纤维混凝土隧道衬砌地震动力响应特性的振动台试验研究

 为研究纤维混凝土隧道衬砌在地震动力作用下的动响应特性，对普通混凝土隧道衬砌与纤维混凝土隧道衬砌开展大型振动台模型试验，分析隧道衬砌的震害特征、地震动应变、结构内力和应变基线响应规律。试验结果表明：水平地震荷载及地层压力共同作用下，2种隧道衬砌均为仰拱最先开裂，其次为拱腰开裂，衬砌结构破坏模式主要为开裂、掉块和裂缝两侧挤压破坏；素混凝土隧道衬砌出现开裂破坏早，裂缝易贯通，裂缝两侧混凝土基体在振动过程中相对位移大；纤维混凝土隧道衬砌出现开裂破坏晚，裂缝两侧混凝土基体在振动过程中相对位移小，裂缝呈挤压破坏状；纤维延缓衬砌结构裂缝的产生和阻碍裂缝的扩展；地震波加速度峰值从0.1 g增大到1.0 g时，素混凝土隧道衬砌动应变极值和裂缝宽度显著增大，而纤维混凝土隧道衬砌动应变极值和裂缝宽度先在一定范围内缓慢增长然后迅速增大，但最终2种衬砌动应变极值和裂缝宽度大致相等，说明纤维混凝土隧道衬砌在一定地震荷载范围内可以有效避免开裂和减小裂缝宽度；纤维混凝土隧道衬砌压缩变形率较小，当输入地震波加速度峰值为0.1 g和0.4 g时，纤维混凝土隧道衬砌结构动弯矩极值较低，受力更均衡，能有效地抵御地震荷载。

Seismic responses of fiber reinforced concrete tunnel#br# lining with shaking table test

Seismic dynamic responses of the fiber reinforced concrete tunnel lining were studied with large scale shaking table model tests and by comparing with the plain concrete tunnel lining. The damage characteristics，dynamic strain，internal force and compressive deformation were analyzed. The cracking occurred in the invert at first，then in the haunch under the horizontal seismic load and rock-soil pressure for two kinds of tunnel lining. The failure modes are cracking，peeling and attrition crushing in cracks. Cracking damage appeared early and the penetrating cracks occurred easily in the plain concrete lining. The crack opening displacement was large in the loading process. Cracking damage appeared relevantly late in the fiber reinforced concrete lining and the crack opening displacement was small in the loading process，and the cracks presented an extrusion damage state. Fiber prevented the appearing and developing of cracks effectively. The maximum strains and crack width in plain concrete lining increased with the peak acceleration of seismic waves，while those in fiber reinforced concrete lining increased slowly in a certain range and then increased rapidly. The final maximum strains and crack width of two kinds of tunnel lining were almost the same. So it was certain that the fiber reinforced concrete effectively avoided cracking and reduced the crack width within a certain seismic load. The fiber reinforced concrete lining had the low extreme bending moments and a well-distributed stress when the input acceleration peak values were 0.1 g and 0.4 g，and it had small compressive deformation rate in the tests，which indicated that fiber reinforced concrete tunnel lining can resist seismic load effectively.