超重力离心模拟与实验装置设备基础模态分析中侧土弹簧刚度的取值

Lateral Soil Spring Stiffness in Modal Analysis for Foundation of Centrifugal Hypergravity and Interdisciplinary Experiment Facility

在对超重力离心模拟与实验装置的地下设备基础进行模态分析以获得结构动力特性的工程设计中,由于设备基础埋置较深,须充分考虑侧面土对结构的约束作用。根据不同土层的性质,采用线性的弹簧单元模拟设备基础与土各接触面的边界条件,并采用了旁压试验等5种不同依据对弹簧刚度进行取值。5组模型计算结果规律近似,结果的离散偏差较小,使模态分析结果更为可靠。进一步对设备基础结构侧面的边界弹簧的刚度进行了敏感性分析,并额外通过补充切向弹簧考虑了土对设备基础结构切向约束的因素。通过数值结果,更全面地把握了侧土边界在本项目中对模型机、重载机、高速机各段超重力离心机设备基础结构体系自频的影响能力,从而以引导工程设计,避免无效的造价投入。

In the engineering design of modal analysis for the foundation of Centrifugal Hypergravity and Interdisciplinary Experiment Facility(CHIEF)to obtain structural dynamic characteristics,as the equipment foundation is deeply embedded,the restraint effect of side soil on the structure must be fully considered.According to the properties of different layers of soil,the linear spring element was used to simulate the boundary conditions of each contact surface between foundation and soil,and five different bases such as lateral loading test were used to take the value of spring stiffness.The calculation results of the five groups of models were similar,and the discrete deviation of the results was small,which led to more reliable modal analysis results.Further,the sensitivity analysis of the stiffness of the boundary spring on the side of the foundation structure was carried out,and the tangential constraint of soil on the foundation structure was considered by the tangential spring.Through the numerical results,the influence of the side soil boundary on the natural frequency of each section of the hypergravity centrifuge foundation in the project was more comprehensively grasped,so as to guide the blueprint design and avoid invalid investment.