Study On The Experiment And Structure Design Of A Variety Of Materials In The Preparation Of Artificial Reef

The continuous development of land resources leads to the shrinking or even exhaustion of its resources,and the contradiction between population growth and resource shortage becomes more and more serious,which makes people turn their attention to the sea for the development of marine resources.Artificial reef is an important construction unit and main body of marine ranching.It can not only cultivate and conserve marine resources,but also repair the marine environment and increase fish catches to generate economic benefits.Therefore,many countries have begun to construct and research artificial reefs.Reef-making materials and reef structure design have a direct impact on the performance of reefs and are therefore the most important in the construction of artificial reefs.At present,there are few researches on artificial reef materials.From the research content of domestic and foreign scholars,it is a major development trend to take waste materials as admixtures or directly as the main body of reef,and it is also a major direction for the development of reef materials towards green and environmental protection.The design of the reef structure reflects the stability of the reef itself and the effect of the flow field.It plays an important role in checking whether the reef will slip,overturn and other instability risks.Accordingly,the main research contents of this paper are as follows:（1）The artificial reef is prepared with sludge,shell powder,and cement as the main materials.A total of 9 different material ratios were designed and strength tests,PH tests of soaking solution and nutrient precipitation tests were conducted to explore the feasibility of mixing sludge and shell powder into reefs as admixtures and the influence of shell powder content and water-cement ratio on reef performance.（2）Taking sludge,basalt fiber and concrete as the main reef-making materials,16different ratios were designed and tests of compressive strength,splitting resistance and chloride ion penetration resistance were carried out on this basis.According to the test data and previous research results,the influence of the content of sludge and basalt fiber on the performance of the reef body was summarized.（3）According to the test results of the two materials,a relatively optimal ratio combination was selected as reef material,and then the hole diameter range of 0.1-0.4m was set to design the structure form of reef and calculate fluid force and stability coefficient to ensure its stability.Meanwhile,the cost of reef material was calculated to ensure its economy.The main conclusions are as follows:（1）When artificial reef blocks are prepared from sludge,shell powder and cement,both water-cement ratio and shell powder content have an effect on the strength of reef blocks,but water-cement ratio has a greater effect.When the ratio of cement:sludge:shell powder=1:0.2:0.6 and the water-cement ratio is 0.5,the maximum strength is 27.4MPa.After sludge is added,the reef block can precipitate out nutrient salts NH4⁺and PO4^3-,and the precipitation rule is linear.Meanwhile,with the increase of time,the concentration of nutrient salt is higher,which is similar to the effect of slow-release of fertilizer effect.Water-cement ratio is the main factor affecting NH4⁺precipitation,followed by shell powder content.The water-cement ratio and shell powder content had almost no effect on the precipitation of PO4^3-.The PH of immersion solution of reef block with different material ratio is different,and the PH is significantly affected by the strength.High shell powder content and low water-cement ratio will make the immersion solution PH of reef block relatively lower,which is closest to the PH value of ordinary sea water,so that the reef block has better hydrophilicity.（2）When using sludge,basalt fiber,and concrete as raw materials to prepare artificial reef blocks,when the sludge content is 3%-9%,the artificial reef concrete has compressive strength,splitting tensile strength and resistance to chloride ion penetration the worse the performance,but its impact on the tension-compression ratio is not great;when the external volume of basalt fiber is 0.1%-0.15%,all the properties of the reef block are improved.However,when the fiber content was 0.2%,except the splitting tensile strength continued to rise,the pressure resistance and chloride ion permeability were slightly reduced,but still stronger than those without fiber.When the content of sludge and basalt fiber is 3%-9%and 0.1%-0.2%respectively,the sludge content is the main factor influencing the resistance to pressure,splitting strength and chloride ion permeability,followed by the basalt fiber content.（3）According to the hydrological conditions of Wuzhizhou Island in Sanya,an optimal ratio was selected from each of the two new reef materials for material combination,and a box-shaped reef with a hole diameter of 0.1-0.4m was designed based on this.The new fish reef material studied provides a form of realization.After calculation of basic parameters,fluid force,stability and economic efficiency,it is found that the box-shaped reef designed with a hole diameter of 0.4m is optimal in all aspects within the range of 0.1-0.4m.