不同中主应力下压实黄土变形特性的真三轴试验研究

True triaxial tests on the deformation characteristics of compacted loess with different intermediate principal stress

通过压实黄土在不同中主应力系数和不同σ3时的真三轴试验,研究了中主应力对压实黄土变形特性的影响。研究表明：随着中主应力系数的增大,达到同一主应变的主应力差σ_1～σ_3越大,且曲线从一开始就呈硬化型,证明中主应力对压实黄土的强度有一定的加固作用。不同的中主应力系数下,ε_1～ε_v关系曲线除b=1之外均出现“峰值”,且大约在主应变发展至4%～6%左右出现了交叉,交叉后曲线变化有明显的区间效应。随着中主应力系数b的增加,达到相同广义剪应变对应的广义剪应力q也越大。对广义剪应力与平均主应力比（q/p）与主应变（ε_1）归一化,随着b值的增加,曲线依次降低。在b=0～0.5之间,曲线之间的区分度较好,曲线降低幅度较大。b=0.5～1之间曲线之间的区分度较差,曲线几乎重合。

Through true triaxial tests on compacted loess with different intermediate principal stresses coefficients and different σ3, the effect of the intermediate principal stress on the deformation characteristics of compacted loess is examined. The test results show that with the increasing coefficient of the principal stress, achieving the same principal strain needs higher principal stress difference, and the relation curves from the beginning shows hardening phenomenon, indicating that the intermediate principal stress has certain reinforcement effect on the stress strength of the compacted loess. Under different coefficients of the intermediate principal stress, the ε1 and εv relationship curve shows the ＂peak value＂ except when b is 1, and the curves appear the cross when the main strain develops to about 4% - 6%. After the cross the curves changes have an obvious interval effect. With the increasing coefficient of the principal stress b, achieving the same generalized shear strain corresponds to the higher generalized shear stress q. With the increase of b, the relation normalization curve between the ratio of the generalized shear stress to the average principal stress （p/q） and the principal strain declines remarkably. When b varies between 0 and 0.5, the curves have better discrimination, and reduce more rapidly. When b ranges from 0.5 to 1, the curves have poorer discrimination and are nearly in a doublication state.