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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。
As a basic parameter of soil properties, shear wave velocity provides a method for evaluating the ability of soil to resist seismic liquefaction. Based on the field liquefaction data collected by others, a total of 49 earthquakes and 618 liquefaction / liquefaction site data were reviewed. The critical liquefaction threshold , The liquefaction critical curve based on modified shear wave velocity and surface peak acceleration is given and the rationality of liquefaction critical curve position on the change of value of fine particle content, effective overburden pressure and earthquake magnitude is analyzed. The sensitivity of the uncertainty of the liquefaction threshold to the uncertainty of the cyclic stress of the soil layer compared to the CSR coefficient of shear stress reduction, magnitude calibration factor, effective overburden correction factor and other factors is estimated. The results show that the liquefaction critical curve has good applicability to various influencing factors. Using Monte Carlo simulation, weighted maximum likelihood method and weighted empirical probability method, the empirical relationship and probability contour of the proposed liquefaction safety factor and liquefaction probability are given, Ⅱ and Ⅲ earthquake-resistant materials foundation, respectively, proposed the corresponding liquefaction critical curve. The method is based on a wealth of on-site liquefaction data and has a wide range of application prospects.