黏塑流变本构模型力学参数辨识研究

伴随着各种复杂地质条件,大型地下洞室围岩流变特性与其长期稳定性密切相关,流变本构模型是认识围岩流变力学特性非常重要的一个方面。流变本构模型力学参数是流变本构模型准确应用的一个首要条件。本文主要开展了三个方面的工作:(1)研究推导了岩体黏塑流变本构模型,对其力学参数进行了理论分析;(2)对砂岩进行了不同围压下瞬时三轴压缩试验和三轴流变压缩试验,得到了砂岩相关试验数据,其可以较好的反映砂岩的瞬时力学特性和流变力学特性;(3)基于不同围压下瞬时三轴压缩试验和三轴流变压缩试验,结合改进粒子群优化算法,对流变本构模型的力学参数进行了拟合优化,得到了不同围压下整体流变力学参数。与试验数据对比发现,拟合得到的流变模型力学参数可以较好的反映岩体的流变力学特性,可以为流变本构模型实际应用提供参考。

Study on Identification of Mechanical Parameters of Viscoplastic Rheological Model

Accompanied by complicated geological conditions, the rheological characteristics of surrounding rock of large underground cavern are closely related to its long-term stability. The rheological constitutive model is a very important aspect to understand rheological mechanical properties of the surrounding rock. Mechanical parameters of rheological constitutive model are the first and foremost condition of accuracy applications of rheological constitutive model. Three aspects of works are mainly carried out: (1) Based on earlier study of derived visco-plastic rheological constitutive model, the theoretical analysis of mechanical parameters of rheological constitutive model has been done; (2) Instantaneous triaxial compression tests and triaxial rheological compression tests under different confining pressures of sandstones were done, and the test data of sandstone have been obtained. The test data of instantaneous triaxial compression tests and triaxial rheological compression tests under different confining pressures can reflect the instantaneous mechanical properties and rheological mechanical properties; (3) Based on instantaneous triaxial compression tests and triaxial rheological compression tests under different confining pressures, combined with the improved particle swarm optimization algorithm, fitting and optimization of mechanical parameters of rheological constitutive model have been done, the overall rheological mechanical parameters under different confining pressures were obtained. It is found in comparison with experimental data that the mechanical parameters obtained from fitting of rheological model can reflect rheological mechanical properties of rock mass better. And the references for the practical application of rheological constitutive model are provided.