珊瑚礁地质大直径钢管打入桩承载特性研究

马尔代夫中马友谊大桥采用钻孔灌注桩基础,主墩基础施工过程中,将35根大直径钢护筒施沉至中等—强胶结礁灰岩地层,作为钻孔平台的临时桩基础。以主墩大直径钢护筒沉桩记录为依据,并结合高应变动力检测方法,对珊瑚礁地质大直径打入桩的承载性能进行研究。研究结果表明:1)以钙质砂为主的覆盖层侧阻力较小; 2)礁灰岩侧阻力随胶结程度的增加而增大; 3)中等—强胶结礁灰岩可以作为打入桩的持力层,端阻力约占总承载力的70%; 4)打入桩的承载力恢复系数较小,仅为1.1。

Study on bearing behavior of large diameter driven steel pipe pile in coral reef geology

Bored and cast-in-place pile foundation was employed in the construction of the China Maldives Friendship Bridge. The 35 large-diameter steel pile casings of the main piers were all driven to the layer of medium to favorably cemented reef limestone, which served as a temporary foundation for drilling platform. In this paper, based on the driving records of piles, using the methods of high strain dynamic testing, the bearing behavior of large diameter driven steel pipe in coral reef geology is studied. The results show that: 1) The side resistance of the pile in calcareous sand layer is relatively weak; 2) The stronger the cementation degree of reef limestone, the greater the side resistance; 3) Medium to favorably cemented reef limestone can act as the holding layer of driven piles, and the end resistance accounts for about 70% of the total bearing capacity; 4) The recovery coefficient of bearing capacity of driven piles is only 1.1.