流变性软土地层桩基沉降位移的粘弹性解析方法

Viscoelastic Analytical Method for Settlement Displacement of Pile Foundation in Rheological Soft Soil Layer

考虑流变性软土地层桩基工程特性,并通过构建桩底土体虚拟柱状结构模型,建立了由桩体变形和桩底沉降时效特性的桩基沉降位移计算模型及其理论解。研究了桩基承载模式及其随荷载的演变规律、对应承载模式条件下桩基沉降位移及其时效特性。结果表明:软土地层中桩基荷载通过桩周阻抗自上而下传递,桩基承载模式随荷载增大存在摩擦承载模式、摩擦与桩端共同承载模式及其随荷载与环境条件逐步演化的动态关系;当桩基处于摩擦承载模式时,桩基沉降位移等于桩体压缩瞬态弹性变形;当桩基承载模式处于摩擦与桩端共同承载状态时,桩基总位移为桩体变形和桩底土体沉降位移的叠加,受土体的流变特性影响,桩基总位移呈现显著的时效特性,且随荷载增大桩端承载效果以及桩基位移的时效性愈加显著。

By considering the engineering characteristics of pile foundation in rheologic soft soil layer, the pile foundation settlement displacement calculation model and its theoretical solution, were established by constructing virtual column structure model of pile bottom soil based on the pile deformation and time effect property of pile bottom settlement. The bearing mode of pile foundation and its evolution with load, the settlement displacement and its time effect property by corresponding bearing mode are studied. The results show that: the load of pile foundation in soft soil stratum is transmitted from top to bottom through the impedance around the pile. With the increase of load, the bearing mode of pile foundation has friction bearing mode, friction and pile end joint bearing mode. It is dynamic relationship with the gradual evolution of load and environmental conditions. When the pile foundation is in friction bearing mode, the settlement displacement of pile foundation is equal to the transient elastic deformation of pile compression. When the bearing mode of pile foundation is in the state of friction and pile end bearing, the total displacement of pile foundation is the superposition of pile deformation and settlement displacement of soil at the bottom of pile. Affected by the rheological properties of soil, the total displacement of pile foundation presents significant time-dependent characteristics, and the pile end bearing increases with the load. The loading effect and time effect of pile foundation displacement are more and more obvious.