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针对福建标准砂,进行了系列真三轴排水剪切试验,重点探讨了应力路径、中主应力系数对砂土应力-应变关系、广义剪应力比-应变关系及抗剪强度指标的影响,并利用试验实测的三轴拉伸和压缩条件下的内摩擦角及不同中应力系数条件下的强度实测值,验证了岩土材料非线性统一强度模型在π平面上的强度包线。试验结果表明,应力路径完全相同的情况下,砂土的抗剪强度q和广义剪应力比q/p随中主应力系数的增大而减小,强度指标?随中主应力系数的增大而增加;中主应力系数越大,砂土的剪胀特性越明显;不同应力路径对砂土应力-应变关系影响很大,但对应力比-应变关系及抗剪强度指标?的影响相对较小;岩土材料非线性统一强度模型能够很好地描述砂土的非线性强度特性。
A series of true triaxial drainage shear tests were carried out for Fujian standard sands. The stress path, the relationship between stress factors and stress-strain relationship, generalized shear stress ratio-strain relationship and shear strength index were discussed. The strength envelope of the nonlinear uniform strength model of geomaterials in the π plane was verified by the measured internal friction angle under triaxial tensile and compressive conditions and the measured values under different medium stress coefficients. The experimental results show that under the same stress path, the shear strength q and generalized shear stress ratio q / p of sand decrease with the increase of the principal stress coefficient, and the strength index? Increases with the increase of the principal stress coefficient But the dilatancy characteristics of sand are more obvious. The different stress paths have a great influence on the stress-strain relationship of sand, but the relative stress-strain relationship and the shear strength index are relatively The non-linear unified strength model of geomaterials can well describe the nonlinear strength characteristics of sand.