广义位势理论本构模型的加卸载准则探讨

Discussion on Loading-unloading Criterion of Constitutive Model Based on the Generalized Potential Theory

经典弹塑性理论一般通过屈服函数来确定加卸载准则。由于土体的应力应变特性比较复杂,因此,建立屈服函数的过程也较为复杂,通常需要较多的假设。广义位势理论从数学原理出发,直接建立岩土材料的本构模型,具有明确的数学依据和较少的物理假设,建模精度高。从数学角度来看,加卸载准则是广义位势理论中状态方程的分段条件。该文从数学原理和状态方程的确定方法出发,提出了分段型加卸载准则,该准则物理意义明确而且简单实用。最后,以基于广义位势理论的类剑桥模型为例,说明分段型加卸载准则的建立步骤及其合理性。

The loading-unloading criterion is generally determined by the yield function in classical elasto-plastic theory.Due to the complexity of the stress-strain characteristics of soil,the process of establishing the yield function is also complicated,and sometimes more assumptions are needed.Based on mathematical principles,the generalized potential theory directly establishes the constitutive model of geotechnical materials,which has clear mathematical basis and less physical hypothesis.The modeling accuracy of this theory is high.From the mathematical views,loading-unloading criteria are piecewise conditions of state equation in the generalized potential theory.Therefore,based on the mathematical principle and the determination method of state equation,this paper proposes the piecewise loading-unloading criterion,which has clear physical meaning and is simple and practical.Finally,the Similar Cam-clay model based on generalized potential theory is taken as an example to illustrate the establishment steps and the rationality of the piecewise loading-unloading criterion.