A riprap ecological revetment system adaptive to water level recession

Abstract

The present application relates to the field of ecological revetment in the field of hydraulic engineering, and particularly relates to a riprapping ecological revetment system suitable for water level drawdown. The system comprises an ecological soil base layer, a filter layer, a riprapping revetment, a simulated wood pile scour protection belt and a planting groove; the ecological soil base layer has a compaction degree of greater than or equal to 93%, providing a dense support; the filter layer ensures smooth seepage and prevents soil loss; the riprapping revetment is formed by stacking large-diameter block stones according to gradation, forming a rigid skeleton resistant to scour; the planting groove is fixed in the riprapping structure, providing space for vegetation and anchoring the surface riprapping. The present application forms a closed-loop protection system through the cooperation of the five, effectively solving the problems of traditional riprapping revetment, such as easy scouring and instability during water level drawdown, and high maintenance cost, and has the advantages of scour resistance, ecology and universality, and is suitable for water level rapid rise and fall scenes such as regulating and storing lakes, reservoir drawdown zones, tidal river shorelines and the like.

Description

Technical Field

[0001] This invention relates to the field of ecological bank protection in water conservancy engineering, specifically to a riprap ecological revetment system that adapts to water level drop. Background Technology

[0002] Urban parks, lakes, and water storage ponds often employ riprap ecological revetments. These revetments consist of stacked graded stones filled with organic matrix, providing microhabitats for organisms and serving both ecological and protective functions. However, traditional riprap ecological revetments have the following drawbacks:

[0003] The design did not specifically address the water level drop: When the water level of the reservoir drops rapidly, the water flow will cause concentrated scouring along the slope, especially within 2m below the normal water level. The drag force of the water flow and the seepage pressure are superimposed, which can easily cause the displacement of riprap, loss of soil in the cracks and exposure of vegetation roots, leading to instability of the revetment structure and degradation of ecological functions.

[0004] The protection is not targeted enough: Most existing revetments adopt the method of full-line reinforcement or simple rock dumping, which fails to achieve precise protection of key areas of erosion, resulting in the contradiction of "high cost of full-line protection and failure of protection in key areas".

[0005] Poor structural synergy: Traditional rockfill, vegetation and protective components are mostly set up independently, failing to form a closed-loop synergistic system of "energy dissipation-erosion resistance-soil stabilization", resulting in high maintenance frequency and cost in the later stage, and making it difficult to adapt to working conditions with frequent water level changes. Summary of the Invention

[0006] To address the problems of existing technologies, this invention provides a riprap ecological revetment system that adapts to water level drops.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A riprap ecological revetment system adapted to water level drop includes:

[0009] The ecological soil base layer is an improved soil mixture of loam, humus, and slow-release fertilizer, with a thickness of 300mm and a compaction degree of ≥93%.

[0010] The filter layer is laid between the ecological soil base and the riprap revetment. It uses non-woven geotextile or graded gravel with a unit area mass of ≥300g / ㎡. The particle size of the graded gravel is 2mm-40mm and the overlap width of the non-woven geotextile is ≥200mm.

[0011] The riprap revetment, laid on top of the filter layer, has a slope ratio of 30°. It is formed by stacking boulders with a saturated compressive strength >50MPa in a gradation of large: medium: small size = 5:3:2. Large-diameter boulders are laid in the lower layer on the water-facing side to form a rigid skeleton to resist water erosion.

[0012] The imitation wood pile anti-erosion strip is vertically arranged along the elevation zone 2m ± 0.3m below the normal water level of the riprap revetment slope.

[0013] The imitation wood piles are made of fiber-reinforced composite materials, with a length of 1.5m, a diameter of 150mm-200mm, a wedge-shaped tip at the bottom, and the top of the pile protruding from the slope. The pile spacing is 0.5m-0.8m, and the piles are connected together as a whole by flexible connectors.

[0014] The aforementioned riprap ecological revetment system adapted to water level drop is characterized by further including a planting trough, which is set within the riprap structure of the riprap revetment, located above the imitation wood pile anti-erosion zone, with the bottom elevation of the trough 0.3m-0.5m higher than the top of the imitation wood piles.

[0015] The planting trough is made of porous concrete or eco-ceramic material. The trough is pre-drilled with inclined drainage holes and root penetration holes. The bottom is equipped with a barbed structure or fixed to the pebbles with stainless steel pins to provide a stable growing space for vegetation and anchor the surface pebbles.

[0016] The surface of the imitation wood pile is decorated with interlaced raised patterns.

[0017] The flexible connector is a galvanized steel wire or a flexible rope.

[0018] The planting trough has a trapezoidal cross section, with a barbed structure that engages with the gap between the bobbins, and stainless steel pins that can be detachably fixed to the bobbins.

[0019] Compared with existing technologies, the beneficial effects of the invention are as follows: the positioning and parameters of the imitation wood pile anti-erosion strip are derived from hydraulic calculations and model tests, accurately covering the peak flow velocity area, effectively attenuating water kinetic energy by ≥65%, avoiding scouring in key areas, and the five layers of ecological soil base, filter layer, riprap, imitation wood pile, and planting trough work together to form a composite structure of "dense support + rigid skeleton + flexible energy dissipation + root anchoring", with overall erosion resistance far superior to that of single component superposition; the riprap gradation and interlocking design take into account both permeability and erosion resistance, and the pore water pressure dissipates smoothly, greatly improving structural stability.

[0020] The natural shapes of the imitation wood piles (fiber-reinforced composite materials) and riprap simulate the ecology of natural riverbanks, avoiding the harshness of hard concrete. The vegetation in the planting troughs further enhances the ecological landscape effect; the survival rate of vegetation is improved, and the maintenance costs and frequency of later repairs and replanting are reduced by ≥60%. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention.

[0022] In the picture: 1 - planting trough, 2 - riprap revetment, 3 - imitation wood pile anti-erosion strip. Detailed Implementation

[0023] The present invention will be further described in detail below through embodiments. These embodiments are only used to illustrate the present invention and do not limit the scope of the present invention.

[0024] A riprap ecological revetment system adapted to the receding water level of a regulating lake includes:

[0025] The ecological soil base layer is an improved soil mixture of loam, humus, and slow-release fertilizer. The improved soil is prepared by mixing loam, humus, and slow-release fertilizer in a ratio of 6:3:1, with a thickness of 300mm and a compaction degree of ≥93%. It serves as the foundation support of the revetment and is used to prevent seepage damage to the underlying soil. Specifically, it forms a dense and stable support structure, preventing seepage damage to the underlying soil from the source and providing reliable foundation support for the upper revetment structure.

[0026] The filter layer is laid between the ecological soil base and the riprap revetment 2. It uses non-woven geotextile or graded sand and gravel with a unit area mass of ≥300g / ㎡. The particle size of the graded sand and gravel is 2mm-40mm. The overlap width of the non-woven geotextile is ≥200mm. It prevents the upper soil particles from being lost with seepage, while ensuring smooth water seepage, avoiding the accumulation of pore water pressure, and ensuring structural stability.

[0027] The riprap revetment 2, laid above the filter layer, has a slope ratio of 30°. It is formed by stacking large-diameter (800mm-1500mm): medium-diameter (400mm-800mm): small-diameter (<400mm) stones in a ratio of 5:3:2, with the lower layer on the water-facing side containing large-diameter stones to form a rigid framework against water erosion. During construction, the lower layer on the water-facing side prioritizes laying 800-1500mm large stones, ensuring their sides are tightly fitted to the imitation wood piles and partially embedded in the gaps between the piles, forming a rigid framework of "pile-stone interlocking". The self-weight and interlocking force of the large-diameter stones directly resist water erosion and wave erosion; after interlocking with the imitation wood piles, they form an integral load-bearing unit, dispersing impact force and improving erosion resistance.

[0028] The simulated wooden pile anti-erosion zone 3 is vertically arranged along the elevation zone 2m ± 0.3m below the normal water level of the riprap revetment 2. This elevation zone is determined based on hydraulic calculations and physical model tests of the spillway flow, and is the peak flow velocity zone (average velocity 1.2~1.8m / s). The core hydraulic calculation formula is as follows, used to accurately calculate the flow velocity and scouring force in this elevation zone, and to determine the scientific basis for the arrangement of the simulated wooden piles:

[0029] 1. Calculation of the flow velocity of the spillway along the slope:

[0030] In the formula: The average flow velocity of water on the slope (m / s) is 1.2 to 1.8 m / s as measured in this invention; The roughness coefficient is taken as 0.035~0.045, taking into account the characteristics of the riprap slope. The hydraulic radius (m) is the ratio of the surface runoff depth to the wetted perimeter. The slope is the slope of the rockfill revetment of this invention, which has a slope ratio of 30°. It is converted into a decimal form and substituted into the calculation.

[0031] 2. Calculation of water flow scouring force (corrected drag force formula): In the formula: The drag force (Pa) exerted by the water flow on the slope is the core calculation parameter for the scouring force. Let be the density of water (kg / m³), and take it as 1000 kg / m³. Let gravitational acceleration be 9.81 m / s². , The parameters are consistent with those in the above formula.

[0032] The above formula shows that the water flow drag force in the elevation zone 2m ± 0.3m below the normal water level reaches 18 to 25 Pa, which is the area with the maximum scouring force on the entire slope. This is consistent with the results of the MIKE 21 numerical simulation (using the RNG k-ε turbulence model) and physical model test (scale ratio 1:20). Therefore, the imitation wood pile anti-scouring strip is precisely arranged in this area.

[0033] The simulated wood piles are made of fiber-reinforced composite material (glass fiber and resin mixed and cured), 1.5m in length, 150mm-200mm in diameter, with a wedge-shaped tip at the bottom (embedded ≥0.5m into the ecological soil base layer), and the top of the pile protruding from the slope. The pile spacing is 0.5m-0.8m, optimized through model tests to balance energy dissipation efficiency and structural stability. The piles are connected together as a whole by flexible connectors. The surface of the simulated wood piles has interlaced raised textures. The piles are connected together as a whole by galvanized steel wire or flexible ropes. The simulated wood piles are used for cutting and disturbing water level drop. The water flow attenuates the kinetic energy of the water, blocks scouring, and forms an integral whole with the riprap; it is directly placed in the peak velocity zone, and through the cutting and disturbance of the water flow by the pile body, it breaks down the high-speed water flow into turbulence, so that the kinetic energy of the water is attenuated by ≥65%, reducing the direct impact on the riprap behind it; it blocks the direct erosion of the soil behind the riprap gap by the water flow, protects the filter layer and the base layer, and avoids soil loss; it blocks the direct erosion of the soil behind the riprap gap by the water flow, protects the filter layer and the base layer, and avoids soil loss; the fiber-reinforced composite material has a certain degree of flexibility, can adapt to the small deformation of the foundation, and is not easily brittle.

[0034] Planting trough 1 is set in the riprap structure of the riprap revetment 2, located above the imitation wood pile anti-erosion zone 3. The bottom elevation of the trough is 0.3m-0.5m higher than the top of the imitation wood pile. It is made of porous concrete or ecological ceramic material. The trough body is pre-reserved with inclined drainage holes and root penetration holes. The bottom is equipped with a barbed structure or fixed to the riprap by stainless steel pins. It is used to provide stable growth space for vegetation and anchor the surface riprap.

[0035] Planting trough 1 has a trapezoidal cross-section, with a hook structure that engages with the gaps between the riprap and the rocks. Stainless steel pins are detachably fixed to the riprap. This provides a stable growing space for plants, improving vegetation survival rates. Plant roots penetrate the gaps between the riprap through pre-drilled holes in the trough, anchoring with the soil filling the gaps and further reinforcing the surface riprap to prevent soil loss. The hook / pin fixing structure ensures that planting trough 1 does not shift under the impact of waves and water flow, guaranteeing long-term ecological function.

[0036] In this system, the large-diameter stones of the riprap revetment 2 are tightly integrated with the imitation wood pile anti-erosion strip 3, forming an integrated load-bearing unit by embedding them into the gaps between the piles. The ecological soil base, the filter layer, the riprap revetment 2, the imitation wood pile anti-erosion strip 3, and the planting trough 1 work together to form a water level drop protection system of "energy dissipation and erosion prevention - skeleton stability - root anchoring". This system constructs a closed-loop collaborative system of "energy dissipation - erosion resistance - soil stabilization": the imitation wood pile anti-erosion strip 3 first implements precise energy dissipation for the drop water flow, reducing the kinetic energy of the water flow; the riprap revetment 2 further resists residual erosion through the interlocking skeleton, while relying on the high-pressure compacted ecological soil base and the filter layer to ensure foundation stability; the plant roots in the planting trough 1 finally anchor the surface structure, solidify the soil, and achieve "layer-by-layer protection between components and synergistic effect in function".

[0037] The application of imitation wood piles in riprap ecological revetments involves using these piles as energy dissipation and erosion prevention components for water level drop / tidal rise and fall. They are vertically arranged along the peak velocity elevation zone of the revetment slope, 2m ± 0.3m below the normal water level. By cutting and disturbing the water flow, the piles reduce the kinetic energy of the water flow by ≥65%, blocking scouring and interlocking with the riprap to form an integral whole. This method is suitable for scenarios with periodic rapid rise and fall of water levels, such as regulating lakes, reservoir drawdown zones, downstream of dams, and tidal river shorelines. A composite erosion control structure suitable for revetments in areas with fluctuating water levels includes: a filter layer laid on the base surface to prevent soil loss; a simulated wood pile erosion control strip 3, arranged in the peak water flow velocity zone of the revetment slope, made of fiber-reinforced composite material, 1.5m in length, with a pile spacing of 0.5m-0.8m, used for energy dissipation, deceleration, and scouring; a large-diameter riprap layer, tightly embedded with the simulated wood pile erosion control strip 3, forming a rigid skeleton by embedding it into the gaps between the piles, with a saturated compressive strength >50MPa and a large particle size of 800mm-1500mm, used to further resist water flow impact; and an ecological planting unit, including a planting trough 1 and vegetation set above the large-diameter riprap layer, used to reinforce the surface riprap and enhance ecological properties; together forming a "energy dissipation, erosion resistance, and soil stabilization" protection system, adaptable to working conditions with frequent water level fluctuations.

[0038] Example 1

[0039] A riprap ecological revetment system adapted to the receding water level of a regulating lake, with a structure as follows: Figure 1 As shown, the specific implementation is as follows:

[0040] 1. Construction preparation:

[0041] On-site investigation of hydrological data of the reservoir (water level drop velocity, frequency, flow velocity, and elevation range) was conducted. The MIKE 21 model was used to simulate and determine the peak flow velocity zone, and the direction, length, and 30° slope ratio parameters of the revetment were clarified. Materials such as fiber-reinforced composite wood-look piles (180mm in diameter, 1.5m in length, with raised texture on the surface and wedge-shaped tips at the bottom), granite blocks (400mm-1500mm) with a saturated compressive strength of 60MPa, improved ecological soil, 300g / ㎡ non-woven geotextile, and porous concrete planting troughs were procured.

[0042] 2. Foundation excavation and treatment:

[0043] Excavate to the design elevation according to the design cross section, remove loose soil, silt and debris from the base, and level and compact it; lay a 300g / ㎡ non-woven geotextile filter layer with an overlap width of 200mm to ensure that the laying is flat and wrinkle-free.

[0044] 3. Construction of ecological soil base course:

[0045] Prepare ecological soil by mixing loam, humus, and slow-release fertilizer in a ratio of 6:3:1, lay it to a thickness of 300mm, and compact it using a tamping device to ensure a compaction degree of ≥93%.

[0046] 4. Construction of the imitation wood pile anti-erosion zone 3:

[0047] Lay out a line along the elevation zone 2m below the normal water level, and use a hydraulic vibratory hammer to vertically drive the imitation wood piles into the ecological soil base layer, with an embedment depth of 0.6m, the top of the pile protruding 0.9m above the slope surface, and a pile spacing of 0.6m; connect all the imitation wood piles with galvanized steel wire to ensure that the pile body is vertical, neatly arranged, and perpendicular to the slope surface; check the pile interlocking effect to ensure that the subsequent stone placement can be embedded in the gap between the piles.

[0048] 5. Construction of riprap revetment 2:

[0049] Starting from the toe of the slope, place large stones of 800mm-1500mm as base stones close to the backwater side of the imitation wood piles, ensuring that the sides of the stones are tightly fitted to the imitation wood piles and partially embedded in the gaps between the piles, forming an integrated pile and stone structure; then stack medium and small diameter stones in a 5:3:2 ratio, compacting them layer by layer to ensure that the stones are tightly interlocked, and maintain a slope ratio of 30°.

[0050] 6. Construction of Planting Trough 1:

[0051] In the riprap structure 0.4m above the imitation wood pile, a planting trough 1 is reserved for installation; the porous concrete planting trough 1 (with a hook structure inserted into the gap of the riprap) is fixed to the riprap with stainless steel pins to ensure the stability of the trough; the trough is filled with improved soil and planted with aquatic plants such as calamus and iris to complete the installation of planting trough 1.

[0052] Example 2 (Application Scenario Expansion and Implementation)

[0053] The difference between this embodiment and Embodiment 1 is that the system is applied to tidal river shorelines:

[0054] 1. Based on the hydrodynamic calculations of tidal river rise and fall, the simulated wooden pile anti-scour zone 3 is determined to be located at an elevation of 2m ± 0.3m below the normal water level (the peak tidal velocity zone of rise and fall).

[0055] 2. The imitation wood piles use higher-strength carbon fiber reinforced composite materials to improve their resistance to tidal wave impact;

[0056] 3. The gradation ratio of riprap has been optimized to large: medium: small = 6:2:2, further increasing the proportion of large stones and improving the resistance to tidal erosion;

[0057] 4. Plant mangrove plants that are resistant to tidal flooding are planted in planting trough 1 to meet the ecological needs of tidal scenarios.

[0058] The results show that the system also has excellent erosion resistance and ecological adaptability on tidal river shorelines, verifying its universality.

Claims

1. A riprap ecological revetment system adapted to water level drop, characterized in that, include: The ecological soil base layer is an improved soil mixture of loam, humus, and slow-release fertilizer, with a thickness of 300mm and a compaction degree of ≥93%. The filter layer is laid between the ecological soil base and the riprap revetment. It uses non-woven geotextile or graded gravel with a unit area mass of ≥300g / ㎡. The particle size of the graded gravel is 2mm-40mm and the overlap width of the non-woven geotextile is ≥200mm. The riprap revetment, laid on top of the filter layer, has a slope ratio of 30°. It is formed by stacking large-diameter, medium-diameter, and small-diameter boulders with a saturated compressive strength >50MPa in a ratio of 5:3:

2. Large-diameter boulders are laid on the lower layer on the water-facing side to form a rigid framework to resist water erosion. The imitation wood pile anti-erosion strip is vertically arranged along the elevation zone 2m ± 0.3m below the normal water level of the riprap revetment slope. The imitation wood piles are made of fiber-reinforced composite materials, with a length of 1.5m, a diameter of 150mm-200mm, a wedge-shaped tip at the bottom, and the top of the pile protruding from the slope. The pile spacing is 0.5m-0.8m, and the piles are connected together as a whole by flexible connectors.

2. The riprap ecological revetment system adapted to water level drop as described in claim 1, characterized in that, It also includes planting troughs, which are set in the riprap structure of the riprap revetment, located above the imitation wood pile anti-erosion zone, with the bottom of the trough being 0.3m-0.5m higher than the top of the imitation wood pile.

3. The riprap ecological revetment system adapted to water level drop as described in claim 2, characterized in that, The planting trough is made of porous concrete or eco-ceramic material. The trough is pre-drilled with inclined drainage holes and root penetration holes. The bottom is equipped with a barbed structure or fixed to the pebbles with stainless steel pins to provide a stable growing space for vegetation and anchor the surface pebbles.

4. The riprap ecological revetment system adapted to water level drop as described in claim 3, characterized in that, The surface of the imitation wood pile is decorated with interlaced raised patterns.

5. The riprap ecological revetment system adapted to water level drop as described in claim 1, characterized in that, The flexible connector is a galvanized steel wire or a flexible rope.

6. The riprap ecological revetment system adapted to water level drop as described in claim 4, characterized in that, The planting trough has a trapezoidal cross section, with a barbed structure that engages with the gap between the bobbins, and stainless steel pins that can be detachably fixed to the bobbins.

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