Analysis On Bearing Capacity Of Wide And Shallow Bucket Foundation In Silty Clay

As a new type of offshore wind turbine foundation,bucket foundation has a good adaptability.The deformation of bucket foundation is too large to keep the whole structure stable in the silt clay with low compression modulus focused on most ocean of our country.Up to now,there are many study on the bearing capacity of bucket foundations,but research on wide and shallow bucket foundations is few.This paper in-depth studied the bearing capacity of wide and shallow composite bucket foundation in clay by finite element,experimental and theoretical methods.The main contents and results of this thesis are as following:(1)The test of vertical bearing capacity was carried out.Under extreme vertical loads,we can determine the failure mode for the whole foundation of shear failure with reference to the soil cracking form and P-S curve.For each part of the bearing capacity of the bucket foundation,the difference between theoretical value and experimental value do not exceed 10%.When reaching the limited vertical load,the cap takes up the most of the total load,about 40%-50%,inner and outer sides friction resistance about 40%,the tip resistance about 15%.This proves that the bearing mode of wide and shallow bucket foundation is top cap bearing capacity.Compare the curves of the total and separated force with two theoretical calculations of Terzaghi and Hansen,and prove that both of them are suitable.(2)The test of horizontal bearing capacity was carried out,assisted by finite element calculation to obtain the extreme horizontal load and overturning angle.We observed the destroy phenomenon under horizontal and moment and,studied the distribution of earth pressure on the cap and sides,then proved that under horizontal and moment,the bucket foundation’s instability occurs mainly due to large rotational displacement and a little slip displacement.The center of rotation is around the axis.Three methods of theoretical calculation of ultimate bearing capacity were compared.The calculation of the safety factor method can obtain the position of the center of rotation.The result is within the error range of 10% compared with experiment and finite element.