【摘要】 在-0.95℃恒温状态下对青藏人工冻结粉土试样进行不同动应力幅值下的振动单轴压缩试验,获得2种频率下不同动应力幅值时冻土试样累积应变和振动次数之间的关系曲线,发现冻土的累积应变随着振动次数的增加呈增长的趋势,且表现出稳定型、破坏型和临界型3种形态;在振动次数相同时,动应力幅值越大,累积应变越大;加载初始阶段应变速率随时间的增大而减小,且应变速率对数与时间对数间均有较好的线性关系,但随着振动时间的增加,破坏型曲线的应变速率达到一个最小值后开始增大,稳定型曲线的应变速率则在一定幅度的范围内波动;振动频率越高、动应力幅值越大,应变速率越大;振动频率越高,临界动应力越小。更多还原

【Abstract】 Dynamic uniaxial compressive tests on Qinghai artificial frozen silt are carried out with different dynamic stress amplitudes at the steady temperature of-0.95 ℃.The relationships between accumulated strain and vibration times for frozen silt at different dynamic stress amplitudes under two kinds of frequencies are obtained.The results show that accumulated strain increases with the increasing vibration times.The relation curves of accumulated strain and vibration times can be classified into three types,i.e.failure type,stable type and critical type.When vibration times is same,the higher the dynamic stress amplitude is,the larger the accumulated strain is.The strain rate decreases with time at the beginning and the logarithm of strain rate is linearly related to the logarithm of time.With the increase in vibration time,the strain rate of failure type curve reaches a minimum value and then increases,while the strain rate of stable type curve fluctuates in certain range.The higher the vibration frequency and dynamic stress amplitude are,the larger the strain rate is.The higher the vibration frequency is,the lower the critical dynamic stress is.更多还原