Dynamics of Liquefaction During the 1987 Superstition Hills, California, Earthquake

Abstract

Simultaneous measurements of seismically induced pore-water pressure changes and surface and subsurface accelerations at a site undergoing liquefaction caused by the Superstition Hills, California, earthquake (24 November 1987; M = 6.6) reveal that total pore pressures approached lithostatic conditions, but, unexpectedly, after most of the strong motion ceased. Excess pore pressures were generated once horizontal acceleration exceeded a threshold value.

Responses of Liquefiable Soils in Pile Group Foundations of Tall Buildings from Shaking Table Tests

“…is scaled down to 8.8 s (by a factor of 0.1633) in Fig.5. The acceleration displays spikes associated with simultaneous drops in the pore pressure that have also been observed by other researchers (e.g., Holzer et al 1989). These acceleration spikes and pore pressure drops are identified by the numbers (1) to (15) in Fig.6.…”

Strong Ground Motion Estimation

“…This site shows historically one direct in situ observation of nonlinearity in borehole data. The Wildlife Refuge liquefaction array recorded acceleration at the surface and 7.5-m depth, and pore pressure on six piezometers at various depths (Holzer et al, 1989). The acceleration time histories for the Superstitio n H i l l s e v e n t s a t G L -0 m a n d G L -7 .5 m, respectively, are shown in Figure 4.5 (left).…”

“…The stress-strain loops form an S-shape and the strains are as large as 1.5%. At this depth, there is a piezometer (P5 according to Holzer et al, 1989). With this information it is also possible to reconstruct the stress path (bottom right of Figure 4.5).…”

“…This site is located in southern California in the seismically active Imperial Valley. In 1982 it was instrumented by the U.S. Geological Survey with downhole and surface accelerometers and piezometers to record ground motions and pore water pressures during earthquakes (Holzer et al, 1989). The Wildlife site is located in the flood plain of the Alamo River, about 20 m from the river's western bank.…”

Study of soft classification approaches for identification of earthquake-induced liquefied soil

“…(a) the nature of the sediments, the grain size and intragranular packing (Seed 1970;Holzer 1989); (b) earthquake hypocentral distance (Papadopoulos & Lefkopoulos 1993); (c) depth of the water table (Seed 1970;Roeloffs 1998); (d) depth of deposit (data available mainly down to a depth of 15 m Krinitzsky et al 1993); (e) nature and thickness of the cap rock; (f) degree of water saturation of the soil (Seed 1970;Roeloffs 1998); (g) earthquake-induced changes in the pore water pressure (Ishihara et al 1981); (h) regional topography (Seed 1970). Sarkar and Chander (2003) attributed the reasons of soil liquefaction to (a) shallow water table (less than 15 m) or (b) well-sealed clayey soil overlying thick liquefiable sediments, causing the released water to persist on the earth surface for several days after the main shock.…”