基于真三轴试验的黄土力学损伤特性研究

Study on Mechanical Damage Characteristics of Loess Based on True Triaxial Test

以真三轴仪为基础,模拟了在三维应力条件下Q_(2)黄土的受力状况,通过4个含水率、4个中主应力比、4个不同固结围压下的Q_(2)黄土真三轴试验,在研究了不同含水率下黄土的应力应变变化的基础上,研究了Q_(2)黄土的损伤特性变化规律。结论如下:基于不同含水率、不同中主应力比、不同固结围压下Q_(2)黄土全量剪切模量的变化规律,揭示了Q_(2)黄土损伤演化发展特性。同一固结围压、含水量条件下,不同中主应力比时损伤比变化曲线均趋于1,同一含水量条件下,随着固结围压增大,初始剪切损伤比逐渐减小;同一固结围压下,随着含水量增大,初始剪切损伤比逐渐增大。围压较大时,Q_(2)黄土的原生强度得到充分发挥,剪切初始损伤比较小,剪切过程中损伤比变化区间较大;含水率大时,Q_(2)黄土表现出原生结构强度较小,剪切初始损伤比较大,剪切过程中损伤比变化区间较小。

Based on the true triaxial apparatus in this paper,simulated under the condition of three dimensional stress state of stress on Q_(2)loess,moisture content through four,four principal stress ratio,confining pressure under four different consolidation of Q_(2)loess true triaxial test,the loess under different moisture content was studied on the basis of the stress and strain changes,the change law of damage characteristics of Q_(2)loess was studied.The conclusions as following:based on the shear modulus change laws of Q_(2)loess with different water content,a damage factor was expressed by the structural loess modulus,partly damaged loess modulus and disturbed loess.The change laws of damage factor with axial strain are showed under different consolidation pressure and stress path.The damage factor increases with shear strain development and equal 1.0 finally under different middle main stress ratio condition.And the initial shear damage factor is small at low b value.At the same consolidation pressure,the initial shear damage than gradually increasing with the moisture content increasing.When the confining pressure is high,the original strength of Q_(2)loess is fully exerted,the initial shear damage is relatively small,and the damage ratio varies in a large range during the shear process.When the moisture content is high,Q_(2)loess exhibits less strength of original structure,greater initial shear damage,and smaller change interval of damage ratio during shear.