滨海软黏土加速蠕变特性试验研究

为了研究滨海软黏土加速蠕变特性,采用典型的滨海相软黏土进行室内蠕变和加速蠕变试验,研究不同围压、加荷比、振动频率、动应力比对软黏土蠕变特性的影响,并通过对比得出了不同试验条件下滨海软黏土的加速蠕变的变化规律。试验结果表明:滨海软黏土具有非线性应力–应变关系的流变特性,其蠕变试验曲线呈衰减型,蠕变变形大部分应变量发生在蠕变前期,变形随时间增长趋于一个定值;静载作用下,围压越大初始蠕变速率越大。初始加荷压力一致,加荷比越大破坏应力越小。循环动荷载作用下,应变在动荷载阶段变化缓慢,而动荷载结束后进入稳定阶段后应变发生突变,急剧变大最后趋于稳定;此外在不同振动频率和动应力比下试样承受荷载等级不同,均存在一个临界安全荷载,超过这个临界值试样会发生蠕变破坏现象。

Triaxial tests on creep characteristics of coastal soft soils

To explore the creep properties of typical structural soft clay in the coastal area of Tianjin, a series of triaxial creep tests are carried out considering the factors such as confining pressure, loading ratio, frequency and so on. The stress-strain-time curves of coastal soft clay under different conditions are obtained. According to the comparison of indoor tests between the original soils and the soils under different experimental conditions, the accelerated creep properties are found. The results show that the coastal silt clay in Tianjin exhibits nonlinear rheological properties of stress-strain, and its creep curves are attenuated. The creep deformation mostly occurs in its early stage, and the deformation tends to be a constant value with the passage of time. Under static loads, the greater the confining pressure, the greater the initial creep rate. Under the same initial loading pressure, the failure stress decreases with the increase of the loading ratio. Under cyclic loads and the same experimental conditions, there exist a structural yield stress and a critical frequency. Once exceeding the two critical value, the phenomenon of creep failure will occur.