Abstract: In order to study the dynamic characteristics of saturated sand under cyclic loading, the calculation method of cumulative dissipated energy () of saturated sand under cyclic loading was established by taking the straight line as the migration curve, based on thermodynamic equilibrium conditions and particle entropy theory. A series of cyclic triaxial tests of saturated Nanjing fine sand were carried out, and the influence of factors such as initial cyclic stress ratio (CSR) and effective confining pressure (σ′c) on the liquefaction characteristics of Nanjing fine sand was investigated. The test results show that the cumulative dissipation energy is found to be consistent with a three-stage development law: slow growth stage, transition stage and rapid growth stage. The pore pressure ratio (ru) corresponding to the transition stage is about 0.6 to 0.7. The required cumulative dissipation energy to liquefy Najing fine sand is independent of CSR, but positively related to the effective confining pressure. The pore pressure ratio increases with the increase of cumulative dissipation energy. The function relationship between the cumulative dissipation energy and the effective confining pressure in the initial liquefaction is established, and the energy model of the development of pore pressure ratio is established based on the cumulative energy consumption ratio R.

Key words: geotechnical engineering, thermodynamic, dissipation energy, cyclic triaxial test, pore pressure ratio, effective confining pressure

摘要： 为了研究饱和砂土在循环荷载作用下的动力特性，从热力学平衡条件入手，结合颗粒熵理论，以直线为迁移曲线构建了饱和砂土在循环荷载作用下累积耗散能的计算方式；针对饱和南京细砂开展了循环三轴试验，探讨了初始循环应力比CSR、有效围压σ′c等因素对南京细砂液化特性的影响。结果表明：累积耗散能的发展表现出缓慢增长段、过渡段、急速增长段等3阶段特性，且过渡段对应的孔压比ru处于0.6～0.7的水平；液化所需的累积耗散能与初始循环应力比CSR无关，但与有效围压σ′c呈现出正相关关系；孔压比ru随着累积耗散能的增加而增大。构建了初始液化时的累积耗散能f与有效围压σ′c之间的函数关系，并以累积耗能比R为标准，建立了孔压比ru发展的能量模型。

关键词: 岩土工程, 热力学, 耗散能, 循环三轴试验, 孔压比, 有效围压