Analytical and Numerical Investigation of Effectiveness of Ground Modification around Piled-Raft Foundation for Tall Wind Turbine in Weak Soil

A site with favorable wind condition may not have suitable subsurface condition for building tall wind turbines. In such situation, it may be economical to improve the subsurface properties to gain net economic advantage. In this study, the effectiveness of ground improvement to support an 80 m tall wind turbine on a piled-raft foundation was investigated using analytical and 3D finite element methods. First, analytical designs were conducted to determine the length of the piles for the assumed raft and pile size and number of piles to meet the safety and serviceability requirements. Three different depths of improvements were considered in the design. Then, 3D FE models of the piled-raft foundations and supporting soils were created and analyzed using ABAQUS. In the FE modeling, the lateral distance was varied in addition to the depth of ground improvement. Both methods show that significant economic advantage can be achieved by improving the ground.