Study on Dynamic Strength Characteristics of Malan Loess

Vibration effect is a major inducing factor of loess slope hazards and the basis of revealing loess slope mechanism, which often changes loess structure and decreases loess strength. Based on the GDS Lab System, the dynamic triaxial test was performed by using equivalent sine wave under strain controlling. The results are described as follows: (1)there is an obvious phenomenon of stress relaxation during the cyclic loading test on Malan loess, and the degree of stress relaxation decreases with the increase of confining pressure and dynamic strain. Under the low confining pressure, Malan loess reaches certain strain only by small dynamic stress within 2% strain ranges. Under high confining pressure, Malan loess will also reach certain strain value by small dynamic stress within 1% strain ranges. At the same time, with the increase of confining pressure, the peak value of dynamic stress increases gradually. (2)The dynamic failure stress of Malan loess increases linearly with the increase of confining pressure. The correlation coefficient is 0.99 and the linear regression equation is 6(d) = 0.00163 + 0.019. (3)On the basis of Molar Coulomb failure criterion, the index of dynamic strength was c =3.36kPa, phi=16 degrees. In comparison with the static strength, the internal friction angle decreases significantly while the cohesion slightly.