复杂应力条件下砂土的强度规律及传统强度准则适应性分析

Adaptability of Sand Strength Change Laws Traditional Strength Criterion Under Complex Stress Condition

在砂土真三轴试验的基础上,分析了砂土在复杂应力条件下的强度变化规律,以及三个经典的强度理论(Lade-Duncan准则、Matsuoka-Nakai准则、Mohr-Coulomb准则)和真三轴试验之间的差异,探讨在复杂应力条件下经典强度准则的适应性,定量指出各个准则的强度误差。结果表明,在不同应力路径下,经典强度准则的常数项并不一直为常数,而是随着应力路径的变化而变化。在三个经典强度理论中,Mohr-Coulomb准则试验误差最大,Lade-Duncan准则试验误差最小。对于砂土,中主应力对强度参数φ值有一定影响。对于强度参数φ13随着中主应力比b值的增大而增大,在平面应变状态下(b=0.3左右)达到最大值,之后趋于稳定。

On the basis of true triaxial tests on sand, the strength variation of sand in the complex stress conditions, and the difference between the triaxial tests and three classical theory (Lade-Duncan criterion, Matsuoka-Nakai criterion, Mohr-Coulomb criterion) have been analyzed, the adaptability of three classical theory under complex stress conditions is to been explored, quantitative errors pointed out the strength of each criterion. The results show that the constant of the classic strength criterion is not constant under different stress paths, but changes with the change of stress path. In the three classical strength theory, Mohr-Coulomb criterion has the maximum experimental error, and Lade-Duncan criterion test error is minimized. For the sand, the principal stress has a certain influence on the strength parameters φ values. For strength parameters φ13, with the principal stress ratio b value increases, and the plane strain condition (b=0.3) reaches a maximum, and then stabilized.