土-箱基-框架结构动力相互作用大比例模型野外试验研究

通过野外大比例(1∶2)结构模型动力试验,研究了土与箱基及框架结构动力相互作用。分别用脉动和牵引释放法测试了试验模型的自振频率及阻尼比,通过三维有限元计算理论值与现场实测值的对比发现,考虑土-结构动力相互作用(SSI)时模型自振频率比不考虑SSI作用时模型第一阶自振频率最大降低8.5%。从牵引释放试验中基础测点和地面测点速度频谱对比可以发现,地面测点振动以纵向运动为主,并且与土体特征频率接近的高频分量得到加强。由近场地面爆破振动试验可知,对于高柔框架结构,其顶部速度反应主要是由基础转动引起的摇摆分量组成,上部结构弹性变形次之,基础平动分量最小。试验为进一步研究具有埋置基础的土-结构动力相互作用提供了计算实例和丰富的试验对比数据。

LARGE-SCALE FIELD MODEL TEST ON DYNAMIC SOIL-BOX FOUNDATION-STRUCTURE INTERACTION

A large-scale (1: 2) field model experiment of dynamic soil-box foundation-structure interaction was carried out. Based on the pulsation and release tests, the nature frequency and damping ratio of the model were tested. By comparing the differences of nature frequency between experimental and three-dimensional finite element method analysis results, it is found that the fundamental nature frequency of the system considering soil-structure interaction (SSI) is about 8.5% less than that of the fixed-base structure. Comparison of the velocity spectra at the measuring points on the foundation and on the ground surface shows that the main portion of the velocity response on the ground surface is longitudinal and the high frequency component close to the soil natural frequency is amplified. The results of near-field blasting vibration test show that the main portion of the velocity response at the top of flexible super structure is rocking, followed by elastic deformation. The swing response is very small. The experiment provides test data for further numerical modeling of soil-structure interactions.