不同施工工艺微型桩的承载性能试验

Experimental investigatin on bearing capacity of micropiles with different construction technologies

采用不同施工工艺的微型桩的成桩效果、承载性能存在一定的差别。通过现场原型试验,对采用一次注浆、二次注浆、直接灌注细石混凝土3种成桩工艺的微型桩进行研究。结果表明:二次注浆的桩头混凝土密实,成桩效果最佳;压力注浆对单桩抗拔承载力、桩侧摩阻力、水平承载力提升效果显著;二次注浆能显著提高群桩抗拔承载力;群桩的水平受荷性能对施工工艺的变化不敏感。在微型桩实际的施工过程中应注重对桩身的二次注浆。

Different construction technologies leaded to a difference on construction effects and bearing capacity.In this study,the in-situ tests on the micropiles using three different kinds of construction technologies,involving pressure grouting,secondary pressure grouting and direct pouring fine aggregate concrete,were conducted.The test results indicate that if using secondary grouting,the concrete of pile top was more compact and the construction effect is best.In the meantime,the larger uplift capacity,lateral friction force and horizontal capacity of single micropile could be achieved using pressure grouting technology.Furthermore,the secondary pressure grouting technology improved uplift capacity of group piles significantly.On the contrary,the horizontal capacity of group piles was not sensitive to the change of the construction technology.Hence,we should pay more attention to the secondary pressure grouting in actual construction process of micropiles.