A rigid-flexible combined debris flow apron structure and construction method

Abstract

This invention discloses a rigid-flexible composite structure for debris flow revetment and its construction method. The revetment covers the entire cross-section of the downstream channel of the debris flow barrier, continuously laid along the channel's flow direction. Its total length is determined based on debris flow velocity, dam height, and flow rate parameters, while its total width matches the effective width of the channel. The overall structure is a rectangular planar structure without stepped drops. It consists of a frame plate, skirts, and sidewalls. The frame plate is cast with reinforced concrete, and its width and height are dynamically adjusted according to the channel's scour depth. The sidewalls are located on both sides of the channel, and the skirts are located at the downstream end of the frame plate. The skirts extend above the frame plate. The frame plate is arranged within the framework formed by the revetment and skirts, forming a rigid skeleton. Layers of compacted boulders are placed within the frame to form a flexible, impact-resistant layer. This invention achieves the goals of impact resistance, abrasion resistance, scour prevention, and ecological compatibility through a rigid skeleton foundation, flexible filling for energy dissipation, and the use of locally sourced materials.

Description

Technical Field

[0001] This invention belongs to the field of debris flow protection engineering technology, specifically relating to a rigid-flexible debris flow retaining structure and its construction method. Background Technology

[0002] Debris flow areas are characterized by steep tectonic slopes (mostly 25°-45°) and abundant loose solid materials (large reserves of weathered rock layers and colluvial deposits). Debris flows are often characterized by high-speed flow, high sand content, and complex conditions involving large-diameter boulders. This not only causes devastating damage to villages and farmland along the flow but also seriously threatens the operational safety of infrastructure such as railways, highways, and power transmission lines.

[0003] Debris flow revetments are a key protective link at the outlet of debris flow retaining structures (such as sand-blocking dams and grid dams). Their core function is to weaken the residual kinetic energy of debris flows after they leave the station by dissipating energy and slowing down, resisting erosion and wear, and preventing scouring and stabilizing the foundation. This helps to prevent slope collapse and instability of structures caused by channel downcutting erosion, and ultimately stabilizes the channel boundary and ensures the safety of downstream areas.

[0004] Existing debris flow protection designs have significant limitations due to their single structural design, making them unsuitable for the complex working conditions in the southwestern mountainous regions. The shortcomings of rigid abutments: Traditional rigid abutments (concrete, masonry, and reinforced concrete structures) rely on high rigidity and thickness to resist impact. While they can withstand the erosion of moderate-intensity debris flows, their impact toughness is insufficient under the instantaneous impact of large-diameter boulders in the mountainous areas of Southwest China. The peak stress generated by the impact of boulders (reaching 100-200 MPa) easily leads to surface breakage and corner chipping, with cracks rapidly propagating along weak points in the structure, ultimately causing overall instability. More importantly, the fully rigid cover design of rigid abutments completely blocks the connection between the ditch bed and groundwater, destroying the habitat of aquatic organisms (such as river crabs and stone frogs), exacerbating the ecological degradation of mountain rivers, which contradicts current ecological protection concepts. At the same time, the inconvenient transportation in the mountainous areas of Southwest China requires the long-distance transport of building materials such as cement and steel for rigid abutments, resulting in a long construction period (usually 2-3 months) and significant difficulties in emergency repairs after disasters.

[0005] The bottlenecks of flexible revetments: Although flexible revetments (such as geogrid reinforcement, flexible metal mesh, and eco-bags) have a certain impact resistance and toughness, in the high sand content and strong abrasion environment of the southwestern mountainous areas, flexible materials (such as geogrids or eco-bag fabrics) are easily eroded by fine particles of mud and sand in debris flows over a long period of time, resulting in aging and damage (short service life). More seriously, when the sand content of debris flows exceeds 70%, the pores of the flexible structure are easily blocked by mud and sand, leading to poor drainage, rising water levels in the gully, and then triggering seepage and scouring of the base, ultimately causing the overall sliding of the debris flow retaining dam. In addition, flexible revetments have weak resistance to impact from large-diameter boulders. In the debris flow conditions with a boulder content of more than 30%, which are common in the southwestern mountainous areas, structural tearing and local collapse are likely to occur, resulting in a significant reduction in the protective effect. Summary of the Invention

[0006] The purpose of this invention is to provide a rigid-flexible debris flow protection structure and construction method that combines the overall stability of rigid protection with the impact resistance and toughness of flexible protection. It is perfectly adapted to the complex geological and climatic conditions and debris flow conditions in the southwestern mountainous areas. At the same time, it solves the shortcomings of traditional protection structures, such as ecological damage, inconvenient construction, and short service life, and provides an economical, efficient and sustainable technical solution for debris flow disaster prevention in the southwestern mountainous areas.

[0007] In response to the complex geological conditions and debris flow situations in the mountainous areas of Southwest China, this invention proposes a rigid-flexible debris flow revetment structure and construction method. Through a design approach that combines a rigid framework for foundation stabilization, flexible filling for energy dissipation, and the use of locally sourced materials, it achieves multiple objectives including impact resistance, abrasion resistance, scour prevention, and ecological compatibility. Specific optimizations are as follows: (1) Structural adaptability optimization: to fit the complex working conditions in mountainous areas.

[0008] The rigid main structure employs a combination design of frame panels, hammer arrays, and sidewalls to precisely address the high impact and strong lateral pressure characteristics of debris flows in the southwestern mountainous areas. The frame panels are cast from reinforced concrete, with their width and height dynamically adjusted according to the scour depth of the gully, forming a robust protective framework that can directly withstand the instantaneous impact of large-diameter boulders and stabilize flexible materials, preventing overall slippage and overturning of the revetment. The skirts and sidewalls are located around the frame panels, extending 500mm above their height, effectively preventing lateral overflow of debris flows and protecting the gully banks. The frame is filled with locally sourced boulders (moderately weathered granite and basalt), with a particle size of 150-300mm. Through layered compaction (compaction degree ≥95%), a flexible impact-resistant layer is formed. When debris flows impact, the boulders can self-compress and disperse the impact force, reducing stress concentration in the rigid structure and lowering the risk of breakage, perfectly solving the problem of rigid revetments being brittle and prone to cracking.

[0009] (2) Targeted enhancement for working conditions: adaptable to environments with high sand content and strong abrasion.

[0010] The natural gaps between the stones within the frame can not only trap some of the mud and sand debris in the debris flow (the trapping rate can reach 20%-30%), reducing the downcutting erosion of the debris flow, but also form natural drainage channels to avoid poor drainage caused by mud and sand blockage. The stones are made of moderately weathered hard rock widely distributed in the southwestern mountainous areas, with a compressive strength ≥60MPa, a softening coefficient ≥0.85, and a wear and corrosion resistance far exceeding that of flexible materials, with a service life of 15-20 years.

[0011] (3) Construction and ecological adaptation: Adapting to the actual conditions of mountainous areas: The flexible filling material uses locally sourced boulders, eliminating the need for long-distance transportation of building materials and significantly reducing construction costs caused by inconvenient transportation in the southwestern mountainous areas. The construction cycle is shortened to within one month, and emergency repairs can be carried out quickly after disasters. The porous structure formed by the boulders retains the natural air permeability and water permeability of the ditch bed, ensuring the connection between groundwater and ditch water, providing habitat for aquatic organisms, and achieving protection and ecological compatibility. At the same time, the boulders laying process is simple and requires low-end construction equipment (only a small crane and vibratory roller are needed), making it suitable for operation in narrow construction sites in mountainous areas and greatly reducing construction difficulty.

[0012] This application proposes a rigid-flexible debris flow revetment structure and construction method. The core design concept is rigid-flexible composite and local material utilization. It adopts a flat layout, with the two sides of the ditch serving as the sidewalls of the revetment. The downstream end of the frame plate is a skirt. The middle revetment uses reinforced concrete frame plates to form a rigid skeleton. Stone blocks are laid in layers in the frame as flexible materials to form a rigid-flexible composite overall reinforcement structure.

[0013] To achieve the above objectives, the present invention provides a rigid-flexible combined debris flow protection structure, comprising: The protective slope is designed to be laid continuously along the flow direction of the gully across the entire cross-section downstream of the dam outlet. The total length is determined based on parameters such as debris flow velocity, dam height, and flow rate. The total width is consistent with the effective width of the gully. The overall structure is a rectangular planar structure with no stepped drop, ensuring straight flow and uniform energy dissipation of the debris flow.

[0014] The protective tank consists of a grid plate, a hammer group, and sidewalls.

[0015] The sidewalls are arranged on both sides of the ditch, and the skirts are arranged downstream of the ditch to form a closed structure with the retaining dam. The grid panels are installed inside the closed structure and arranged continuously in rows and columns to divide the closed structure into several grids. The grids are filled with locally sourced stones.

[0016] Furthermore, the formula for calculating the tank length L is as follows: In the formula: The length of the tank is in meters (m). The horizontal velocity of the debris flow over the dam is given in m / s. The depth of the overflow water upstream of the dam crest, in meters; The difference in water levels between upstream and downstream; This is the acceleration due to gravity, in m / s². 2 .

[0017] Furthermore, as a rigid framework, the height, width, and spacing of the grid plate need to be designed and determined based on the characteristic parameters of debris flow.

[0018] Effective height of the frame plate Based on the debris flow erosion depth, the foundation depth of the frame grating is usually determined by the effective height. Therefore, the total height of the frame grating... The width of the grating is 0.4m. Effective height. Calculation formula:

[0019] The effective height of the grating (height above ground) is in meters (m). This refers to the standard particle size (mm) of riverbed sand and gravel, meaning that 90% of the solid material is smaller than this particle size. To control the dam's height, m; For unit width flow rate, m 2 / s.

[0020] Furthermore, to ensure that the grating panels do not deform excessively, the spacing between adjacent rows or columns of grating panels... The calculation uses impact stiffness constraints, and the formula is as follows: In the formula, This refers to the spacing between the grid panels; The width of the grating is in mm. Take 0.4m.

[0021] The standard value of the axial compressive strength of the concrete in the lattice slab, in MPa; The effective height of the frame border, in mm; Maximum impact intensity of debris flow, kPa; for small and medium-sized debris flows in the southwestern mountainous areas, take 50-150 kPa. Impact coefficient, taking into account the instantaneous nature of debris flow impact, is taken as 0.8-1.0.

[0022] Furthermore, the sidewalls adopt a U-shaped closed arrangement with longitudinal (both sides) and transverse (downstream) skirts. The sidewalls on both sides block the lateral overflow of debris flows, while the skirts at the downstream end resist backflow and scouring, forming full-boundary protection. The sidewalls and skirts have the same structure and burial depth. The effective height of the skirts... The design extends 0.5m above the effective height of the grating, i.e. The burial depth is also taken as the effective height, therefore the total height of the skirt is... The width of the hammer array is increased by 0.1m compared to the frame width to enhance impact resistance and meet the bending and shear resistance requirements under conventional lateral impact.

[0023] Further reinforcement design: The frame slab is internally reinforced with longitudinal and transverse main bars of Ф14@120mm, running the entire length of the frame. Distribution bars are bidirectional distribution bars of Ф10@150mm, tied to the main bars to form a steel mesh. At each corner, four Ф16@100mm reinforcing bars, 600mm in length, are installed to address stress concentration at the corners. The protective layer thickness of the steel mesh is ≥50mm.

[0024] The skirt reinforcement configuration is as follows: vertical main bars Ф20@200mm, horizontal distribution bars Ф12@200mm, and the thickness of the steel mesh protective layer is ≥50mm.

[0025] Furthermore, locally sourced stones are selected from hard rocks such as moderately weathered granite and basalt, which are widely distributed in the southwestern mountainous areas, while avoiding the use of weathered rocks and weak rocks. Particle size: 150-300mm (minimum particle size ≥ 1 / 5 of the net width inside the frame to prevent loss from the frame gaps); Mechanical properties: compressive strength ≥60MPa, softening coefficient ≥0.85, abrasion rate ≤10%.

[0026] Layered filling: Lay in layers of 300mm / layer, for a total of 2-3 layers, to match the frame height; Compaction requirements: After each layer is laid, it shall be compacted with a small vibratory roller (excitation force ≥20kN) to achieve a compaction degree ≥95% and ensure that the stones are tightly interlocked. Joint filling treatment: The gaps between the stones are filled with crushed stone with a particle size of 50-100mm, with a filling rate of ≥90%, to prevent fine particles of mudslide from directly eroding the inner wall of the frame.

[0027] Surface treatment: After filling, the surface of the stone blocks is 100mm higher than the upper edge of the frame plate, forming a flat and slightly rough impact-resistant surface to enhance the energy dissipation effect.

[0028] A construction method for a rigid-flexible debris flow retaining wall structure includes: Step 1. Investigation of disaster characteristics and calculation of debris flow movement parameters: Collect data on the formation conditions, basic characteristics and hazards of debris flows, and calculate the design velocity, maximum rock size, annual outbreak frequency, abutment length, grid height and skirt height based on the collected data.

[0029] Step 2. Draw construction drawings based on the survey results, and determine the burial depth of the frame plate, hammer group and sidewall. Use equipment to accurately locate the outline of the sidewall of the apron, the axis of the skirt and the layout of the frame plate downstream of the retaining dam. Step 4. Construction of the skirt and side wall: Embed anchor bolts in the foundation pit of the skirt and side wall, conduct pull-out tests, arrange the steel mesh and formwork of the skirt (side wall), pour concrete and cure, and remove the formwork after the strength meets the requirements. Step 5. Frame panel installation: Use machinery to arrange the prefabricated frame panels according to the control lines and adjust the levelness; Step 6. Fill with flexible boulders: Lay locally sourced boulders in layers of 300mm / m, with the filling height 50mm below the top edge of the frame plate. After each layer is laid, compact it with a small vibratory roller. Fill the gaps between the boulders with crushed stone with a particle size of 50-100mm and level it manually. After filling, the surface of the boulders should be 50mm above the top edge of the frame plate.

[0030] Furthermore, reinforcing bars are added at the corners of the side walls and the steel mesh of the hammer group, steel formwork is installed, the flatness error of the formwork is ≤3mm / m, and sealing strips are used to seal the joints to prevent grout leakage.

[0031] Furthermore, adjacent frame panels are joined using tongue and groove joints, with water-swellable sealing strips embedded at the joints.

[0032] Furthermore, the levelness error is ≤5mm / m, and the outer side of the flat joint is sealed with C40 epoxy mortar.

[0033] Furthermore, welding is performed at the joints between the grating and the side wall, or between the grating and the hammer group. 14 steel bars, 500mm in length, enhance overall connectivity.

[0034] The beneficial effects of this invention are: (1) Strong impact resistance and energy dissipation capacity: The rigid frame of the apron (concrete frame plate) resists the impact and erosion of large rocks in the debris flow; the flexible layer (block crushed stone) reduces the impact force by 40%–60% through deformation energy dissipation and friction deceleration, protecting the rigid structure from brittle failure.

[0035] (2) Strong adaptability of foundation to deformation: The flexible layer can adapt to uneven settlement, frost heave or ditch slope deformation, and has strong adaptability to adverse geological conditions such as soft foundation and broken bedrock. It does not require large-scale foundation treatment and has low foundation cost.

[0036] (3) Improvement of the watershed water environment: The present invention protects the embankment to be permeable and breathable, maintain the groundwater supply and runoff connection of the ditch, avoid the groundwater level drop and wetland degradation caused by the "hardening blockage" of pure concrete; after intercepting debris flow, the clear water is discharged, and the sediment can be used for irrigation after sedimentation, thus improving the downstream water quality and soil.

[0037] (4) Convenient construction and high economy: The flexible material of the tank protection of the present invention can be sourced locally and laid directly, which greatly shortens the construction cycle and has high economic benefits. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the tank shield structure.

[0039] Figure 2 This is a schematic diagram of the longitudinal section of the tank protection structure.

[0040] Figure 3 This is a schematic diagram of the cross-section of the tank protection structure.

[0041] Figure 4 A schematic diagram of the completed construction according to an embodiment of the present invention.

[0042] In the diagram, 1-frame plate, 2-skirt, 3-barrier dam, 4-side wall. Detailed Implementation

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Note: Unless otherwise specified, the experimental methods in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0045] The principle of this invention: In this invention, the retaining dam 3 is used to intercept mud, sand, and rocks from debris flows, blocking coarse material and allowing fine material to pass through. When a debris flow passes, the main products of the debris flow are blocked by the retaining dam 3, while finer materials enter the apron. The apron structure prevents the debris flow from damaging the retaining dam 3. Downstream of the retaining dam 3, the apron protects against erosion of the downstream foundation of the retaining dam 3 after the debris flow passes through it. The apron is enclosed by skirts 2 and divided into several blocks by frame plates 1, which increases both the integrity and rigidity of the apron, thus dispersing and mitigating the destructive effect of the debris flow.

[0046] In this invention, the function of the revetment sidewall 4 is to contain debris flows, preventing them from overflowing the gully and eroding the banks on both sides. The function of the skirt 2 is to prevent debris flows from eroding the foundation of the entire revetment, thus extending its service life. The purpose of the grid plate 1 is to stabilize the backfill riprap of the revetment; it is a rigid structure mainly designed to withstand the enormous impact force generated after the overflow from the overflow outlet of the retaining dam 3.

[0047] Example 1: As Figures 1 to 4 As shown, taking a debris flow control project in a certain area as an example. (1) Site survey and scheme optimization: Disaster Characteristics: Through remote sensing, drone aerial photography, geological drilling, geophysical exploration, and ground surveys, the formation conditions, basic characteristics, and hazards of debris flows were identified. The drainage area of ​​a debris flow in a certain area is 25.52 km². 2 The main gully is 10.16 km long, with the highest peak reaching 5900 m above sea level and the confluence of the gully mouth and main river at 1660 m above sea level. The relative elevation difference within the gully is approximately 4240 m, and the overall average longitudinal slope of the gully is 334‰. The total amount of loose solid material in the gully is approximately 12.3844 million cubic meters, with a dynamic reserve of approximately 2.3626 million cubic meters capable of participating in flash floods and debris flows. The main sources are landslide debris, glacial till, and gully debris. On August 3, 2024, between 3 and 4 AM, a flash flood and debris flow occurred at this location, dislodging 520,000 cubic meters of solid material.

[0048] Debris flow motion parameters calculation: Determine the design flow velocity, maximum rock particle size, and annual outbreak frequency of debris flow. Using the above formulas, calculate key parameters such as the length of the retaining wall (length of sidewall 4), the height of the grid plate 1, and the height of the skirt 2.

[0049] Tank length L: =24.3m, take 25m; Frame plate 1 height H: H=2 =2.86m, take 3m, foundation depth 1.5m; Skirt height Z: Z=2 =3.86m, take 4m, foundation depth 2m; Material sourcing: Determine the lithology of locally sourced boulders (preferably moderately weathered granite and basalt), reserves, and transportation routes: Ensure that the boulders have a compressive strength ≥60MPa, a particle size of 150-300mm, and that the sourcing point is ≤5km from the construction site to reduce transportation costs.

[0050] Detailed plan: Based on the survey results, detailed construction drawings were drawn up. The foundation of the frame slab was buried at a depth of 1.5m, and the foundations of sidewall 4 and skirt 2 were buried at a depth of 2m. For narrow ditches or steep slopes, the construction site layout was optimized and the operation route of small equipment was planned.

[0051] (2) Measurement, layout and positioning: A total station was used to accurately locate the outline of the revetment, the axis of the skirt 2, and the control line for the frame plate 1. The positions of the anchor bolts were marked in the foundation pit of the side wall 4 and the skirt 2 to ensure uniform spacing.

[0052] (3) Construction of the anchoring system with sidewall 4 and skirt 2: Anchor bolt pre-embedding: Drill holes at the bottom of the foundation pit of side wall 4 and skirt 2 according to the markings. The hole diameter is 100mm and the depth is ≥1000mm. After pouring M30 cement mortar, insert Ф22 anchor bolts to ensure that the verticality error of the bolts is ≤2°. After curing for 7 days, conduct a pull-out test (pull-out force ≥60KN).

[0053] Reinforcement binding and formwork installation: Bind the steel mesh (vertical main reinforcement Ф20@200mm, horizontal distribution reinforcement Ф12@200mm) of the skirt 2 (side wall 4), and add reinforcing bars at the corners; install steel formwork, with a flatness error of ≤3mm / m, and apply sealing strips to the joints to prevent grout leakage.

[0054] Concrete pouring and curing: Pour C35 concrete, with the vibrator insertion spacing ≤500mm to ensure compaction without honeycomb or pitting; after the concrete has initially set, cover it with geotextile for moisture retention and curing for ≥14 days. Remove the formwork after the strength reaches 75% of the design value.

[0055] (4) Installation of frame plate 1: A small crane is used to lift the precast frame 1, and the units are laid out flat according to the control line to ensure alignment between units. Adjacent frame 3 are spliced ​​with tongue and groove joints, and water-swellable sealing strips are embedded at the tongue and groove joints.

[0056] Adjust the level of the frame plate 1 to an error of ≤5mm / m; seal the outside of the flat joint with C40 epoxy mortar; weld Ф14 steel bars (500mm in length) at the joint between the frame plate 1 and the hammer group 2, or between the frame plate 1 and the side wall 4 to enhance the overall connection.

[0057] (5) Flexible rubble filling: Layered laying: Lay locally sourced stones in 300mm / layers, with the filling height slightly lower than the upper edge of the frame plate 1 by 50mm. After each layer is laid, compact it with a small vibratory roller with a vibration force ≥20kn to ensure a compaction degree ≥955.

[0058] Joint filling: Fill the gaps between the stones with crushed stone with a particle size of 50-100mm, and manually level the surface to ensure there are no obvious voids; after filling, the surface of the stones is 50mm higher than the upper edge of the frame board to form a rough, impact-resistant surface.

[0059] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A rigid-flexible debris flow protection structure, characterized in that, include: The protective slope is designed to be laid continuously along the flow direction of the gully across the entire cross section downstream of the dam outlet. The total length is determined based on the debris flow velocity, dam height, and flow rate. The total width is consistent with the effective width of the gully. The overall structure is a rectangular planar structure with no stepped drop. The retaining wall consists of a grid plate, a skirt, and sidewalls. The grid plate is made of reinforced concrete. The width and height of the frame are dynamically adjusted according to the scour depth of the gully. The sidewalls are arranged on both sides of the gully, and the skirt is arranged at the downstream end of the retaining dam. The sidewalls and skirts have the same structure and burial depth. The height of the skirt is higher than that of the grid plate. The grid plate is arranged within the frame formed by the retaining dam and the skirt, forming a rigid skeleton. The frame is filled with layers of compacted boulders to form a flexible impact-resistant layer. The boulders are moderately weathered hard rocks widely distributed in the southwestern mountainous areas.

2. The structure according to claim 1, characterized in that, The formula for calculating the length L of the shield is as follows: In the formula: The length of the tank is in meters (m). The horizontal velocity of the debris flow over the dam is given in m / s. The depth of the overflow water upstream of the dam crest, in meters; The difference in water levels between upstream and downstream; This is the acceleration due to gravity, in m / s². 2 .

3. The structure according to claim 1, characterized in that, The effective height of the frame plate The foundation depth of the frame grating is determined based on the depth of the debris flow scour. The effective height is taken as the foundation depth, and the total height of the frame grating is used as the foundation depth. The width of the grating is 0.4m, and the effective height is... Calculation formula: The effective height of the grating is in meters (m). Standard particle size of riverbed sand and gravel, mm; To control the dam's height, m; For unit width flow rate, m 2 / s.

4. The structure according to claim 1, characterized in that, The spacing of the frame plates The calculation uses impact stiffness constraints, and the formula is as follows: In the formula, This refers to the spacing between the grid panels; The width of the frame border is in mm; The standard value of the axial compressive strength of the concrete in the lattice slab, in MPa; The effective height of the frame border, in mm; Maximum impact strength of debris flow, kPa; Impact coefficient.

5. The structure according to claim 1, characterized in that, The effective height of the skirt The height of the skirt is 0.5m above the effective height of the frame grating, and the burial depth is taken as the effective height. The width of the hammer group is 0.1m wider than the width of the frame.

6. The structure according to claim 1, characterized in that, The frame plate is equipped with longitudinal and transverse main bars of Ф14@120mm, which run through the entire length of the frame; the distribution bars are bidirectional distribution bars of Ф10@150mm, which are tied with the main bars to form a steel mesh; at the corners of each frame, Ф16@100mm reinforcing bars are set at the four corners, with a length of 600mm, and the thickness of the steel mesh protective layer is greater than or equal to 50mm.

7. The structure according to claim 1, characterized in that, The vertical main reinforcement bars of the skirt are Ф20@200mm, the horizontal distribution bars are Ф12@200mm, and the thickness of the steel mesh protective layer is greater than or equal to 50mm.

8. The structure according to claim 1, characterized in that, It also includes the layered compaction of the boulders: laid in layers of 300mm each, for a total of 2-3 layers, to match the frame height.

9. The structure according to claim 1, characterized in that, It also includes stones with a particle size of 150-300mm, a compressive strength of ≥60MPa, a softening coefficient of ≥0.85, and an abrasion rate of ≤10%.

10. The structure according to claim 1, characterized in that, This also includes compacting each layer of paved stones with a small vibratory roller, achieving a compaction degree of ≥95%; filling the gaps between the paved stones with crushed stone with a particle size of 50-100mm, achieving a filling rate of ≥90%; and ensuring that the surface of the paved stones is 100mm higher than the upper edge of the frame plate after filling, forming a flat and rough impact-resistant surface.

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