循环荷载作用下粉细砂累积变形的等效黏塑性本构模型

Equivalent viscoplastic model for cumulative deformation of sandy silt under long-term cyclic loading

提出了适用于长期循环荷载作用下粉细砂累积变形计算的等效黏塑性本构模型及数值模拟方法。该模型基于经典弹塑性理论框架及结构安定理论,考虑了砂土材料的双屈服面及剪胀性特征,引入塑性应变随加载次数的增量表达式,预测粉细砂土材料累积不均匀变形。通过粉细砂的动静三轴试验确定模型参数,并研究了砂土累积变形规律。数值模拟结果表明,该模型对于粉细砂长期循环累积塑性变形具有良好的模拟能力,而且计算步长可任选取,适用于长期循环加载的计算。

A new constitutive model, namely equivalent viscoplastic model, deformation computation of sandy silt under long-term cyclic loading is proposed adaptive to cumulative shakedown theory and in the classic elastoplastic theoretical frame with double yield characteristic taken into account. The equation of plastic strain increment proposed The model is based on surfaces and dilatancy is also introduced into the model. The comparison of the computational result with laboratory test data shows that the proposed model is capable of efficiently predicting the long-term cumulative deformation. Since the traditional stepby-step calculation is avoided, the proposed viscoplasticity framework can be used in the realistic boundary value problems under large number cyclic loading.