Study On Ultimate Bearing Capacity Of Pile-bucket Composite Foundation

As a kind of high-rise structure, the foundation of wind turbine usually bearslarge eccentric load which further leads to uncontrollability of the different settlement.Wind turbine research group of Tianjin University has developed a novel type ofPile-Bucket composite foundation, which can adapt the complicated wind conditionand geologic characteristic around the offshore wind power plant. The new type offoundation has broad application prospects for its bearing superiorities of both pipefoundation and bucket foundation which can control the vertical displacement andhorizontal displacement simultaneously. This article provide a systemic analysis aboutthe failure mechanism and bearing capacity envelope of the Pile-Bucket compositefoundation, respectively, under one direction load and combined loading mode. Themain results of this study are as follows:1. After summarizing the main structures of the offshore wind turbine foundationand delivering an introduction about the research background and the history ofbucket foundation and single pile foundation, the Pile-Bucket composite foundationstructure and its bearing characteristic are proposed.2. By analyzing the deformation characteristic of Pile-Bucket compositefoundation under external load, pile diameter, bucket diameter, pile length, bucketlength are defined as the main structural factors. Dimensionless normalized method isadopted to analyze the relationship between such main factors and ultimate bearingcapacity of soil. Using dimensionless quantity Vult/ASu，Hult/ASu，Mult/ADSutodescribe vertical load, horizontal load and ultimate bending resistance of soil, thefitting relation between the dimensionless quantities and D/d, l/L.3. The foundation failure mechanism and bearing capacity envelope under thecombined loading mode with the condition that the diameter ratio of bucket and pileD/d equate to2,3,4,6can be given by limited analysis. The regulation between thebearing capacity envelope and the diameter ratio of bucket and pile are pointed.4. H-M load space bearing capacity experiment for Pile-bucket compositefoundation model was carried out to test the load displacement curve. And then theresult with the fundamental load displacement curve deriving from finite elementanalysis are compared.