Experimental research on suction beneath pile foundation being pulled out from cohesive soil bed
2022
Yu, Hui | Wang, Wenkai | Wang, Yuchuan
When pile foundations, exampling engineering structures, are pulled out from the underwater cohesive soil bed, negative pressure will be produced beneath them. The suction arisen from negative pressure can affect the structural stability and pull-out resistance of pile foundation to some extent. However, its variation characteristics and rules remain unclear at present. For this reason, it is of essential practical significance to research the suction beneath pile foundation being pulled out from the cohesive soil bed. In this research, physical experiments were carried out to measure the shape changes of the cavity, variations of the pressure and pull-out force beneath the model pile during its vertical pull-out from the cohesive soil bed. Efforts were also made to analyse the effects of parameters, including pull-out velocity, embedment ratio of pile foundation and soil properties etc. on pressure beneath the pile. Consequently, the experimental results indicate that in cohesive soil bed the suction arisen from negative pressure beneath the pile foundation exerts a certain effect on the pull-out resistance. Besides, during the pull-out process, a pore water cavity will be generated beneath the pile foundation. Under the same embedment condition, the negative pressure beneath the pile foundation increases from 4.4 kPa to 7.8 kPa with the acceleration of pull-out velocities from 1 mm•sE−1 to 9 mm•sE−1, but when the pull-out velocity accelerates above 7 mm•sE−1, its effect on the negative pressure is no longer obvious. At the pull-out velocity of 1 mm•sE−1, the negative pressure of pile foundation increases from 6.2 kPa to 8.3 kPa with the increase of the embedded depth.
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