基于水平层状场地自振频率的一致质量剪切质点系法基本原理,考虑传统剪切质点系法刚性半空间假设对计算结果的影响.引入半无限单元,发展和建立可考虑半空间弹性的改进剪切质点系法.以改进剪切质点系法分析传统半空间刚性假设对场地自振频率计算结果的影响.分析表明,半空间刚性假设引起的计算误差随着剪模比、覆盖层厚度及半无限单元衰减系数的增大而减小.对于一般实际场地,在剪模比和覆盖层厚度不是很小的情况下,采用传统刚性假设剪切质点系法计算场地自振频率亦可获得比较满意的精度.
Based on the principles of consistent mass shear mass point system' method for evaluation of natural frequency of horizontal layered soil site and taking account of the influence of rigid half space hypothesis on the evaluation, the semi-infinite element is introduced and a modified shear mass point system method incorporated with half space elastic is developed, established and used to analyzed the influence of traditional rigid assumption of half space on the site natural frequency. The analysis results show that the calculation error caused by rigid half space assumption will decrease with the increase of modulus ratio, soil thickness and attenuation factor of semi-infinite element. For common actual soil sites, if the covering layer thickness and modulus ratio are not very small, there will be a good calculation precision when traditional shear mass point system method incorporated with rigid half space is used.