地下管线在空间随机分布的地震作用下的反应

SEISMIC RESPONSE OF UNDERGROUND PIPELINES TO GROUND MOTION WITH SPATIAL RANDOMNESS

强震作用下地下管线地震反应计算以往多采用波动法求解。这种方法假定地震波为一行进波,沿管线的轴向或成某一角度传播,它只能求得地面运动的相位差引起的管线的变形和内力。有些文献将地震地面运动假定为空间变化的平稳随机过程,用随机振动理论求得管线的地震反应,但不能反映地面运动的非平稳性对管线地震反应的影响。而地面运动的非平稳性,特别是时域非平稳性很可能是产生地下管线变形和内力的最重要原因。根据地面运动的统计模型生成管线轴线上各点的地面运动时程,用级数解法求管道的地震反应。由于这种方法能较好地反映地面运动的时域非平稳性,所以得到的计算结果更真实。

The seismic response of underground pipelines is usually calculated by the wave theory that assumes seismic wave as a traveling wave, which propagates along the axial direction or at some angle with the axial direction. This method can only solve the axial force and strain of pipeline due to the phase difference of ground motion. Some reference documents assumed the earthquake ground motion as a stationary random process distributed in space and time, and worked out the seismic response of pipelines using random vibration theory. But they neglected the effect of non-stationary ground motion, and especially the non-stationary ground motion in time domain that may be the most important factor giving rise to the axial force and the strain of the pipeline. In this paper, the ground motion time histories of each spot in the pipeline axis are generated based on the statistical model of ground motion, and the seismic responses of the pipeline are worked out by the series method. The results may better reflect the non-stationarity of ground motion in time domain and are closer to reality than those by wave theory and stationary random vibration theory.