软土地基大直径超长钢管桩试验研究

Experimental research on large-diameter and super-long steel tube piles in deep soft soil foundation

通过对海南洋浦港软土地基中桩长74 m、桩径1.5 m的大直径超长钢管桩的高应变全程动测、压桩试验、拔桩试验和桩身轴力测试,探讨深厚入土地基层中大直径超长钢管桩工程性状和压桩及拔桩土侧阻力的分布规律,得出如下结论：1）同一土层侧阻力随着入土深度的增加而递增,一定深度后,其增幅减缓,趋向稳定;2）深厚软土地基中,大直径超长钢管桩拔桩和压桩侧阻力的比值为56.9%~75.0%;3）只有桩端位移达到1.1%~1.3%桩径时候,软土地基大直径超长钢管桩能充分发挥桩端土阻力,此时端阻力值约为承载力的19%。这对软土地基中的超长大直径超长钢管桩的理论研究和工程应用具有指导作用。

The 74 m-long and 1.5 m-diameter steel tube piles are driven into Yangpu harbor of Hainan province. According to the whole-process PDA test, pile pressing test, pile pulling test and axial force test, we discuss the distributing law of shaft friction on compressive and tensile load of large diameter and super-long steel tube piles in deep clay area and draw the conclusions as follows. Firstly, along with the increase of penetration, the shaft friction of the same soil increase, but after reaching certain depth of the penetration, its amplification reduces and becomes steady. Secondly, the shaft friction of large diameter and super-long steel tube piles under compressive load is 56.9% -75.0% of its under tensile load. Thirdly, only when the displacement of pile top reaches 1.1% 1.3% of its diameter, tip resistance of large diameter and super-long steel tube piles can be fully functional, and it is about 19% of carrying capacity. Furthermore, the distributing law of shaft friction on compressive and tensile load in deep clay area is discussed can give instruction to the bearing capacity of large diameter and super-long steel tube piles for theoretical research and engineering practice.