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研制真空压缩装置以制备不同强度的粉土土样,并进行动三轴试验,测试不同强度粉土的液化特性。建立了土的强度与动剪应力比的关系,确立孔压增长模型及其参数,探讨土的强度和动应力对液化的影响。结果表明,(1)真空压缩装置制备土样过程中,土体超孔压在24 h内基本消散完毕,28 d贯入阻力达300～400 N,不排水抗剪强度达8 kPa,达到黄河口软弱土的强度;(2)土的强度与动剪应力比基本呈线性关系,且土的强度越高,孔压增长曲线越呈现上凸趋势,破坏时的孔压比也越大;(3)指数模型能够较好模拟黄河口粉土孔压增长情况,其中参数a和b分别位于0.77～5.63和0.17～4.65之间;对于孔压比上限,参数a,b分别为0.92和4.65;孔压比下限,参数a,b分别为1.25和0.89。
The vacuum compression device was developed to prepare silt soil with different strength, and the dynamic triaxial test was carried out to test the liquefaction characteristics of silts with different intensities. The relationship between soil strength and dynamic shear stress ratio is established. The pore pressure growth model and its parameters are established. The influence of soil strength and dynamic stress on liquefaction is discussed. The results show that (1) during the preparation of soil samples by vacuum compression device, the excess pore pressure of soil is basically dissipated within 24 h, the penetration resistance reaches 300-400 N at 28 d, and the undrained shear strength reaches 8 kPa, reaching the Yellow River (2) The relationship between soil strength and dynamic shear stress ratio is basically linear, and the higher the soil strength, the more the pore pressure growth curve is convex upward, and the pore pressure ratio at the time of failure is also larger; ( 3) The exponential model can better simulate the pore pressure growth of the Yellow River mouth silt, in which the parameters a and b are located between 0.77 and 5.63 and between 0.17 and 4.65 respectively; for the upper limit of pore pressure ratio, the parameters a and b are 0.92 and 4.65 respectively; Hole pressure ratio lower limit, the parameters a, b were 1.25 and 0.89.