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通过Fourier-Bessel函数展开法,推导平面SV波垂直入射下半无限弹性介质中圆形双层衬砌结构、围岩–减震层–衬砌洞室的动应力集中系数级数解,分析入射波频率、减震层弹性模量和厚度对动应力集中系数的影响,并结合数值模拟分析结果对比,深入研究减震层减震机制。研究结果表明:入射频率对衬砌动应力集中系数有显著影响,减震层对低频波具有较好的减震效果;由于减震层剪切模量低,围岩和隧道可以剪切变形,从而减小了作用在衬砌外部的法向作用力,降低了衬砌内侧最大动应力集中系数,但围岩和衬砌外侧切向应力增大;随着减震层与围岩弹性模量之比减小,减震层厚度增大,二次衬砌动应力集中系数变小,减震层与围岩的弹性模量比宜低于1/10~1/20,和减震层弹性模量对应,存在一个最优的减震层厚度值。以一公路隧道为背景,开展隧道减震层结构大型振动台试验研究,结果表明:隧道衬砌设置减震层后,可以显著降低衬砌内力,减小衬砌裂缝的数量。
Through the Fourier-Bessel function expansion method, the series of dynamic stress concentration factor series solution of circular double-layered lining structure, surrounding rock-cushioning layer-lining cavity in the semi-infinite elastic medium with plane SV wave vertical incidence is deduced, and the frequency of incident wave , The influence of the elastic modulus and the thickness of the cushioning layer on the dynamic stress concentration factor, and the damping mechanism of the cushioning layer in-depth study are compared with the numerical simulation results. The results show that the incident frequency has a significant influence on the dynamic stress concentration factor of the lining and the damping layer has a good damping effect on the low frequency waves. Because the shear modulus of the damping layer is low, the surrounding rock and the tunnel can be sheared and deformed The normal force acting on the outside of the lining is reduced and the maximum dynamic stress concentration coefficient inside the lining is reduced, but the tangential stress on the outside of the surrounding rock and the lining increases; as the ratio of the damping layer to the surrounding rock decreases, , The thickness of shock absorbing layer increases and the concentration coefficient of dynamic stress of secondary lining becomes smaller. The elastic modulus ratio of shock absorbing layer and surrounding rock should be less than 1/10 ~ 1/20, which corresponds to the elastic modulus of shock absorbing layer An optimal damping layer thickness value. Taking a highway tunnel as a background, a large-scale shaking table experiment on the tunnel shock-absorbing layer structure is carried out. The results show that the internal lining force can be significantly reduced and the number of lining cracks can be reduced after the tunnel lining is provided with a shock-absorbing layer.