基于现场液化试验的饱和砂土孔压增量计算模型

采用现场液化试验，研究水平场地孔压增长模式，提出孔压增量计算模型。通过不同密实度砂土的液化试验，以加速度、埋深、砂土密实度等现场参数为指标构建孔压增量模型，发现现场和室内试验孔压增长模式的区别和联系，并验证该孔压模型的可靠性。研究结果表明：等幅循环荷载下，与现有动三轴等土单元试验的孔压增量随作用次数一直呈单调递减模式不同，现场试验孔压增量随作用次数呈现出先增大后减小的规律，中间存在阈值；通过参数分析和试验实例验证，构建的孔压增量计算模型，可更方便地用于随机荷载下水平场地的饱和砂土孔压计算。

An incremental model of pore pressure for saturated sand based on in-situ liquefaction test

Through in-situ liquefaction tests under dynamic artificial loading, the pore pressure variation of saturated sand in level ground is measured, and an incremental model of predicting pore pressure is proposed. Using the results of in-situ testing in different cases, a new incremental model is established considering acceleration, buried depth, density of sand, common properties used to describe soil characteristics in-situ. The correlation and difference of response for pore pressure increase between in-situ test and laboratory test are also analyzed. Parameter analysis and validation through in-situ liquefaction tests indicate that the new model is reliable. The number-of-cycle effect by in-situ tests is different from the results obtained from laboratory tests. The main conclusions are as follows: (1) Under uniform cyclic loading conditions, the variation of pore pressure increment in saturated sand in field is not monotonically decreasing with increasing numbers of cycles, but increasing at the beginning followed by decreasing after a specific number of cycles, which can be defined as a threshold number; (2) The proposed incremental model can also be used to predict pore pressure buildup of saturated sand under irregular loadings.