高地温隧道初期支护混凝土力学性能劣化与结构热-力耦合响应研究OA

To address the problem that the initial support of high-geothermal tunnels in western China is prone to cracking due to the deterioration of concrete strength under extreme temperature conditions,this study systematically investigates the variations in compressive strength,splitting tensile strength,and elastic modulus of concrete under elevated temperatures through laboratory mechanical tests and thermo-mechanical coupled numerical simulations.Particular attention is given to the thermo-mechanical response characteristics of the initial support under different height-to-span ratios.The results show that the mechanical properties of concrete exhibit nonlinear deterioration with increasing temperature,with accelerated degradation above 60 ℃;Moreover,the deterioration in tensile strength is significantly more severe than that in compressive strength.The rise in temperature leads to a sharp increase in tensile stress within the support structure-up to 5.8 times-considerably higher than the 1.4-fold increase in compressive stress.At 80 ℃,the cross-section with a height-to-span ratio of 0.65 demonstrates the most favorable mechanical performance,characterized by the lowest stress level and the smallest sidewall convergence deformation.The findings provide important theoretical and practical guidance for section design,material optimization,and thermal hazard mitigation of supporting structures in high-geothermal tunnels.