Abstract:

Loess seismic subsidence is a type of disaster when the earthquake occurred in a loess area. The characteristics of loess seismic subsidence with depth is studied by indoor dynamic triaxial test of 5 groups of original Malan loess Q3 samples in different depths. The results show that: (1) In terms of natural water contend, humidification or dehumidification, the depth of the loess seismic subsidence, with the increase dynamic stress, has a process of from smooth to rapid lowering, and then converging to the maximum depth of seismic subsidence. (2) Dynamic stress intervals are different corresponding to stages, interval in rapid lowering stage becoming narrow; the minimum dynamic stress shrinking with increase of water content; and the minimum dynamic stress can lower by 30% in term of 20% comparing to 5%. (3) The maximum depth of loess seismic subsidence is found and it is not affected by the dynamic stress and water content. Only the water content is able to reduce minimum dynamic stress when reaching maximum depth of the seismic subsidence and speeds up the development process. At last, the loess seismic subsidence curves of the depth converging to the maximum of depth of seismic subsidence with increasing of the dynamic stress; and in this experiment the maximum depth is 15.5 m.

Key words: depth characteristics of loess seismic subsidence, maximum depth, water content, dynamic stress, humidification, dehumidification