渣场松散碎石土应力-应变特性研究

Stress-Strain Characteristics of Incompact Coarse-grained Soil in Slag Field

对取自某渣场边坡坡顶和坡底的2种松散碎石土试样,开展了4组大型三轴固结排水剪切试验,研究了松散碎石土剪切破坏过程中的应力与应变、体应变与轴向应变、实测泊松比随应力水平变化的关系以及邓肯-张E-ν和E-B模型的适用性。研究结果表明:①渣场松散碎石土应力-应变曲线基本呈硬化型、无显著峰值、强度参数φ与选取的应变标准关系密切且随应变标准的增加而变大;②松散碎石土在剪切破坏过程中基本呈单调剪缩,表明剪切过程中试样内部以颗粒平动引起的结构压缩为主,而由颗粒转动和力链调整引起的剪胀基本可忽略;③松散碎石土实测泊松比与应力水平基本呈线性关系,且坡顶与坡底料有较明显的差异。从实测泊松比与邓肯-张模型比较结果来看,邓肯-张E-B模型对坡顶料有较好的适用性,而坡底料比较适用于邓肯-张E-ν模型。

Four groups of large-scale triaxial consolidated-drained shear test were carried out on two types of incompact coarse-grained soil samples taken from the top and bottom of slope at a slag field.The relations of stress and strain,volumetric strain and axial strain,measured Poisson’s ratio against stress level,as well as the applicability of Duncan-Chang E-νand E-B models were examined.Research results demonstrated that:1)the stress-strain curve of the incompact coarse-grained soil displayed hardening features with no significant peak.Strength parameterφwas closely related to and augmented along with the increase of reference strain.2)The incompact coarse-grained soil showed monotonous shear shrinkage in the whole process of shearing,which indicated that the structural compression caused by translational motion of particles dominated the whole process,while the particle rotation and force chain adjustment were negligible.3)The measured Poisson’s ratio was in a linear relation with stress level,yet with an evident difference between top and bottom materials of slope.In addition,the Duncan-Chang E-B model had a good fitting result for the Poisson’s ratio of slope top materials,while the Duncan-Chang E-νmodel was more applicable for slope bottom materials.