Researches On Technology Of Pre-stressed High Strength Concrete Pile Applied In Soft Soil Area

Pre stressed high strength concrete pile (PHC pile for short in the following) isused widely in soft soil area because of its superiorities,such as high bearingcapacity of single pile, stable and reliable in quality, convenient construction,andso on. But there are some problems during using PHC piles in soft soil area.including the stability problem caused by movement of soil around the piles, soilcompaction effect, negative friction, depression of bearing capacity and buildinguneven subsidence induced by negative friction. Study on these problems is in greatpractical significance for the development of PHC pile.Embarking from design andconstruction of PHC pile, this paper introduces the principle and applicationexperience in soft soil of pile design. It also introduces static pressure pile-sinkingand driven pile, which are most commonly used methods in pile driving. On thebasic of former study, further research on the mechanism of soil compaction andnegative friction is taken, and the harm is discussed, as well as the preventivemeasures.The emphasis of this passage is the study on stability of pile duringexcavation. The soil around pile easily produces displacement towards excavationunder the effect of external load and disturbance, which causes imbalance force onthe sides of pile. In this case, the pile is called " passive pile". The key to studyingstability of passive pile is the interaction of passive pile and soil around it, which isstudied from earth pressure and soil movement. The stability of passive pile isdiscussed,combined with two engineering examples in which PHC piles were usedin soft soil foundation, one successful while another failed. And practicablepreventive measures are put up, finally.