主应力轴偏转下的滨海结构性软土试验研究

Experimental Study on Coastal Structural Soft Soils under Principal Stress Axis Rotation

对现有的空心圆柱试样制备技术进行了改进,解决了原有制样技术存在的扰动大、步骤繁琐等问题;采用空心扭剪仪为试验设备,以不同频率、不同动应力幅值为影响因素分析了其对紫金港软黏土轴向累计应变和软化指数的影响。在主应力轴旋转条件下,滨海结构性软土存在明显的临界循环应力值,当频率在0.1 Hz~1 Hz范围内变化时,空心圆柱试样在0.1 Hz循环荷载作用下达到破坏状态需要的次数最少;同时,频率和循环应力比对滨海结构性软土的软化特性具有显著的影响,且频率、动应力比对轴向累计应变及软化指数的影响是相互耦合、互相影响的,并不单独存在。

The existing hollow cylindrical sample preparation technology has been improved to solve the problems of large disturbance and cumbersome steps in the original sample preparation method. The hollow torsion shear apparatus is used as the test equipment, with different frequencies and different dynamic stress amplitudes. For the influencing factors, the influence on the axial cumulative strain and softening index of Zijingang soft clay is analyzed. Under the rotation of the principal stress axis, there is an obvious critical cyclic stress value for coastal structural soft soils. When the frequency changes within the range of 0.1 Hz to 1 Hz, the number of cycles required for the hollow cylindrical specimen to reach the failure state under the action of the 0.1 Hz cyclic load. At the same time, frequency and cyclic stress ratio have a significant influence on the softening characteristics of coastal structural soft soils, and the effects of frequency and dynamic stress ratio on the axial cumulative strain and softening index are mutually coupled and mutually influencing, not alone exist.