基于一种新的土体非线性压缩模型,建立了考虑瞬时荷载和变荷载的一维非线性固结方程。采用有限差分法获得了该固结方程的解,并通过与半解析解对比验证了差分法解的可靠性。基于该解,详细讨论了外荷载、土体初始压缩系数及压缩指数与渗透指数比值Cc/Ck对土体固结和沉降特性的影响。结果表明:Cc/Ck通过影响固结系数进而影响到土体固结速率,固结系数随Cc/Ck取值的减小而增大,因此土体固结速率随Cc/Ck取值的减小而增大;当土体初始压缩系数很小时,土体压缩性很小而接近弹性,此时可以忽略土体的非线性而直接采用Terzaghi固结解答计算;与李冰河所得固结解答相比,本文采用的非线性模型不需要考虑土体初始有效应力的影响,工程运用时相对更方便。
Abstract
A one-dimensional nonlinear consolidation equation considering transient loading and time-dependent loading is established based on a new nonlinear compression model of soil. The solution of the consolidation equation is obtained by using finite difference method, and the correctness of the difference method is verified by comparison with a semi-analytical solution. Based on the proposed solution, the effects of external load, initial compressibility coefficient of soil and Cc/Ck (ratio of compressibility index to permeability index) on soil's consolidation and settlement characteristics are discussed in detail. Results reveal that Cc/Ck affects the consolidation rate of soil by changing the consolidation coefficient, which increases with the decrease of Cc/Ck; therefore the consolidation rate of soil increases with the decrease of Cc/Ck. When the initial compressibility coefficient of soil is small, the compressibility of soil is small and close to elasticity. In this case, the nonlinear characteristics of soil can be ignored and the Terzaghi consolidation solution can be used directly. Compared with the consolidation solution obtained by Li Binghe, the nonlinear model used in this paper does not need to consider the influence of the initial effective pressure of soil, and therefore is relatively more convenient for engineering applications.
关键词
软土 /
一维固结 /
非线性 /
有限差分法 /
孔隙演变
Key words
soft soil /
one-dimensional consolidation /
nonlinear /
finite difference method /
pore evolution
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基金
国家自然科学基金项目 (41972289,41672313); 国家重点基础发展计划资助“973”计划项目 (2011CB710605)
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