不同地震波频率作用下砂土液化特性的振动台试验研究

The Study on the Liquefaction Characteristics of Sandy Soil under Different Seismic Wave Frequencies Using Shaking Table Tests

摘要: 为研究地震波频率对饱和砂土液化特性的影响，进行了振动台模型试验，对相对密实度为78%的饱和粉砂土模型加载不同频率的EI-Centro地震波，分析不同频率条件下土体超静孔隙水压力、超静孔压比及沉降变化规律。试验结果表明：在1 Hz和2 Hz频率条件下，土体均发生完全液化，其中1 Hz工况液化时间约为110 s，2 Hz工况液化时间约为65 s，孔隙水压力快速累积并导致有效应力消失；当频率增大至4 Hz时，土体仅在表层出现局部液化现象，中下部未达到液化判据。随着振动频率增大，砂土液化程度整体减弱，沉降量明显减小，液化临界加速度呈增大趋势。研究表明，地震波频率对砂土液化发展具有显著影响，低频振动更易引起饱和砂土发生液化，基于试验数据拟合得到液化临界加速度与频率的二次多项式关系式，可为场地液化评价及工程抗液化设计提供参考。

Abstract: To investigate the influence of seismic wave frequency on the liquefaction characteristics of saturated sandy soil, shaking table model tests were conducted using EI-Centro seismic waves with different frequencies. A saturated sandy soil model with a relative density of 78% was subjected to seismic loading, and the variations of excess pore water pressure, excess pore pressure ratio, and settlement under different frequency conditions were analyzed. The experimental results indicate that complete liquefaction occurred under frequencies of 1 Hz and 2 Hz. The liquefaction time was approximately 110 s for the 1 Hz condition and about 65 s for the 2 Hz condition, during which the excess pore water pressure rapidly accumulated and led to the loss of effective stress. When the frequency increased to 4 Hz, only partial liquefaction occurred near the surface layer, while the middle and lower layers did not reach the liquefaction criterion. With the increase of vibration frequency, the overall liquefaction intensity of sandy soil decreased, the settlement reduced significantly, and the critical liquefaction acceleration increased. The results demonstrate that seismic wave frequency has a significant influence on the development of sandy soil liquefaction, and low-frequency vibration is more likely to induce liquefaction in saturated sandy soil. A quadratic polynomial relationship between critical liquefaction acceleration and frequency was established based on experimental data, providing a reference for site liquefaction evaluation and engineering anti-liquefaction design.