Pore-Water Pressure Changes during Soil Liquefaction

by H. Bolton Seed, (M.ASCE), Prof. of Civ. Engrg.; Univ. of California, Berkeley, Calif.,
John Lysmer, (M.ASCE), Assoc. Prof. of Civ. Engrg.; Univ. of California, Berkeley, Calif.,
Philippe P. Martin, Grad. Research Asst.; Univ. of California, Berkeley, Calif.,

Serial Information: Journal of the Geotechnical Engineering Division, 1976, Vol. 102, Issue 4, Pg. 323-346

Document Type: Journal Paper


An analytical procedure is presented for evaluating the general characteristics of pore-water pressure buildup and subsequent dissipation in sand deposits both during and following a period of earthquake shaking. It is shown that in layers of fine sand, excess hydrostatic pressures may persist for an hour or more after an earthquake. However evidence of subsurface liquefaction may not appear at the ground surface until several minutes after the shaking has stopped and the critical condition at the ground surface may not develop until 10 min-30 min after the earthquake. However, for coarse sands and gravels with an impedance of drainage due to the presence of sand seams or layers, pore pressures generated by earthquake shaking may dissipate so rapidly that no detrimental build-up of pore pressure or a condition approaching liquefaction can develop. Improving the drainage capability of a sand deposit may thus provide an effective means of stabilizing a potentially unstable deposit. Analyses of the type described also provide the means for assessing whether subsurface liquefaction will have any serious effects on structures supported near the ground surface.

Subject Headings: Soil pressure | Soil liquefaction | Earthquakes | Pore water | Pore pressure | Layered soils | Subsurface environment | Drainage

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