基于Duncan-Chang模型的地基沉降分层总和 分析方法探讨

地基沉降分析方法是土力学研究的重要内容。该文在地基沉降变形力学机理研究基础上，首先考虑埋深或初始地应力即先期固结应力对地基土变形模量的影响，并将其区分为初始地应力的体积应力和偏应力影响两部分，引进分级加载思想，建立出不同埋深地基土变形模量的确定方法；其次，将地基沉降区分为附加体积应力和附加偏应力引起的沉降两部分，建立出地基沉降分析计算模型；然后，考虑地基变形的非线性变化特征，引进增量分析方法、虎克定律和Duncan-Chang模型，建立出附加体积应力和附加偏应力引起的地基压缩层变形的分析方法，并利用地基沉降分层总和法分析原理，建立出基于Duncan-Chang模型的地基沉降分析新方法。该方法不仅可以反映初始地应力和附加应力对地基土变形模量的影响，而且，可避免地基土压缩试验曲线和地基静载试验曲线的使用；最后，通过工程实例计算与分析，并与实测沉降值和现有分析方法的计算结果进行比较，表明了该方法可以满足工程计算精度要求，具有一定的合理性与可行性。

Layerwise summation method for ground foundation settlement based on Duncan-Chang constitutive model

Ground foundation settlement analysis is an important content of soil mechanics. Based on the discussion on ground foundation deformation mechanism, firstly, the effects of the buried depth or the initial ground stress, i.e., the preconsolidation stress, on the deformation modulus of foundation soils are considered, and they are divided into two parts: volume stress and partial stress of the initial stress. An idea of step-loading is introduced, and a determinstic method for deformation modulus of ground soils at different depths is established. Secondly, the ground foundation settlement is divided into two parts: settlement caused by additional volume stress and that by additional partial stress, and a ground foundation settlement analysis model is developed. Thirdly, the nonlinear variation characteristics of the ground foundation deformation are considered, the incremental analysis, the Hooke's law and the Duncan-Chang constitutive model are introduced, and the relevant methods for deformation of ground foundation compressed layers caused by the additional volume stress and additional partial stress are put forward. Also, a new ground foundation settlement analysis method based on the Duncan-Chang constitutive model is proposed by adopting the layerwise summation theory. This method can reflect the effects of the initial ground stress and the additional stress on the deformation modulus of the ground soils and avoid the use of the compression curves of ground soils and the static load test curves of ground foundation. Finally, through practical calculation and analysis as well as comparison with the measured settlements and the calculated values of other existing analytical methods, the proposed method meets the requirements of the calculation accuracy and is reasonable and feasible.