液化对地表运动影响的现场试验研究

Effect of soil liquefaction on ground motion using artificial vibration

通过现场人工激震土体液化试验，研究液化对地表地面运动的影响，以求从一个新的角度得到地表运动与液化关联性的认识。设计了受到不同震动幅值下3种不同密实度的饱和砂土样人工激震试验，得到了其液化水平与地表加速度的关系以及液化对地表运动的影响规律，试验结果表明：荷载较小不足以使砂土发生完全液化时，砂土相对密度对孔压上升极限值起控制作用；荷载能使砂土液化时，砂土相对密度对孔压上升速率起控制作用，其中密实砂土最为敏感；以孔压比作为液化水平特征量，液化土体开始影响土表加速度的孔压比门槛值在0．3左右，液化土体削减地表加速度的孔压比在0．3-0．7之间，该值与饱和砂土的相对密度正相关、与荷载幅值负相关，而液化土体显著影响地表加速度的孔压比在0．7以上。

By means of artificial vibration triggering liquefaction, the effectled that the correlation of soil liquefaction and ground motion is acquaintedof liquefaction on ground motion is stud-in a new way. Three artificially vibratingtests of three relative-density saturated sands under different amplitudes loading are conducted to obtain the groundacceleration with respect to liquefaction, and the influence of liquefaction on ground motion. The test results indi-cate ： （ 1 ） when the loading is too small to trigger liquefaction, the pore water pressure increasing limit is controlledby relative density; （2） when the loading can trigger liquefaction, the relative density controls the rate of pore waterpressure increase typically for the dense sand; （3）liquefaction starts to affect ground acceleration at pore waterpressure ratio around 0.3, and then decreases ground acceleration between pore water pressure ratio 0.3 to 0.7,and remarkably affects ground motion with pore water pressure ratio above 0.7. These typical pore water pressureratios are positively related to sand relative densities, but negatively related to loading.