Marine ecological restoration seawall based on sand beach and construction method thereof

Abstract

The invention relates to the field of seawalls, in particular to a marine ecological restoration seawall based on a sand beach and a construction method thereof. The seawall comprises three defensive lines, the first defensive line serves as a wave dissipation platform by laying an artificial sand beach, and an original wave wall and a riprap protection bottom are transformed to construct a first-stage wave wall; curbs are heightened and transformed into secondary wave walls by the middle road defense line, and a levee top road is laid to serve as a wave dissipation platform; a flower bed is transformed on a rear defense line, a low retaining wall is a three-stage wave wall, a drainage system is arranged, and residents are protected by combining buildings behind the road and flood prevention measures. The three-dimensional defense line can achieve wave dissipation and damp blocking, and the wave overtopping amount is reduced. The method aims at the shoreline with the requirement for the dike crest elevation and insufficient moisture-proof capacity in marine ecological restoration, and is particularly suitable for constructing a mature urban dike. The damp-proof flood-proof seawall aims at keeping the original appearance of the seawall as much as possible, reducing damage to existing roads and environments, improving the damp-proof capacity, promoting organic fusion of the seawall and surrounding characteristics and building the damp-proof flood-proof seawall for marine ecological restoration.

Description

Technical Field

[0001] The invention relates to the field of seawalls, in particular to a seawall for marine ecological restoration based on a beach and a construction method thereof. Background Art

[0002] In many coastal areas, there are central urban areas with rapid economic development and dense population. These areas have special geographical environments and are also one of the areas most seriously affected by typhoon storm surges. During the annual astronomical high tide, if a typhoon occurs, the sea level will rise abnormally due to the combined effects of the high tide and typhoon surge. The magnitude of this rise far exceeds the peak water level under normal circumstances, thus forming a typhoon storm surge with great destructive power. Once a typhoon storm surge occurs, it will cause extremely huge losses to the lives and property of the people in the coastal areas of the central urban areas, as well as industrial and agricultural production, such as serious consequences such as houses being flooded, farmland being washed away, and infrastructure being damaged.

[0003] For more mature areas like the central urban area, the construction of seawalls faces many limitations and challenges. As the city has matured, the environment and infrastructure around the seawalls have become relatively fixed, so large-scale excavation and construction activities cannot be carried out, nor can the seawalls be simply widened and raised. When considering the construction or renovation of seawalls, it is necessary to make a comprehensive trade-off from multiple aspects. Including measures that can be implemented in the existing environment, meet urban planning needs, and protect the surrounding ecological environment. Based on these comprehensive factors, it is urgent to explore a new type of seawall construction plan, that is, an ecological seawall that has little impact on the environment, can improve biodiversity, has good versatility, can be adapted to different environments, has a convenient construction process, and can meet the requirements of flood control, and has better economic performance. Summary of the invention

[0004] The purpose of the present invention is to provide a seawall based on beach marine ecological restoration and its construction method, which plays a significant constructive role in improving the flood control capacity of the central urban area, serving urban development, combining the characteristics of the natural ecosystem to increase its stability and ecological function, and eliminating the hidden dangers of seawall safety facilities.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A beach-based marine ecological restoration seawall, including the first line of defense, the middle line of defense and the rear line of defense;

[0007] The first line of defense includes a primary retaining wall and a primary wave-breaking platform, wherein the primary retaining wall includes a vertical buried stone concrete retaining wall and a riprap footing, and the primary wave-breaking platform is an artificial beach, including surface sand and bottom sand;

[0008] The middle defense line includes a secondary retaining wall and a secondary wave-breaking platform, wherein the secondary retaining wall is a first reinforced concrete retaining wall of a dock-type structure, and the secondary wave-breaking platform is a levee road, and a rainwater collection system is constructed at the bottom of the levee road;

[0009] The rear defense line includes three-level retaining walls, which are second reinforced concrete retaining walls, and ecological plants are planted along the retaining walls.

[0010] Furthermore, the embankment road is paved with a % cement stabilized gravel base layer, an emulsified asphalt slurry seal layer, a medium-grained asphalt concrete layer, and a fine-grained asphalt concrete layer from bottom to top.

[0011] Correspondingly, the present invention also proposes a construction method of a seawall for marine ecological restoration based on a beach, comprising:

[0012] First line of defense construction steps:

[0013] Basic survey: Investigate the marine environment quality and coastal dynamic environment to determine the beach development conditions, artificial beach scale, sand material parameters, and beach morphology, so as to replenish sand;

[0014] Site cleaning: cleaning up construction waste, boulders and steel pontoons in the shore section of the sand replenishment area;

[0015] Beach sand replenishment: first replenish the bottom sand dry beach, then replenish the surface sand beach;

[0016] Beach laying: adopt the spiral laying method from outside to inside and the layered compaction method.

[0017] Establish monitoring points: establish leveling points and hydrological benchmarks, and set equal side points;

[0018] Backfill construction: backfill uphill when the water level is high, and backfill downhill when the water level is low; mechanical leveling and post-monitoring maintenance;

[0019] Construction steps of the middle line of defense:

[0020] The C35 reinforced concrete retaining wall combined with the sidewalk is made of a prefabricated assembled dock structure, which is transported and installed after being made in the prefabrication yard;

[0021] The embankment road is paved with 5% cement stabilized gravel base, emulsified asphalt slurry seal, medium-grained asphalt concrete, and fine-grained asphalt concrete from bottom to top, and the wave dissipation coefficient is reduced through the road and rainwater collection system;

[0022] Construction steps for the rear defense line: Build a flower bed C35 reinforced concrete retaining wall, and use the flower bed retaining wall material and the embankment top elevation to achieve moisture-proof function.

[0023] Furthermore, the numerical model of coastal sediment transport is used to simulate and predict the existing ocean dynamic processes, siltation and erosion areas, and sand replenishment effects, and then the optimal sand replenishment method is selected.

[0024] Furthermore, through a comprehensive analogy analysis of the settlement, overfill and loss of the beach, the theoretical comprehensive calculation formula for the beach is obtained:

[0025]

[0026] V——Design volume of artificial beach (m 3 );

[0027] V y ——Volume of artificial beach filling (m 3 ), which is the volume between the designed elevation of the fill area and the original ground surface;

[0028] ΔV c ——Original foundation settlement of artificial beach (m 3 ), that is, the additional engineering volume due to the sinking of the original foundation in the beach area caused by the beach load before the completion acceptance;

[0029] V t ——Overfill volume (m 3 ), calculated based on the average allowable deviation of the elevation of the beach project; μ——the loss rate of fill soil after entering the beach filling area (%), determined based on the soil particle size, the location and height of the spillway and the distance from the sand delivery pipe, the beach filling area, the layout of the sand delivery pipe, the filling height and the hydraulic conditions, and the specific construction conditions and experience.

[0030] Furthermore, a beach monitoring method is set up in combination with the characteristics of the construction and operation periods. Sediment sensors are used to measure the thickness and type of sediments on the beach surface. The sensors collect data in real time and transmit it to the monitoring center to provide information for evaluating the health of the beach.

[0031] The present invention has the following beneficial effects:

[0032] The overall seawall consists of the first line of defense, the middle line of defense and the rear line of defense. This layered defense line design can be adapted to different environments and has little impact on the environment while meeting the requirements of flood control, which meets the current demand for ecological seawalls. The artificial beach and the ecological plants planted along the retaining wall of the rear line of defense provide a place for organisms to live and reproduce, which helps to improve biodiversity.

[0033] The construction methods of each line of defense in the present invention fully consider the existing environment and conditions, and the construction process is convenient. At the same time, through reasonable design and material utilization, it performs better in terms of economy. For example, the beach paving method of the first line of defense can reduce the risk of foundation settlement, the prefabricated retaining wall of the middle line of defense reduces the interference to the surrounding environment and improves the construction quality and safety, and the rear line of defense uses the flower bed retaining wall to achieve the moisture-proof function, which is simple and effective. Basic surveys and beach monitoring methods ensure the quality and stability of the artificial beach, thereby ensuring the wave and tide-breaking function of the first line of defense. The retaining wall and road construction methods of the middle line of defense and the setting of the rainwater collection system effectively improve the tide-breaking capacity and wave-breaking effect of the tide level. The construction of the flower bed retaining wall and the planting of ecological plants in the rear line of defense not only enhance the moisture-proof ability but also protect the ecological environment.

[0034] Through scientific models and analysis, we can accurately determine the parameters of artificial beaches, select the best sand replenishment method, ensure the stability and functionality of the beach, and thus improve the wave and tide resistance of the first line of defense. Beach monitoring methods can understand the health of the beach in real time, identify problems in time and take measures, which is conducive to the long-term maintenance of the beach's ecology and protection functions.

[0035] Instruction Manual

[0036] Figure 1 It is a structural schematic diagram of a specific implementation method of the present invention.

[0037] The numbers in the figure are: 1. Bottom layer of sand; 2. Surface layer of sand; 3. Riprap footing; 4. Vertical buried stone concrete retaining wall; 5. First reinforced concrete retaining wall; 6. Road on top of embankment; 7. Second reinforced concrete retaining wall. DETAILED DESCRIPTION

[0038] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0039] See also Figure 1The present invention consists of a three-line defense system: The first line of defense: by laying an artificial beach, restoring the sandy coastal ecological base as a first-level wave-breaking platform, transforming the original upright seawall wave-blocking wall, and riprap to build a first-level wave-blocking wall. The middle line of defense: by raising and transforming the curbstones along the road, while meeting the ecological landscape, the tide level and tide-blocking requirements are improved, as a second-level wave-breaking wall; the embankment road is simultaneously laid as a second-level wave-breaking platform. The back line of defense: according to the requirements of different urban construction, the flower beds along the street and the existing low retaining walls can be transformed, and ecological planting can be planted in the flower beds to improve the ecology of the coast. As a third-level wave-breaking wall, a drainage system is laid along the line to increase the ability to collect overtopping. Combined with the buildings behind the road and temporary flood control measures, it protects residents, and is also the last line of defense. Construct a three-dimensional defense line to meet the effects of wave breaking, tide blocking, and reducing overtopping.

[0040] The first line of defense includes a primary retaining wall and a primary wave-breaking platform. The primary retaining wall includes a vertical buried stone concrete retaining wall 4 and a 100-150kg riprap footing 3. The primary wave-breaking platform is an artificial beach, including surface sand 2 and bottom sand 1. The surface sand particle size is 0.3-0.4mm, and the cushion sand particle size is 0.4-0.5mm.

[0041] The construction process includes:

[0042] Basic survey: The artificial beach needs to be investigated in the early stage, including the marine environment quality, coastal dynamic environment, sediments, topography, coastal evolution history, etc. The local beach development conditions are determined, combined with the topography, dynamic conditions, sediment movement, etc., and then the beach profile, plane morphology, artificial structures, beach shoulder elevation, sand replenishment sediments and other comprehensive designs are carried out, and numerical model prediction analysis and design optimization are carried out to determine the scale of the artificial beach, sand material parameters, beach morphology and other parameters for sand replenishment.

[0043] Site cleaning: Usually, the sand area may be distributed with construction waste, boulders, piles of rocks and abandoned steel pontoons, etc. The shore section of the sand replenishment area should first be cleaned up of these debris.

[0044] Beach profile design: The calculation method of the beach equilibrium profile adopts the equation (III-3-14) in Volume 3 of the American Coastal Engineering Manual (2002 Edition):

[0045] h=Ay2 / 3

[0046] Where h is the depth (m), y is the distance from the shore (m), and A is the coefficient. The value of A is determined using the data listed in Table III-3-3 of the book.

[0047] Optimal beach shoulder elevation design: According to the "Technical Guide for Beach Maintenance and Restoration" (HY / T255-2018), the beach shoulder elevation design of beach maintenance and restoration projects can be determined by multi-year return period water level and wave run-up parameters: Beach shoulder elevation = multi-year return period water level + wave run-up When waves are transmitted from the open sea to the nearshore, they will rush onto the beach to form water run-up. The wave run-up formula uses the Stockdon formula:

[0048]

[0049] Where H0 is the deep-water wave height, L0 is the deep-water wave length, and Bf is the shoreface slope.

[0050] Beach sand replenishment: first replenish the bottom sand dry beach, then replenish the surface sand beach.

[0051] Beach laying: The angle of the construction plane of the artificial beach (1 and 2) is gradually laid in a spiral from the outside to the inside, which can effectively reduce the risk of foundation settlement and uneven settlement. By gradually filling, the soil can be gradually compacted, making the foundation more solid and stable. This laying technology can also cope with different geological conditions and soil characteristics. The filling materials and filling methods can be adjusted according to actual conditions to ensure the reliability and durability of the project. In addition, the sand piles on the periphery can form temporary embankments to reduce the impact of waves and tides in the sand filling area, providing a safe environment for construction.

[0052] The artificial beach is laid using the layered compaction method, which ensures the uniform distribution and tight connection of the filling sand. The construction workers pour the filling material into the pit in batches and use a vibrating rammer to compact each layer until the entire area is paved.

[0053] Establish monitoring points: Leveling points and hydrological benchmarks should be set up during beach construction, and several equal side points should be set up in the middle section from the foot of the downslope to the top of the upslope in the construction area for construction monitoring and measurement.

[0054] Backfill construction: When the water level is high, backfill construction can be carried out in the uphill direction. When the water level is low, backfill construction can be carried out in the downhill direction during the tide.

[0055] Mechanical leveling and subsequent monitoring and maintenance: Finally, mechanical leveling is carried out, and monitoring and maintenance are carried out in the later stage.

[0056] The middle defense line includes a secondary retaining wall and a secondary wave-breaking platform. The secondary retaining wall is a C35 reinforced concrete retaining wall combined with a sidewalk, and the structural form is a dock-type structure. The secondary wave-breaking platform is a road on the top of the embankment.

[0057] Construction process: The secondary retaining wall is a C35 first reinforced concrete retaining wall 5 combined with a sidewalk, and the structural form is a dock structure. The dock structure adopts prefabricated assembly, which is completed in the prefabrication yard and then transported to the target location for installation. This construction method not only reduces the interference of the construction site on the surrounding environment, but also avoids various uncontrollable factors in the construction process. At the same time, since the construction process is carried out in the prefabrication yard, it can effectively improve the safety and quality control of the construction.

[0058] Construction of secondary wave-breaking platform: The paving of the road on the top of the embankment can be divided into 5% cement-stabilized crushed stone base with a thickness of 300mm, emulsified asphalt slurry seal with a thickness of 6mm, medium-grained asphalt concrete with a thickness of 60mm (AC-20C), and fine-grained asphalt concrete with a thickness of 40mm (AC-13C) from bottom to top. In the case where the elevation of the top of the sea embankment cannot be increased, the road and road administration rainwater collection system are used to make the waves touch the bottom at the road position, reduce the wave-breaking coefficient, and reduce the impact force on the embankment to meet the requirements of wave-breaking defense.

[0059] The rear defense line includes three levels of retaining walls, which are the second reinforced concrete retaining wall 7 of the flower bed C35. : Construction process: Through the construction materials of the flower bed retaining wall and the elevation of the embankment top, multiple scientific moisture-proofing is achieved, and the wave-breaking and moisture-proofing functions of the urban seawall are completely completed.

[0060] Secondary plants (such as thick vine, sea bean, and sea tobby, etc.) that have good ecological protection effects against seawater erosion and soil erosion are selected in the sandy area behind the beach. Through multiple planting-maintenance-destruction-replanting, a stable beach plant community is formed.

[0061] Beach design optimization: Use numerical models of coastal sand transport to simulate and predict ocean dynamics, siltation and erosion areas, and sand replenishment effects, select the best sand replenishment method, consider factors such as cost-effectiveness, environmental impact, construction feasibility, and long-term maintenance, to ensure beach stability and control costs.

[0062] Calculation of beach engineering quantity: Through comprehensive analogical analysis of the settlement, overfill and loss of the beach, the theoretical comprehensive calculation coefficient of the beach is obtained, and it is verified with the actual sand replenishment to ensure accuracy.

[0063] Beach monitoring: The beach monitoring method is set up in combination with the characteristics of the construction period and the operation period. Sediment sensors are used to measure the thickness and type of sediment on the beach surface. The sensors collect data in real time and transmit the data to the monitoring center through wireless transmission or automatic recording system to evaluate the health of the beach.

[0064] The construction of beaches can not only serve as wave-breaking platforms, reduce the destructive power of extreme weather on the coast and enhance disaster prevention and mitigation capabilities; it can also serve as a transitional purification zone between the ocean and land, help reduce the impact of land-based pollution, improve nearshore water quality, and provide good water quality conditions for marine ecology.

[0065] The beach-based seawall protects the coastline resources, repairs the coastline damaged by natural erosion or human destruction, meets the requirements of an ecologically resilient coastline, forms an ecological base, provides habitats and breeding grounds for marine life, and gradually restores the coastal biological communities, which helps to restore and increase biodiversity and achieve the purpose of marine ecological restoration.

[0066] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A seawall for marine ecological restoration based on a beach, characterized in that: It includes the first line of defense, the middle line of defense and the rear line of defense; The first line of defense includes a primary retaining wall and a primary wave-breaking platform, wherein the primary retaining wall includes a vertical buried stone concrete retaining wall (4) and a riprap footing (3), and the primary wave-breaking platform is an artificial beach, including a surface layer of sand (2) and a bottom layer of sand (1); The middle defense line comprises a secondary retaining wall and a secondary wave-breaking platform, wherein the secondary retaining wall is a first reinforced concrete retaining wall (5) of a dock-type structure, and the secondary wave-breaking platform is a levee road (6), and a rainwater collection system is constructed at the bottom of the levee road (6); The rear defense line includes three levels of retaining walls, wherein the three levels of retaining walls are second reinforced concrete retaining walls (7), and ecological plants are planted along the retaining walls.

2. The marine ecological restoration seawall based on the beach according to claim 1 is characterized in that: The embankment top road (6) is paved with a 5% cement stabilized crushed stone base layer, an emulsified asphalt slurry seal layer, a medium-grained asphalt concrete layer, and a fine-grained asphalt concrete layer from bottom to top.

3. A construction method for a seawall for marine ecological restoration based on a beach, characterized in that: First line of defense construction steps: Basic survey: Investigate the marine environment quality and coastal dynamic environment to determine the beach development conditions, artificial beach scale, sand material parameters, and beach morphology, so as to replenish sand; Site cleaning: cleaning up construction waste, boulders and steel pontoons in the shore section of the sand replenishment area; Beach sand replenishment: first replenish the bottom sand dry beach, then replenish the surface sand beach; Beach laying: adopt the spiral laying method from outside to inside and the layered compaction method. Establish monitoring points: establish leveling points and hydrological benchmarks, and set equal side points; Backfill construction: backfill uphill when the water level is high, and backfill downhill when the water level is low; Mechanical leveling and subsequent monitoring and maintenance; Construction steps of the middle line of defense: The C35 reinforced concrete retaining wall combined with the sidewalk is made of a prefabricated assembled dock structure, which is transported and installed after being made in the prefabrication yard; The embankment road is paved with 5% cement stabilized gravel base, emulsified asphalt slurry seal, medium-grained asphalt concrete, and fine-grained asphalt concrete from bottom to top, and the wave dissipation coefficient is reduced through the road and rainwater collection system; Construction steps for the rear defense line: Build a flower bed C35 reinforced concrete retaining wall, and use the flower bed retaining wall material and the embankment top elevation to achieve moisture-proof function.

4. The method for constructing a seawall for marine ecological restoration based on a beach according to claim 3, characterized in that: Using the numerical model of coastal sediment transport, we simulate and predict the existing ocean dynamic processes, siltation and erosion areas, and sand replenishment effects, and then select the optimal sand replenishment method.

5. The method for constructing a seawall for marine ecological restoration based on a beach according to claim 4, characterized in that: Through a comprehensive analogy analysis of the settlement, overfill and loss of the beach, the theoretical comprehensive calculation formula for the beach is obtained: V——Design volume of artificial beach (m 3 ); V y ——Volume of artificial beach filling (m 3 ), which is the volume between the designed elevation of the fill area and the original ground surface; ΔV c ——Original foundation settlement of artificial beach (m 3 ), that is, the additional engineering volume due to the sinking of the original foundation in the beach area caused by the beach load before the completion acceptance; V t ——Overfill volume (m 3 ), calculated based on the average allowable deviation of the elevation of the beach project; μ——the loss rate of fill soil after entering the beach filling area (%), determined based on the soil particle size, the location and height of the spillway and the distance from the sand delivery pipe, the beach filling area, the layout of the sand delivery pipe, the filling height and the hydraulic conditions, and the specific construction conditions and experience.

6. The method for constructing a seawall for marine ecological restoration based on a beach according to claim 4, characterized in that: A beach monitoring method is set up in combination with the characteristics of the construction period and the operation period. Sediment sensors are used to measure the thickness and type of sediments on the beach surface. The sensors collect data in real time and transmit it to the monitoring center to provide information for assessing the health of the beach.

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