含水炭质板岩非线性蠕变损伤模型及应用:碳质板岩

　　作者简介：张永兴（1961），男，教授，博士生导师，主要从事土木工程研究，（Email）yxzhang@cqu.edu.cn。摘要：对深埋隧道炭质板岩进行高围压不同含水状态三轴蠕变试验。蠕变过程中，随着加载应力水平提高及含水量的增加，炭质板岩产生衰减、稳态及加速蠕变3阶段。将Burgers模型串联一个由非线性黏壶η(n,t)与塑性体并联而成的非线性粘塑性元件，改进后的模型可描述加速蠕变曲线。由该模型建立本构方程，拟合分析不同含水状态炭质板岩的蠕变参数，结果显示粘滞系数ηM、瞬时变形模量EM、粘弹性变形模量EK、粘弹性粘滞系数ηK随含水率增加呈指数形式递减，但递减规律并不相同。引入含水损伤变量D(w)，计算得到各蠕变参数指数型含水损伤演化方程，进而建立了考虑含水损伤的非线性蠕变模型，可充分反映不同含水状态对炭质板岩的蠕变损伤特性。建立数值模型，计算不同含水状态隧道围岩时效变形规律，结果显示初期支护体系于168 h左右闭合能有效限制围岩蠕变变形发展，二衬宜于初期支护闭合后360 h左右施作。
　　关键词：隧道；炭质板岩；非线性蠕变模型；含水损伤；围岩稳定性
　　中图分类号：TU454 文献标志码：A文章编号：16744764（2012）03000109
　　Nonlinear Creep Damage Model of Water Bearing
　　Carbonaceous Slate and Its Application
　　ZHANG Yongxing, WANG Gengfeng, ZHOU Xiaoping, XIONG Xiaohui,
　　WANG Guilin，HUANG Da
　　（College of Civil Engineering, Chongqing University, Chongqing 400045, P. R. China）
　　Abstract:Triaxial compression rheological experiments on carbonaceous slate specimens of deep buried tunnel were carried out on the rock rheology testing machine. Along with the increase of loading stress level and the improvement of moisture conditions, the initial attenuation creep phase, the stabilization creep phase, and the speedup creep phase were produced. By connecting Burgers model and the nonlinear viscoplastic body consisted of nonlinear viscous component η(n,t) parallel connected with the plastic component in series, the improved model could describe the speedup creep phase. Using this model to fit and analyze the rheological parameters of different moisture conditions, it is shown that ηM、EM、EK and ηKwill decrease with negative exponential trend. Then water damage D(w) was introduced, and through deriving damage evolution equation, the nonlinear viscoelasticplastic model with water damage effect was established. Finally, the time effect deformation of surrounding rock under different times and different moisture conditions was studied by numerical simulation, and the results show that primary support should close in 168 h, and the best construction time for secondary lining is 360 h after the primary support is closed.
　　Key words:tunnels; carbonaceous slate; nonlinear creep model; water damage; stability of surrounding rock
　　岩石的蠕变特性是工程岩体重要力学特性之一［1］，其往往表现出非线性的流变力学性质，传统的线性元件模型无法反映这点。因此，国内外学者对非线性蠕变模型开展了广泛的研究。Challamel等［2］从连续热力学出发建立了岩石非线性流变软化模型；Vyalov［3］提出了非线性关系的修正Bingham模型；Maranini等［4］基于Cristescu理论提出了岩石蠕变的非关联粘塑性本构方程；Keedwell［5］建立了变弹性模量和变粘滞系数的非线性Kelvin模型；Findley等［6］研究了材料非线性流变性态，得到了不同时刻的蠕变方程。Sun等［7］指出可用非线性元件代替线性元件的方法建立非线性流变模型；陈沅江等［8］提出了蠕变体和裂隙塑性体2种非线性元件；邓荣贵等［9］提出了能描述岩石加速蠕变的非牛顿体粘滞阻尼元件。已取得的研究成果极大的促进了岩石流变力学的发展，但考虑岩体流变含水损伤劣化效应的蠕变模型尚不多见。尤其是遇水强度软化可达0.5～0.8的泥岩、页岩、板岩等软岩［10］。随着含水量的增加，软弱岩体变形的时效积累显著，易引发岩体工程失稳，地下工程岩体长期稳定性依赖于应力与水长期共同作用下的耦合流变过程［11］。因此，研究不同含水条件下软岩的蠕变特性对地下工程围岩长期稳定性有重要意义。〖=D(〗张永兴，等：含水炭质板岩非线性蠕变损伤模型及应用〖=〗