Abstract: Jacked pipe has been widely used in practical engineering. The excess pore water pressure at the pile-soil interface has a great influence on the performance of jacked pile. Most current researches focus on the distribution of excess pore water pressure in the soil around the pile rather than the real situation of stress at the pile-soil interface. In this paper, by drilling holes in pile body and embedding silicone piezo-resistance pore water pressure sensor, static pile pressure test was conducted on two groups of model piles in clayey soil. The variations of pore water pressure and excess pore water pressure at the pile-soil interface were investigated. The pore water pressure generated at the pile-soil interface during pile jacking has been successfully monitored for the first time by the silica-piezo-resistance sensor. The pore water pressure and excess pore water pressure of pile-soil interface both increased with the growth of pile jacking depth. In the meantime, the excess pore water pressure generated in the process of pile jacking was relatively large, up to 4.21 kPa, which was about 75% of the effective overburden soil weight. In practical engineering, the relatively large excess pore water pressure generated in the process of pile jacking should be paid attention to. The excess pore water pressure at the same depth dissipated, and such dissipation attenuated with the increase of depth. In practical engineering, effective measures should be taken to prevent from excessive excess pore water pressure. The test results offer reference for static pressure pile construction and theoretical research on pile-soil interface.

Key words: jacked pile, pile-soil interface, pore water pressure, excess pore water pressure, silicon piezo-resistive pore water pressure sensor