremely robust and durable threaded connection foundation for the entire adjustable double-ended screw support structure, fundamentally eliminating the risk of support failure due to bushing displacement.

[0061] In another embodiment of this invention, the deformation resistance of the formwork for the post-cast strip of the underground structure relies entirely on the constraints provided by external support components, such as clamping channel steel and vertical pads. Since external support points are typically located at the edge of the formwork, the central area often lacks direct and effective support. When concrete is poured, enormous lateral pressure is concentrated in the center of the formwork, which is only resisted by the formwork's own rigidity and the indirect constraints of the edge supports. This easily leads to bulging deformation in the central part of the formwork, ultimately resulting in an uneven surface on the formed underground structural wall. This not only affects aesthetics but may also impact structural performance, and subsequent repairs require additional time and cost.

[0062] This embodiment fundamentally strengthens the structure of the template itself. Multiple reinforcing ribs, integrally formed with the template, are arranged at transverse intervals on the inner surface of the template facing the post-cast strip. These reinforcing ribs are not laterally welded or glued attachments, but rather an integral structure formed simultaneously with the template substrate during template manufacturing through rolling or molding processes, ensuring the highest connection strength and integrity between them and the template.

[0063] Each reinforcing rib extends vertically along the template, with its ends reaching the top and bottom edges of the template, respectively. More importantly, the cross-section of the reinforcing rib is designed as an isosceles trapezoid, with its thickness gradually decreasing from the inner surface of the template outwards. This gradually decreasing isosceles trapezoidal cross-section offers significant mechanical advantages. The trapezoidal hypotenuse effectively disperses concentrated lateral pressure to both sides, avoiding stress concentration common at the corners of rectangular cross-sections, thus providing higher bending stiffness with the same amount of material.

[0064] The long reinforcing ribs provide reinforcement. They absorb and redistribute the concentrated lateral pressure from the concrete acting on the central area of ​​the formwork, effectively transferring the force vertically to the main support structure at the top and bottom edges of the formwork, which consists of clamping channel steel and vertical spacers. This transforms the enormous load originally borne solely by the central part of the formwork into a uniformly distributed load shared by the entire support structure, significantly reducing the risk of bulging deformation in the central area. Through this built-in, integrated reinforcement structure, the formwork of this invention no longer passively relies on external supports but actively participates in load resistance and transfer, significantly improving the reliability and forming quality of the entire support structure.

[0065] Although the embodiments of this utility model have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for this utility model. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, this utility model is not limited to the specific details and examples shown and described herein.

Claims

1. A formwork support assembly for an underground structural wall, wherein the formwork is used to seal the inner surface of the post-cast strip, characterized in that, Supporting components include: Multiple pairs of pre-embedded sleeves are pre-embedded in the concrete walls on both sides of the post-cast strip, and a flange is provided at one end inside the concrete. Nylon bushings are embedded in the pre-embedded sleeves. Multiple vertical pads are spaced apart and placed on the outside of the template, between each pair of pre-embedded sleeves; Multiple clamping channel steels are arranged at vertical intervals. Each clamping channel steel is clamped to the outside of multiple vertical pads. Both ends of the clamping channel steel are provided with elongated holes, and the length direction of the elongated holes is vertical. Multiple pairs of adjustable double-ended screws are provided. Each adjustable double-ended screw includes a first external thread section and a second external thread section with opposite directions of rotation at both ends, and an adjusting sleeve threadedly connected to the first and second external thread sections. The first external thread section is screwed into a nylon bushing. The second external thread section passes through the elongated hole of the template and the clamping channel steel in sequence, and a fixed nut is screwed onto one end of the second external thread section on the clamping channel steel. A flat washer and an elastic washer are placed between the nut and the clamping channel steel. The adjusting sleeve is provided with at least two anti-loosening pins, which penetrate the adjusting sleeve radially and abut against the first and second external thread sections respectively. A sealing strip is provided at the edge of the template that contacts the concrete wall.

2. The underground structural wall formwork support assembly according to claim 1, characterized in that, The anti-loosening pin is an internal hexagon set screw with a tapered tip at the end, which is tightly embedded in the threaded grooves of the first external thread section and the second external thread section. A spare nut is provided at the connection between the first external thread section and the internal thread of the pre-embedded sleeve. After the first external thread section is screwed into place, the spare nut is tightened to make it press against the outer end face of the pre-embedded sleeve.

3. The underground structural wall formwork support assembly according to claim 1, characterized in that, An elastic pad with a thickness of 3-5mm is installed between the flange of the compression channel steel and the vertical pad.

4. The underground structural wall formwork support assembly according to claim 1, characterized in that, The outer end of the pre-embedded sleeve is provided with a temporary sealing structure, which includes a plastic protective cap that is threaded to the outer end of the pre-embedded sleeve; and multiple through-holes for overflow grout are opened on the flange, and a water-swellable sealing ring is embedded around the inner end face of the pre-embedded sleeve.

5. The underground structural wall formwork support assembly according to claim 1, characterized in that, Metal reinforcing sleeves are embedded in the inner walls of the elongated holes at both ends of the clamping channel steel. The metal reinforcing sleeves are made of stainless steel. The axial length of the metal reinforcing sleeves is the same as the thickness of the clamping channel steel. Both ends of the metal reinforcing sleeves are turned outward to form annular flanges. The outer diameter of the annular flanges is larger than the diameter of the elongated holes. The annular flanges are fixedly connected to the inner and outer surfaces of the clamping channel steel by spot welding.

6. The underground structural wall formwork support assembly according to claim 1, characterized in that, The sealing strip on the edge of the template has an integrally formed strip-shaped protrusion on the side near the inner side of the template. The template has a strip-shaped groove at the corresponding position that matches the strip-shaped protrusion. The strip-shaped protrusion is inserted into the strip-shaped groove with an interference fit. The sealing strip has 3-4 serrated sealing lips extending along the length of the sealing strip on the side away from the template, with a height of 1-2mm for each serrated sealing lip.

7. The underground structural wall formwork support assembly according to claim 1, characterized in that, On the side of the nut on the second external thread section away from the clamping channel steel, there is an anti-loosening cover plate. The center of the anti-loosening cover plate has a through hole that matches the second external thread section. The edge of the anti-loosening cover plate extends towards the clamping channel steel to form an annular retaining edge. The inner wall of the annular retaining edge is interference-fitted with the outer circumferential surface of the nut on the second external thread section. The flat gasket has an annular groove on the side facing the elastic gasket, and the elastic gasket has an annular protrusion on the side facing the flat gasket that matches the annular groove. The annular protrusion is interference-fitted into the annular groove.

8. The underground structural wall formwork support assembly according to claim 1, characterized in that, The outer circumferential surface of the nylon bushing is provided with at least two annular bosses spaced axially. The inner circumferential surface of the pre-embedded sleeve is provided with an annular groove that matches the annular bosses. The annular bosses are interference-fitted into the annular grooves. The end of the nylon bushing facing the interior of the concrete wall is provided with a radially extending limiting flange. The limiting flange abuts against the inner end face of the flange of the pre-embedded sleeve. The limiting flange and the flange are fixedly connected by at least two countersunk screws.

9. The underground structural wall formwork support assembly according to claim 1, characterized in that, Multiple reinforcing ribs are provided at horizontal intervals on the inner surface of the template facing the post-pouring strip. The reinforcing ribs extend vertically and have an isosceles trapezoidal cross section. The thickness of the reinforcing ribs gradually decreases from the inner surface of the template outward. The two ends of each reinforcing rib extend to the upper and lower edges of the template, and the reinforcing ribs and template are integrally formed.

Images