基于UU试验的原状黄土结构演化规律研究

Study on structural evolution law of undisturbed loess based on UU triaxial test

结构性对黄土的承载力、变形特点以及强度具有重要影响。为研究未受扰动情况下黄土的结构性演化,采用不固结不排水剪切试验的方法,研究黄土在常规三轴应力条件下压-剪过程中结构性演变的宏观试验规律。试验结果表明,初始含水率增加使黄土应力应变曲线从软化型向硬化型发展,围压增大促使应力应变曲线由弱硬化向相对强硬化转变,围压和含水率都对结构性演变具有重要影响。土结构在未受固结扰动的情况下,围压和初始含水率影响了结构演变的路径,低围压下结构衰减要快于高围压下;低含水率时,结构性衰减对围压较敏感,含水率升高后敏感程度降低。

The bearing capacity,deformation law and strength of loess are influenced by its structural characteristic. We concentrate on the structural evolution of undisturbed loess by performing unconsolidated- undrained shear tests to investigate the structural evolution under regular triaxial test characterized as compact- shear stress condition. The results show that increase of the initial water content turns the stress- strain curves from softening type to hardening type,while the confining pressure increment changes the stress- strain curves from weak hardening into relatively strong hardening,demonstrating that the two factors influence the structural evolution significantly. When the loess is not disturbed by consolidation process,both the initial water content and confining pressure have impacted on the structural evolution routine,the structure damps faster under lower confining pressure than it does under higher confining pressure. In a lower water content environment,the damping of the structure is more sensitive to confining pressure than it is under higher water content.