长期循环荷载下珊瑚砂累积变形特性试验研究

对取自南海的珊瑚砂进行等向和K_0固结的三轴排水剪切试验,发现固结路径对珊瑚砂的剪切行为有显著影响。在此基础上,采用K_0固结条件,设计一系列不同围压和循环动应力比的长期排水循环加载三轴试验,研究得到珊瑚砂具有门槛颗粒破碎循环动应力比,安定性理论可用于解释不同动应力比长期循环加载下珊瑚砂的累积变形发展模式。基于静力和动力试验结果,引入相对偏应力水平,建立能反映初始固结状态和循环动应力比的珊瑚砂排水循环加载轴向残余累积应变显式计算模型,对预测循环荷载下珊瑚砂地基长期沉降有积极意义。

Experimental study on cumulative deformation characteristics of coral sand under long-term cyclic loading

The drained triaxial shear tests on isotropic and K₀ consolidation of coral sand samples taken from the South China Sea reveal that the consolidation path has a significant effect on the strength characteristics of the coral sand. On this basis, using the K₀ consolidation condition, a series of long-term drained cycle triaxial tests with different confining pressures and cyclic dynamic stress ratios are carried out. The results show that the coral sand has a threshold cyclic dynamic stress ratio, which makes its particles obviously broken. The stability theory can be used to explain the cumulative deformation development patterns of the coral sand under long-term cyclic loading with different dynamic stress ratios. Based on the results of static and dynamic test results, the relative deviator stress level is introduced to establish an explicit model for the axial residual cumulative deformation of the coral sand, which can reflect the initial consolidation state and cyclic dynamic stress ratio of the coral sand under drained cyclic loading. The proposed model is of positive significance for predicting the long-term settlement of the coral sand foundation under cyclic loading.