软岩蠕变损伤特性的试验与理论研究

EXPERIMENTAL AND THEORETICAL STUDIES OF CREEP DAMAGE BEHAVIOR OF SOFT ROCK

在高地应力软岩隧道修建过程中,由于围岩蠕变损伤导致其变形具有明显的时效性和非线性。岩石的蠕变损伤与其内部微裂纹的延伸和扩展密切相关,宏观表现为蠕变过程中的体积扩容,通过对岩石扩容过程中损伤耗散能变化规律的分析,建立蠕变损伤演化方程,通过引入蠕变损伤因子对ABAQUS软件自带的蠕变模型进行修正,得到非线性蠕变损伤模型。应用所建立的蠕变损伤模型,对宜巴高速泥质红砂岩的三轴蠕变试验结果进行反演,结果表明,该模型可以很好地反映高地应力软岩在蠕变中的减速蠕变、等速蠕变和加速蠕变3个阶段。

When tunnelling in high geostress region,the surrounding rock is often subjected to high geostress,and the increasement of deformation and creep damage for surrounding rock will show clear time effects and nonlinearity.The creep damage evolution of rock is related to its dilatancy which is caused by development of internal mico-crack of rock,and by analyzing the damage energy dissipation in process of dilatancy,a new creep damage evolution equation is established.The creep model of ABAQUS is amended by introducing the creep damage factor,and a new nonlinear creep damage model is obtained.This model is used to analyse the result of triaxial creep test for red sandstone which is got from Yichang-Badong expressway.The back analysis results show that the creep model can describe decay creep,stability creep and accelerate creep of rock in triaxial creep test.