静钻根植桩抗压抗拔承载性能试验研究

通过一组静钻根植桩的现场抗压抗拔静载试验,研究了抗压和抗拔状态下静钻根植桩的承载性能.对两根试桩的荷载位移曲线进行了比较分析,并采用有效应力法对试桩的极限侧摩阻力进行计算.试验结果表明:受桩周土体应力状态和桩身泊松效应影响,静钻根植抗拔桩的极限侧摩阻力小于抗压桩的极限侧摩阻力;抗拔桩侧摩阻力完全发挥时的桩顶位置值大于抗压桩侧摩阻力完全发挥时的桩顶位置值;采用有效应力法计算土层的极限侧摩阻力时,需要考虑土层的极限深度(或极限竖向有效应力),当土层深度超过极限值时,采用有效应力法计算土层的极限侧摩阻力需采用极限深度时对应的竖向有效应力值.

Experimental Study on Bearing Capacity of Pre-bored Grouted Planted Pile under Compression and Tension

The bearing capacity of pre-bored grouted planted (PGP) pile under compression and tension is investigated based on a group of field compression and tension tests. The load-displacement curves of two test piles are compared and analyzed, and the effective stress method is adopted to estimate the shaft capacity of the test piles. The test results show that: the ultimate shaft resistance of PGP pile under tension is smaller than the ultimate shaft resistance of PGP pile under compression, due to the different stress conditions of the soil around the pile and the Poisson''s ratio of pile shaft; the pile head displacement needed to fully mobilize the shaft resistance of test pile under tension is larger than the displacement needed to fully mobilize the shaft resistance of test pile under compression; a ultimate depth (or ultimate vertical effective stress) exists when the effective stress method is adopted to calculate the ultimate skin friction of the soil layers, and the value of the vertical effective stress corresponding to the ultimate depth should be adopted in the calculation of ultimate skin friction in effective stress method.