陕西子洲原状黄土平面应变试验研究

Study on the Plane Strain Test of Shaanxi Zizhou Undisturbed Loess

采用多功能三轴压缩仪对陕西子洲原状黄土进行常规平面应变试验及单侧限平面应变试验,分析含水率、围压及侧限条件对原状黄土强度的影响,结果表明:除土样在低含水率、小围压条件下产生脆性破坏外,原状黄土的应力应变关系曲线大多呈强硬化型;在围压一定的情况下,含水率越大,达到同一应变时的主应力差越小,含水率对黄土的结构强度起削弱作用;在含水率一定的情况下,围压越大,黄土的强度越大,达到同一应变时主应力差越大,围压对黄土的结构强度起增强作用;单侧限条件下,土样的应力应变曲线与双侧限呈现相同规律,且同荷载下单侧限土样变形大于双侧限条件下的变形;一定含水率范围内,随着含水率的增大,黏聚力减小,内摩擦角变化幅度不大。

Reformed TS-526 multi-function triaxial compression apparatus were used to carry out conventional plane strain tests and unilateral limit plane strain tests on undisturbed loess of Shaanxi Zizhou,and analyzed the influence of moisture content,confining pressure and confining condi-tions to the strength of undisturbed loess . The results show that in addition to the soil samples with low moisture content and small confining pressure produce brittle fracture,the stress-strain curves of loess show most of hardening types;In the same confining pressure cases,the higher moisture content is,the lower principal stress difference under the same strain is,moisture content plays a weakening effect on loess structure strength;In the same moisture content cases,the higher confining pressure is,the higher loess strength is,and the higher principal stress difference under the same strain is,confining pressure plays a enhancing effect on loess structure strength;Stress-strain relation curves of soil samples with unilateral limit condition are similar to the relation curves of conventional plane bilateral limit condition,and under the same confining pressure,samples de-formation under unilateral limit condition is higher than that of bilateral limit condition;Within a certain moisture content,c decreases with the in-crease of moisture content,variance of φ is not sharp.