基于β-屈服函数的炭质泥页岩统一硬化模型

Unified hardening model of carbonaceous shale based on β-yield function

炭质泥页岩普遍存在于中国西南地区矿山高边坡的软弱夹层中,在雨水浸润作用下容易发生劣化,进而对矿山高边坡的稳定性产生不利影响。在复杂加载条件下,炭质泥页岩会发生弹塑性破坏,表现出应变软化和剪胀等特点。将炭质泥页岩视作超固结黏土,基于β-屈服函数建立了相应的修正统一硬化模型。与修正剑桥模型的应力—剪胀方程相比,该模型能够更为准确地描述炭质泥页岩的剪胀特性。此外,借助β-屈服函数,该模型能考虑屈服面几何形状对模型计算结果的影响,从而提高模型的计算精度。将模型计算结果与炭质泥页岩等材料的排水三轴压缩试验结果进行对比发现,拟合效果较好,表明模型能准确描述炭质泥页岩的力学特性。

The carbonaceous shale is widely distributed in the weak intercalated layer of high mine slopes in southwest China,the stability of which would be affected by the rain infiltration induced delegation of the carbonaceous shale.Carbonaceous shale can be regarded as a typical elastro-plastic material as ductile failure can be observed under complex loading conditions,which is similar with the over-consolidated clays.This paper developed a modified unified hardening model for carbonaceous shale to account for the strain-softening and dilatancy features.Besides,a β-yield function was adopted to better capture the negative dilatancy deformation.Moreover,the proposed model is able to account for the effect of the shape of yield locus on the model predictions,and the model performance can be then improved.Model predictions were compared with the drained triaxial test results of carbonaceous shales,form which a well-agreement was achieved,and consequently the model’s performance was verified.