纵向非一致激励下非均匀场地中埋地管道的振动台试验研究
Shaking table tests on buried pipelines in inhomogeneous soil under longitudinal non-uniform seismic excitation
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摘要: 埋地管道的地震响应主要受管道沿线地震动空间分布特性及场地非均匀性的影响。为研究非均匀场地中埋地管道在纵向非一致激励下的抗震性能,开展了均匀和非均匀场地中埋地管道的多点非一致激励振动台模型试验。分析了均匀和非均匀场地中埋地管道在不同地震强度作用下的应变响应,研究了纵向非均匀场地对埋地管道地震反应的影响。试验结果表明,在纵向一致激励作用下,非均匀场地中埋地管道轴向方向上的最大峰值应变出现在场地变化的过渡区,且其高于均匀场地下的峰值应变。在纵向非一致激励作用下,在较低加载等级下,管道峰值应变的大小与均匀场地下相比有所减小,但在较高加载等级下,峰值应变却急剧增加。与纵向一致激励作用不同,在纵向非一致激励和非均匀场地的共同作用下,最大峰值应变可能出现在场地变化的过渡区或土体介质较软的场地中。研究结果为进一步研究非均匀场地对埋地管道地震响应的影响提供了依据。Abstract: The seismic response of buried pipelines is primarily affected by the spatial variation characteristics of earthquake motion and the soil inhomogeneity. To investigate the seismic performance of pipelines buried in inhomogeneous soil under longitudinal non-uniform seismic excitation, two multi-point shaking table tests are carried out on model pipelines: one model is buried in homogeneous soil, and the other is buried in inhomogeneous soil. The test results are analyzed and discussed in terms of the strains of the pipelines buried in both homogeneous and inhomogeneous soils under different earthquake intensities, and the influences of longitudinal inhomogeneous sites on the seismic response of the pipelines are studied. The test results indicate that the peak strain of the pipelines in the transient zone where the soil properties change in the inhomogeneous soil model is higher compared with the response in the homogeneous soil model under longitudinal uniform seismic excitation. The maximum strain along the pipeline axis occurs in the transient zone. However, under the longitudinal non-uniform seismic excitation, although the magnitude of the strain peak is decreased compared with the homogeneous soil case at lower loading intensity, similar magnitudes of strain are observed at higher loading intensity, and there is a sharp increase in the strain peaks. Unlike the longitudinal uniform excitation case, the maximum strain peak may appear in the transient zone or soil changed zone due to the combined action of longitudinal non-uniform excitation and inhomogeneous soil. The results may provide insights into the site effects of inhomogeneous soil conditions on the seismic response of buried pipelines.