Seismic deformation and failure modes and mechanism of soil mass

To study the seismic deformation effect of soil mass, a field investigation on slopes reinforced by shotcrete-bolt system and road embankments along Dujiangyan to Yingxiu highway was conducted. The investigation shows that the seismic deformation and failure modes of soil mass laterally unrestrained as slopes and road embankments are characterized by subsidences and lateral landslides, while soil mass laterally restrained by retaining wall is characterized by subsidences and concavo-convex deformation, i.e., alternative settling and bulging deformation. Seismic subsidence rate and concave-convex amplitude rise with the increase of seismic intensity and obey a normal distribution. Seismic damage level of the upper slope is affected by plane alignment of highway. The slope damage of a convex-curve section is more serious than a concave-curve section, and the damage of a linear section is most light. Shaking table tests of soil mass models laterally unrestrained or laterally bounded were conducted, and the results are consistent with the field investigation ones. The threshold of peak ground acceleration from subsidence to concave-convex deformation is approximate 0.6 times of gravity acceleration.