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通过对-6℃的冻结黄土及冻结改良黄土在1~15 MPa的围压范围内进行一系列的三轴试验,分析其变形和三轴强度特性。研究发现:随着围压的增大,冻土的应力-应变曲线相继体现出应变软化和应变硬化特征,初始切线模量随围压的增大呈现出先增大后减小的趋势;冻结黄土和冻结改良黄土的三轴强度随围压的增大表现出先增大后减小的趋势,改良后冻结黄土的强度得到明显的提高,且水泥比石灰的改良效果更为显著。基于莫尔-库仑强度准则,得到冻结黄土和冻结改良黄土的广义黏聚力和广义内摩擦角随围压的变化规律。同时,建立非线性莫尔-库仑强度准则,用以描述冻结黄土及冻结改良黄土的强度随围压非线性变化的现象。
A series of triaxial tests were carried out on the frozen loess at -6 ℃ and the frozen improved loess at a confining pressure of 1-15 MPa to analyze the deformation and triaxial strength characteristics. The results show that with the increase of confining pressure, the stress-strain curves of frozen soil show the features of strain softening and strain hardening successively. The initial tangent modulus increases first and then decreases with the increase of confining pressure. And the triaxial strength of the frozen improved loess tends to increase at first and then decrease with the increase of the confining pressure. The strength of the frozen loess is improved obviously after the improvement, and the improvement effect of the cement over the lime is more significant. Based on the Mohr-Coulomb strength criterion, the generalized cohesion and the generalized internal friction angle of frozen and loessified loess with the variation of confining pressure are obtained. At the same time, a nonlinear Mohr-Coulomb strength criterion is established to describe the non-linear change of the strength of frozen loess and frozen loess with the confining pressure.