水泥土群桩承载力特性的原位试验研究

Experimental study on bearing capacity property of cement soil pile group in situ

通过现场足尺试验,研究了软土中水泥土群桩的承载力特性.利用埋设的土压力盒等测试元件,针对单桩、四桩、九桩复合地基情况,分别测试了承台土反力、桩身轴力及复合地基变形等参数.从影响水泥土桩复合地基承载力的三大控制要素着手,根据系统的原位试验结果,定量分析了桩长、桩间距、桩数等对水泥土群桩复合地基承载力特性的影响.结果发现,发挥承载力的临界桩长为12倍桩直径,增大置换率能显著提高复合地基承载力,群桩复合地基承载力约为单桩复合地基承载力的80%.

Systematic in situ tests were carried out to study the bearing capacity of composite foundation with cement-soil piles in soft clay. Data on pressure under cap, axis force along pile and composite foundation deformation were obtained through those tests. The composite foundation tests included those for single pile, four piles, and nine piles. Three key factors which strongly influence bearing capacity were discussed to show their influences on the composite foundation bearing capacity in those cases. The valid pile length which can contribute to capacity was about 12 times pile diameter; increase in replacement ratio could enhance the bearing capacity markedly, and the pile group composite foundation bearing capacity was about 80 percent that of the single pile.