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针对黄土的竖向裂隙及强化联结与水平面内各向同性的横观各向同性结构,沿竖向分别施加大、中、小主应力,进行了不同固结围压常中主应力比值的固结排水真三轴试验研究。依据八面体平面上应力状态域关于竖向主应力轴的几何对称关系,分析了竖向和任意水平向施加大主应力的三个空间域不同中主应力比值子午平面的强度变化规律,以及粘聚力和内摩擦角随中主应力比值的变化规律;得到了横观各向同性结构黄土在八面体平面上关于竖向主应力轴对称的强度破坏面。在假定沉积面内正交两个主应力轴相对于竖向主应力轴无旋转的条件下,应用Lade提出的竖向主应力轴与沉积面内正交两向主应力对角线轴平面内主应力空间旋转的描述方法,对3?-SMP各向同性强度表达式进行修正,建立了横观各向同性的3?-SMP强度准则。与黄土试验结果相对比,表明该准则描述横观各向同性黄土的三维空间强度破坏面具有较好的适用性。
In view of the vertical fractures of the loess and its transversely isotropic transversely isotropic structure, large, medium and small principal stresses are applied vertically and the normal principal stress ratios of different consolidation confining pressures are fixed True triaxial test of drainage. According to the geometrical symmetry relationship between the stress state of the octahedral plane and the vertical principal stress axis, the variation of the strength of the meso-meridian plane with different medium-principal stress ratios in the three spatial domains under vertical and arbitrary horizontal principal stresses is analyzed. Cohesion force and internal friction angle with the ratio of the principal stress, and obtained the axial symmetry strength failure plane of the transversely isotropic structural loess on the octahedral plane. Under the assumption that the two principal stress axes orthogonal to the vertical principal stress axis are not rotated in the sedimentary plane, the vertical principal stress axes proposed by Lade and the two principal principal stress diagonal axes in the plane of deposition The stress space rotation method is used to modify the isotropic intensity expression of 3? -SMP, and the transverse isotropic 3? -SMP strength criterion is established. Compared with the loess test results, it shows that the criterion has good applicability in describing the failure of three-dimensional space strength of transversely isotropic loess.