构造应力场中的大断面隧道结构地震反应研究

Study on the seismic response of the large-span tunnel in tectonic geo-stress

构造应力场下围岩级别对大断面隧道地震响应影响一直是学术界和工程界的关键科学问题.以新建贵广客运专线油竹山双线隧道为依托,采用三维数值模拟,研究竖向、水平地震荷载同时激励下隧道衬砌动力响应.衬砌以水平速度为主,竖向速度约为水平速度三分之一,随着围岩强度降低,振动速度越来越小,岩体地震作用下易于破坏,起到吸震作用.速度、加速度、变形峰值发生时刻均滞后相应方向的地震波加速度激励峰值时刻.衬砌水平、竖向最大加速度差异较大,放大系数在2.5～5.3之间.随着地震时间延长,变形持续增加,围岩强度降低对结构约束作用减弱.对于围岩较好的隧道,衬砌以震动破坏为主,设计宜采用高标号抗震混凝土;而较差围岩隧道,以衬砌发生较大剪切变形破坏为主,设计阶段应加大配筋率,防止其受剪(拉)破坏.

Seismic response of large section tunnel with different classification of surrounding rock in tectonic geo-stress has been a key scientific problem on. By taking on Youzhu Mountain tunnel on Guiyang-Guangzhou high-speed passenger rail line, three-dimensional numerical simulation was carried out to investigate the dynamic response of lining. The results suggest that the maximum horizontal velocity is three times the vertical velocity under the vertical and horizontal seismic loads. The maximum horizontal acceleration is different from that of the vertical. The amplification is in the range be- tween 2.5 and 5.3. With the rock strength reducal, rock mass is prone to damages and the vibration velocity is less. With time, the deformation is more and confinement effect of surrounding rock weakens. In teams of preferable rock mass, the lining of the tunnel is subjected to damaging vibration. Consequently, high grade concrete should be performed. For bad rock mass, the lining bears shearing deformation damage. The reinforcement ratio of lining should be improved to avoid shearing and tensile failure.