Experimental Research On Ultra-high Performance Grouting For Offshore Wind Power

Vigorously developing clean and renewable energy is an important way to solve the global climate problem,strive to achieve carbon neutrality,build an environment-friendly economic development model,and get rid of the dependence on traditional fossil energy.Wind power is environmentally friendly and the world is rich in wind energy.Offshore wind power has developed rapidly in recent years.China started late in this field,but the country has invested heavily in recent years,and more and more offshore wind power projects will be built in the future."China's 14 th Five-Year" Power Development Planning Research "pointed out that the 14 th Five-Year period is expected to increase the installed capacity of wind power290 million kilowatts,an annual increase of 58 million kilowatts.Grouting is usually used to connect the offshore wind turbine with the lower pile foundation.The grouting material with excellent performance is the key material for the development of offshore wind power projects.Due to its special working environment,the grouting materials for offshore wind power have higher performance requirements than the previous grouting materials.There are few researches in the field of offshore wind power grouting materials in China,and relevant researches are urgently needed.In view of the lack of independent products of offshore wind power grouting products and long-term dependence on imports,this paper systematically studies the mortar-sand ratio,water-binder ratio,water reducing agent,defoaming agent,plastic expansion agent,mineral admixtures on the performance and mechanics of the grouting material.Due to the influence of performance and expansion performance,the mixing ratio of the offshore wind power grouting material that meets the predetermined performance requirements is optimized.The performance of the optimal mix ratio of the grouting material is improved from the two aspects of the mixing system and the volume of steel fiber.Finally,the effect of the grouting material with different volume of steel fiber on the axial pressure performance of the offshore wind power grouting connection model is studied.The content of steel fiber was optimized.The main research work and conclusions of this paper are as follows:(1)Through the systematic study of the mixture ratio parameters of ultra-high performance offshore wind power grouting material,the amount of admixtures and mineral admixtures,the mixture ratio of ultra-high performance offshore wind power grouting material is optimized.Under the experimental conditions of this paper,the optimal grouting material cement-sand ratio is 1.0,water-binder ratio is 0.20,water reducing agent is 0.60%,defoaming agent is 0.15%,plastic expansion agent is 0.30%.(2)Through the study of the grouting material mixing system,it is found that with the increase of the number of mixing cycles,the fluidity of the grouting material first increases and then decreases,and the strength has a similar change rule.The optimal number of standard mixing cycles is 2.The increase of steel fiber content can improve the mechanical properties of grouting material,but decrease the fluidity and vertical expansion rate.Considering the properties of grouting material,the volume content of steel fiber should not exceed 1.0%.When steel fiber volume content increases from 0.0% to 1.0%,the initial fluidity of grouting material decreases by 3.4%,and the 28 d flexural strength and compressive strength increase by 65.4% and 31.0%,respectively.(3)According to the structural characteristics of the grouting connection section of offshore wind power,a small model of the grouting connection section is designed;Based on this,the influence of steel fiber volume content on the axial compressive resistance of the grouting joint model was studied.The research results show that the small grouting joint model proposed in this paper can reflect the performance difference of different steel fiber content grouting materials used in grouting connection,and it is a simple and convenient simulation experiment method for the performance of offshore wind power grouting materials.Adding an appropriate amount of steel fiber into the grouting material for offshore wind power can improve the ultimate bearing capacity and ultimate displacement of the grouting joint model,and increase the ductility of the grouting joint.It is an effective method to improve the performance of the grouting material for offshore wind power.The optimal volume of steel fiber is 1.0%.When the volume of steel fiber increases from 0% to 1.0%,the ultimate bearing capacity and ultimate displacement of the grouting joint increase by 12.0%and 15.5%.(4)Under the action of axial load,the main stress and deformation parts of the grouting connection segment model are the shear key at the upper part of the inner cylinder and the lower part of the outer cylinder.In the future design of the grouting connection segment,these parts can be strengthened appropriately to give full play to the overall performance of the grouting connection segment.