冻结粉土动强度的荷载效应及长期极限动强度

荷载效应包括速率效应和疲劳效应两部分．速率效应使冻土的动强度和退荷回弹动弹模随应变速率加快而提高；疲劳效应使冻土的动强度随振频增加而下降，但在低应变速率下却使动强度略有提高．在高应变速率下动强度大于静强度，在低应变速度下动强度小于静强度，其间存在一个临界应变速率．通过动强度－破坏振次关系，可确定长期极限动强度．

Loading Effect of Dynamic Strength and Limit of Long-Term Dynamic Strength of Frozen Silt

The dependence of dynamic strength of frozen silt on loading effect under constant strain rate are discussed in this paper. Losding effect consists of rate effect and fatigue effect. Dynamic strength and unloaded dynamic elastic modulus increase with increasing strain rate. However dynamic strength of frozen silt decreases due to fatigue effect, except for low strain rate. In high strain rate the dynamic strength is larger than the static strength of frozen soil, and in low strain rate the former is less than the later. There is a critical strain rate in between. Limit of long-term dynamic strength can be derived from the relationship between the dynamic strength and the vibratory number to failure.