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对砂土类材料,各向异性状态参数定义为材料微观结构张量与标准化偏应力张量之间的联合不变量。通过在Lade破坏准则内耦合各向异性状态参数,建立了横观各向同性砂土类材料的破坏准则,并分别结合中密和密实的Santa Monica河滩砂的扭剪和真三轴实验资料进行了验证工作。研究结果表明:局部剪切带、加荷方向与材料主轴方向间的相对方位是影响砂土内摩擦角的主要因素;与扭剪实验和真三轴实验进行验证时均发现,当中主应力比b在0.18-0.85范围内时,由于砂样易出现局部的剪切带,这使砂样在达到其真正的峰值强度前破坏,从而使预测出的砂土内摩擦角均大于其实测值;但当b≤0.18和b≥0.85时,砂样始终呈现无剪切带的均匀变形破坏,因此预测出的砂土内摩擦角基本等于其实测值。这些研究结果说明了该横观各向同性砂土的破坏准则是合理的。
For sand-like materials, the anisotropic state parameter is defined as the joint invariant between the tensor of the material microstructure and the normalized deviatoric stress tensor. The failure criteria for transversely isotropic sand-soil materials were established by coupling anisotropic state parameters in the Lade failure criterion, and were respectively based on the torsional shear and true triaxial experimental data of the mid-dense and dense beach sand of the Santa Monica Verification work. The results show that the relative orientations of the local shear band, the loading direction and the principal axis of the material are the main factors that affect the internal friction angle of sand. When torsional shear test and true triaxial test are used to verify, the principal stress ratio When b is in the range of 0.18-0.85, the local shear band appears easily in the sand sample, which destroys the sand sample before it reaches its true peak intensity, so that the predicted sand internal friction angle is larger than the actual measured value. However, when b≤0.18 and b≥0.85, the sand samples always show uniform deformation and failure without shear band, so the predicted internal friction angle of sand is almost equal to the measured value. The results of these studies show that the damage criterion of this isotropic sand is reasonable.