低频振动下库区粉土的动力特性试验研究

Test research on dynamic characteristics of reservoir area silt under low frequency vibration

针对三峡库区某滑坡粉质粘土,开展了等压固结下重塑试样在低频振动下三轴动力剪切试验,研究了不同频率下土体的应力应变关系、动弹模、阻尼比的变化特性.实验结果表明：轴向动荷载作用下,随着振动次数增加各土样的变形均逐渐累积增大,且频率在0.5～2Hz范围内,在振幅相同的动荷载条件下,频率越高,动应变的累积变形越慢.在此频率范围内,动孔压经历了逐步升高到骤降的过程.振动频率越高,动模量越高,且随着动荷载幅值的增大,动模量随变形逐渐降低.变形累积到一定时,阻尼比随着频率的增加而增大,阻碍了土体的变形发展.

The triaxial shear test with low frequency vibration used remolded clays sample from a landslide in Three Gorges Reservoir area is carried out. Based on the test results, it can be studied that the dynamic behavior of clay such as the relationship between stress and strain, the values of dynamic elastic modulus and damping ratio. In this study, it＇s found that when the frequence increase from 0.5 Hz to 2 Hz,but the strain of the sample decreases under the same conditions. And the higher the times of vibration, the larger the dynamic strain. The pore water pressure experienced a gradual rise to dip process. With the higher fre- quency, the sample with the same deformation has a larger dynamic modulus. The damp ration increase with the increse of frequency; when the damp ration increase to a constant value, thus prevent the expansion of soil.