自重、渗流及地震耦合作用下人工岛动力稳定性分析

Dynamic stability of an artificial island triggered by self weight,seepage and earthquake

针对人工岛在自重、渗流、地震等耦合作用下动力稳定性研究较少的现状,以某人工岛边坡为例,首次将强度折减动力分析法引入到人工岛动力稳定性分析中,建立有限元数值分析模型,采用Finn-Byrne和修正Hardin-Drnevich动力本构,对多场耦合作用下人工岛液化范围、受力情况及动力稳定性进行分析。计算表明:1在设防烈度地震作用下,人工岛能够满足动力稳定性要求,由于海底淤泥层抗剪强度很低,地震下的最终破裂面由抛填块石下部与淤泥层共同组成;2岛内侧降水,使得海水渗流方向由岛外指向岛内,增加岛外侧土体有效应力,提高其抗液化能力,降低了岛内土体的有效应力,因此地震作用下内侧土体更易液化;3由于受到周围土体的约束作用,土体局部液化不会产生液化大变形,只有液化土体较多才会产生大变形。研究结果为人工岛动力分析提供参考。

Because there are few papers published about dynamic stability of an artificial island under coupled actions of gravity,seepage,and earthquake,the strength reduction dynamic analysis method was introduced to study the dynamic stability of an artificial island. Its finite element model was built,the dynamic constitutive equations of FinnByrne and the modified Hardin-Drnevich were used for this artificial island under multi-field coupled actions. Its scope of liquefaction,stress distribution,and dynamic stability were analyzed. Calculation results showed that 1） this island can meet the requirement of dynamic stability under earthquake,because shear strength of muck layer is quite low,the final fracture surface is composed of the lower part of stones filled and mud layer under earthquake; 2） owing to precipitation,water seepage flows from outside to inside of the island,the effective stress and liquefaction resistance ability of soil increase in the outside of the island,however,those in inside of the island drop lower,so the soil in inside is more likely to be liquefied; 3） due to constraints of surrounding soils,soil local liquefaction doesn＇t lead to high deformation,only more liquefied soil does. The results provided a reference for dynamic analysis of artificial islands.