【作者】 蓝柳和；

【导师】 谢康和；

【作者基本信息】 浙江大学 ， 岩土工程， 2002， 博士

【摘要】 基于多层地基—维线弹性固结解析解和迭代法，建立了能求解复杂一维固结问题的半解析算法，并将其分别应用于求解成层软粘土线性流变一维固结问题（采用三元件线性流变模型）和成层软粘土非线性流变一维固结问题（采用时间线非线性流变模型）。 首次编制了能同时考虑土的非线性流变特性、成层性、渗透性变化以及土体自重和变荷载的固结计算程序AODNRCLS，并且通过与已有的解析解或数值方法计算结果进行比较，验证了本文半解析算法和程序的正确性。当不考虑土的流变特性时，本文的计算程序AODNRCLS就可退化到现有的成层地基一维非线性固结计算程序NAODCLS；而当进一步不考虑土的非线性时，程序便可化为成层地基一维线弹性固结计算程序ODCALS。 利用本文程序详细地分析了单层、双层和多层地基线性流变和非线性流变固结性状，绘制了大量的固结曲线，讨论了各种因素对地基孔压消散、沉降以及固结度发展的影响。分析研究表明：当考虑土的流变时，存在着两种不同定义的平均固结度，即按有效应力定义的固结度U_p和按沉降定义的固结度U_s，前者反映了地基中超静孔压的消散率（或有效应力的增长率），而后者反映的则是地基表面的沉降率，两者在数值上有较大的差异，特别是对于成层地基。一般而言，影响非线性流变固结和沉降固结过程的主要因素有：压缩指数与渗透指数之比（c_c／c_k或λ／β）、次固结系数与压缩指数之比（c-a／c_c或ψ／λ）以及c_e／（1+e₀）、参考时间t_ref、自重应力（或q_n／（?））和加荷速率(T_vc或t_c)等值。土体流变不仅会使地基沉降增加，还会显著地减小土中超静孔压的消散速率；同样，超静孔压的消散也影响着土的流变发展。这种耦合作用说明了把固结过程人为地划分成主固结和次固结两个相对独立的过程是欠合理的。 本文工作首次将软粘土的非线性、成层性、流变等重要特性同时纳入固结理论研究中，并为获得成层地基一维非线性流变固结解提供了有效工具，从而发展和完善了固结理论。更多还原

【Abstract】 Based on the iterative methods and general analytical solution available for the problem of one-dimensional linear elastic consolidation of layered soils, a semi-analytical method is established herein for complex one-dimensional consolidation problems. By adopting linear rheological model of three units and non-linear rheological model of time lines, the semi-analytical method is respectively applied to solve the problem of one-dimensional consolidation of layered soft clayey soils with linear or non-linear rheological characteristics.A corresponding computer program named AODNRCLS is developed for the first time for solving non-linear rheological consolidation problem, in which important characteristics of soft clay such as its non-linear rheological and layered properties, the variation of permeability, the self-weight and time-dependent loading can be taken into account. The reliability of the program is verified through being compared with other known analytical solutions and numerical methods. Once the non-linear rheological characteristics of soils ignored, AODNRCLS turns to be the available computer program NAODCLS that was for solving small-strain non-linear consolidation problem. If the nonlinear property of soils is ignored further, AODNRCLS will return to ODCALS that was developed based on the one-dimensional linear elastic consolidation theory of layered soils.Both linear and non-linear rheological consolidation behavior of soft clayey soils are then analyzed in detail by using AODNRCLS. A variety of consolidation curves are prepared and the influence of various factors on the dissipation of pore pressure and the development of settlement and degree of consolidation are discussed.It has been shown that in one-dimensional consolidation problem considering rheological characteristics of soil, there exists two consolidation degrees defined in different terms, i.e. Up which is in terms of effective stress and Us which is in terms ofsettlement. While Up shows the rate of the dissipation of excess pore pressure (or the increase of effective stress), Us indicates the rate of the development of the surface settlement of the system. And there exists significant difference in numerical value between Up and Us, especially for layered soils. Generally, the main factors affecting non-linear rheological consolidation behavior are: the ratio of compression index and permeability index (i.e. cc/ck or); the ratio of coefficient of secondary consolidation and compression index (i.e. ca/cc or ); the non-dimensional parameter cc /(I + e0); reference time tref ; self-weight of soil (or the ratio qu/z0) and the rate of loading (Tvc or tc).The study also shows that rheology of soil not only increases settlement, but also observably decreases the rate of the dissipation of excess pore pressure. On the other hand, the dissipation of excess pore pressure also affects the development of rheological deformation of soil. This coupling action between the rheology of soil and the dissipation of excess pore pressure demonstrates that it is not reasonable to factitiously divide the process of consolidation into two independent ones, i.e. primary consolidation and secondary consolidation.It is the work presented herein that for the first time in the study of consolidation theory takes consideration of important properties of soft clayey soils such as non-linear characteristic, layered behavior and rheology in the same time, and provides efficient tools to give solution to one-dimensional non-linear rheological consolidation of layered soils. This develops consolidation theory and makes it more perfect.更多还原