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根据长期动荷载作用下的蠕变试验结果,研究了冻结粉土的变形和动强度特征.试验分3组,第一、二组是小振幅动荷载试验,且第二组的动荷载幅值为第一组的两倍;第三组是大振幅动荷载试验,荷载最小值取接近于零的值,最大值与第一组对应.试验结果表明:各种振幅的动荷载作用下,冻土的累积应变随荷载振动次数的变化规律相同(都包括初始蠕变阶段、稳定蠕变阶段、渐进流阶段)但数值上有差异.在初始和稳定蠕变阶段,第三组试验的累积应变小于第一、二组的,但是第三组试验稳定蠕变阶段的应变速率很大,蠕变曲线迅速进入渐进流阶段,此后其累积应变值大于小振幅动荷载试验的;第一、二组试验的应变幅值随振次的变化规律相似,但与第三组的有明显不同,而且,第三组试验的应变幅值明显大于第一、二组试验的.各种振幅动荷载作用下冻土的残余应变随振次的变化规律相同,且偏移荷载载越大或动荷载振动幅值越大,残余应变越大;冻土的动强度随荷载振动次数的增加而衰减,直至趋于极限动强度,大振幅动荷载试验的极限动强度明显小于小振幅动荷载试验的.
According to the results of creep test under long-term dynamic loading, the deformation and dynamic strength characteristics of frozen silt were studied.The experiment was divided into three groups, the first and second groups were small amplitude dynamic load test, and the second group dynamic load amplitude The first group is twice that of the first group, the third group is the large-amplitude dynamic load test, the minimum load value is close to zero, the maximum value corresponds to the first group.The experimental results show that: under the dynamic load of various amplitudes, The accumulative strain of soil changes regularly with the number of load oscillations (both initial creep phase, steady creep phase, progressive flow phase) but differs in value. In the initial and steady creep phases, the cumulative strain of the third group of tests However, in the third group of tests, the strain rate in the stable creep phase was very large and the creep curve quickly entered the progressive flow stage. Since then, the cumulative strain value was larger than the small amplitude dynamic load test. The first and second groups The variation of strain amplitude with vibration is similar, but it is obviously different from that of the third group, and the strain amplitude of the third group is obviously larger than those of the first and second groups. The residual strain of frozen soil varies with vibration times The variation law is the same, and the larger the offset load or the larger the amplitude of the dynamic load, the larger the residual strain; the dynamic strength of the frozen soil decays with the increase of the number of the load vibration until it reaches the ultimate dynamic strength, The ultimate strength of the test is obviously smaller than that of the small amplitude dynamic load test.