泾渭地区深层Q_(2)黄土工程力学特性的试验研究

Experimental Study on Mechanical Properties of Deep Q_(2) Loess in Jing-wei Area

Q_(2)黄土是中更新世沉积具有弱湿陷性和结构性的粘性土。文中以真三轴仪为基础,模拟了在三维应力条件下Q_(2)黄土的受力状况,进行了不同固结围压、含水率和中主应力比下Q_(2)黄土的真三轴试验,研究了不同含水率黄土的应力应变特性。得到了如下结论:通过4种含水率、4种中主应力比、4种不同固结围压下的Q_(2)黄土真三轴试验结果,分析了复杂应力条件下不同含水率、中主应力比率和固结围压条件下Q_(2)黄土的非线性应力应变特性。表明低含水率及固结围压条件下,随着中主应力比率的增大,应力应变曲线由强软化型逐渐转化为弱软化型或弱硬化型;同一固结围压及中主应力比率条件下,随着含水率的增大,应力应变曲线由弱硬化型或弱软化型转化为硬化型;同一含水率及中主应力比率条件下,随着固结应力增大,应力应变曲线由软化型转化为强硬化型。

Q_(2)loess is a kind of clay with weak collapsibility and structural properties in natural environment.Based on the new true triaxial apparatus made by the stress and strain relations and strength surface in stress space of Q_(2)loess with different water content were measured by the new true triaxial tests.The conclusions as following:Through true triaxial tests of Q_(2)loess,the nonlinear stress-strain characteristics of Q_(2)loess,changing with water content,consolidation pressure and principal stress ratios,is analyzed under the complex stress conditions.The stress-strain curves of loess with low water content is in the strongly softening type under low middle main stress ratio and in hardening type under high middle main stress ratio.The stress-strain curve of loess is from weak softening type transforming into harden type with increasing the water content.Stress-strain curves of loess is by the softening type transforming into the hard type with increasing consolidation stress under the same moisture content and the ratio of principal stress conditions.