钢管混凝土复合桩竖向承载特性离心模型试验

Centrifuge model tests of vertical bearing characteristics of steel pipe concrete composite pile

为研究水域环境中的钢管混凝土复合桩的竖向承载特性,选取钢管埋深和钢管挤土区土体模量为变量,通过离心模型试验方法,研究钢管埋深为8、12、16、20cm时和挤土区模量为1.1E、1.2E、1.3E、1.4E、1.5E(E为非挤土区土体模量)时钢管混凝土复合桩的竖向承载特性,得到了钢管混凝土复合桩的荷载(P)-位移(S)曲线、桩身轴力曲线及桩侧摩阻力曲线。研究结果表明:钢管埋深在12cm范围内增大时,能明显提高钢管混凝土复合桩竖向极限承载力,超过12cm后继续增大钢管埋深,仍能提高钢管混凝土复合桩竖向极限承载力,但增幅已不明显,钢管埋深从8cm增大到20cm时,钢管混凝土复合桩竖向极限承载力影响度从3.1%增大到6.7%;随着钢管挤土区土体模量的增加,钢管混凝土复合桩钢管段侧摩阻力逐渐变大,钢管挤土区土体模量从1.1E增大到1.5E时,钢管混凝土复合桩竖向极限承载力影响度从3.1%增大到5.1%。提出的适用于钢管混凝土复合桩的竖向承载力计算公式及工程建议,可为水域环境中钢管混凝土复合桩的设计与施工提供可靠的理论依据与技术支持。

In order to study the steel pipe concrete composite pile in the aquatic environment,soil moduli of steel pipe depth and steel pipe soil compaction zone were selected as variables.Vertical bearing characteristics of steel pipe concrete composite pile with 8,12,16,20 cm of steel pipedepth and 1.1 E,1.2 E,1.3 E,1.4 E,1.5 E（where Eis soil modulus in non-compaction zone）of steel pipe soil compaction zone soil modulus were studied by centrifuge model tests,and the load（P）-displacement（S）curve,axial force curve and lateral friction curve of steel pipe concrete composite pile were obtained.The results show that vertical bearing characteristics of steel pipe concrete composite pile improves obviously when the steel pipe depth increases in the range of12 cm.Vertical bearing characteristics of steel pipe concrete composite pile still improves when the steel pipe depth increases out of 12 cm,but the increase is not obvious.When the steel pipe depth increases from 8 to 20 cm,vertical bearing characteristics of steel pipe concrete composite pile increases from 3.1% to 6.7%.With the increase of the soil modulus in steel pipe soil compaction zone,the lateral friction of steel pipe concrete composite pile increases gradually.When the steel pipe soil compaction zone soil modulus increases from 1.1 E to 1.5 E,vertical bearing characteristics of steel pipe concrete composite pile increases from 3.1% to 5.1%.The proposed formulas for calculating of the vertical bearing characteristic of steel pipe concrete composite pile and engineering suggestion provides a reliable theoretical basis and technical support for design and construction of steel pipe concrete composite pile in aquatic environment.1 tab,11 figs,20 refs.