An advanced grain-based model to characterize mechanical behaviors of crystalline rocks with different weathering degrees
An advanced grain-based model to characterize mechanical behaviors of crystalline rocks with different weathering degrees
复制标题
一种先进的基于颗粒的模型，用于表征不同风化程度结晶岩石的力学行为
DOI：
10.1016/j.enggeo.2020.105951
复制
发表时间：
2021-01-01
影响因子：
7.4
通讯作者：
Tai, Daping
中科院分区：
文献类型：
--
作者：
Huang, Xiaolin;Qi, Shengwen;Tai, Daping
室内试验表明，随着风化程度的提高，结晶岩在无侧限压缩下的峰前应力-应变力学响应明显地从近似线性转变为非线性，宏观力学性能也随之减弱。然而，到目前为止，很少有数值研究定量描述结晶岩石受风化程度影响的力学行为由强到弱的转变。提出了一种改进的基于颗粒的模型(AGBM)，该模型使用通用离散元代码(UDEC)来描述不同风化程度的结晶岩石的力学特性。风化引起的组织劣化表现为晶界的松动和性能的减弱。结果表明，考虑压缩硬化非线性变形和拉伸或剪切线性弹性变形的颗粒接触模型是可行的，适用于描述不同风化程度的结晶岩的力学行为。颗粒接触的压缩硬化变形对裂纹闭合、裂纹模拟、裂纹稳定扩展和不稳定扩展的宏观非线性应力应变关系和应力门槛值有显著影响。我们对风化引起的结晶岩石宏观力学特性的削弱有了新的认识，这是由于颗粒接触变形性能的减弱而不是颗粒接触强度的减弱。
Laboratory tests revealed that by enhancing the weathering degree, a transition of pre-peak stress-strain mechanical responses of crystalline rocks under unconfined compression from approximate linearity to nonlinearity was evident, as was the weakening of macro-mechanical properties. However, thus far, very few numerical studies have been conducted to quantitatively characterize the strong-to-weak transition of the mechanical behaviors of crystalline rocks modulated by the weathering degree. We propose an advanced grain-based model (AGBM) using Universal Distinct Element Code (UDEC) to characterize mechanical characteristics of crystalline rocks with different weathering degrees. The weathering-induced deterioration of microstructures was treated as loosening of grain contacts and weakening of their properties. It was proved that the grain contact model that considered hardening nonlinear deformation in compression and linearly elastic deformation in tension or shear was feasible and applicable to characterize the mechanical behaviors of crystalline rocks with different weathering degrees. The compression hardening deformation of grain contacts significantly affected the macro nonlinear stress-strain relation and stress thresholds of crack closure, crack imitation, stable crack growth, and unstable crack growth. We acquired new insights on the weathering-induced weakening of macro-mechanical characteristics of crystalline rock, which resulted from weakening of deformation properties of the grain contact more than grain contact strength.