Field Test of Excess Pore Water Pressure at Pile–Soil Interface Caused by PHC Pipe Pile Penetration Based on Silicon Piezoresistive Sensor

Prestressed high-strength concrete (PHC) pipe pile with the static press-in method has been widely used in recent years. The generation and dissipation of excess pore water pressure at the pile-soil interface during pile jacking have an important influence on the pile's mechanical characteristics and bearing capacity. In addition, this can cause uncontrolled concrete damage. Monitoring the change in excess pore water pressure at the pile-soil interface during pile jacking is a plan that many researchers hope to implement. In this paper, field tests of two full-footjacked piles were carried out in a viscous soil foundation, the laws of generation and dissipation of excess pore water pressure at the pile-soil interface during pile jacking were monitored in real time, and the laws of variation in excess pore water pressure at the pile-soil interface with the burial depth and time were analyzed. As can be seen from the test results, the excess pore water pressure at the pile-soil interface increased to the peak and then began to decline, but the excess pore water pressure after the decline was still relatively large. Test pile S1 decreased from 201.4 to 86.3 kPa, while test pile S2 decreased from 374.1 to 114.3 kPa after pile jacking. The excess pore water pressure at the pile-soil interface rose first at the initial stage of consolidation and dissipated only after the hydraulic gradient between the pile-soil interface and the soil surrounding the pile disappeared. The dissipation degree of excess pore water pressure reached about 75-85%. The excess pore water pressure at the pile-soil interface increased with the increase in buried depth and finally tended to stabilize.