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以广甘高速公路施工期隧道塌方调研为依托,利用快速有限差分法对强震区软岩隧道支护及围岩的余震动力响应规律进行分析。分析结果显示:余震作用下,塌方发生次数最多、塌方量最大的位置为隧道拱肩部位,围岩主应力极值分布由静力作用下的“十”字型变为“X”型分布,隧道拱肩至拱顶位置处岩体易发生破损;隧道初支内外侧承受拉压交替作用,拱肩位置出现内力极值;当初支背后存在空洞时,围岩主应力极值分布于空洞周围,围岩塑性区显著增大,空洞位置处的初支内力急剧增大,极易发生破坏。时程分析法结果所揭示的规律与现场统计情况一致,研究结果对认识强震区软岩隧道施工中坍塌破坏机理有一定的借鉴意义。
Based on the survey of tunnel collapse during the construction of Guang-Gan Expressway, the dynamic finite element method is used to analyze the aftershock dynamic response of soft rock tunnel support and surrounding rock in strong earthquake area. The results show that under the effect of aftershocks, the landslide occurs most frequently and the place with the largest landslide is the arch shoulder of the tunnel. The extreme distribution of the main stress of the surrounding rock changes from “十 ” to “X ”Type distribution, the tunnel arch shoulder to the vault location of rock prone to damage; the inner and outer side of the tunnel under the action of tension and compression alternating role, the location of the internal arch spikes appear; when there is a hole behind the back, the main stress of the extreme value of the surrounding rock Distributed around the hollow, the plastic zone of surrounding rock significantly increases. The initial internal force at the empty hole increases sharply and is easily damaged. The results revealed by the time-history analysis are consistent with the field statistics. The results of this study can be used as a reference for understanding the failure mechanism of collapse in soft rock tunnel construction in strong earthquake areas.