铁路隧道洞口合理抗震设防长度

为确定隧道洞口段衬砌的合理设防长度,使隧道结构抗减震性能达到最优,以单线140 km/h、跨度6.4 m的铁路隧道为例,采用数值模拟方法,建立了隧道洞口段的动力分析模型;分析了围岩条件、衬砌物理力学参数等因素对地震作用下隧道洞口段衬砌内力响应的影响,讨论了围岩加速度响应和衬砌结构内力响应规律.数值模拟结果表明:距离超过洞口段3倍隧道跨度后,衬砌结构内力响应明显减小;振动台试验结果表明:洞口段抗震设防长度为3倍隧道跨度时,减震效果显著,验证了抗震设防长度的合理性. 

Rational Seismic Protective Length for Portal of Railway Tunnel

In order to determine the rational seismic protective length for tunnel portal and achieve the optimal earthquake-resistant performance, a dynamic analysis model for tunnel portal was set up to a 140 km/h single-line railway tunnel with a width of 6.4 m, the influences of surrounding rock conditions and physical and mechanical parameters of lining on the internal force responses of lining at tunnel portal under seismic action were analyzed. The acceleration response of surrounding rock and the distribution of lining internal force responses were discussed. The numerical simulation results show that lining internal forces will obviously reduce beyond 3 times the tunnel width far from the portal. The shaking table test carried out with 3 times tunnel width as seismic protective length at tunnel portal indicates that shock absorption effect is remarkable to verify the rationality of the seismic protective length.