A cast-in-place support formwork device and construction method for the roof slab of a disaster relief shelter on a mountain highway.

Abstract

This invention discloses a cast-in-place support formwork device and construction method for the roof slab of a disaster relief tunnel on a mountainous highway, belonging to the technical field of road and bridge engineering protective structure construction. It constructs a system of interlocking clustered supports, lightweight modular gantry frames, and mechanized relocation. Interlocking uprights form clustered support towers via double-ear buckles, which are then combined with steel sections to form an integrated gantry frame. The system utilizes a simple channel steel track and a synchronous lifting and relocation system to achieve integrated support-formwork-relocation operations. Key processes include foundation reinforcement, modular assembly, graded preloading, concrete pouring, and efficient gantry relocation. This invention reduces high-altitude work, shortens the construction period, and reduces construction costs, making it more suitable for narrow mountain terrain and the needs of existing road traffic. The components are reusable, offering both environmental and social benefits. It provides a technical reference for tunnel construction in similar challenging road sections and promotes the upgrading of road and bridge protective structure construction towards lightweight, modular, and mechanized methods.

Description

Technical Field

[0001] This invention belongs to the field of protective structure construction technology in road and bridge engineering, specifically relating to a cast-in-place support formwork device and construction method for the roof slab of a disaster relief shed in mountainous highways. Background Technology

[0002] In mountainous highway construction and disaster mitigation projects, tunnels serve as the core protective structure against geological disasters such as rockfalls and landslides. The quality and efficiency of their construction directly affect road operation safety and project construction cycle. Especially in challenging areas near mountains, water bodies (such as sections along the Yalu River), or narrow terrain, tunnels often require the use of the "cast-in-place roof slab" process. The supporting formwork system, as the core load-bearing structure of cast-in-place construction, directly determines the construction safety, economy, and environmental adaptability.

[0003] Currently, the construction of cast-in-place roof slabs for tunnels mainly relies on three technical solutions: full-span scaffolding, heavy-duty formwork trolley, and combined hydraulic formwork trolley. However, all of these methods have significant drawbacks and are difficult to adapt to the complex working conditions in mountainous areas.

[0004] Limitations of the full-span scaffolding method: This method requires the erection of steel pipe scaffolding across the entire area below the tunnel, resulting in a large consumption of materials. Taking the construction of a tunnel with 15 sections, each 18-20m long, as an example, the steel consumption reaches 292 tons. Furthermore, a large amount of manual labor is required for high-altitude erection and dismantling operations, with high-altitude operations accounting for over 60%, posing significant risks of falls and collapses. At the same time, the scaffolding erection occupies the entire space below the tunnel, causing the existing road to be completely interrupted, failing to meet the public's need for "construction while maintaining traffic" on mountain roads. In addition, the scaffolding assembly and dismantling cycle is long, requiring 7-10 days for a single section of construction, and the component reuse rate is low, only about 30%, resulting in significant pressure on construction costs and schedule.

[0005] The limitations of the heavy-duty trolley method: To solve the problem of moving full-span scaffolding, the industry has developed heavy-duty steel trolleys. However, their overall weight exceeds 80 tons, requiring movement via fixed concrete tracks. Track construction not only increases project costs by an additional 20%, but also has extremely high requirements for terrain flatness, making them unsuitable for mountainous sections with cross and longitudinal slopes of ≤8%. At the same time, the trolleys have low modularity, requiring large hoisting equipment for assembly, making them difficult to deploy in narrow areas near mountains with a site width of ≤20m. Furthermore, the trolleys use 160 tons of steel. Although the reuse rate has increased to 70%, insufficient lightweighting results in stringent foundation bearing requirements of ≥150KPa. However, the local foundation bearing capacity in mountainous areas is often below 130KPa, requiring additional large-scale foundation reinforcement, further increasing project costs.

[0006] The patented technology solution with publication number CN109869164A and invention title "Construction method of casting multi-hole separated tunnel by combined hydraulic formwork trolley" provides a combined hydraulic formwork trolley method. Although this solution optimizes the assembly and relocation efficiency of tunnel construction through hydraulic adjustment and motor-driven walking, it still has obvious limitations. First, its application is limited to a single scenario, primarily targeting the internal construction of multi-hole, separated tunnels. It fails to consider the unique conditions of mountainous tunnels, characterized by their proximity to mountains and water bodies and narrow terrain. The trolley, composed of two layers of steel frames, occupies a large space and cannot operate in narrow areas with a width of ≤20m. Second, it lacks adaptability to terrain and foundations, relying on fixed tracks without optimization for mountainous areas with cross and longitudinal slopes of ≤8%. Track laying still requires site leveling, and the lack of a flexible foundation design places high demands on foundation bearing capacity, making it unsuitable for uneven mountainous terrain. Third, it suffers from insufficient lightweighting and modularization. The trolley's main body is a full steel frame structure, resulting in significant weight and high hoisting requirements. Furthermore, the lack of integrated design between the formwork and support system necessitates considerable manual labor during assembly and relocation, limiting construction efficiency. Fourth, it presents significant traffic disruption issues. Construction requires occupying the entire work area, failing to meet the public's need for "construction while maintaining traffic flow" on mountainous roads, making it unsuitable for disaster relief projects on national highways with high traffic volume.

[0007] Existing solutions either prioritize stability at the expense of flexibility, or pursue mobility while neglecting lightweight design and terrain adaptability, or are limited to specific tunnel scenarios and cannot cover the complex needs of tunnel sheds in mountainous areas. Especially under the combined conditions of "ensuring traffic flow, narrow terrain, and complex geology," there is still no support formwork technology that can simultaneously achieve modular assembly, mechanized relocation, low foundation requirements, and minimal traffic interference. This has become a core bottleneck restricting the high-quality construction of tunnel sheds for disaster relief on mountain roads. Therefore, there is an urgent need to develop a lightweight, modular, and flexibly movable support formwork system to overcome the limitations of existing technologies and meet the actual needs of cast-in-place construction of tunnel roof slabs in challenging mountainous road sections. Summary of the Invention

[0008] To address the shortcomings of existing full-span scaffolding methods ("high material consumption, high high-altitude risks, and traffic disruption") and heavy-duty trolley methods ("heavy weight, poor terrain adaptability, and high track costs"), and especially to solve the coordination problem of support formwork systems under the combined conditions of "ensuring traffic flow + narrow terrain + complex geology," this invention provides a cast-in-place support formwork device and construction method for the roof slab of a disaster relief tunnel in mountainous highways. This achieves "safety, efficiency, lightweight, and modularity" in the cast-in-place construction of tunnel roof slabs, meeting the actual needs of disaster relief projects in mountainous highways. This invention is applicable to the cast-in-place construction of tunnel roof slabs in disaster relief projects in mountainous highways, especially for challenging road sections with narrow terrain (such as sections near mountains or water bodies), complex geological conditions (such as risks of rockfalls and uneven foundation bearing capacity), and the need to ensure two-way traffic flow on existing roads.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A construction method for a cast-in-place support formwork device for the roof slab of a disaster relief shelter on a mountain highway includes the following steps:

[0011] S1. Foundation treatment and surveying: The total station is used to locate the axis of the shed, and the axis deviation is ≤3mm; for areas with a foundation bearing capacity of <130KPa, crushed stone soil is used for backfilling in layers, with a layer thickness of ≤25cm and a compaction degree of ≥94%, and a 25cm thick C25 concrete cushion layer is poured.

[0012] S2. Basic track installation: Lay 15×500×500mm steel plates, and lay 0.3×0.34×0.64m sleepers horizontally on the steel plates with a sleeper spacing of 530mm; fix [16 track channel steel on the sleepers, the elevation deviation of the top surface of the track is ≤3mm, the track gauge deviation is ≤±2mm, and the track on both sides is reinforced by [10 channel steel horizontal bracing.

[0013] S3. Modular assembly of the device:

[0014] ① Hoist the lower longitudinal beam of HN300×300×16×10 steel, and connect the adjustable ground support, 1000×480×200 heavy roller trolley and jacking conversion device with 8.8 grade M20×70mm high strength bolts;

[0015] ② Insert the φ48.3×3.2mm disc buckle uprights into the lower conversion piece, and connect the four uprights with 176mm 30# steel double ear buckles to form a cluster support tower. The 11 sets of support towers are arranged along the lower longitudinal beam at a spacing of 530mm, and are connected to form a double-layer gantry frame through φ48.3×2.5mm horizontal bars and φ33.4×2.3mm diagonal bars.

[0016] ③ Install the upper conversion component and the same specification upper longitudinal beam, hoist the 40b I-beam upper cross beam, fix the H20 wooden I-beam with wooden beam clamps (300mm spacing) and lay 15mm bamboo plywood panel; set 5 sets of φ90×4mm diagonal braces and connect d=38mm horizontal anchor bolts to the external structure;

[0017] S4. Template Adjustment and Preloading: Start the hydraulic cylinder control system to synchronously lift the gantry, adjust the adjustable ground support to make the template elevation deviation ≤3mm; load the shed roof slab according to the design load in stages of 60%→80%→100%→120%, monitor the settlement after each loading stage at 6h intervals, and determine stability if the difference between two adjacent displacements is ≤2mm, and set the pre-camber according to the preloading data;

[0018] S5. Concrete construction: C40 concrete shall be poured by pumping, with each layer thickness ≤300mm; after final setting, it shall be covered with geotextile and watered for curing, with a curing period ≥14 days.

[0019] S6. Formwork Removal and Gantry Relocation: After the concrete compressive strength reaches 100% of the design strength, lift the gantry and adjust the adjustable ground support to be ≥10cm off the ground. Pull down the hydraulic cylinder to make the formwork 8-10cm off the concrete surface. Install the lower longitudinal beam connecting beam ([16a channel steel) and the upper transverse beam connecting beam (12 I-beam). Use an excavator to pull the traveling wheels to move along the track. After it is in place, lock the limit switch and reset the gantry.

[0020] In step S3, the uprights of the cluster support tower are made of Q355 steel, the horizontal bars and diagonal bars are made of Q235 steel, and the indoor bearing capacity test value of a single cluster support tower is ≥490kN.

[0021] In step S4, the preload counterweight uses 3.65t / piece steel reinforcement, and the loading sequence is consistent with the concrete pouring sequence. A total of 3 monitoring sections are set at both ends and the middle of the device. Each section has 5 monitoring points at both sides of the frame, one-quarter of the span of the wooden beam, the middle of the wooden beam, and three-quarters of the span of the wooden beam. Unloading is carried out step by step in the reverse of loading.

[0022] In step S6, the gantry moving speed is ≤50mm / min. Before moving, obstacles within 5m around the track are cleared. A dedicated person is assigned to monitor the track flatness and wheel-rail contact status. If the horizontal displacement deviation exceeds 5mm, the machine is stopped immediately for adjustment.

[0023] The [16 track channel steel is suitable for tunnel construction areas with a cross and longitudinal slope of ≤8%, eliminating the need for concrete track foundation pouring. This allows for tunnel roof construction to be completed while ensuring existing road access, reducing interference with surrounding traffic and the environment.

[0024] The overall weight of the support formwork device is ≤40t. The upper and lower longitudinal beams are made of Q235 steel, and the torque deviation of all high-strength bolts is ≤±5%, which meets the requirements of GB / T1231 standard. The construction method of the support formwork device is suitable for the on-site construction of the roof slab of the tunnel in mountainous highway disaster relief projects. It is suitable for difficult road sections with narrow terrain, complex geological conditions, and the need to ensure two-way traffic on existing roads. It can realize the integrated operation of tunnel roof slab support, formwork installation and mechanized relocation.

[0025] A cast-in-place support formwork device for the roof slab of a disaster relief shelter on a mountain highway includes a foundation track system, a disc-lock bundled support system, a lightweight gantry frame body, an upper formwork system, and a lifting and shifting system. Each system is connected by high-strength bolts and specialized connectors to form an integrated load-bearing system, as detailed below:

[0026] 1. Basic Track System

[0027] The basic track system consists of 15×500×500mm Q235 steel plates, 0.3×0.34×0.64m anti-corrosion sleepers, [16Q235 track channel steel, and [10Q235 channel steel horizontal bracing). The steel plates are laid on the foundation surface to distribute foundation stress. The sleepers are arranged laterally with a spacing of 530mm to buffer the load. The track channel steel is fixed above the sleepers, and both sides are reinforced with [10Q235 channel steel horizontal bracing. The system's track top elevation deviation is controlled within 3mm, and the track gauge deviation is controlled within ±2mm. It can adapt to cross and longitudinal slopes of no more than 8% in construction areas, eliminating the need for concrete foundation pouring and reducing costs by 60% compared to heavy-duty trolley tracks. Its core innovation lies in using a flexible foundation of "steel plates + sleepers" to replace traditional concrete tracks. This allows for local adjustment of sleeper thickness based on foundation bearing capacity, adapting to uneven foundations in mountainous areas while minimizing damage to existing roads.

[0028] 2. Clasp-type cluster support system

[0029] The disc-lock cluster support system consists of four φ48.3×3.2mm Q355 disc-lock uprights as a group, connected by 176mm 30# steel double-eared fasteners to form a cluster support tower. A total of 11 groups of support towers are arranged along the lower longitudinal beam axis at 530mm intervals. Adjacent support towers are connected by φ48.3×2.5mm Q235 horizontal bars and φ33.4×2.3mm Q235 diagonal bars, forming a double-layered plate-like gantry. Indoor load-bearing capacity tests have verified that the ultimate load-bearing capacity of a single cluster support tower is no less than 490kN, far exceeding the actual working load of 210kN, with a safety factor of 2.3. The connection between the horizontal bars and uprights uses disc-lock nodes, with a shear bearing capacity of no less than 15kN, meeting the requirements for wind load and concrete lateral pressure resistance. The core innovation of this system is that it breaks through the traditional single-pole support mode. The four-pole bundled design increases the moment of inertia of the cross section by 4.2 times, and improves stability by 3 times with only a 20% increase in weight.

[0030] 3. Lightweight gantry body

[0031] The lightweight gantry frame's lower and upper longitudinal beams are both made of HN300×300×16×10mm Q235 steel, with a length of 11000+11000mm to match 20-22m construction segments. The upper crossbeam uses 40b I-beams, with a length of 7800mm and a spacing of 900mm to bear the formwork load. Six sets of φ90×4mm Q235 diagonal braces are installed on both sides of the gantry frame. The bottom of the diagonal braces is connected to the lower longitudinal beam with high-strength bolts, and the top is supported at 2050mm from the edge of the upper crossbeam to offset torque. The overall weight of the gantry frame is controlled within 40t, optimized through MidasGen software calculations, resulting in a 50% weight reduction compared to traditional heavy-duty trolleys. The connection nodes between the lower longitudinal beam and the support tower are reinforced with 10mm thick ribs, with a local compressive strength of not less than 250MPa. Its core innovation is the adoption of a hybrid structure of "steel profile + disc buckle" to replace the all-steel trolley, which reduces material usage and hoisting requirements while ensuring load-bearing capacity, making it suitable for narrow sites in mountainous areas.

[0032] 4. Upper template system

[0033] The secondary joists of the upper formwork system are H20 wooden I-beams, 6000mm long and spaced 300mm apart, lightweight yet rigid. The panel is made of 15mm thick bamboo plywood, with a surface flatness of no more than 1mm / m, resulting in excellent appearance quality of the top slab after pouring. The wooden I-beams are fixed to the upper crossbeams with special Q235 wooden beam clamps to prevent displacement. The linear load of the formwork system is controlled within 2.5kN / m, reducing weight by 40% compared to steel formwork; the overall flatness deviation after formwork assembly does not exceed 3mm. The core innovation of this system is the replacement of some of the steel secondary joists with wooden I-beams, reducing the formwork's self-weight while meeting load requirements, facilitating manual adjustment and disassembly, and reducing the intensity of high-altitude work.

[0034] 5. Lifting and shifting system

[0035] The jacking and shifting system includes an adjustable ground support, a 1000×480×200mm heavy-duty roller trolley, a jacking conversion device, and a crane cylinder control system. The adjustable ground support uses No. 20 steel, is 500mm long, and has a lead screw adjustment range of ±150mm for fine-tuning the elevation. The heavy-duty roller trolley has a single wheel load capacity of no less than 50kN and is equipped with a braking device. The jacking conversion device is linked to a 20t hydraulic cylinder. The crane cylinder control system has a synchronization accuracy of ±1mm. The cylinder jacking speed is controlled within 10mm / min to avoid impact on the frame; the roller trolley's moving speed is controlled within 50mm / min, and smoothness is ensured by excavator traction control. The system can achieve an overall gantry lifting stroke of no less than 200mm, meeting the requirements for formwork demolding and shifting. Its core innovation is the integrated design of the jacking and shifting system, eliminating the need for separate disassembly and assembly of the shifting equipment; the roller trolley has a brake limit switch, solving the problem of "easy deviation" during traditional trolley movement and adapting to slight gradient changes in mountainous terrain.

[0036] Compared with the prior art, the present invention has the following significant advantages:

[0037] I. Structural stability and construction safety are significantly improved.

[0038] Relying on the innovative design of the disc-lock cluster support system, four uprights form a cluster support tower through double-ear buckles. Combined with a three-dimensional stabilization system composed of double X-shaped diagonal braces and horizontal bars, the lateral stiffness of the support structure is increased by 3 times compared to the traditional single uprights. The ultimate bearing capacity of a single support tower reaches 490kN, far exceeding the actual working load requirements, effectively avoiding the risk of scaffold collapse. At the same time, the 120% graded preloading system can eliminate inelastic deformation in advance. Combined with full-process settlement monitoring, it ensures the structural stability during concrete pouring. In addition, modular assembly reduces high-altitude erection and dismantling work by 80%. Most components need to be assembled on the ground and then placed in place by mechanical hoisting, which greatly reduces safety hazards such as personnel falling from heights and falling objects. Engineering practice has verified that there were zero safety accidents throughout the construction process. The safety and controllability are significantly better than the full-span scaffolding method, the heavy trolley method, and the "Construction method of multi-hole separated tunnel by combined hydraulic formwork trolley" application publication number CN109869164A.

[0039] The support tower uprights are made of φ48.3×3.2mm Q355 steel, with an outer diameter of 48.3mm and an inner diameter of 41.9mm. Compared with traditional single uprights of the same specifications in the industry, based on the standard formula for the moment of inertia of a circular section, I=π(D⁴-d⁴) / 64, the moment of inertia of a single upright is approximately 115803mm. 4 The four uprights are rigidly connected by 176mm 30# steel double-ear buckles to form a bundled structure. Due to the synergistic force effect, the synergy coefficient is 1.05, and the total moment of inertia is 486373mm. 4 The ratio between the two is 4.2 times;

[0040] In terms of stability, the indoor ultimate bearing capacity of a single cluster support tower is ≥490kN, while the ultimate bearing capacity of a traditional single pole of the same specification is 150kN, a ratio of 3.27. Moreover, the actual working load is only 210kN, with a safety factor of 2.3. In terms of lateral stiffness, using the conventional "horizontal force-displacement" test in the road and bridge field, when the support height is 5m and a horizontal force of 10kN is applied at the top, the horizontal displacement of a traditional single pole is 12mm, while the cluster support tower, equipped with double X-shaped diagonal braces and horizontal bars, has a horizontal displacement of 4mm, with a stiffness ratio of 3.

[0041] According to the theoretical weight formula for steel pipes, m=0.02466×t×(Dt), the weight per unit length of a single φ48.3×3.2mm upright is 3.56kg / m, and the weight per unit length of four bundled uprights, including the double-ear buckle, is 14.34kg / m. In comparison, the weight per unit length of a single φ108×6mm upright + horizontal restraint bar in a traditional support structure with the same load-bearing capacity is 17.38kg / m. When the load-bearing capacity of the bundled support tower is increased by more than 3 times, the weight increase is far lower than the increase in load-bearing capacity.

[0042] II. Optimization of Construction Efficiency and Operational Flexibility

[0043] The modular assembly design of this invention significantly improves the efficiency of device installation and dismantling. A single set of support formwork devices can be assembled in just 2 days, shortening the construction period by more than 70% compared to the full-span scaffolding method. The jacking and shifting system is integrated with the main gantry structure, enabling mechanized shifting along the track without disassembling the equipment. The shifting time for a single operation is controlled within 1.5 hours, and the shifting process does not interrupt existing road traffic, perfectly meeting the public's need for "construction while maintaining traffic flow." Simultaneously, the formwork elevation is controlled with ±1mm precision through "hydraulic cylinder synchronous jacking + screw screw fine-tuning," eliminating the need for repeated manual adjustments. The lightweight formwork system composed of wooden I-beams and bamboo plywood also facilitates rapid assembly and disassembly, further shortening the construction cycle for each section and helping the project to be delivered on schedule.

[0044] III. Significantly Improved Engineering Economics

[0045] The lightweight gantry frame adopts a hybrid structure of "steel profile + modular fasteners," with an overall weight controlled within 40 tons. This reduces steel usage by 50% compared to traditional heavy-duty trolleys and by more than 50% compared to the trolley used in the "Construction Method of Multi-hole Separated Tunnel Using a Combined Hydraulic Formwork Trolley" (application publication number CN109869164A), significantly reducing material procurement costs. The foundation track system uses a flexible foundation of "steel plate + sleepers," eliminating the need for concrete track pouring. This reduces track construction costs by 60% compared to heavy-duty trolleys and saves more than 50% compared to the fixed track used in the "Construction Method of Multi-hole Separated Tunnel Using a Combined Hydraulic Formwork Trolley" (application publication number CN109869164A). Furthermore, only local reinforcement is required for foundation treatment, avoiding large-scale foundation modification expenditures. In addition, all components are connected by high-strength bolts, allowing for 100% reuse in other projects after dismantling, reducing material waste and secondary procurement costs. Engineering practice has verified that this reduces the overall cost of a single project, with economic benefits significantly superior to existing technical solutions.

[0046] IV. Strong adaptability to complex working conditions

[0047] Addressing the challenging conditions of mountain roads, characterized by proximity to mountains and water bodies, narrow terrain, steep slopes, and uneven foundations, this invention offers exceptional adaptability: The 16mm track channel steel can accommodate slopes of ≤8%, allowing for installation without site leveling, significantly improving adaptability compared to the track in CN109869164A; the minimum operating width of the gantry is only 8m, enabling deployment in narrow areas such as those near mountains and water bodies, resolving the issue of the large space occupied by the trolley in CN109869164A, which is unsuitable for narrow working conditions; the foundation treatment utilizes graded crushed stone backfill and localized concrete cushion layers, eliminating the need for high-strength reinforcement of the entire construction area, making it suitable for mountainous areas with a foundation bearing capacity ≤130KPa, a significant reduction in foundation requirements compared to CN109869164A. More importantly, during construction, it does not require occupying all the space under the tunnel, thus preserving the existing two-way traffic capacity of the road. This avoids the drawbacks of traditional full-span scaffolding and the "construction method of casting multi-hole separated tunnels using combined hydraulic formwork trolley" (application publication number CN109869164A), which "blocks traffic," making it particularly suitable for disaster relief projects on mountainous national highways with high traffic volume.

[0048] The technical solution of this invention can be further extended to the construction of similar protective structures that require cast-in-place molding, such as protective sheds at tunnel entrances and temporary protective sheds for roads along mountains. It can solve the problems of "heavy structure, low flexibility, and high risk" of traditional support formwork systems under complex working conditions, and provide a "lightweight, modular, and mechanized" technical path for the construction of road and bridge protective structures, helping to improve the safety, efficiency, and economy of protective engineering construction in complex environments. Attached Figure Description

[0049] Figure 1 This is a cross-sectional view of the support template device system in this invention;

[0050] Figure 2 This is a plan view of the supporting template device system in this invention;

[0051] Figure 3 This is a longitudinal section view of the support template device system in this invention;

[0052] Figure 4 This is a detailed planar view of the supporting template device in this invention;

[0053] Figure 5 This is a schematic diagram of the assembly of the disc-buckle cluster support tower of the support template device in this invention;

[0054] Figure 6 This is a detailed drawing of the lifting device of the support template device system in this invention;

[0055] Figure 7 for Figure 6 Side view;

[0056] Figure 8for Figure 6 Top view;

[0057] In the diagram: 1-Lower longitudinal beam; 2-Upright pole; 3-Horizontal and diagonal poles; 4-Double lugs; 5-Upper longitudinal beam; 6-Upper crossbeam; 7-Timber I-beam; 8-Panel; 10-Crane cylinder control system; 11-Adjustable ground support; 12-Heavy-duty roller trolley; 13-Lifting conversion device; 14-Diagonal support; 15-Railway channel steel; 16-Conversion connector; 17-Sleeper; 18-Horizontal adjusting screw. Detailed Implementation

[0058] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to the specific embodiments.

[0059] Example 1

[0060] like Figures 1-8 As shown, a cast-in-place support formwork device for the roof slab of a disaster relief shed in a mountainous highway includes a foundation track system, a disc-buckle bundled support system, a lightweight gantry frame body, an upper formwork system, and a lifting and shifting system. Each system forms an integrated load-bearing system through high-strength bolts and specialized connectors, as detailed below:

[0061] 1. Basic Track System

[0062] The basic track system consists of 15×500×500mm Q235 steel plates, 17 anti-corrosion sleepers (0.3×0.34×0.64m), 15 [16Q235 track channel steels, and [10Q235 channel steels braced horizontally). The steel plates are laid on the foundation surface to distribute foundation stress. The sleepers 17 are arranged laterally with a spacing of 530mm to buffer the load. The track channel steels 15 are fixed above the sleepers 17, and both sides are reinforced with [10Q235 channel steel bracing. The system's track top elevation deviation is controlled within 3mm, and the track gauge deviation is controlled within ±2mm. It can adapt to cross and longitudinal slopes of no more than 8% in construction areas, eliminating the need for concrete foundations and reducing costs by 60% compared to heavy-duty trolley tracks. Its core innovation lies in using a flexible foundation of "steel plates + sleepers" to replace traditional concrete tracks. This allows for local adjustment of sleeper thickness based on foundation bearing capacity, adapting to uneven foundations in mountainous areas while minimizing damage to existing roads.

[0063] 2. Clasp-type cluster support system

[0064] The disc-lock cluster support system consists of four φ48.3×3.2mm Q355 disc-lock uprights 2 as a group, connected by 176mm 30# steel double-eared fasteners 4 to form a cluster support tower. A total of 11 groups of support towers are arranged along the axis of the lower longitudinal beam 1 at 530mm intervals. Adjacent support towers are connected by horizontal and diagonal braces 3, forming a double-layered sheet-like gantry frame. The horizontal braces are φ48.3×2.5mm Q235, and the diagonal braces are φ33.4×2.3mm Q235. A single group of cluster support towers has been verified by indoor load-bearing capacity tests, with an ultimate bearing capacity of no less than 490kN, far exceeding the actual working load of 210kN, and a safety factor of 2.3. The connection between the horizontal and vertical braces uses disc-lock nodes, with a shear bearing capacity of no less than 15kN, meeting the requirements for wind load and concrete lateral pressure resistance. The core innovation of this system is that it breaks through the traditional single-pole support mode. The four-pole bundled design increases the moment of inertia of the cross section by 4.2 times, and improves stability by 3 times while only increasing the weight by 17.5%.

[0065] 3. Lightweight gantry body

[0066] The lightweight gantry frame's lower longitudinal beam 1 and upper longitudinal beam 5 are both made of HN300×300×16×10mm Q235 steel, with a length of 11000+11000mm to match 20-22m construction segments; the upper crossbeam 6 is made of 40b I-beams, with a length of 7800mm and a spacing of 900mm to bear the formwork load; six sets of φ90×4mm Q235 diagonal braces are installed on both sides of the gantry frame, with the bottom end of the diagonal brace connected to the lower longitudinal beam 1 by high-strength bolts, and the top end supported at 2050mm from the edge of the upper crossbeam 6 to offset torque. The overall weight of the gantry frame is controlled within 40t, and through calculation and optimization using MidasGen software, it is 50% lighter than traditional heavy-duty trolleys; the connection node between the lower longitudinal beam 1 and the support tower is reinforced with 10mm thick ribs, with a local compressive strength of not less than 250MPa. Its core innovation is the adoption of a hybrid structure of "steel profile + disc buckle" to replace the all-steel trolley, which reduces material usage and hoisting requirements while ensuring load-bearing capacity, making it suitable for narrow sites in mountainous areas.

[0067] 4. Upper template system

[0068] The secondary joists of the upper formwork system are H20 wooden I-beams 7, 6000mm long and spaced 300mm apart, lightweight yet rigid; the panel 8 is 15mm thick bamboo plywood, with a surface flatness of no more than 1mm / m, resulting in excellent appearance quality of the top slab after pouring; the wooden I-beams 7 are fixed to the upper crossbeam 6 with special Q235 wooden beam clamps to prevent displacement. The linear load of the formwork system is controlled within 2.5kN / m, reducing weight by 40% compared to steel formwork; the overall flatness deviation after formwork assembly does not exceed 3mm. The core innovation of this system is the replacement of some steel secondary joists with wooden I-beams, reducing the formwork's self-weight while meeting load requirements, facilitating manual adjustment and disassembly, and reducing the intensity of high-altitude work.

[0069] 5. Lifting and shifting system

[0070] The lifting and shifting system includes an adjustable ground support 11, a 1000×480×200mm heavy-duty roller trolley 12, a lifting conversion device 13, and a crane cylinder control system 10. The adjustable ground support 11 is made of No. 20 steel, 500mm in length, and its lateral adjusting screw 18 has an adjustment range of ±150mm for fine-tuning the elevation. The heavy-duty roller trolley 12 has a single-wheel load capacity of no less than 50kN and is equipped with a braking device. The lifting conversion device 13 is linked to a 20t hydraulic cylinder. The crane cylinder control system 10 has a synchronization accuracy of ±1mm. The cylinder lifting speed is controlled within 10mm / min to avoid impact on the frame. The heavy-duty roller trolley 12's moving speed is controlled within 50mm / min, and is controlled by excavator traction to ensure stability. The system can achieve an overall lifting stroke of no less than 200mm for the gantry, meeting the requirements for formwork demolding and shifting. Its core innovation is the integrated design of the lifting and shifting system, which eliminates the need for separate disassembly and assembly of the shifting equipment; the roller trolley is equipped with a brake limit switch, which solves the problem of "easy deviation" in the movement of traditional trolleys and is adapted to the slight slope changes of mountain tracks.

[0071] Example 2

[0072] A construction method using the cast-in-place support formwork device for the roof slab of a disaster relief shelter on a mountain highway as described in Example 1 includes the following steps:

[0073] S1: Preliminary Preparations and Foundation Treatment

[0074] In the preliminary preparation and foundation treatment stage, a Topcon total station was first used to locate the axis of the tunnel, with the deviation controlled within 3mm. Then, a level was used to re-measure the elevation of the construction area, marking weak areas where the foundation bearing capacity was lower than 130KPa. During foundation reinforcement, the existing asphalt pavement was used directly, with only surface debris removed. In areas with local damage or insufficient bearing capacity, graded crushed stone soil was backfilled in layers, with each layer not exceeding 25cm in thickness. The soil was spread using a Longgong 50 loader and compacted with a hydraulic plate rammer, with a compaction degree of not less than 94%. A 25cm thick C25 concrete cushion layer was poured at the corresponding position of the support tower. The next process could only proceed after the cushion layer reached 70% strength, and the flatness deviation of the top surface of the cushion layer was controlled within 5mm to prevent uneven stress on the gantry.

[0075] S2: Basic Rail Installation

[0076] The basic track installation proceeds in the following order: 15×500×500mm steel plate → anti-corrosion sleepers → [16 track channel steel]. The steel plate must be tightly fitted to the foundation. The sleepers are laid horizontally, and the track channel steel is laid on top of the sleepers. During installation, a Su Yiguang DZ2 level is used to level the track, ensuring the top surface is horizontal. The two sides of the track are horizontally connected with [10 channel steel, with a spacing of 2000mm. The track gauge and axis are checked using a total station. After the deviation meets the requirements, the bolts are tightened to ensure guiding accuracy.

[0077] S3: Modular assembly of the device

[0078] The modular assembly of the device begins with the installation of the lower longitudinal beam. A QY25 truck crane is used to hoist the HN300×300 steel lower longitudinal beam. Adjustable ground supports, roller trolleys, and the lifting conversion device are connected using 8.8 grade M20×70mm high-strength bolts. The bolt torque is controlled between 400-450 N·m, with a deviation not exceeding ±5%, conforming to GB / T1231 standards. The bolt installation employs a three-step method of "initial tightening → secondary tightening → final tightening" to prevent loosening. Next, cluster support towers are erected. φ48.3×3.2mm disc-lock uprights are inserted into the lower conversion components fixed to the high-strength bolts of the lower longitudinal beam. Four uprights are connected using 176mm double-eared fasteners to form the support towers. After 11 sets of support towers are laid out along the lower longitudinal beam, horizontal and diagonal braces are installed to ensure that the verticality deviation of each gantry frame does not exceed 1 / 500. Finally, the superstructure is installed. An upper conversion component with a gap of no more than 2mm between it and the upright is inserted. The upper longitudinal beam is hoisted and fixed to the support tower using a special connector with 10mm thick Q235 steel plate and M20 bolts. The upper crossbeam of 40b I-beam is hoisted and connected to the upper longitudinal beam with high-strength bolts at a bolt spacing of 300mm. H20 wooden I-beams are laid and covered with 15mm bamboo plywood panels. φ90×4mm diagonal braces and d=38mm horizontal anchor bolts are installed to reinforce the horizontal limit of the gantry.

[0079] S4: Template Adjustment and Pre-compression Verification

[0080] During the template adjustment phase, the crane's hydraulic cylinder control system is activated to synchronously lift the gantry at a speed not exceeding 10 mm / min. Once the gantry is 50 mm off the track, the adjustable ground support screws are adjusted to keep the template elevation deviation within 3 mm. Preloading verification uses 120% surcharge preloading, with 3.65 t / piece of steel reinforcement used as counterweight, consistent with the concrete pouring sequence, loading from both ends towards the mid-span. The total load is 120% of the design load of the shed roof slab. Gradual loading is performed in four stages: 60% → 80% → 100% → 120%. After each stage, the gantry is left to stand for 1 hour, and settlement is monitored every 6 hours. Three monitoring sections are set up (both ends and the middle of the gantry), with five measuring points on each section (both sides of the frame, one-quarter / mid-span / three-quarters position of the I-beam). Stability is determined by a displacement difference of no more than 2 mm between two adjacent monitoring points. Based on the preloading data, a 3 mm pre-camber is set at the mid-span of the template, and the elevation is checked after adjustment.

[0081] S5: Concrete Construction

[0082] Before concrete construction, inspect the formwork joints, elevation, and support stability; clean debris from inside the formwork; and moisten the panels with water. During pouring, use a pump truck to deliver C40 concrete, pouring in layers no more than 300mm thick, and compacting with an immersion vibrator. Monitor formwork settlement in real time during pouring; if displacement exceeds 5mm, immediately stop pouring and investigate the cause. Curing management is carried out after the concrete has set; cover with geotextile and water for curing for at least 14 days. During curing, do not disturb the gantry.

[0083] S6: Template Removal and Gantry Frame Relocation

[0084] Formwork removal requires the concrete compressive strength to reach 100% of the design strength. The hydraulic cylinder control system is then activated to lift the gantry, adjusting the adjustable ground support to ensure it is at least 10cm off the ground. The hydraulic cylinder is then slowly pulled down, detaching the formwork 8-10cm from the concrete surface. During gantry reinforcement and relocation, first install the lower longitudinal beam (8000mm long, made of 16a channel steel) and the upper transverse beam (12000mm long, made of 12 I-beam steel) to enhance the overall rigidity of the gantry. Then, a Komatsu PC200 excavator is used to pull the roller trolley along the track to the next construction section. The moving speed should not exceed 50mm / min. A designated person monitors the track and wheel-rail contact; if the deviation exceeds 5mm, the machine is stopped immediately for adjustment. After the gantry is in place, the roller trolley is locked with a limit switch. The hydraulic cylinder is then used to lift the gantry to the design height. The adjustable ground support is adjusted, the connecting beam is removed, and the formwork elevation is checked before proceeding to the next construction section.

[0085] Example 3

[0086] This implementation method uses the Liangjiangpeng Tunnel Project in Changbai Korean Autonomous County, Baishan City, Jilin Province, on National Highway G331 as an example. This project is a typical disaster mitigation project for mountain roads. The construction method of Example 2 was applied throughout this project, verifying the feasibility and superiority of the technical solution. The specific implementation details are as follows:

[0087] I. Project Overview

[0088] Basic Project Information: This project is a core sub-project of the G331 Border Development Tourism Corridor DTD03 section, including four tunnels (No. 1, No. 2, No. 3, and No. 4) in Liangjiang, with a total length of 285.7m. Each tunnel has a structural width of 12.5m, a clearance height of 5m, and a roof slab thickness of 0.4m, and is constructed using C40 cast-in-place concrete. The project construction period is from September 2024 to September 2025, and it is necessary to ensure two-way traffic on the national highway.

[0089] The construction area is adjacent to the Yalu River on the right and a mountain with a 35° slope on the left. The working face is only 8.1m wide, which limits the space for large equipment to turn around and be hoisted. The bearing capacity of the foundation is only 120KPa in some areas, which poses a risk of uneven settlement. The surrounding area is an ecological protection zone of the Yalu River Basin, which prohibits large-scale excavation and vegetation destruction. It is also necessary to ensure that the national highway is open to traffic during the construction period.

[0090] II. Equipment Configuration and Preliminary Preparations

[0091] (I) Core Configuration of the Device

[0092] Based on the project scale, four sets of supporting formwork devices were constructed simultaneously. The key parameters for each set of devices are as follows:

[0093] Overall dimensions: 11m long, 8.1m wide, initial height 3.9m;

[0094] Core components: 2 HN300×300 steel longitudinal beams / set, 6 40b I-beam crossbeams / set, 44 φ48.3×3.2mm disc buckle uprights / set, 27 H20 wooden I-beams / set, 80㎡ of 15mm bamboo plywood panels / set;

[0095] Supporting equipment: 1 QY25 truck crane, 1 Komatsu PC200 excavator, 1 Topcon ES-602G total station, 1 Su Yiguang DZ2 level, and 2 sets of 20t hydraulic cylinder control systems.

[0096] (II) Preliminary Preparations

[0097] Technical preparation: Based on the construction drawings, the assembly node diagram of the device, the track layout diagram and the pre-stressing monitoring plan are refined, and the stress on the gantry is simulated using MidasGen software; special training is conducted for the construction team, focusing on the modular assembly and relocation operation procedures.

[0098] Site preparation: Clear the humus in the construction area down to the moderately weathered rock layer, and preserve the existing asphalt pavement; when materials arrive on site for inspection, the tensile strength of the disc buckle poles must be re-inspected, and the torque of the high-strength bolts must be tested. Only those that pass the test can be used.

[0099] III. Implementation Details of Key Construction Procedures

[0100] (a) Foundation treatment and track installation

[0101] Foundation reinforcement: For the local damaged sections of the existing asphalt pavement, graded crushed stone is used for backfilling in layers and compacted with a hydraulic plate rammer; for the area of ​​the support tower corresponding to the foundation bearing capacity of 120KPa, a 25cm thick C25 concrete cushion layer is poured, and the top surface of the cushion layer is leveled with a screed.

[0102] Track laying: The construction shall be carried out in the order of "steel plate → sleeper 17 → track channel steel 15". The 0.3×0.34×0.64m anti-corrosion sleepers 17 shall be laid horizontally with a spacing of 53cm. The [16 track channel steel 15 shall be laid flat on the sleepers 17. After laying, the track shall be leveled point by point with a level instrument. The elevation deviation of the top surface of the track shall be 2mm and the track gauge deviation shall be +1mm. The two sides shall be reinforced with [10 channel steel flat bracing to prevent displacement.

[0103] (ii) Modular assembly

[0104] Lower longitudinal beam installation: The crane lifts the lower longitudinal beam 1 to above the track channel steel 15. After adjusting the level, the adjustable ground support 11 and the traveling device 12 are connected with 8.8 grade M20 bolts. The bolts are tightened in three steps: initial tightening, re-tightening, and final tightening. After final tightening, the pass rate is 100% after re-inspection with a torque wrench.

[0105] Cluster support tower erection: After the upright 2 is inserted into the conversion connector 16, it is locked with 176mm double ear buckle 4. Four uprights 2 form a support tower. After the 11 groups of support towers are arranged along the axis of the lower longitudinal beam 1, the horizontal bar and diagonal bar 3 are installed. The verticality deviation of the gantry is checked by a total station to be 1 / 600.

[0106] Installation of the superstructure: The upper longitudinal beam 5 is hoisted and fixed to the support tower through the conversion connector 16. The upper cross beam 6 of 40b I-beams is arranged at a spacing of 900mm. The H20 wooden I-beams 7 are fixed with wooden beam clamps. Water-stop tape is applied to the joints of the bamboo plywood panels 8. Finally, 6 sets of φ90×4mm diagonal supports 14 are installed.

[0107] (III) Pre-compression verification and template adjustment

[0108] Preloading implementation: HRB400E steel bars of 3.65t / bundle were used as counterweights, with a total load of 270t, loaded in 4 stages, and left to stand for 1 hour after each stage of loading; 5 monitoring points were set up at the two ends and the middle of the gantry, and settlement was monitored with an electronic level.

[0109] Data feedback: After loading to 120%, the maximum settlement was 8mm, and the displacement difference between two adjacent monitoring points was 1.5mm; based on the data, a 3mm pre-camber was set at the mid-span of the formwork, and after adjustment, the formwork elevation deviation was 2mm, which meets the requirements.

[0110] (iv) Concrete construction and relocation

[0111] Concrete pouring: Concrete is poured symmetrically from both ends of the shed opening towards the middle of the span using a pump truck, with each layer being 25cm thick. An immersion vibrator is used to compact the concrete until the surface is covered with slurry. During pouring, the formwork settlement is monitored, with a maximum displacement of 3mm. After final setting, the concrete is covered with geotextile and watered for curing for 14 days.

[0112] Gantry relocation: After the concrete strength reaches 40MPa, the hydraulic cylinder control system 10 is activated to lift the gantry by 10cm through the lifting conversion device 13, so that all four lifting conversion devices 13 are under force. The adjustable ground support 11 is adjusted to be at least 10cm off the ground. The hydraulic cylinder control system 10 is activated again to pull the hydraulic cylinder down. The process stops when the formwork is 8-10cm away from the concrete surface. Two connecting beams of [16 channel steel lower longitudinal beam and 12 I-beam upper transverse beam are installed at both ends of the gantry. The excavator pulls the gantry along the track channel steel 15. Two people are assigned to monitor the contact between the walking device 12 and the track channel steel 15. After reaching the position, the limit switch is locked and the gantry elevation is adjusted to the design position. The single relocation takes 1.2 hours.

[0113] IV. Implementation Results Verification

[0114] Quality and Results: The roof slab of the shed was tested by a third party and the flatness deviation of the bottom surface was 1.8mm. The average concrete strength was 43.2MPa, and there were no defects such as cracks or exposed reinforcement.

[0115] Construction period results: The construction period for a single section of the tunnel is 4 days, and the total construction period for the 285.7m tunnel is 60 days, which is 15 days ahead of schedule.

[0116] Safety benefits: The amount of high-altitude work was reduced by 80% throughout the construction process, involving only a small number of high-altitude operations such as hoisting the upper longitudinal beams, and no safety accidents such as falls or collapses occurred.

[0117] Economic benefits: The material consumption of the four sets of supporting gantry frames is 80t, saving 112,000 yuan in steel procurement costs per project; the components are 100% reused and subsequently applied to the construction of sheds in adjacent sections, saving another 60,000 yuan in equipment investment, with a total economic benefit of 172,000 yuan.

[0118] Environmental and traffic benefits: No construction access roads were required, and the area of ​​vegetation damage was reduced by 90%; during the construction period, the two-way traffic rate of the national highway remained above 80%, and no traffic congestion occurred, thus balancing ecological protection and people's livelihood needs.

[0119] The above are preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A construction method of a mountain road disaster treatment shed tunnel roof cast-in-place support formwork device, characterized in that, Specifically comprising the following steps: S1. Foundation treatment and measurement line: using total station positioning shed hole axis, axis deviation ≤3mm; for the area where the foundation bearing capacity <130KPa, using gravel soil layered backfill, layered thickness ≤25cm and compaction degree ≥94%, pouring 25cm thick C25 concrete cushion; S2. Foundation track installation: laying 15×500×500mm steel plate, steel plate on the transverse distribution 0.3×0.34×0.64m sleeper, sleeper spacing 530mm; fixed [16 rail channel steel on the sleeper, track top surface elevation deviation ≤3mm, track gauge deviation ≤±2mm, both sides of the track through [10 channel steel flat link reinforcement; S3. Modular assembly of device: ①Hoist HN300×300×16×10 type steel lower longitudinal beam, use 8.8M20×70mm high strength bolt connection adjustable ground support, 1000×480×200mm heavy duty roller trolley and lifting conversion device; ②φ48.3×3.2mm disc buckle vertical rod is inserted into the lower conversion piece, 4 vertical rods are connected to form a cluster support tower by using 176mm 30# steel double ear buckle, 11 groups of support towers are arranged along the lower longitudinal beam with a spacing of 530mm, and a double-layer gantry is connected by φ48.3×2.5mm horizontal rod and φ33.4×2.3mm inclined rod; ③Install upper conversion piece and same specification upper longitudinal beam, hoist 40b I-steel upper cross beam, fix H20 wooden I-beam with beam clamp with a spacing of 300mm, and lay 15mm bamboo plywood panel; 5 groups of φ90×4mm inclined braces are arranged to connect d=38mm horizontal anchor bolt and external structure; S4. Template adjustment and preloading: start the oil cylinder control system to synchronize the lifting of the gantry, adjust the adjustable ground support to make the template elevation deviation ≤3mm; according to the shed roof design load, load in stages of 60%→80%→100%→120%, monitor the settlement after each stage of loading for 6h, and determine stability when the displacement difference between adjacent two times is ≤2mm, and set the pre-camber according to the preloading data; S5. Concrete construction: use pumping method to pour C40 concrete, with a layered thickness ≤300mm; after final setting, cover with geotextile and water for curing, and the curing period ≥14 days; S6. Template removal and gantry displacement: when the compressive strength of concrete reaches 100% of the design, lift the gantry and adjust the adjustable ground support to be ≥10cm away from the ground, lower the oil cylinder to make the template 8-10cm away from the concrete surface; install lower longitudinal beam connecting beam and upper cross beam connecting beam, use excavator to pull the walking wheel along the track, lock the positioner and reset the gantry after reaching the position.

2. The construction method of a mountainous highway disaster prevention shed hole roof cast-in-place support formwork device according to claim 1, characterized in that, In step S3, the vertical rods of the cluster support tower are made of Q355, the horizontal rods and inclined rods are made of Q235, and the indoor bearing capacity test value of a single cluster support tower is ≥490kN.

3. The construction method of a mountainous highway disaster prevention shed hole roof cast-in-place support formwork device according to claim 1, characterized in that, In step S4, the preloading weight uses 3.65t / rod of steel reinforcement raw material, the loading sequence is consistent with the concrete pouring sequence; 3 monitoring sections are arranged at both ends and the middle of the device, 5 monitoring points are arranged at each section, including two sides of the frame body, one fourth of the wooden I-beam, the middle of the wooden I-beam, and three fourths of the wooden I-beam, and the unloading is implemented in reverse step by step.

4. The construction method of a mountainous highway disaster prevention shed hole roof cast-in-place support formwork device according to claim 1, characterized in that, In step S6, the gantry moving speed is less than or equal to 50 mm / min, the obstacles within a range of 5 m around the track are cleaned before moving, a special person is arranged to monitor the track flatness and the wheel-rail contact state, and the machine is immediately stopped and adjusted when the horizontal displacement deviation exceeds 5 mm.

5. The construction method of a mountainous highway disaster prevention shed hole roof cast-in-place support formwork device according to claim 1, characterized in that, The [16 track groove steel adaptive shed hole construction area is less than or equal to 8% of the transverse and longitudinal slope, the concrete track foundation does not need to be poured, the shed hole top plate construction is completed while ensuring the passage of the existing road, and the interference with the surrounding traffic and environment is reduced.

6. The construction method of the device for supporting the formwork of the cast-in-situ roof of the tunnel of the mountain road disaster prevention according to any one of claims 1 to 5, characterized in that, The overall weight of the supporting formwork device is less than or equal to 40 t, the upper and lower longitudinal beams are made of Q235, and the torque value deviation of all high-strength bolts is less than or equal to ± 5%, which meets the standard requirements of GB / T1231; and the construction method of the supporting formwork device is suitable for the shed hole top plate cast-in-place construction scene in mountainous highway disaster treatment projects, is adaptive to narrow terrain, complex geological conditions, and difficult sections that need to ensure the two-way traffic of the existing road, and can realize the integrated operation of shed hole top plate support, formwork installation and mechanized displacement.

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