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为了深入研究新型螺旋挤土灌注桩(SDS桩)和长螺旋灌注桩(CFA桩)在承载变形性状方面的差异性,以在澳大利亚、德国和中国进行的三组承载力足尺对比试验研究成果为依据,对SDS桩相对于CFA桩承载力的提高幅值及其技术优势的内在机理进行了分析与探讨。研究结果表明这种SDS桩新技术适用于各类可压缩土层,而短螺旋挤扩钻头在成桩过程中所产生的挤土正效应,促进了桩周土体物理性能的改进与应力水平的提高,改善了桩周土体的承载变形性能,从而通过提高桩侧摩阻力,达到了大幅度提高螺旋挤土灌注桩极限承载力的目的。
In order to further study the difference of the bearing deformation characteristics of the new spiral cast-in-place piles (SDS pile) and long spiral pile (CFA pile), the results of three groups of full-scale comparative tests of bearing capacity carried out in Australia, Germany and China As the basis, the inherent mechanism of increasing the bearing capacity of SDS pile with respect to CFA pile and its technical advantages are analyzed and discussed. The results show that the new technology of SDS piles is applicable to all kinds of compressible soil layers, and the positive effect of squeezing soil generated by the short spiral squeezing and expanding drill bit in pile forming process promotes the improvement of soil physical properties and stress level So as to improve the bearing deformation performance of the soil around the pile, so that the ultimate bearing capacity of the screw squeezed soil piles can be greatly improved by increasing the frictional resistance of the pile.