富水泥质板岩隧道围岩蠕变力学特性研究

CREEPING PROPERTIES OF WATER-RICH ARGILLACEOUS SLATE SURROUNDING TUNNEL

目前,对于考虑含水劣化的软岩蠕变力学特性研究存在一定的局限性。针对此问题,以沪昆客运专线长昆湖南段姚家隧道施工期泥质板岩的蠕变问题为出发点,通过三轴压缩蠕变试验分析应力状态及吸水率对泥质板岩蠕变特性的影响规律,在已有Burgers蠕变本构模型的基础上,引入水劣化因子,建立泥质板岩考虑吸水率的黏弹塑性蠕变本构方程,将蠕变参数转化为prony级数,在ANSYS软件中验证蠕变本构方程的合理性。研究结果表明:随着吸水率的增大,泥质板岩的蠕变变形和蠕变率增大,进入等速及加速蠕变阶段的进程加快;应力差的增大预示着泥质板岩进入等速及加速蠕变阶段的进程加快,时间缩短;随着吸水率的增大,泥质板岩蠕变参数(变形模量、黏滞系数、体积模量)呈指数函数减小。将顾及了水劣化因子的蠕变本构模型输入至ANSYS软件中,计算结果与三轴压缩蠕变试验结果吻合度较高,表明考虑吸水率的黏弹塑性蠕变本构模型具有较强的实效性,可以用于描述富水泥质板岩隧道围岩的蠕变规律。

The creeping problems of argillaceous slate in the construction period of Yaojia Tunnel at Changsha—Kunming(Hunan) Section of Shanghai—Kunming Passenger Railway Line were investigated. The influence of stress state and rate of water absorption on the creeping properties of argillaceous slate were analyzed with the creeping tests under triaxial compression. A water degradation factor was introduced based on the Burgers constitutive model of creeping and a visco-elasto-plastic constitutive equation for creeping considering the rate of water absorption of argillaceous slate was established. The rationality of constitutive equation for creeping was verified with the software ANSYS using prony series transformation. With the increase of the rate of water absorption,the creeping deformation and creeping rate of argillaceous slate were increased and the process of entering the constant rate and accelerated creeping stages were speeded up. The increasing of stress difference meant that the process of entering the constant rate and accelerated creeping stages were speeded up and the time length was shortened. With the increase of water absorption rate,the creeping parameters(deformation modulus,viscosity coefficient,bulk modulus) decreased exponentially. The constitutive model for creeping considering the water degradation factor was planted into ANSYS. The numerical calculated results fit the experimental results of creeping test.