为计及岩土类材料塑性力学行为的中主应力影响或应力路径相关性,通常将应力张量Lode角/Lode数引入屈服函数与塑性势函数.由此在计算塑性应变增量时必然涉及Lode角/Lode数对应力的导数张量(记为T).然而,应力张量主值有重根时T的计算存在困难.论文给出了T的主值计算方法及谱分解表达式并详细讨论了张量T的基本性质. In order to account for the influence of middle principal stress or stress path in the plastic behavior of geotechnical materials, the stress tensor Lode / Lode is usually introduced into the yield function and the plastic potential function, which inevitably involves in calculating the plastic strain increment Lode angle / Lode number of the stress tensor (denoted as T) .However, the main value of the stress tensor when there are many difficulties in the calculation of T. The paper gives the principal value of T and spectral decomposition of expressions and detailed The basic properties of tensor T are discussed.