液化土层上建筑物不均匀震陷的数值研究

Numerical study on earthquake-induced uneven settlement of liquefiable soil layers

饱和砂土地基在地震作用下液化引起的建筑物的不均匀沉降是地震破坏的典型特征之一,会导致建筑物倾斜和失效。建立模拟液化引起不均匀震陷的数值方法对结构抗震设计和工程减灾尤为重要。基于对不均匀震陷机制的认识,对可液化地基上某建筑物模型在输入地震波作用下的震陷情况进行了数值模拟试验,分析了不均匀震陷发展过程中地震动输入、基底动应力、孔隙水压力、地基压缩模量和结构沉降之间的关系,并提出一套数值计算液化引起地基不均匀震陷的方法。结果显示:(1)使用的孔压模型能够模拟孔压在不规则荷载作用下的上升,且能够反应固结比对孔压的影响,以及记录结构地基土体真实的孔压发展过程;(2)计算方法使用的压缩模量模型能够反应由孔压变化引起的时程变化;(3)计算方法能够跟踪记录土层变形随孔压上升的时程变化。

The earthquake-induced asymmetrical settlement of buildings on saturated soil layer is one of the typical phenomena in earthquake damages, which will lead to the inclination and the function loss of the buildings. Developing numerical methods for simulating the liquefaction-induced uneven settlements of the buildings is significant for seismic design of buildings and engineering disasters reduction. This paper investigated the relationship between inputting waves, vertical dynamic stresses, pore water pressures and building settlements, and proposed a new numerical method for calculating the liquefaction-induced uneven settlement. The results indicate ： （ 1 ） The pore water pressure model used in the method is able to simulate the process of water pressure rising during the irregular loads, and calculate the effect of the consolidation ratios on the pore water pressure variation, and attain the actual process of water pressure for the soils below the buildings ; （2） The compression modulus can reflect the variation of pore water pressure ; （3） The method is able to follow the tracks of the deformation process of the soil layers with the increasing of the pore water pressure.