地基弹性参数对于长型大截面地下结构横向自由振动的影响

Effect of Soil Elastic Parameters on Lateral Free Vibration of Long Large Cross-section Underground Structure

自由振动分析是地下结构地震动力响应分析的基础。本文利用笔者先前得到的长型地下结构的自由振动方程,研究了地基弹性参数对地下结构自由振动的影响。由分析可以看出,随着地基弹性参数值的增加,结构中波速值总的趋势是增加,但是温克尔地基参数对结构中波速的影响远大于第二地基参数的影响;地下结构振动频率总的趋势是随着温克尔地基参数k和第二地基参数gP值的增加而增加;与地基参数对地下结构中波的传播速度的影响不同,k和gP对地下结构振动频率的影响是同阶的,因此不能忽略gP对地下结构自由振动的影响。

Free vibration analysis is the foundation of dynamic seismic analysis for underground structures. The effect of soil elastic parameters on the free vibration of long large cross section underground structure is studied on the basis of the vibration equation of linear underground structures derived by the authors previously.Parameter study shows that in general wave propagation velocities in the structure increase with soil elastic parameters.But the influence of Winkler＇s parameter k is significant,while the effect of the second soil elastic parameter gP is insignificant.Free vibration frequency of underground structure increases with relative wave number and soil elastic parameters.Differing from the influence of soil elastic parameters on wave propagation velocities,the influences of soil elastic parameters k and gP on vibration frequency of underground structure have the same order,therefore the influence of the second soil parameter gP on free vibration of underground structure should not be neglected.