水泥土应力-应变特性真三轴试验研究

True triaxial test on stress-strain characteristics of cement-soil

采用研制的真三轴仪对水泥土进行等小主应力3σ、等中主应力参数b真三轴试验,研究中主应力参数、小主应力对水泥土应力-应变特性的影响。试验结果表明,相同σ3条件下,水泥土应力-应变曲线的初始切线模量、破坏强度均随b的增大而增加,破坏时的大主应变则随b值的增大而减小;水泥土破坏强度与中主应力参数b近似呈线性关系,直线斜率随σ3的增加而增大。对于相同b值,水泥土的应力-应变曲线初始切线模量、破坏强度、破坏时的大主应变均随σ3的增加而增大;水泥土破坏强度与σ3近似呈线性关系,且随b值的增大,线性关系更加明显。随着中主应力和σ3的增大,水泥土应力-应变曲线逐渐由软化型向硬化型过渡。破坏应力比则随σ3的增加和b值的增加而逐渐降低。获得了水泥土的广义Tresca准则和广义Mises准则模型参数,对比分析表明广义Tresca准则更适用于水泥土。

To investigate the influence of intermediate principal stress factor b and minor principal stress on stress-strain characteristics of cement-soil, true triaxial tests are conducted under the conditions of constant minor principal stress σ3 and intermediate principal stress factor b. The results show that both the initial tangent modulus and the peak strength of cement-soil have positive correlation with b; however, the correlation between major principal strain at failure state and b is opposite. What＇s more, there is a linear relationship between the peak strength and b, and the straight slope increases with the minor principal stress. For the same value of b, the initial tangent modulus, the peak strength and the major principal strain of cement-soil increase with increasing minor principal stress. The peak strength linearly rises with confining pressure as b is increased. The stress-strain curve changes gradually from softening type to hardening type, along with the increasing of confining pressure and intermediate principal stress. Failure stress ratio becomes lower due to the increased σ3 and intermediate principal stress factor b. Finally, the parameters of the generalized Mises yield criterion and the generalized Tresca yield criterion are obtained. Comparative analysis shows that the former criterion is superior to the latter criterion to describe the mechanical behavior of the cement-soil.