饱和粉土液化及再固结后力学特性试验研究

Experimental Study on Mechanical Properties of Saturated Silt after Liquefaction and Reconsolidation

为了研究围压和粉粒含量对饱和粉土的抗液化强度以及液化再固结后力学特性的影响规律,以郑州东区某一施工现场粉土为原料土,利用GCTS动三轴试验系统,开展以围压和粉粒含量为变量的液化试验。结果表明:随着围压和粉粒含量的增加,饱和粉土的动强度逐渐增大,且液化势随着粉粒含量的增加而降低,其中围压值的增大可在相同振次下明显提高动剪切强度,而粉粒含量的增加可在相同荷载下提高破坏振次数;饱和粉土液化再固结后再单调加载时,其孔隙水压力消散速度加快,偏应力值增加速度提高,土样剪胀特性明显;随着围压和粉粒含量的增加,粉土液化再固结后的不排水剪切强度增大,可用对数曲线模型较好地反映粉土液化再固结后的变形特性。

In order to study the influence of confining pressure and silt content on the liquefaction resistance of saturated silty soil and the mechanical properties after liquefaction and reconsolidation.Taking silt from a construction site in eastern Zhengzhou as raw material,and the liquefaction test with confining pressure and silt content as variables was carried out by using GCTS dynamic triaxial test system.The results show that with the increase of confining pressure and silt content,the dynamic strength of saturated silt increases gradually,and the liquefaction potential decreases with the increase of silt content.The increase of confining pressure can significantly improve the dynamic shear strength under the same vibration frequency,and the increase of silt content can increase the number of failure vibration under the same load.When saturated silty soil is liquefied and reconsolidated,and then monotonically loaded,the dissipation rate of pore water pressure is accelerated,the increase rate of deviatoric stress value is increased,and the dilatancy characteristics of soil samples are obvious.With the increase of confining pressure and silt content,the undrained shear strength of silt after liquefaction and reconsolidation increases,and the logarithmic curve model can better reflect the deformation characteristics of silt after liquefaction and reconsolidation.