Bouc-Wen土体动力模型的阈值应变研究

Threshold strain study of dynamic Bouc-Wen model for soils

探讨Bouc-Wen土体动力模型的适用条件与参数对滞回圈的影响等。基于热力学基本定律，研究了Bouc．Wen土体动力模型的增量耗散函数表达式，讨论了不同动应变水平下某筑坝土石料的能量耗散机制。发现筑坝土石料的动力特性存在2个阈值应变，即第1和第2阈值应变。其对应的模量比分别为0．94左右及0．50～0．80之间。第2阈值应变与传统意义上以孔压升高或体积变化为标准的门槛应变相当。对进一步认识土体动应力一应变特性有一定意义。

The applicable conditions of dynamic Bouc-Wen model and influence of the model parameters on hysteretic loop, etc. are discussed. Based on the laws of thermodynamics, the incremental dissipation functional expressions of Bouc-Wen dynamic model are formulated. Then the energy dissipation mechanism of damming earth and rocks are analyzed under different levels of dynamic strain; and two threshold strains are found defined as the first threshold strain and the second threshold strain respectively. The corresponding modulus ratios are around 0.94 and between 0.50-0.80. The second threshold strain is equated with the traditional threshold strain using pore water pressure build-up or volume changes as standard. It is good for the further understanding of the dynamic response of soil.