循环荷载下高温冻土的变形和强度特性

Deformation and strength of warm frozen soils under cyclic loading

对-1℃的冻土试样在频率为3,5,8 Hz的循环荷载下进行了单轴压缩试验,探讨了冻土在循环荷载下的累积变形和动强度。结果表明:循环荷载作用下冻土的累积变形大小由加载的最大动应力大小决定,同一频率下加载的最大动应力越大,相同循环次数时的累积应变越大;根据加载的最大动应力的大小,累积应变与循环次数的关系曲线可表现为破坏型、稳定型和过渡型3种形态之一。加载频率对冻土累积应变的影响规律复杂,且受加载的最大动应力影响;当最大动应力较小时,频率的影响不明显;当最大动应力比较适中时,大体上频率越高,累积应变越大;当最大动应力比较大时,频率越高,累积应变越小。在3%,5%和10%的破坏应变下,频率为8 Hz时冻土的动强度最大,而3 Hz和5 Hz的动强度比较接近。

The uniaxial compression tests on frozen soils under-1℃ and cyclic loading are carried out.The vibration frequencies are 3,5 and 8 Hz.The cumulative deformation and dynamic strength of the frozen soils under cyclic loading are studied.The results show that the cumulative deformation of the frozen soils under cyclic loading is dependent on the maximum cyclic stress.When the frequency is the same,the larger the maximum cyclic stress,the larger the cumulative strain.According to the maximum cyclic stress,the changing curves of the cumulative strain with cyclic number can be divided into failure type,stable type and transition type.The loading frequency affects the cumulative strain in a complex way.When the maximum cyclic stress is small,the frequency has slight effect on the cumulative strain.When the maximum cyclic stress is moderate,on the whole,the higher the frequency,the greater the cumulative strain.When the maximum cyclic stress is large,the higher the frequency,the smaller the cumulative strain.When the failure strains are 3%,5% and 10%,the dynamic strength is the greatest under loading frequency of 8 Hz,and the dynamic strength under 3 Hz is close to that under 5 Hz.