基于触变效应的湛江组结构性黏土单桩模型试验

Model test of Zhanjiang Formation structural clay piles foundation based on thixotropic effect

基于湛江某桩基工程的实际,利用自制的模型箱装置对湛江组结构性黏土中不同桩长、桩径的9组模型桩在不同休止龄期的承载性状进行研究,分别测定模型桩应变、沉降,同时对模型桩的桩周土进行十字板剪切试验以便测定其抗剪强度,探寻湛江组结构性黏土触变性与单桩时效性的量化关系。结果表明:不同桩长、桩径的模型桩极限承载力及桩周土的抗剪强度和触变强度比率随着休止龄期的增加均表现出增长的趋势,且前期增长快,后期增长慢;模型桩极限承载力增长幅度与桩周土强度恢复幅度呈正相关,土体的触变性越强,单桩的时效性越明显。

Based on the practice of a single pile project in Zhanjiang,the self-made model box device was used to study the bearing behavior of 9 groups of model piles with different pile length and pile diameters in different resting stages for Zhanjiang Formation structural clay.The strain and settlement of model pile were measured respectively.The shear strength of the soil around the model pile was measured by the vane shear test,to explore the quantitative relationship between the thixotropy of structural clay and the timeliness of single pile in Zhanjiang Formation structur-al clay.The results show that(1)the ultimate bearing capacity of model piles with different pile length and pile di-ameter,the shear strength and thixotropic strength ratio of the soil around the piles all show an increasing trend with the increase of the resting stage.The growth is fast at first stage,then slows later.(2)The increase range of ultimate bearing capacity of model pile is positively related to the recovery range of soil strength around the pile.The stronger the thixotropy of soil is,the more obvious the timeliness of single pile are.