浅埋偏压洞口段隧道地震响应振动台模型试验研究

STUDY OF SHAKING TABLE MODEL TEST FOR SEISMIC RESPONSE OF PORTAL SECTION OF SHALLOW UNSYMMETRICAL LOADING TUNNEL

首先对试验装置、模型相似比、相似材料、试验模型箱和测试技术等进行介绍,然后通过围岩与隧道结构的加速度响应、地层变形及内力分布规律等对振动台模型试验及数值计算结果进行分析和比较。分析结果表明:振动台模型试验和数值模拟结果有较好的吻合性;加速度随着高程的增加有明显的放大效应,偏压隧道地表临空坡面导致放大效应明显增加;地层随高程产生呈抛物线分布的相对位移值,相对位移值大小与围岩类型有关;隧道结构对地层有明显的追随性和依赖性;隧道衬砌横截面共轭45°方向为较大内力值分布部位,无偏压隧道结构横截面内力呈反对称分布,偏压隧道有较不利的内力值分布与较大峰值等。以上成果对于合理认识浅埋偏压隧道的地震响应特征具有重要意义,并对隧道实际工程设计和施工的抗震设防提供宝贵的基础资料。

The whole test scheme is systematically introduced firstly, including test facility, design of similarity ratio, similar materials, design of mould case, measuring technology and so on. Then, the test results which include acceleration characteristic of rock and tunnel structure, laws of geologic strata deformation, and distribution of internal force are analyzed and compared with the numerical analysis results. The analysis results indicate that test and numerical analysis results are in good agreement. Acceleration has an apparent amplification effect which increases obviously at the unsymmetrical loading tunnel surface; the displacement of geologic strata which increases with the heightening of elevation is parabolic distribution; and relative displacement is influenced by rock types. Conjugate 45 ~ directions at the cross-section of tunnel structure are great internal force distributing： internal force of symmetric loading tunnel is anti-symmetric： unsymmetrical loading tunnel has unfavorable internal force and great internal force peak. The results above will have great significance to reasonably comprehend seismic response character of the shallow unsymmetrical loading tunnel and be precious basic data for the aseismic design and construction of practical engineering.