黏弹性人工边界地震动输入方法及实现

本文对实现黏弹性边界的常用方法进行了总结,对相应于黏弹性边界的地震动输入公式进行了详细推导,把自由场应力的求解也转化为自由场速度的求解,简化了地震动输入公式,并给出了地震动输入的简化方法。基于ABAQUS软件,进行算例分析并和理论解进行对比,验证了各种黏弹性边界实现方式及本文地震动输入方法的合理性和正确性。最后,对大朝山重力坝典型挡水坝段进行地震响应分析,通过施加黏弹性边界并输入相应地震动,评价了无限地基辐射阻尼的影响,并与无质量地基模型的计算结果进行了比较。结果表明,考虑辐射阻尼效应后坝体地震响应明显降低,故在实际工程抗震分析时对其影响应予以适当考虑。

Method and realization of seismic motion input of viscous-spring boundary

Crop coefficient can reflect the effects of crop biological characteristics, yield level, the condition of soil water fertilizer and the effect of management level on crop water requirement, which is the basis of calculating crop water requirement. In this paper the ISAREG model which is on the basis of soil water balance is adopted to simulate the variation process of soil water content of summer maize in the whole growth period, and the crop coefficient is back calculated according to the observed data of summer maize in Beijing Daxing Experiment Station of IWHR in the year of 2007 and 2008 . According to the observed transpiration data of sap flow, the basal crop coefficient is 0.98 and 0.28 respectively in the middle and end of growth season With the calculated basal crop coefficient values, the transpiration and evaporation can be estimated. The validity of the estimation is verified by observed data. Then the change process of evaporation and actual crop evapotranspiration of summer maize in the year of 2007 and 2008 were simulated and estimated. Results showed that the estimated mid-season crop coefficient accords well with the observed data, but the crop coefficient at the end of growth season is underestimated. The ratio of evaporation to actual crop evapotranspiration of summer maize is about 39%~43.6%.