褥垫层厚度对劲芯搅拌桩复合地基承载特性影响与优化

Influence of Cushion Thickness on Bearing Characteristics of Composite Foundation with Reinforced Mixing Piles

对水泥土劲芯搅拌桩地基处理工法在软土地基条件下进行了室内模型试验.在不同厚度的褥垫层作用下,监测不同含芯率和芯长比的劲芯搅拌桩在桩顶与桩底的应力应变情况.比较不同含芯率与芯长比的劲芯搅拌桩的极限承载力找出最佳含芯率与芯长比.试验表明:褥随着上部荷载的逐渐增大,褥垫层的厚度对复合地基的沉降量的影响越来越显著.一方面由于含芯率的不同,水泥土桩与芯桩的荷载分担比也不尽相同,芯桩都是承担了大部分的上部荷载,另一方面随着上部荷载的增大复合体材料中弹性模量较小的水泥土桩的大压缩变形致使芯桩与水泥土桩之间的相对位移逐渐增大,使得芯桩承担了更大的摩擦压力,这也是提高复合地基承载力的因素.

Indoor model tests were carried out on the foundation treatment method of cement-soil reinforced mixing pile under soft soil foundation conditions.Under the action of cushion layers with different thicknesses,the stress and strain of reinforced mixing piles with different core ratio and core length ratio at the top and bottom of the pile were monitored.Comparing the ultimate bearing capacity of reinforced mixing piles with different core ratio and core length ratio,the best core ratio and core length ratio can be found,which will prepare for the design optimization of composite foundation.The test shows that with the gradual increase of the upper load,the thickness of cushion layer has more and more significant influence on the settlement of composite foundation.On the one hand,due to the difference of core content,the load sharing ratio between cement-soil pile and core pile is different,and core pile bears most of the upper load.On the other hand,with the increase of the upper load,the relative displacement between the core pile and the cement-soil pile increases gradually due to the large compression deformation of the cement-soil pile with small elastic modulus in the composite material,which makes the core pile bear greater friction pressure.