深厚砂层强震液化机制数值分析

目前勘察规范对砂层液化的判断一般在20 m埋深范围内，为进一步确定强震条件下，深厚砂层在持续振动条件的液化情况，对某水电工程的地质情况建立二维模型，施加经过调整后的地震波，分别在自由场和上覆大坝两种情况下，运用有限差分软件FLAC3D进行震动液化的数值模拟。结果显示:对于埋深大于20 m的深厚砂层，在强烈震动条件下持续震动亦很难发生液化。坝址河床砂层液化易发生在河床两侧接近岸边附近。模型施加大坝后砂层上覆有效应力，对砂土的液化有明显的抑制作用，印证了增加上覆有效应力对抗液化的有效性。

Numerical Analysis of Liquefaction Mechanism of Deep Sand Layer under Strong Earthquake

At present, the judgment of sand layer liquefaction in the survey specification is generally within 20 m. in order to further determine the liquefaction condition of deep sand layer under continuous vibration condition, a two-dimensional model is established for the geological condition of a hydropower project, and the adjusted seismic wave is applied. In the two cases of free field and overlying dam, the finite difference software FLAC3D is used for the numerical simulation of vibration liquefaction. The results show that it is difficult to liquefy the deep sand layer with a depth of more than 20 m under strong vibration. The liquefaction of sand layer in the river bed of the dam site is easy to occur near the bank on both sides of the river bed. After the model is applied to the dam, the overlying effective stress of the sand layer can obviously inhibit the liquefaction of sand, which proves the effectiveness of increasing the overlying effective stress of the sand layer against liquefaction.