Development of cyclic shear deformation characteristics test of soil under extreme nonlinear region

对286个场地进行了11次地震作用下的地震反应分析，结果表明，当量线性分析中，除位移外的地震运动指标最大，总应力是真正的非线性有效应力分析。利用482个循环剪切变形特性试验数据，对常用的应力-应变模型如双曲线模型和R-O模型进行了适用性检验。与双曲线模型相比，R-O模型在大应变情况下的适用性较差。考虑到这一点，提出了一种仅使用参考应变和剪切强度的应力-应变模型，并发展了一种新的试验方法，以再现地震过程中的地应力状态和加载条件。K0场地条件下的试验结果与常规各向同性应力条件下的试验结果相比，表现出不同的循环剪切变形特性。

Seismic response analysis on 286 sites is made under 11 earthquake motions showed that earthquake motion indices except displacement are largest in equivalent linear analysis, then total stress truly nonlinear and effective stress analyses.Applicability of frequently used stress-strain model such as the hyperbolic and the R-O models are examined by using 482 cyclic shear deformation characteristics test data. The R-O model shows less applicability at large strains than the hyperbolic model. Considering this, a new stress-strai model which uses only the reference strain and the shear strength is proposed.A new test method is developed in order to reproduce in-situ stress state and loading condition during earthquakes. Test results under K0 site condition showed somewhat different cyclic shear deformation charactetistics compared with conventional test result under isotropic stress conditions.