Abstract:  Landslide is a kind of geological hazard with wide distribution, large quantity and great harm. It is of great significance to determine the landslide sliding face accurately. Traditional exploration methods such as drilling and geophysical methods have many limitations in the undulating landslide terrain. Based on Dongchizhuang landslide in Pingshan County, Shandong Province, a soft soil landslide model with undulating terrain is established. Rayleigh wave field simulation is carried out and the horizontal/vertical (H/V) spectral ratio curve is calculated after model separation. The characteristics of wave field propagation and H/V spectral ratio curve are compared and analyzed. It is found that the peak frequency of the geophone in the center can be used as the superior frequency for calculating the earthrock interface in the 110channel geophone arrangement. Landslide models with soil thickness of 25, 31 and 35 m are designed, and it is found that there is a negative correlation between soil thickness and peak frequency. The frequencydepth empirical formula is given when the stratum is clay and mudstone, and the information of continuous sliding surface is obtained. The results of the empirical formula agree well with the actual model.

Key words: weak landslide, H/V spectral ratio curve, wave field simulation, peak frequency