摘要
基于空间滑动面(SMP)屈服准则改进的修正剑桥模型,考虑土体超固结比及土体强度的三维力学特性,在不排水条件下采用应力空间转换方法推导了圆孔扩张问题的弹塑性解答。在此基础上,根据饱和软土地层静压沉桩机理,考虑桩端阻力影响范围和土体分层情况,分别采用柱孔扩张和球孔扩张模拟桩身和桩端应力状态,得出了软土饱和地层静压沉桩阻力的计算方法。通过实测结果与理论计算值的对比,验证了计算方法的有效性,进而分析了沉桩阻力的影响因素。研究结果表明:由于采用的本构模型充分考虑了土体强度的三维力学特性,因而可以较准确地预测软土地层静压沉桩阻力;与桩端阻力相比,沉桩过程中桩侧阻力较小,软土地层静压沉桩阻力主要为桩端阻力,其影响范围取决于桩径和土体特性;桩径、土体超固结比对桩身阻力和桩端阻力影响显著,土体有效内摩擦角对沉桩阻力影响较小。
Based on the SMP criterion-based Cam-clay model, which can incorporate the over consolidation ratio and properly describe soil strength in three-dimensional stresses state, the cavity expansion solutions are derived under undrained conditions by using the stress transformed method. Then, according to the pile-sinking mechanism in the saturated layered soft clay and considering the influence range of the pile tip, the stress fields around the pile tip and pile shaft during the pile-sinking process are modeled as spherical cavity and cylindrical cavity expansion respectively, and the methods for calculating the pile-sinking resistance in the layered soft clay are yielded. To verify the validity of predictions using this new expression, the results are compared with the measured data~ and the influence factors for pile-sinking resistance are discussed. The results show that the proposed method can predict the pile-sinking resistance accurately because the 3D strength characteristics of soils are sufficiently Considered by the constitutive model. Compared with the pile tip resistance, the pile shaft resistance is relatively small, the pile-sinking resistance in saturated soft clay mainly consists of pile tip resistance, and the influence range of the pile tip resistance depends on the pile diameter and the s0il properties. Both the pile tip resistance and pile shaft resistance are significantly influenced by the pile diameter and the over consolidation ratio. In addition, the pile-sinking resistance is slightly influenced by the effective internal friction angle.
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2015年第8期1454-1461,共8页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(41272288)
关键词
沉桩阻力
SMP准则
修正剑桥模型
圆孔扩张
超固结比
piling resistance
SMP criterion
modified Cam-clay model
cavity expansion
over consolidation ration
作者简介
作者简介：李镜培（1963-），男，江西信丰人，博士，教授，博士生导师，主要研究方向为岩土力学及桩基础工程。E-mail：lijp2773@tonji．edu．cn。
