Freeze-thaw Deterioration Mechanism and Damage Constitutive Model of Tunnel Surrounding Rock in Cold Region Based on Pore Evolution
Rock freeze-thaw damage is a crucial issue in cold-region tunnel-engineering research. To better understand the mechanical properties of cold-region rocks and the microdamage caused by the freeze-thaw action,compression,acoustic-wave,and computed tomography (CT) scanning tests were conducted on granite under the freeze-thaw action. The physical and mechanical parameters of the rock and the microdamage characteristics were obtained.Based on three-dimensional reconstruction,a quantitative analysis of pore evolution was performed,which reveals the mechanism of frost damage in the cold-region tunnel surrounding rock. Based on continuum damage theory and microelement statistical theory,a mechanical damage constitutive model considering the initial freeze-thaw damage and residual deformation was derived. The results show that after 50 freeze-thaw cycles,the longitudinal wave velocity of the specimen decreases by 16.60％ and the total porosity increases from 7.98％ to 10.01％.The linear elastic modulus,peak stress,and residual strength decrease as the peak strain increases.The freeze-thaw action can enhance the development of connectivity between pores,intensify seepage effects,and increase the probability of rock ductile failure,thereby exhibiting clear softening characteristics. The parameters of the new constitutive model can be determined easily and present clear physical significance,high accuracy,and practicability.The model is suitable for describing the stress-strain relationship of the frost-rock damage process and for reflecting the residual-strength characteristics of rocks.The results of this study provide theoretical guidance for the service-performance analysis of cold-region tunnels.
万方数据
维普
