【摘要】 剪切波速作为土性的基本参数,为评价土体抵抗地震液化的能力提供了一种方法。回顾了以剪切波速和地表峰值加速度为依据的场地地震液化判别方法的演化历史,依据他人收集的现场液化资料,合计49次地震、618例液化/不液化场地数据,提出了确定液化临界曲线的基本原则,给出了基于修正剪切波速与地表峰值加速度的液化临界曲线,验证了液化临界曲线的位置对细粒含量、有效上覆压力、震级等因素取值变化的合理性,分析了估计土层循环应力比CSR的剪应力折减系数、震级标定系数、有效上覆压力修正系数等因素的不确定性对液化临界曲线的敏感性。结果表明:液化临界曲线对各种影响因素具有很好的适用性。利用Monte Carlo模拟、加权最大似然法和加权经验概率法,给出了建议的液化临界曲线的名义抗液化安全系数与液化概率的经验关系式及概率等值线,并对核电厂Ⅰ类、Ⅱ类和Ⅲ类抗震物项地基,分别建议了相应的液化临界曲线。该方法以丰富的现场液化数据为依据,具有广泛的应用前景。更多还原

【Abstract】 As a fundamental parameter of soil, the shear wave velocity(denoted VS)offers a means to determine the seismic resistance of soil to liquefaction. The historical developments of VS and peak ground acceleration(denoted PGA) — — based assessment method of soil liquefaction potential is reviewed. The basic principle to determine liquefaction triggering curve is given.The corresponding liquefaction triggering curve is proposed based on the database used by Kayen, Andrus, Saygili and Chu for a total of 49 earthquakes, 618 case histories. The position of liquefaction triggering curve is verified with respect to various factors based on the case history database, such as fines content, overburden stress and magnitude scales. In addition, the sensitivity of the database’s interpretation to a number of aspects and components of the analysis framework is examined, such as the shear stress reduction factor that accounts for the dynamic response of the soil profile, the magnitude scaling factor, the overburden correction factor for cyclic stress ratio. And the results show these factors have slight effects on the position of the proposed liquefaction triggering curve. At last, the relationship between nominal safety factor and probability of liquefaction as well as the probabilistic contours for the proposed liquefaction triggering curve are given based on Monte Carlo simulation, the weighted maximum likelihood method and weighted empirical probability data. The soil liquefaction triggering curves are proposed for the seismic design category Ⅰ 、 Ⅱ and Ⅲ of the structure, system and component of nuclear power plants, respectively. The presented assessment is provided with wide application prospects.更多还原