基于离心振动试验的深埋砂层液化研究

Liquefaction of Deep Buried Sand Layer Based on Centrifugal Vibration Test

砂层地震液化的判别经验一般在10~20 m深度范围内,基于离心振动试验研究30~40 m埋深砂层是否地震液化的问题。用密度较大的钢球堆积体模拟上覆土层,进行埋深15 m和25 m这2种情况下砂层离心机振动台试验,研究深部12.8 m厚砂层在地震作用下孔隙水压力发展规律并进行液化判别。试验表明,2种埋深条件下砂土超静孔隙水压力比均<1,未发现砂土液化现象。通过对比,砂土中各测点初始孔隙水压力和试验过程中的超静孔隙水压力随着上覆厚度增加而逐渐变大,但超静孔压比随着上覆厚度的增加逐渐减小,表明砂层埋深对抗液化能力提升明显。

In discrimination experience,seismic liquefaction typically occurs within the depth range of 10-20 meters in sand layers.In this study we explore whether seismic liquefaction occurs in sand layers of 30-40 meters depth via centrifugal vibration test.The overlying soil layer is simulated through the accumulation of high-density steel balls.By conducting centrifuge shaking table tests,we investigate the pore water pressure development within a 12.8-meter thick sand layer buried at depths of 15 and 25 meters,respectively,under seismic action,and subsequently assess the liquefaction susceptibility.Results reveal that the excess pore water pressure ratio in the sand remains well below 1 at both burial depths,indicating no liquefaction occurrence.Comparatively,initial pore water pressure and excess pore water pressure increase gradually with greater overburden thickness.However,the excess pore water pressure ratio diminishes with increased overburden thickness.This trend suggests that the increase of buried depth of sand layer can obviously improve liguefaction resistance.