低围压下埕北海域重塑粉土动强度特性

Study on dynamic strength of remolded silt in Chengbei sea area under low confining stress

为了探讨低围压下粉土的动强度特性,利用低围压条件下固结不排水振动三轴试验,对埕北海域3种不同黏粒质量分数的重塑粉土进行研究。结果表明:低围压条件下埕北海域重塑粉土的破坏准则采用以往的破坏准则不合适,将应变达到2%~3%作为低围压条件下粉土的破坏准则;低围压条件下粉土动应力曲线具有幂函数曲线特征;粉土动强度受固结比的影响,动强度的最大值出现在固结比约为1.5;低围压条件下埕北海域重塑粉土内摩擦角介于8.6°~15.26°,内聚力介于1.20~4.86 kPa,临界循环应力比为1.45。

The study on the remolded silts with three different clay contents in Chengbei sea area was carried out by consolidated undrained dynamic triaxial test under the low confining stress, in order to explore the dynamic strength characteristics of silts under the low confining pressure. The results show that, the previous collapse criterion for soils is not suitable for remolded silts in Chengbei sea area under the low confining pressure environment. The axial strain with the value of 2%-3% should be the new collapse criterion under that condition. Under the condition of low confining pressure, the dynamic stress curve of the silty soil can be fitted by the power law function. The dynamic strength is obviously affected by the consolidation ratio and the maximum value of the strength occurs when the consolidation ratio is 1.5. Moreover, for the remolded silt in Chengbei sea area under the low cofining pressure, the internal friction angle is between 8.6 ° and 15.26 °, the cohesive force is between 1.20 kPa and 4.86 kPa, and the critical cyclic stress ratio is 1.45.