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一、前言饱和松散的砂土地基,在强震情况下,可能会引起地基的液化破坏,造成建筑物失稳。液化现象,是地基土粒骨架应力与水的应力发生改变的结果。在正常情况下,建筑物地基应力σ_o全部由土粒骨架承担,即σ_o=σ′;但当遭遇地震时、砂土颗粒,由于受到震动,将由松散状态趋于密实,使孔隙水受到降压;同时也由于地震波历时短暂、排水受到限制,从而引起地基中孔隙水压力的瞬时升高,此时地基中的应力由下式表示;
I. INTRODUCTION Saturated and loose sand foundations, in the case of strong earthquakes, may cause liquefaction damage to the foundation and cause structural instability. The liquefaction phenomenon is the result of changes in the stress and water stress of the foundation particles. Under normal circumstances, the foundation stress σ_o of the building is entirely borne by the soil particle skeleton, ie, σ_o=σ′; but in the event of an earthquake, the sand particles, due to the vibration, will tend to be compacted by the loose state and cause the pore water to be depressurized At the same time, due to the short duration of the earthquake wave and the limitation of drainage, the pore water pressure in the foundation increases instantaneously. At this time, the stress in the foundation is represented by the following formula;