Seismic waves in soil layers. Soil behaviour during recent strong earthquake / Сейсмические волны в слоях почвы. Поведение почвы во время недавнего сильного землетрясения

Soil response to seismic motion (cyclic dynamic loading) depends on the mechanical properties of the soil. Soil behavior under various conditions of loading is defined by one or the other of its mechanical properties. In conditions of heavy loading, soils can exhibit dynamic instability, when their deformability and the probability of destruction increase.

Dynamic properties of soils have been investigated since the 1900s and addressed in a number of renowned studies of K. Terzaghi, N.M. Gersevanov, V.A. Florin, Ya.I. Frenkel, M. Biot, and others. A qualitatively higher level of the research has been reached in the late 1960s and early 1970s after the catastrophic earthquakes of 1964 in Anchorage (Alaska) and Niigata (Japan) and the 1971 earthquake in California. Severe damage and economic losses caused by these earthquakes were associated with numerous cases of liquefaction of sandy soils. Since in those years the construc-tion of nuclear power plants began in the USA and Japan, investigation of dynamic properties of soils has become a research priority. The milestone developments were related to the studies of Hardin and Drnevich (1972), Casagrande (1975), Castro (1975), Castro and Poulos (1977), Ishihara et al. (1975, 1980, 1992, 1998, 1982, 1985), Youd et al. (1978, 1985), Seed (1968, 1978), Seed and Chan (1957), Seed and Lee (1966), Seed et al. (1976, 1992), Seed and Idriss (1970, 1971, 1982), Idriss and Seed (1967, 1968), Idriss (1990), Finn et al. (1977, 1978, 1986), Finn (2000), Lee (1976), Lee and Finn (1978) and others. To increase the reliability of estimation of the response of constructions on soil foundations in strong ground motion, elastic, filtering, damping characteristics of soils were studied, and the dynamic stability and changes in the rheological properties of soils under dynamic loading were evalu-ated, such as, the deformability and strength degradation. In laboratory experiments, nonlinear hysteretic stress–strain relations were obtained for various types of soils (Hardin and Drnevich 1972). <...>