负乘幂本构模型的切线模量

邓肯-张模型假设土体应力-应变关系符合双曲线关系，而且假定相关参数与围压的关系也是某种固定关系，这样的做法不仅违反了土体性质多样的现实，也容易造成模型与试验结果不符，引起误差。为此，提出了通过常用软件试算获取参数及直接寻求参数与围压最佳关系函数的思想，改变了参数与围压只有一种固定关系的思路。在邓肯-张模型基础上提出了负乘幂本构模型，它能够通过调整一个参数实现曲线形式的变化，从而体现出土体应力-应变关系的多样性；负乘幂模型采用前面提及的思想来获取参数，经过推导得到了该模型的切线模量公式。通过比较，证明负乘幂模型能够更好地与试验曲线吻合。

Tangent modulus of negative-power constitutive model

Duncan-Chang model assumes the stress-strain relation of soils to be hyperbolical and presumes that the relationships between some parameters and ambient pressure are fixed, which not only goes against the fact of varied feature of soils but also can’t make the results of model agree with those of test perfectly. Based on analysis of test. with the development of computer, a lot of software is produced, which can fitting curves. So the parameters are able to be got by pilot calculation and the optimum functional relationships between some parameters and ambient pressure also are able to be hunted through these software. This method is different to that of Duncan-Chang model. On the basis of Duncan-Chang model, the negative-power model is established for soils; it’s able to display variety of the stress-strain curve of soils using a changeable parameter; and its parameters are determined in the previously mentioned way. The equation of tangent modulus is deduced based on the new method. The negative-power model can better meet test in comparison with Duncan-Chang model.