AU2021102653A4

AU2021102653A4 - Oyster Reef Structure, Coastal Protection Device, and Coastal Protection Method

Info

Publication number: AU2021102653A4
Application number: AU2021102653A
Authority: AU
Inventors: Jie Cheng; Yujuan DOU; Duian LV; Li Sun; Degang Wang; Miao Yu
Original assignee: Second Institute of Oceanography MNR
Current assignee: Second Institute of Oceanography MNR
Priority date: 2020-07-08
Filing date: 2021-05-18
Publication date: 2021-07-08
Anticipated expiration: 2029-05-18
Also published as: CN111636373A

Abstract

The present disclosure provides an oyster reef structure, a coastal protection device, and a coastal protection method, and relates to the technical field of coastal zone restoration. The oyster reef structure according to the present disclosure includes a reef structure frame, a grounding component, and a protective net component. The grounding component is connected to the bottom of the reef structure frame. The protective net component is connected to and covers the reef structure frame. The oyster reef structure according to the present disclosure may be placed on the seaward side of a natural coast or at the toe of a seawall. The reef structure frame and the coast are protected by the protective net component, thereby preventing erosion of the natural coast or scouring of sediments at the toe of the seawall by water flow, which contributes to maintaining the stability of the coast and can prevent erosion of the natural coast or the toe of the seawall. 1/1 Drawings 1 ' FIG.1 102 006 FI. 0 07 .004 10FIG 10 10 0 06 1054 FIG. 2

Description

1/1

Drawings

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.004FIG.1 102 006

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Oyster Reef Structure, Coastal Protection Device, and Coastal Protection Method Cross-Reference to Related Applications This application claims priority to Chinese Patent Application No. 2020106506737 filed with the Chinese Patent Office on July 08, 2020, entitled "Oyster reef row, sea dyke foot protection device and dyke foot protection method", which is incorporated herein by reference in its entirety.

Technical Field The present disclosure relates to the technical field of coastal zone restoration, and in particular to an oyster reef structure (or oyster reef row), a coastal protection device, and a coastal protection method. Background Art A natural coast is easily eroded by tides and waves, and the protection of the toe of a seawall in an artificial coast plays an important role in maintaining the protection capability of the seawall. The safety of the property of residents on the landward side of the coast will be affected due to the erosion of the natural coast. On the other hand, the toe of the artificial coast is eroded, scoured, and hollowed out by waves, tidewater, and tides for a long time, which causes the destruction of the foundation of the seawall and endangers the stability and safety of the seawall. The damage to the seawall will affect the safety of the lives and property of people living near the sea. In order to ensure the safety of the natural coasts and seawalls, methods such as methods of placing block stones or reinforced concrete blocks or installing steel sheet piles on the seaward sides of the natural coasts or at the toe of the seawalls are currently often used to reduce the direct erosion and scouring for the natural coasts or seawalls by waves and tides, thereby achieving the purpose of protecting the natural coasts and seawalls and extending the service lifetime of the seawalls. However, the method of placing stones or concrete blocks has the following problems:

1. This method involves a large workload and high cost. 2. This method is ecologically unfriendly. The block stones or concrete blocks has low ecological functions and can hardly become an ideal habitat for marine life.

3. There are problems such as displacement and breakage of block stones and concrete blocks due to the elapse of time and their damage by waves, thus their effects in protecting natural coasts or seawalls are decreased year by year, and it is necessary to periodically replenish stones or reinforced concrete blocks. It is necessary to replenish 10% of the initial riprap quantity every three years, therefore higher maintenance cost is required in the later stage. Summary

An object of the present disclosure is to provide an oyster reef structure, a coastal protection device, and a coastal protection method. The oyster reef structure can be placed on the seaward side of a natural coast or at the toe of a seawall, so as to alleviate the technical problem of erosion of the natural coast or seawall by waves. In a first aspect, the present disclosure provides an oyster reef structure, comprising a reef structure frame, a grounding component, and a protective net component. The grounding component is connected to the bottom of the reef structure frame. The protective net component is connected to and covers the reef structure frame. With reference to the first aspect, the present disclosure provides a first possible embodiment of the first aspect, wherein the protective net component comprises a net made of geotextile. With reference to the first aspect, the present disclosure provides a second possible embodiment of the first aspect, wherein the reef structure frame is equipped with an oyster pillar chamber, and an oyster pile is provided in the oyster pillar chamber. With reference to the second possible embodiment of the first aspect, the present disclosure provides a third possible embodiment of the first aspect, wherein the oyster pillar chambers are mounted at both ends of the reef structure frame in a direction perpendicular to the coastline. With reference to the first aspect, the present disclosure provides a fourth possible embodiment of the first aspect, wherein the oyster reef structure further comprises an ecological oyster bag which is provided over the protective net component. With reference to the fourth possible embodiment of the first aspect, the present disclosure provides a fifth possible embodiment of the first aspect, wherein the ecological oyster bag has an inner cavity containing oyster shells, and the ecological oyster bag is provided with pores communicating with the inner cavity. With reference to the first aspect, the present disclosure provides a sixth possible embodiment of the first aspect, wherein the reef structure frame comprises a first side frame, a second side frame, a third side frame, and a fourth side frame.

The first side frame, the second side frame, the third side frame, and the fourth side frame are connected end to end in sequence and form a rectangular frame.

In a second aspect, the present disclosure provides a coastal protection device, comprising a protective pile and the oyster reef structure according to the first aspect. The reef structure frame is arranged on the seaward side of a natural coast or at the toe of a seawall, and the grounding component is inserted into the seabed. The protective pile is provided on a side of the oyster reef structure away from the coast, and the protective pile is inserted into the seabed. In a third aspect, the present disclosure provides a coastal protection method, comprising: constructing a reef structure frame; connecting a protective net component to the reef structure frame to make the protective net component cover the reef structure frame; and fixing the reef structure frame on the seaward side of a natural coast or at the toe of a seawall by means of a grounding component. With reference to the third aspect, the present disclosure provides a first possible embodiment of the third aspect, wherein the coastal protection method further comprises: putting oyster shells in an ecological oyster bag; and arranging the ecological oyster bag over the protective net component.

The embodiments of the present disclosure have achieved the following advantageous effects. The grounding component is connected to the bottom of the reef structure frame, and the protective net component is connected to and covers the reef structure frame. The reef structure frame can be fixed on the seaward side of a natural coast or at the tore of a seawall by means of the grounding component. The reef structure frame and the coast are protected by the protective net component, thereby preventing scouring of coastal sediments by water flow, which contributes to maintaining the stability of the coast and can prevent erosion of the coast. In order to enable clearer and easier understanding of the above objects, features, and advantages of the present disclosure, preferred embodiments will be described in detail below by way of example with reference to the accompanying drawings. Brief Description of the Drawings

In order to more clearly illustrate technical solutions of specific embodiments of the present disclosure or of the related art, drawings required for use in the description of the specific embodiments or the related art will be described briefly below. It is obvious that the drawings in the following description are illustrative of some embodiments of the present disclosure. It will be understood by those of ordinary skill in the art that other drawings can also be obtained from these drawings without any inventive effort.

FIG. 1 is a schematic view of a coastal protection device according to an embodiment of the present disclosure; and FIG. 2 is a top view of an oyster reef structure according to an embodiment of the present disclosure. Reference Numerals: 001-reef structure frame; 101-first side frame; 102-second side frame; 103-third side frame; 104-fourth side frame; 105-frame beam; 002-grounding component; 003-protective net component; 004-oyster pillar chamber; 005-oyster pile; 006-ecological oyster bag; 007-protective pile. Detailed Description of the Embodiments

The technical solutions of the present disclosure will be described below clearly and completely with reference to the accompanying drawings. It is apparent that the embodiments to be described are some, but not all of the embodiments of the present disclosure. All the other embodiments obtained by those of ordinary skill in the art in light of the embodiments of the present disclosure without inventive efforts will fall within the scope of the present disclosure as claimed. In the description of the present disclosure, it should be noted that the terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", and "outside" indicate the orientation or positional relationships shown based on the figures, and these terms are intended only to facilitate the description of the present disclosure and simplify the description, but not intended to indicate or imply that the referred devices or elements must be in a particular orientation or constructed or operated in the particular orientation, and therefore should not be construed as limiting the present disclosure. In addition, terms "first", "second", and "third" are used for descriptive purposes only, and should not be understood as an indication or implication of relative importance. A physical quantity in a formula, if not separately indicated, should be understood as a base quantity in a base unit of the International System of Units, or a derived quantity derived from the base quantity by a mathematical operation such as multiplication, division, differentiation, or integration.

In the description of the present disclosure, it should be noted that terms "mount", "couple", and "connect" should be understood broadly unless otherwise expressly specified or defined. For example, connection may be fixed connection or detachable connection or integral connection, may be mechanical connection or electric connection, or may be direct coupling or indirect coupling via an intermediate medium or internal communication between two elements. The specific meanings of the above-mentioned terms in the present disclosure can be understood by those of ordinary skill in the art according to specific situations. First Embodiment

As shown in FIGS. 1 and 2, an oyster reef structure according to an embodiment of the present disclosure includes a reef structure frame 001, a grounding (or ground gripping) component 002, and a protective net component 003. The grounding component 002 is connected to the bottom of the reef structure frame 001. The protective net component 003 is connected to and covers the reef structure frame 001.

Specifically, the reef structure frame 001 includes concrete members, and the reef structure frame 001 may be in a frame structure with a length of 2 m and a width of 1 m. The four grounding components 002 are connected to the four corners of the bottom of the reef structure frame 001 in a one-to-one corresponding manner. The grounding component 002 may be made of a sharp concrete member similar to a tooth. The bottom of the grounding component 002 is configured as a tip so that it can be inserted into the seabed. The grounding component 002 has a length of about 50 cm. The oyster reef structure is placed on the seaward side of a natural coast or at the toe of a seawall, and the grounding components 002 are inserted into the seabed to prevent a movement of the oyster reef structure. The protective net component 003 is fixedly mounted on the reef structure frame 001. The protective net component 003 can provide filtering, isolating, reinforcing, and protecting functions and can prevent scouring of sediments on the offshore side of the coast by water flow, which contributes to maintaining the stability of the coast and can prevent erosion of the coast. The oyster reef structure according to the embodiment of the present disclosure can properly prevent erosion and damage of a coast and has the advantages of having low cost and good ecological effect and requiring no subsequent maintenance. After the oyster reef structure is deployed, the oyster reef structure provides a better and better coastal protection function with an elapse of time and has an increasingly significant ecological effect with the elapse of time. Not only the coast can be protected from erosion and damage, but also a highly biodiverse oyster reef ecosystem can be created on the offshore side of the natural coast or at the toe of the seawall to enhance the ecological function and value of the natural coast or the seawall near the sea. In an embodiment of the present disclosure, the protective net component 003 includes a net made of geotextile.

Specifically, a net made of geotextile is used as a soft protective material, which can prevent scouring of silt on the coast by water flow, contributes to maintaining the stability of the bottom surface of the seabed on the coast, and also plays a certain role in preventing erosion of the coast. In addition, the protective net component 003 can be used as a carrier for an ecological oyster bag, which can not only maintain good permeability to sea water, but also properly isolate seabed sediments to prevent burying of the ecological oyster bag by the seabed sediments and create a good environment for the growth of oysters to facilitate the production and reproduction of oysters.

It should be noted that the geotextile net is made of geotextile woven from filaments. The geotextile net on each oyster reef structure has a length of about 2 m and a width of about 1 m, which is made of a synthetic fiber such as high-strength industrial polypropylene fiber as a raw material, and has advantages such as high strength, durability, and corrosion resistance. The geotextile net is sized at 500 g/m 2 .

Further, the reef structure frame 001 is equipped with an oyster pillar chamber 004, and an oyster pile 005 is provided in the oyster pillar chamber 004. Specifically, the oyster pillar chamber 004 is connected integrally to the reef structure frame 001 by fasteners. The oyster pillar chamber 004 has a cubic structure, and the six end surfaces of the oyster pillar chamber 004 are provided with openings, respectively. An oyster pile 005 is placed in the oyster pillar chamber 004. The oyster pile 005 can be used as a substrate for attachment of oysters. The length, width, and height of a single oyster pillar chamber 004 are each 40 cm. One oyster pile 005 is placed in each oyster pillar chamber 004. The oyster pile 005 is in the shape of a cylindrical concrete body with a length of 80 cm and a bottom surface diameter of 20 cm. The oyster pile 005 is inserted into the oyster pillar chamber 004, and the oyster pile 005 is fixed in the oyster pillar chamber 004 using fasteners. Further, the oyster pillar chambers 004 are mounted at both ends of the reef structure frame 001 in a direction perpendicular to the coastline.

Specifically, a plurality of oyster pillar chambers 004 are mounted on a side of the reef structure frame 001 near the seaward side of the natural coast or near the toe of the seawall, and a plurality of oyster pillar chambers 004 are provided on a side of the reef structure frame 001 facing away from the coast. An oyster pile 005 is inserted into each of the oyster pillar chambers 004. The spreading growth of oysters on the oyster piles 005 will facilitate the overall stability of the oyster reef structure, thereby slowing down the impact of water flow in the direction perpendicular to the shoreline.

Further, the oyster pile 005 is inserted into the cavity of the oyster pillar chamber 004 from top to bottom, and the side walls of the oyster pillar chamber 004 are provided with side openings communicating with the cavity.

Specifically, sea water can enter the cavities of the oyster pillar chambers 004 through the side openings. The oyster piles 005 are inserted into the oyster pillar chambers 004. The oyster piles 005 allow oysters and barnacles to adhere thereto, thereby gradually improving the stability of the reef structure. The oyster pillar chamber 004 has a height of 40 cm. The inserted oyster pile has a total length about 80 cm and has a height about 40 cm exposed from the oyster pillar chamber. Under normal circumstances, the height may increase by 10 to 20 cm in two to three years due to the growth of oysters. As the number of oysters is increasing, the height and weight of the oyster reef structure will increase further rapidly until it reaches a height unsuitable for growth of oysters (a height at spring tide or high tide). The oyster reef formed at this time can effectively weaken wave energy and excellently protect the coast from erosion and damage. Further, the oyster reef structure further includes an ecological oyster bag 006. The ecological oyster bag 006 is provided on the protective net component 003. Specifically, the ecological oyster bag 006 is made of polyethylene as a raw material. A netting rope for the ecological oyster bag 006 is a polyethylene fiber rope having at least 50 strands of drawn filaments, with a breaking strength 200 N per rope. A sealing rope for the ecological oyster bag 006 and a rope connected to the reef structure frame 001 are each made of a polyester fiber rope having 50 or more strands, with a breaking strength 200 N per rope. Two pieces of rope are tied with a single hard knot, and double hard knots are tied when sealing the ecological oyster bag. The ecological oyster bag 006 has a length of about 1 m, and the total number of meshes of each ecological oyster bag 006 is not more than 3000 meshes. The ecological oyster bag 006 is supported by the reef structure frame 001 and blocked from the seabed sediments by the protective net component 003, thereby avoiding sinking of the ecological oyster bag into the seabed silt due to its excessive weight. The oyster pillar chambers 004, the oyster piles 005, and the ecological oyster bag 006 can provide good environments for attachment, growth, and reproduction of oysters, barnacles, and other reef-building organisms. Oysters grow faster and can grow into adults in about two to three years. Seed oysters introduced into the ecological oyster bag have a size of about 5 to 10 mm and a weight of about 5 to 10 g. The shells of two-year-old oysters can reach a height of 8 to 12 cm and can reach a size more than 20 times the original sizes of the seed oysters. A single oyster can have a weight of 100 to 200 g, which is 20 to 40 times heavier than the seed oyster. Moreover, as the number of oysters is increasing, the number of naturally reproduced young seed oysters increases, and new seed oysters will continue to attach to the shells of adult oysters, so that the size and weight of the reef will increase at a gradually increasing speed and show an exponential increase. In this way, the oyster reef structure is expanded at an increasing speed, the size and weight of the oyster reef structure can be increased quickly, and the stability of the oyster reef structure can be improved rapidly, so that the oyster reef structure can properly defend against storm surge disasters and play an important role in protecting the natural coast or the toe of the seawall.

Further, the ecological oyster bag 006 has an inner cavity containing oyster shells, and the ecological oyster bag 006 is provided with pores communicating with the inner cavity.

Specifically, the total weight of the ecological oyster bag 006 and oyster shells contained therein is greater than or equal to 3 kg. The ecological oyster bag 006 should be guaranteed to have larger pores and higher strength. The oyster shells contained in the ecological oyster bag 006 can be exposed through the larger pores to facilitate the attachment and growth of oysters. A plurality of ecological oyster bags 006 are placed on the protective net component 003. Any two adjacent ecological oyster bags 006 are spaced apart at an interval of 10 cm. About four ecological oyster bags 006 are placed on each reef structure frame 001. The ecological oyster bags 006 are filled with various large shells such as discarded oyster shells and scallops. The discarded shells are environmentally friendly and ecological and can be turned into "treasure" and are more advantageous to the attachment and growth of oysters, so that the ecological oyster bags 006 serve as perfect attachment sites for growth of oysters to facilitate the development of an oyster reef. Further, the reef structure frame 001 includes a first side frame 101, a second side frame 102, a third side frame 103, and a fourth side frame 104. The first side frame 101, the second side frame 102, the third side frame 103, and the fourth side frame 104 are connected end to end in sequence and form a rectangular frame. Specifically, both the first side frame 101 and the third side frame 103 extend in a direction parallel to the shoreline, and both the second side frame 102 and the fourth side frame 104 extend in a direction perpendicular to the shoreline. The first side frame 101 and the third side frame 103 may have a length of 2 m, and the second side frame 102 and the fourth side frame 104 may have a length of 1 m. Further, the reef structure frame 001 further includes a frame beam 105. The frame beam 105 is connected in the rectangular frame, and the frame beam 105 extends in the direction perpendicular to the coastline.

Specifically, two frame beams 105 are provided. The two frame beams 105 extend in a direction parallel to the second side frame 102, respectively, and the two frame beams 105 are spaced apart from each other in the shoreline direction. The frame beams 105 are supported in the rectangular frame, so that the structural strength of the reef structure frame 001 is improved in the direction perpendicular to the shoreline.

Second Embodiment As shown in FIG. 1, a coastal protection device according to an embodiment of the present disclosure includes a protective pile 007 and the oyster reef structure according to the first embodiment. The reef structure frame 001 is arranged on the seaward side of a natural coast or at the toe of a seawall, and the grounding component 002 is inserted into the seabed. The protective pile 007 is provided on a side of the oyster reef structure facing away from the coast, and the protective pile 007 is inserted into the seabed. Specifically, a plurality of reef structure frames 001 are arranged on the seaward side of the natural coast or at the toe of the seawall in the shoreline direction. The protective pile 007 has a radial dimension of 40 cm. The protective pile 007 has a length of 5 m, with a length of 3 m inserted into the seabed and a length of 2 m exposed from the seabed and abutting against the reef structure frame 001. The protective pile 007 prevents the reef structure frame 001 from being washed into a sea area outside the intertidal zone. Third Embodiment As shown in FIGS. 1 and 2, a coastal protection method according to an embodiment of the present disclosure includes: constructing a reef structure frame 001 and fixing the reef structure frame 001 on the seaward side of a natural coast or the toe of a seawall by means of a grounding component 002; connecting a protective net component 003 to the reef structure frame 001 to make the protective net component cover the reef structure frame. The protective net component 003 contributes to maintaining the stability of the bottom surface of the seabed on the offshore side of the coast and also plays a certain role in preventing erosion of the coast. Moreover, it can also play a role in isolating seabed sediments and preventing burying of the oyster reef structure by the seabed sediments, thereby creating a good environment for the growth of oysters to facilitate the rapid formation of an oyster reef.

Further, the coastal protection method further includes: putting oyster shells in an ecological oyster bag 006; and arranging the ecological oyster bag 006 on the protective net component 003. First, fertilized eggs of oysters are collected in an oyster nursery, and the fertilized eggs are bred in a culture tank for 14 to 20 days until tentacles are grown from them and they can attach. After leaving the culture tank, seed oysters are transported to an attachment tank in which sterilized oyster shells are placed for attachment of young seed oysters. After 1 to 2 weeks, when the seed oysters are firmly attached, and 5 to 10 seed oysters are attached to each oyster shell or each shell, the oyster shells are put into the ecological oyster bag 006, and then the ecological oyster bag 006 is connected to the reef structure frame 001 and placed in a sea area of the coastal intertidal zone. Subsequently, oysters will naturally grow and reproduce on the oyster reef structure, and oysters that have died in the early stage will become reef-building materials, leading to a continuous increase in the size and weight of the oyster reef structure. Finally, it should be noted that the above embodiments are merely intended to illustrate the technical solutions of the present disclosure, but not intended to limit the present disclosure. Although the present disclosure has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that the technical solutions disclosed in the foregoing embodiments may still be modified, or some or all of the technical features thereof may be replaced with equivalents. Such modifications or replacements will not cause the essence of the corresponding technical solutions to depart from the scope of the technical solutions of the embodiments of the present disclosure.

Claims

What is claimed is: 1. An oyster reef structure, comprising: a reef structure frame, a grounding component, and a protective net component, wherein the grounding component is connected to a bottom of the reef structure frame; and the protective net component is connected to and covers the reef structure frame.
2. The oyster reef structure according to claim 1, wherein the protective net component comprises a net made of geotextile.
3. The oyster reef structure according to claim 1, wherein the reef structure frame is equipped with oyster pillar chambers, and an oyster pile is provided in each of the oyster pillar chambers.
4. The oyster reef structure according to claim 3, wherein the oyster pillar chambers are mounted at both ends of the reef structure frame in a direction perpendicular to a coastline.
5. The oyster reef structure according to claim 1, further comprising an ecological oyster bag, wherein the ecological oyster bag is provided on the protective net component.