弹黏塑性模型及其在预压处理软基沉降计算中的应用  

Elasto-viscoplastic model and its application to settlement calculation of soft foundation by preloading treatment

作　　者：扈胜霞[1,2] 陈育民[2,3] 闫竹玲[1] 

机构地区：[1]延安大学建筑工程学院,陕西延安716000 [2]河海大学岩土力学与堤坝工程教育部重点实验室,南京210098 [3]河海大学土木与交通学院,南京210098

出　　处：《岩土力学》2014年第4期1173-1180,共8页Rock and Soil Mechanics

基　　金：河海大学岩土力学与堤坝工程教育部重点实验室开放基金项目(No.GH201101);国家自然基金项目(No.51309199);国家科技支撑计划项目(No.2013BAJ06B00);陕西省教育厅项目(No.12JK0922)

摘　　要：以准确计算预压荷载作用下软土路基的工后沉降为目的,分析了不同预压法加固软土地基时土体的应力变化。提出了用弱化应力路径变化过程的弹黏塑性模型表示软黏土的应力-应变关系。结合经典比奥固结理论,推导了预压荷载作用下土体沉降计算的有限单元法。通过具体算例,验证了所提方法。结果表明:(1)不同预压方法的加固机制和应力路径均不相同。堆载预压法加固软基是一不等向的正压固结过程,真空预压法则是在负压作用下的等向固结过程;(2)弹黏塑性模型是不受瞬时施加应力的大小及具体应力路径变化过程影响的软土流变模型,运用于预压荷载作用下的软基时具有不考虑应力路径和不划分主次固结的优越性;(3)在比奥固结理论中,用弹黏塑性模型反映软土的物理方程时,可计算软基考虑了弹黏塑变形性质的固结沉降和工后沉降;(4)弹黏塑性模型的软土体黏性参数?/V和塑性参数?/V对竖向位移都有比较明显的影响。In order to obtain an accurate calculation of settlement after construction of soft soil foundation by vacuum preloading, surcharge preloading and vacuum combined surcharge preloading method, stress changes of soft foundation reinforced by the different preloading method is analyzed. Elasto-viscoplastic model which the specific stress path of change is weakened represents stress-strain relation of soft clay. Combined with classical Biot consolidation theory, the finite element method of calculation the settlement of the soft clay improved by preloading method is deduced. The proposed method is verified through the concrete example. The outcomes as follows： （1） Reinforcement mechanism and stress paths are not the same for the different preloading methods. Surcharge preloading method is an anisotropic consolidation process under positive pressure. Vacuum preloading method is the isotropic consolidation process under negative pressure. （2） elasto-viscoplastic model is a rheological model not affected either by transient stress or the specific influence of stress paths. It have superiority when applied it to the soft foundation reinforced by the different preloading method that neither need to consider stress paths nor need to consider the primary and secondary consolidation division. （3） In the Biot consolidation theory, using the elasto-viscoplastic model to reflect the physical equations of soft soil, consolidation settlement and settlement after construction of soft foundation could be accurately calculated. （4） The vertical displacement of soft soils is influenced obviously by viscosity parameter ψ/ V and plasticity parameter λ/V of elasto-viscoplastic model.

关 键 词：预压荷载 工后沉降 弹黏塑性模型 有限单元法 

分 类 号：TU447[建筑科学—岩土工程]