隧道高陡仰坡抗震性能振动台试验分析

Shaking table tests and analysis on tunnel structures with high steep slope

汶川地震以来,统计发现山岭隧道洞口段受地震破坏较为严重,为了提高山岭隧道洞口段抗震性能,研究可靠的仰坡加固措施,设计并完成了高烈度震区隧道洞口段仰坡抗震性能振动台试验。研究发现:(1)在洞口段仰坡不设防的情况下,均质岩质高陡仰坡在高烈度水平地震作用下,仰坡发生破坏,大量岩土体滑落,此时落石会严重影响隧道结构与运营安全,必须对仰坡进行加固;(2)设置框架梁形式的仰坡支护体系后,即使在高烈度水平地震作用下,只要支护体系没有破坏,均质岩质仰坡整体仍能保持相对完整,仅框架梁内部有少量掉块,提高了仰坡整体的抗震性能;(3)对比洞口段衬砌结构的截面内力,可以看出,设置了框架梁形式的仰坡支护体系后,可以显著降低洞口段衬砌结构的截面轴力与弯矩。综合分析,可以看出由于设置了框架梁支护体系,仰坡岩体整体性增强,限制了仰坡处岩体的自由运动,进而有效防止了仰坡破坏,并降低了洞口段衬砌的内力。

Since the Wenchuan earthquake, statistics has shown that the damage on mountain tunnel entrance by earthquake is getting more serious. To improve the seismic performance of mountain tunnel entrance and design more reliable slope reinforcement structures, a series of shaking table test is designed and conducted. Research shows that： （1）. High steep homogeneous rock slopes without any reinforcements would collapse during high intensity earthquake, leading to massive slump and endanger the safety of both tunnel entrance structures and operation reliability. （2）. Frame beamed slope reinforcement structures would improve the anti-seismic ability of slopes by keeping the overall integrity. Only debris within the framework would slide in high intensity earthquake. （3）. The lining section internal force and momentum decreased by the frame beamed reinforcements at the portal area, compared to the original tunnel entrance. From the analysis, the frame beamed reinforcement structure of high steep slope enhanced the slope integrity by limiting the movement freedom of rock slopes, it also effectively prevents the slope failure and reduces the internal force of tunnel linings.