Abstract: Unloading fractures developed well in the superficial part of deep valley slope and was strongly weathered, which made subcutaneous layer a non-continuum and led to dielectric property difference. Seismic response in this area is complicated. Taking Dongshan slope in Qingchuan city as an example, we firstly analyzed the seismic monitoring data, and then simulated the dynamic response characteristics of the slope by using discontinuous deformation analysis method which is suitable for the analysis of rock slope motion process. We revealed the influences of epicentral distance, elevation, magnitude , terrain and T-shaped mountains and other factors on seismic peak ground acceleration (PGA). The results indicate that the seismic peak acceleration amplification factor at vertical ridge direction and higher elevation is larger, reaching 6.12 times; on the protrusion part of the terrain, seismic wave can also get a certain degree of amplification, reach 3.3 times; in the T- shaped ridge binding site, the PGA amplification ratio will be reduced to a certain degree.which greatly deteriorate its engineering properties. Latest research indicates that the increase of suction and inhomogeneous distribution mainly lead to the shrinking and cracking of expansive soil. However, few experiments about the expansive soil shrinking consider the effect of boundary condition on the shrinking process. In this research, pure montmorillonite is taken as test material,and its shrinking process in the presence of glass and vaseline friction boundaries are tested at different temperatures. The computer image processing technique is employed to quantify the geometric structure and morphologic characteristics of cracks. A conceptual model of shrinking and cracking of clay is established. Test results indicate that during the process of saturation-dehydration, cracks of specimens with vaseline-surface occur late and the critical water content of cracking is obviously lower than that of glass-surface specimens. At temperatures of 20℃, 30℃ and 40℃, the final amount of cracks of vaseline-surface specimen is smaller than that of glass-surface specimen by 70.3%, 79.6% and 77.6%, respectively. Additionally, in the presence of the same boundary friction, the pore water evaporation accelerates and the final amount of cracks increases with the increasing of temperature.

Key words: slope engineering, dynamic response, amplification factor, DDA, peak ground acceleration (PGA), prominent terrain rate montmorillonite, shrinkage, crack, boundary friction effect, temperature effeect