Research Of Grouted Connection To Improve The Axial Bearing Capacity In Offshore Wind

As a result of the earth’s land resources increasingly strained, more and more people are beginning to develop offshore energy development project and with the success of the European offshore wind, the energy conservation and environmental protection of energy utilization in China is becoming more and more widely. Grouted connection plays a transitional role in the foundation of offshore wind, making force of upper structure be safe and effective to the submarine foundation. With the advantages of corrosion resistance, high bearing capacity and convenient construction, we can expand on the offshore platform steel pipe repair and construction of steel structure engineering and so on, in addition to the application of offshore wind power foundation. With more and more large-scale offshore wind power development, the huge cost of foundation also caused people’s attention. Grouted connection as an important part of the foundation also requires continuous improvement. The influence of shape and size of shear key, length of grouted connection, conical form on grouted connection axial bearing capacity was studied with the finite element analysis software ANSYS and the experiments in this paper,which provide efficient and economic reference for actual engineering.The main contents of this paper are as follows:1.The method and principle of grouted connection symmetric finite element model and solid finite element model were introduced in the paper. Surface contact elements were used to simulate the grouting material contact with the pile and steel pipe. When the model and load were axisymmetric,we can use axisymmetric simplify to shorten the calculation time and improve efficiency.2.Three common different shear key shapes (rectangular,triangle, semicircle) were analyzed, and the effect on the axial bearing capacity of the grouted connection were compared. Analysis shows that the semicircle are more likely to cause stress concentration at the end shear key,while the rectangle and triangle are similar. Shear key size affects the stress of the grouted connection, studies have shown that the better height and width of the shear key is20mm and40mm in practical engineering. 3.The shear key, length of the grouted connection, conical form were analyzed and compared by the axial compression experiments, and make recommendations for the final destruction. Experimental results show that the axial bearing capacity of grouted connection without shear key mainly depends on the adhesion between the grout and steel, and surface blasting and other measures were recommended;The length of grouted connection with shear key can effectively reduces the displacement under the same loads, the stress concentration is more likely to occur at the ends of the shear key grouted connection, and it is recommended to strengthen the grouted connection section at both ends; Cone grouted connection in the design of bearing capacity is larger than cylindrical grouted connection when the load is bigger,the damage is more likely to cause the stress concentration in cone grouted connection,and subsection design to realize smooth transition was suggested.4. The grouted connection of monopile foundation was designed.The stress checking was analysed under the actual load conditions by the finite element method. Analysis indicates that the steel pipe is less than the material yield stress,There was no large area of grout cracking and the structure can operate safely.