不同饱水强度灰岩应变特性及劣化损伤本构模型研究

Study on Strain Characteristic and Damage Constitutive Model of Limestone under Different Saturation Strengths

为研究饱水强度作用下灰岩的物理力学特性,对不同饱水强度的灰岩试样进行单轴压缩试验,分析其典型的应力-应变特征,并基于损伤力学理论建立损伤本构模型。结果表明,饱水强度加剧了灰岩的软化效应,高强度饱水灰岩的压密阶段相对延长,而弹性变形阶段相对缩短;随着饱水强度的增加,灰岩峰值强度呈线性降低,但饱水作用未对灰岩的破坏类型造成较大影响,仍以剪切破坏为主;损伤本构模型曲线和试验曲线高度吻合,说明建立的损伤本构模型是可靠的;随着饱水强度的增加,灰岩脆性和强度弱化,参数m和F_(0)分别呈二次函数和三次函数降低。

To investigate the physical and mechanical properties of limestone under the action of saturation strength,the uniaxial compression tests are carried out on limestone samples with different saturation strengths and its typical stress-strain characteristics are analyzed,then the damage constitutive model is established based on the theory of damage mechanics.The results show that,(a)the saturation strength aggravates the softening effect of limestone,the compaction stage of higher saturated limestone is relatively prolonged and the elastic deformation stage is relatively shortened;(b)with the increase of saturation strength,the peak strength decreases linearly,but the saturation environment has no great effect on the failure type of limestone,which is mainly shear failure;(c)the damage constitutive model is highly consistent with the experimental curve,showing that the damage constitutive model is reliable;and(c)with the increase of saturation strength,the parameters of m and F_(0) decrease in a quadratic function and a cubic function respectively.