Model Test Research On The Penetration Resistance Of Bucket Foundation During Installation In Silty Clay

Bucket foundation is a common form foundation for ocean engineering,and bucket foundation has the advantages of easy installation,economic feasibility and recoverability.Bucket foundation is installed by self-weight and suction.The successful installation of bucket foundations is a prerequisite for normal use.But,the soil-skirt Interaction and resistance reduction effect during suction penetration is not very clear.So study the installation of bucket foundation is significant.Installation model test on the bucket foundations were taken in silty clay by this paper.Research content including the soil squeezing effect of walls in jacking installation,the calculation method of lateral and tip resistance,the resistance's difference of foundations with length-to-diameter ratio of 1 and 2 and dissipation of pore water pressure after jacking installation.Meanwhile,effect of suction on the lateral pressures,tip pressures and resistance.The calculating formula of critical suction is given.The main content and conclusion in this thesis are listed as follow.(1)Jacking installation model test on the bucket foundations were taken.The test results show that the soil squeezing effect of the interior is much higher than the exterior,and the soil squeezing effect of the interior reduces during the installation.The compaction extent of the exterior has a linear relationship with the IFR.The tip resistance is directly related to the strength of the soil.According to the standard,based on the undrained shear strength and the CPT,the lateral and tip resistance can be calculated accurately.Due to the difference of soil squeezing effect,? and kf will take larger value when the inner resistance is calculated.The soil squeezing effect and resistance characteristic of bucket foundations with length-to-diameter ratio between 1 and 2 are similar.Excess pore water pressure in the interior is significantly higher than the exterior during the jacking installation.The numerical simulation of jacking installation on bucket foundations was taken,and the pressures of walls were gotten.For soil squeezing effect,effect of tip's angle,dilation angle and frictional angle were studied.(2)Suction installation model test on the bucket foundations were taken.The test results show that effect of suction on the tip and outer resistance is little.But,applied suction can greatly reduce the inner pressure,so it can significantly reduce the inner resistance.The total resistance reduces by twenty percent when suction is applied.The effect of suction on the inner soil decreases along the depth,and the inner friction decreases drastically due to suction.The suction inner resistance computing method is obtained by static equilibrium equations of soil plug,and the more calculation of accurate critical suction is also obtained.