<p>The cast-in-situ pile and pre-bored grouted pre-stressed high-strength concrete (PHC) pile (Bored PHC pile) are two types of non-displacement pile. Nevertheless, the installation effects of cast-in-situ pile and Bored PHC pile should also be considered when installed in vicinity of some important infrastructures. In this research, the installation effects of cast-in-situ pile and Bored PHC pile were analyzed and compared based on an actual engineering project in vicinity of a subway tunnel. The inclinometers, pore water pressure sensors and soil pressure sensors were equipped between the test piles and adjacent subway tunnel. The test results showed that: the disturbance caused by the Bored PHC pile installation was larger than the disturbance caused by cast-in-situ pile, as the drilling speed of Bored PHC pile was much higher than the drilling speed of cast-in-situ pile; while the disturbance induced by the PHC pile insertion stage of Bored PHC pile was close to the disturbance induced by the concrete placing stage of cast-in-situ pile; the excess pore water pressure and the increase of lateral soil pressure caused by cast-in-situ pile and Bored PHC pile installation all recovered rapidly after cast-in-situ pile and Bored PHC pile installation; the disturbance induced by Bored PHC pile and cast-in-situ pile installation became relatively limited when the radial distance reached 4D (D is pile diameter); the research results could provide a theoretical basis for the application of cast-in-situ pile and Bored PHC pile near some important infrastructures such as subway tunnels.</p>

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Field tests on installation effects of cast-in-situ pile and pre-bored grouted PHC pile

  • Jia-jin Zhou,
  • Ri-hong Zhang,
  • Jian-lin Yu,
  • Xiao-nan Gong

摘要

The cast-in-situ pile and pre-bored grouted pre-stressed high-strength concrete (PHC) pile (Bored PHC pile) are two types of non-displacement pile. Nevertheless, the installation effects of cast-in-situ pile and Bored PHC pile should also be considered when installed in vicinity of some important infrastructures. In this research, the installation effects of cast-in-situ pile and Bored PHC pile were analyzed and compared based on an actual engineering project in vicinity of a subway tunnel. The inclinometers, pore water pressure sensors and soil pressure sensors were equipped between the test piles and adjacent subway tunnel. The test results showed that: the disturbance caused by the Bored PHC pile installation was larger than the disturbance caused by cast-in-situ pile, as the drilling speed of Bored PHC pile was much higher than the drilling speed of cast-in-situ pile; while the disturbance induced by the PHC pile insertion stage of Bored PHC pile was close to the disturbance induced by the concrete placing stage of cast-in-situ pile; the excess pore water pressure and the increase of lateral soil pressure caused by cast-in-situ pile and Bored PHC pile installation all recovered rapidly after cast-in-situ pile and Bored PHC pile installation; the disturbance induced by Bored PHC pile and cast-in-situ pile installation became relatively limited when the radial distance reached 4D (D is pile diameter); the research results could provide a theoretical basis for the application of cast-in-situ pile and Bored PHC pile near some important infrastructures such as subway tunnels.