【摘要】 基坑开挖时坑底土体在卸荷作用下会处于三轴拉伸状态 ,剑桥模型采用的扩展 vonMises准则将高估土体的三轴拉伸强度 ,因此利用变换应力法将剑桥模型从三轴试验的轴对称应力状态扩展至一般应力状态 .改进后的剑桥模型采用 SMP准则能较好地反映基坑工程中坑底土体在三轴拉伸状态下的强度和变形特性 ,预测的坑底隆起变形比较可靠更多还原

【Abstract】 The research shows that the soil on the bottom of excavation is sometimes the triaxial extension state under the unloading condition. The extended von Mises criterion used by the Cam Model grossly overestimates strength in triaxial extension. The predicted result is an error as the soil at the bottom of excavation takes on large tension stress. The Cam Model is extended to the three dimensional model by the transformed stress method. The failure criterion of the new model adopts SMP type, which can well reflect the strength and deformation characteristics of the soil in triaxial extension. The predicted heave displacement is more reliable.更多还原