Calculation method for bearing capacity of open-ended pipe pile considering plugging effect of soil based on CPTU

To improve the calculation method for the bearing capacity of open-ended pipe piles considering plugging effect of soil, the field test of the prestressed concrete open-ended pipe pile (PHC) in the Chongqi bridge project was carried out based on the piezocone penetration test (CPTU) technology and static load tests. Based on the CPTU data and the correlation between the cone tip resistance and the pile tip resistance, a new method for CPTU was proposed to calculate the bearing capacity of open-ended pipe piles. The test results show that when the depth in pile sinking is less than 15 m, the growth rate of the plugging effect decreases negatively with the increase of the pile depth. The underlying layer is the hard soil layer. When the depth of pile sinking increases from 20 to 25 m, the growth rate of the plugging effect of soil increases from 0 to 10%. The ratio between the end resistance of the pipe wall and the cone tip resistance measured by CPTU is stable at 0.68. The average error between the bearing capacity of the pipe pile calculated by the proposed method of CPTU and the test results of the static load tests is only 4.5%, which is smaller than the calculation results of other domestic codes. The calculation accuracy is high, so it is worth popularizing in pile foundation engineering. © 2020, Editorial Department of Journal of Southeast University. All right reserved.