مقاله انگلیسی رایگان در مورد مدل سازی عددی فونداسیون سطحی بر روی خاک روانگرا – اسپرینگر 2018

Liquefaction is one of the most natural hazardous phenomena, which harms the constructed environment during earthquake. Effect of liquefaction phenomena in the form lateral sliding, settlement, punching shear failure and tilt. Structures situated at shallow depth and lifelines near around the area mostly affected by liquefaction and caused severe destruction and economic losses all over the world. Sometime structures are damaged so badly that it is uneconomical to repair and hence finally demolished. Earthquake-induced liquefaction is most frequently experiential in loose, saturated, clean sand deposits. This is due to loose sand tends to compress when a load is applied, disparate to denser sands which tend to dilate during shearing, at least after some strains are enforced. When the fully saturated soil is compressed, the water pressure tends to surge and tries to flow out from the soil to regions having lower pore water pressure. Though, if the loading is large enough and, applied dynamically many times at relatively high frequencies, as in case of an earthquake and other loadings, the undrained condition may result in partial or total effective stress loss called liquefaction. When liquefaction phenomenon occurs, the strength and stiffness of the soil decreases and the ability of a soil deposit to sustain structural load is dramatically reduced. The consequences of liquefaction are seen in terms of permanent deformation, building performance, and ground shaking. These consequences depend on site conditions, earthquake loading characteristics, and structures properties. Initial time researchers, (Seed and Lee 1966; Seed and Idriss 1971; Castro and Poulos 1977; Seed 1979; Seed et al. 1985; Kramer and Seed 1988) were focused on experimental work to understand the liquefaction phenomenon and cyclic mobility. While the physical phenomenon is well understood, analytical modeling and computer simulation remains a challenge due to complex behavior of soil under seismic loading. Even if liquefaction does not occur, the development of excess pore pressures may lead to excessive soil softening, weakening or to partial loss of stability and even to bearing capacity failures. Rational analysis for the prediction of earthquake generated pore pressures involves a fundamental description of the soil constitutive behavior. Basically, two-phase porous medium classified as uncoupled and coupled model has been used to study the liquefaction behavior numerically. Numerous investigators including (Finn et al. 1977; Nasser and Shokooh 1979; Liyanapathirana and Poulos 2002) studied the uncoupled investigation of liquefaction in which the response of saturated soil, without considering the effect of soil–water interaction is modeled. The pore water pressure generation and its effect model has been model separately using the results obtained like displacement and volumetric strain. The major dearth in the uncoupled approach is that it is incapable to justify the progressive stiffness degradation caused by pore pressures increment in the soil.