饱和重塑黄土的动力特性

Dynamic properties of saturated remolded loess

基于饱和重塑黄土的静、动力三轴试验结果,探讨了饱和重塑黄土的静、动力特性。分析了静力试验中饱和重塑黄土的应力-应变关系。根据动力试验结果研究了饱和重塑黄土轴向应变、动强度、有效应力路径和滞回圈的变化规律：轴向应变随着振动次数的增加逐渐增大,且变化曲线存在着明显转折点,在较低围压时,εa分为先平缓上升和后陡升至破坏两个阶段,在较高围压时,εa分为振动初期存在陡升然后平缓上升最后又陡升至破坏三个阶段。有效应力路径逐渐向左发展,且移动幅度逐渐加大。每一个振次的有效应力路径形成一个封闭的区域,试验过程中封闭区域的面积逐渐增大。随着振动次数逐渐增大,滞回圈的面积和倾斜度均逐渐增大。通过动弹模试验结果发现饱和重塑黄土在不同围压下1/Ed均随着εa的增大而增大,确定出不同围压下1/Ed~εa关系中的a、b值和最大动弹模Edmax;阻尼比λ随动应变εa的增大逐渐增大,且最终趋于稳定,给出不同围压下阻尼比λ的建议值,从而为指导工程实践提供参考。

Experiments on saturated remolded samples were carried out to study the static and dynamic properties of saturated remolded loess.The stress-strain curves of saturated remolded loess were analyzed in the static tests.Based on the results of dynamic triaxial experiments,the relationships among the axial strain,dynamic shear strength,effective stress paths,hysteresis loops and the number of loading cycles were studied.The results showed that the axial strain increased gradually with the number of cycles,and the axial strain curve variation had an inflexion point;under the lower confining pressure,the axial strain increased gently at the beginning then increase suddenly up to the failure of the samples;under the higher confining pressure,the axial strain exhibited a rapid increase at the outset and then the growth of the axial strain became slower,and increase sharply again at last of the axial strain.The effective stress paths gradually moved to left with the increase of cycles,and the degrees of movement increased gradually.The effective stress paths of each loading cycle consist of a closed area,and the region increased gradually.With the increasing of loading cycles,both the area and inclination of hysteresis loops increased gradually.Through the results from the dynamic elastic modulus tests of saturated remolded loess,we found that 1/Edincreases gradually with the axial strain under the different confining pressure,and the values of a,b and Edmax was determined from the relationship between 1/Edandεa.The damping ratioλincrease with the axial strainεaand reach to a stable value.The proposed values ofλunder the different confining pressures are determined base on the results：which provides a reference for the engineering practice.