土的量化记忆模型参数确定与应用研究

【作者】 宋振河；

【导师】 迟世春；

【作者基本信息】 大连理工大学 ， 防灾减灾工程及防护工程， 2003， 硕士

【摘要】 论文首先介绍了量化记忆(SM)模型的基本理论。SM模型以经典弹塑性理论作为基础，将单调加载情况下的应力－应变曲线的非线性剪切模量变换成量化模量在几何空间上的分段线性分布，然后再以Masing准则作为基础，在循环加载情况下，对这种简化的几何分布进行变化调整，从而使其生成非线性变化的剪切模量。将非线性的问题转化为线性问题进行处理，大大简化了非线性计算的复杂性。其次，采用高精度局部位移计，对筑坝材料进行了动三轴试验，采用Levenberg－Marquardt非线性最小二乘法，编写程序拟合了SM模型6个材料参数：E，(max，(min，h0，r，s，并将量化记忆模型生成的应力应变关系曲线、模量衰减和阻尼曲线与试验曲线进行了比较。结果证明，量化记忆模型生成的曲线和试验曲线之间是相互吻合的。探讨了不同应变水平下滞回圈的SM模型参数的拟合情况，得到了h0，r，s三个参数随动应变幅值变化的规律。同时，本文对双线性SM模型（BSM）模型进行了初步探讨，通过试验初步验证了BSM模型应用的可行性。最后，编写了考虑应力应变切线模量的衰减的真非线性地震反应分析程序。计算了一实际工程，并和等价非线性法进行了对比。计算表明，由试验参数计算得到的真非线性地震响应分布规律和等价线性法得到的响应基本一致，但是要略大于等价线性法得到的结果。由试验参数得到的真非线性地震响应能较好地体现坝体的真实地震响应。更多还原

【Abstract】 Firstly, the scaled memory (SM) model is introduced for dynamic nonlinear analysis of soil structures. The SM translates the nonlinear variation of tangential modules during monotonic loading into a piecewise linear distribution geometrical relationship, which can easily be modified to simulate hysteretic characteristics of soil behavior during cyclic loadings, it also can simulate the dynamic stress-strain response of arbitrary cyclic loadings.In order to determine the parameters of the SM model, the analysis program of nonlinear Levenberg－Marquardt least squares method is developed. The parameters of the SM model , such as ,,,,,, is defined by fitting test results. To compare the dynamic stress-strain relationships, modules attenuation and damp ratio curve between the tests and the calculated results by SM model, it is shown that the SM model is capable and practicable. Because the hysteretic loops are varied as the axial dynamic strain increased, so the SM model parameters will be changed during dynamic loading. The relationship between h0，r，s and axial dynamic strain is induced by the fitting test results. In addition, the parameter of binary scaled model (BSM) is discussed which mean the skeleton curve is different between tensile branch and compression branch. Lastly, a seismic response analysis program of embankment, which combines step-by-step scheme with unbalanced load transfer method, was developed. It has thought of the degradation of soils and can use the parameters of the SM model that has been calculated by the least squares program. Taking a embankment as example, a comparison between the incrementally-iterative numerical technique and the equivalent linearization approach was carried out .It is shown that distribution of dynamic response of dam is mainly alike, but the dynamic response of incrementally-iterative numerical technique using experimental parameter is greater than that of the equivalent linearization approach.更多还原