【摘要】 以国道318线黄草坪2#隧道进洞口段为原型,开展减震措施的大型振动台物理模型试验研究。首先系统介绍整个试验方案,包括试验装置、模型相似设计、模型箱体设计、相似材料设计、测试方案和地震输入及加载制度。然后,结合试验结果对洞口段减震设防区域进行研究,对横向减震层、纵向减震层以及加固围岩等措施的减震效果进行分析。试验结果表明,一般从模型洞口进入洞内120～150 cm(对应原型48～60 m)后,地震反应逐步趋于平稳,该范围是隧道减震设防的重点区域。设置横向减震层和系统锚杆加固围岩均能有效减少衬砌的动土压力和加速度反应,而且加固围岩的效果相对弱于设置横向减震层。通过合理设置纵向减震层间距,可将衬砌动应变量级降低至工程安全可接受水平。最后提出,对山岭隧道洞口段进行地震安全设计时,应该在上述认识基础上采取综合减震措施。更多还原

【Abstract】 In order to study the effects of vibration-absorption measures in mountainous tunnel during earthquake,the entry portal area of Huangcaoping Tunnel No.2 located on National Highway No.318 is selected as the prototype to conduct large-scale shaking table test.Firstly,the whole test scheme is systematically introduced,including the test facility,the design of similarity ratio,the design of mould case,the similarity materials,the layout of measure sensors,the wave input and the load subsequence.Then,combining the test result analysis,the sector of the portal area that needs seismic protection is researched;and the effects of vibration-absorption measures such as lateral buffer layer,longitudinal buffer layer,and reinforcing surrounding rock with systematic bolts are analyzed.The results show that from the entry to the deep locations,the earthquake-induced effect decreases step by stepa,nd gets stable at the distance of 120–150 cm in model(48–60 m in prototype),which can be considered as the most important zone for aseismic design.The results also show that setting lateral buffer layer and reinforcing surrounding rock with bolts are both effective ways to decrease the dynamic earth pressure and the liner acceleration;but the latter is relatively weaker than the former.Properly setting longitudinal buffer layer can effectively reduce the dynamic strain to an acceptable level for project safety.Finallyt,he some suggestions are put forward that synthetical measures for vibration-absorption should be adopted for aseismic safety design of mountainous tunnel portal area on the basis of the above results.更多还原