隧道衬砌结构减震层效能评定方法的振动台试验研究

Shaking table tests for effectiveness evaluation method of damping layer of tunnel lining structure

通过大型振动台模型试验研究了减震层效能评定方法的准确性和减震层作用下衬砌结构与最不利的IV级和V级围岩在激振过程中的相互作用。研究结果表明:减震层效能评定方法可以较为准确地评估减震层在地震动力作用下对衬砌结构的作用效果,但随着激振加速度峰值的提高,试验值会与评估值产生偏差,因此对减震层效能评定方法引入地震动力损伤系数以提高其精确度;围岩级别相较于减震层的厚度对衬砌结构的地震响应更具有决定性作用;在中低烈度地震区,减震层对衬砌结构的保护效果较为明显,但减震层存在最优厚度,超过该厚度,衬砌结构遭遇地震时的震动更加强烈,在高烈度地震区,减震层的效果差异在不同围岩中逐渐不再明显;减震层的存在改变了衬砌结构的自振特性,让衬砌与围岩之间在地震动力作用下有一定的刚性位移裕度,减少了相对位移的幅值。

Here, through large-scale shaking table model tests, the correctness of the effectiveness evaluation method of damping layer and the interaction between lining structure and the most unfavorable class IV and class V surrounding rocks under the action of damping layer were studied. The results showed that the effectiveness evaluation method of damping layer can more accurately evaluate the action effect of damping layer on lining structure under seismic dynamic action, but with increase in peak exciting acceleration, test values can deviate from evaluation values, so the seismic dynamic damage coefficient is introduced into the effectiveness evaluation method of damping layer to improve its accuracy;compared with the thickness of damping layer, the level of surrounding rock plays a more decisive role in evaluating seismic response of lining structure;in seismic areas with middle and low intensities, the protective effect of damping layer on lining structure is more obvious, but there is an optimal thickness of damping layer, if beyond this thickness, seismic response of lining structure is stronger when encountering an earthquake;in seismic area with high intensity, the effect difference of damping layer is no longer obvious in different surrounding rocks;the existence of damping layer can change natural vibration characteristics of lining structure, create a certain rigid displacement margin between lining and surrounding rock under seismic dynamic action, and reduce amplitude of relative displacement.