In engineering practice, the liquefaction potential of a sandy soil is usually evaluated with a semi-empirical, stress-based approach computing a factor of safety in free field conditions, defined as the ratio between the liquefaction resistance (capacity) and the seismic demand. By so doing, an estimate of liquefaction potential is obtained, but nothing is known on the pore pressure increments (often expressed in the form of normalized pore pressure ratio r_u) generated by the seismic action when the safety factor is higher than 1. Even though r_u can be estimated using complex numerical analyses, it would be extremely useful to have a simplified procedure to estimate them consistent with the stress-based approach adopted to check the safety conditions. This paper proposes such a procedure with reference to both saturated and unsaturated soils, considering the latter as soils for which partial saturation has been artificially generated with some ground improvement technology to increase cyclic strength and thus tackle liquefaction risk. A simple relationship between the liquefaction free field safety factor FS, and r_u(S_r) is introduced, that generalizes a previous expression proposed by Chiaradonna and Flora (Geotech Lett, 2020. https://doi.org/10.1680/jgele.19.00032) for saturated soils. The new procedure has been successfully verified against some experimental data, coming from laboratory constant amplitude cyclic tests and from centrifuge tests with irregular acceleration time histories for soils having different gradings and densities.

在工程实践中，通常使用基于半经验，基于应力的方法来评估砂土的液化潜力，该方法计算在自由场条件下的安全系数，定义为液化阻力（容量）与地震需求之间的比率。通过这样做，可获得液化潜力的估计值，但是当安全系数高于1时，地震作用产生的孔隙压力增量（通常以归一化孔隙压力比r _u形式表示）一无所知。虽然_你可以使用复杂的数值分析来估算，如果采用简化的程序来估算它们与检查安全条件所采用的基于应力的方法一致，将非常有用。本文针对饱和土和不饱和土提出了这样的程序，将后者视为已通过一些地面改良技术人为地产生了部分饱和度的土壤，以提高循环强度并从而解决液化风险。自由液化场安全系数FS与r _u（S _r），引入了Chiaradonna和Flora（Geotech Lett，2020。https：//doi.org/10.1680/jgele.19.00032）针对饱和土壤提出的先前表达式。该新方法已经成功地针对一些实验数据进行了验证，这些数据来自于实验室恒定振幅循环测试以及具有不同等级和密度的土壤的不规则加速时间历史的离心测试。