土弹性模量对土-结构共同作用体系影响分析

摘要

A 3 D finite element model of the karst subgrade-piled raft foundation-outer steel frame core tube structure is established to analyze the effect of soil elastic modulus on the interaction sys-tem in karst area, and a contrastive analysis is conducted on the dynamic responses of the upper structure when the soil elastic modulus changes between piles. The results indicate that the change of soil elastic modulus has affected the responses of the interaction system, with an increase in the e-lastic modulus of the soil between the piles;that the peak acceleration, peak displacement and peak inter story drift ratio of the upper structure tend to decrease;that the maximum change rate of peak displacement is 12. 76%, and the change rates of peak acceleration and peak inter story drift ratio are less than 10%;that the moment and shear of the foundation decrease. The reason is that the ri-gidity of the foundation increases with the increase of elastic modulus of the soil between piles, and the soil deformation decreases under earthquake, which increases the restrain to piled raft founda-tion, so that the responses of the upper structure and the internal force of the foundation tend to de-crease.%为了分析岩溶区土的弹性模量对共同作用体系的影响，建立岩溶地基—桩筏基础—钢框架核心筒结构三维有限元模型，对比分析桩间土弹性模量变化时，上部结构的动力响应情况。结果表明：桩间土弹性模量的变化对共同作用体系的动力响应有一定的影响，随着桩间土弹性模量的增加，上部结构加速度峰值、位移峰值、层间位移角峰值整体上有减小的趋势，位移峰值变化率最大为12．76%，加速度峰值和层间位移角峰值变化率都在10%以内；基础的弯矩和剪力减小。分析其原因是桩间土弹性模量的增大，增大了地基的刚度，使地基土在地震作用下的变形减小，对桩筏基础的约束增大，从而使上部结构的动力响应和基础的内力减小。