Creep constitutive model of yellow sandstone under coupling action of unloading and wet-dry cyclic damage  

作　　者：QIN Zhe LIU Zhen ZHANG Run-chang FU Hou-li 

机构地区：[1]College of Civil Engineering and Architecture,Linyi University,Linyi 276000,China [2]Shandong Key Laboratory of Civil Engineering Disaster Prevention and Mitigation,Shandong University of Science and Technology,Qingdao 266590,China [3]Shandong Gold Mining(Laizhou)Co.,Ltd.,Sanshandao Gold Mine,Zibo 261400,China

出　　处：《Journal of Mountain Science》2025年第3期1087-1100,共14页山地科学学报(英文)

基　　金：We gratefully acknowledge the financial support from the Key Laboratory of Geological Safety of Coastal Urban Underground Space,Ministry of Natural Resources(BHKF2022Y03);Shandong Provincial Colleges and Universities Youth Innovation Technology Support Program,Education Department of Shandong Province(grant number 2023KJ092).

摘　　要：The study focuses on the creep characteristics of significant yellow sandstone for water conservancy, hydropower, and other waterrelated slope excavation unloading rock-graded loading creep characteristics. It conducts a uniaxial graded loading creep test on yellow sandstone under different pre-peak unloading and wetting-drying cycles. The improved nonlinear Nishihara model was obtained by introducing a nonlinear viscous element with an accelerated creep threshold switch. The sensitivity characteristics of the parameters of the improved creep model were analyzed and a nonlinear creep constitutive model was established, considering the unloading-cyclic intrinsic damage induced by water intrusion. The research results show that:(1)With an increase in the unloading point, the porosity of the rock samples initially decreases and then increases. As the number of cyclic water intrusions rises, the porosity of the rock samples gradually increases, reaching a maximum of 9.58% at an unloading point of 70% uniaxial compression stress(0.7 Rc) after five cycles.(2) Total creep deformation increases with the number of cyclic water intrusions;however, with an increase in the unloading ratio, the original samples show an initial decrease, followed by an increase in creep deformation. With a higher unloading ratio and various instances of cyclic water intrusion, the total creep time of the rock samples,compared to the original samples, is reduced by 21.8%and 23.02%. The creep damage mode gradually changes from shear damage to tensile damage.(3) The sensitivity characteristics of the improved creep model parameters show that transient elasticity modulus E1 is affected by the coupling of unloading and cyclic water intrusion. The viscoelastic modulus E2 and viscous coefficient η1 are mainly affected by unloading and cyclic water intrusion.(4) Based on the strain equivalence principle of damage mechanics, the damage treatment of the parameters in the original model is improved to construct a nonlinear creep constitutive model that

关 键 词：Pre-peak unloading Dry and wet cycles Creep test Deformation characteristics Creep constitutive model 

分 类 号：TV223.1[水利工程—水工结构工程]