不同应力状态下软黏土蠕变特性试验研究

土的蠕变性质受到许多因素的影响,在不同的应力条件下土会呈现出不同的性状。天津滨海吹填软土同样具有一般软土的蠕变特性,以其为研究对象,利用土体三轴流变试验机进行了三轴不固结不排水蠕变试验和单轴压缩蠕变试验,并选取了10个时间节点取样进行微型十字板剪切试验,研究抗剪强度变化规律。试验结果表明,单轴压缩蠕变和三轴蠕变历时曲线都具有非线性的特征,随应力水平的提高,单轴压缩蠕变的应力-应变等时曲线向应力轴靠拢,三轴蠕变的应力-应变等时曲线向应变轴靠拢;线性蠕变变形的情况下黏滞系数主要与时间有关,非线性的情况下与时间和应力水平都相关;在三轴蠕变状态下压缩模量随时间增长而减小,长期强度随时间先降低再趋于稳定;单轴压缩时压缩模量随时间增长而提高,长期强度随时间先增长后稳定。最后经过推导得出了不同应力状态下的长期强度随时间、偏应力的函数关系式。

Experimental study of creep property of soft clay under different stress conditions

The creep of soil is affected by many factors , behaving variable under different conditions. Tianjin Binhai dredger fill also has soft soil creep characteristics possessed by the general. Unconsolidated and non-drained triaxial tests and uniaxial compression creep tests were carried out with the soil triaxial rheological testing machine to study the creep characteristics of soft dredger fill, 10 time node samplings during creep have been selected for miniature vane shear test to study the variation of long-term strength. The results showed that: uniaxial compression creep and triaxial creep duration curve has a nonlinear characteristic, the isochronous curves deviated to the stress axis with the improvement of stress in uniaxial compression creep, while the isochronous curves deviated to the strain axis in triaxial creep. Viscosity coefficient is merely relative with the time under the linear condition, while associating with time and stress level on the nonlinear condition. In the three axis creep condition，the compression modulus decreases with the time increasing, the long-term strength firstly decreases and then tends to be stable over time. The uniaxial compression modulus increases with time increasing, Therefore the functional relations of the long-term strength are derived with time and deviatoric stress under different states of stress.