摘要
利用已有的离心机预固结加荷装置,开发了一套可以有效控制超固结比的模型桩竖向加荷系统,进行了开挖条件下饱和黏土中单桩竖向承载特性的室内模型试验。在模型试验用高岭土单元体试验的基础上,考虑开挖引起土体K0系数和不排水抗剪强度变化对桩侧极限摩阻力的影响,提出了开挖卸荷条件下饱和黏土中单桩竖向承载特性的非线性简化计算方法,并通过与模型试验结果进行对比验证了计算方法的正确性,算例分析表明:开挖将会使得竖向桩顶刚度和极限承载力的降低,合理的预测方法应该既要考虑开挖卸荷引起的桩侧土上覆压力的减少,又要考虑桩侧土体K0值和不排水抗剪强度的提高。
Based on a centrifuge pre-consolidation loading device, a model of pile vertical loading system can effectively control over consolidation ratio is developed out. The laboratory model tests of a single pile in saturated clay under excavation are carried out. Based on the results of model test, considering the change of undrained shear strength and K0 coefficient of soil caused by excavation, a simplified nonlinear approach for analysis of a single pile under excavation is proposed. Calculated results are compared with the test results of laboratory model tests of pile. Good agreement is achieved. In addition, responses of a single pile after excavation under vertical load are studied by the simplified method. Computational results show that after excavation, the ultimate bearing capacity of pile and pile head stiffness will reduce. A rational prediction method for estimating the loss of bearing capacity should consider not only the decease of the overburden pressure of the surrounding soil, but also the increase of the K0 coefficient and undrained shear strength.
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2016年第2期202-209,共8页
Chinese Journal of Geotechnical Engineering
基金
国家重点基础研究发展计划(973计划)项目(2013CB036304)
关键词
模型试验
开挖
极限承载力
抗剪强度
超固结比
model test
excavation
ultimate bearing capacity
undrained shear strength
over-consolidation ratio
