小净距隧道地震动力响应下的围岩应力场

Surrounding Rock Stress Field under Earthquake-induced Dynamic Response of Tunnels with Small Spacing

针对强地震作用下小净距隧道围岩的力学特征,采用三维数值模拟的手段,并引入基于Mohr-Coulomb准则的屈服接近度函数作评价指标,对多种净距条件下隧道围岩地震动力响应特征进行了深入研究。研究结果表明,在强地震作用下,小净距隧道围岩的破坏发展规律是由边仰坡开始,再逐渐由洞口向洞身段发展;小净距隧道中夹岩的应力状态与其净距密切相关,净距越小,距洞口的距离越近,小净距隧道中夹岩屈服接近度值越大;而洞周其余围岩的应力状态仅在间距较小时与隧道间距有关,当隧道间距增大到一定程度后,不再有相关性;最后建议采用以YAI≤0.2的应力状态作为小净距隧道抗震设计的应力标准。

Considering the mechanical behavior of surrounding rock under strong seismic action on tunnels with small spacing, by introducing the yield approach index （YAI） function based on Mohr-Coulomb yield criterion as evaluation index, 3D numerical simulation was employed to analyze the seismic response characteristics of surrounding rock of tunnel with various kinds of spacing. The results indicate that （ 1 ） the surrounding rock of small spacing tunnels is damaged beginning from front slope, then from tunnel entrance to tunnel trunk; （2） the stress state of the shared rock of small spacing tunnels is closely related to the spacing, the smaller the spacing and the closer to tunnel entrance, the larger the YAI value ; （3） the stress state of other surrounding rock is relevant to tunnel spacing only when spacing is smaller, it is not relevant to tunnel spacing when spacing is larger. Finally, the stress state of YAI≤0. 2 was proposed as anti-seismic design criterion.