沉井基础竖向承载特性的离心模型试验研究

基于离心模型试验对饱和砂土地基中沉井基础在竖向荷载作用下的承载特性进行研究,初步掌握地基极限承载力随基础埋深和基础宽度变化的规律,并对试验结果进行对比分析,结果表明:(1)基础埋深不大于5 m时,荷载-沉降曲线为陡降型,有明显的拐点出现,可取拐点对应的荷载作为极限承载力;基础埋深不小于10 m时,荷载-沉降曲线为缓变型,未出现明显的拐点,建议取相对沉降量(基础的实测沉降量与基础宽度的比值)对应的荷载作为极限承载力。(2)在均质地基环境中,极限承载力随基础相对埋深的增加近似呈指数型曲线增长。(3)进一步推求沉井基础极限承载力随基础宽度和相对埋深变化的函数表达式,其成果可用于估算砂土地基中沉井基础的地基极限承载力。

Centrifugal Model Test on Vertical Bearing Properties of Open Caisson Foundation

Based on centrifuge model test,the bearing properties of open caisson foundation in saturated sand under vertical load are studied,the variation law of the ultimate bearing capacity of soil with the change of the embedded depth and foundation are identified,and contrastive analysis of the test results are conducted. The results show that( 1) when the embedded depth of foundation is less than 5 meters,the curve shape of load-settlement is steep and there is a clear inflection point and the desirable inflection point corresponding to the load is the ultimate bearing capacity; when the embedded depth of foundation is not less than 10 meters,the curve shape of load-settlement is flat and no clear inflection point showed in the curve,and it is suggested the loading with relative settlement S/B = 0. 07 ~ 0. 08 be regarded as the ultimate bearing capacity;( 2) in homogeneous foundation,the ultimate bearing capacity increases exponentially with the increase of the relative embedded depth of foundation;( 3) the expression function on the ultimate bearing capacity of open caisson foundation is further derived in view of the influence of the relative depth and foundation width,which can be used to estimate the ultimate bearing capacity of the open caisson foundation in sand soil.