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Three-dimensional DEM simulation of the nonlinear crack closure behaviour of rocks
International Journal for Numerical and Analytical Methods in Geomechanics ( IF 4 ) Pub Date : 2022-05-13 , DOI: 10.1002/nag.3376
Yang Ye 1 , Yawu Zeng 2 , Shufan Cheng 2 , Xi Chen 2 , Hanqing Sun 2
Affiliation  

Crack-closure behaviour of rock materials is well-known, while the three-dimensional discrete element method (DEM) simulation of crack-closure behaviour is still a challenge. Hence, a numerical method was proposed through the combination of notional surface method and flat-joint model. The pre-existing microcracks with finite width can be inserted into the three-dimensional numerical sample through the present method. Since the two physical mechanisms, that is, closure of pre-existing microcracks and fracture of flat-joint bonds, are included in the simulations, various evolution trends of crack-closure stage can be captured through the present method. Due to the high computational efficiency of flat-joint model, the three-dimensional DEM simulations of crack-closure behaviour can be achieved. The results of parametric study show that the crack intensity determines the crack-closure behaviour and the crack width significantly influences the evolution trend of crack-closure stage. The simulated unconfined compressive strength (UCS) and tensile strength (TS) significantly decrease with the increase of crack intensity. The crack width significantly influences the deformation parameters, such as elastic modulus, Poisson's ratio and crack closure strain. A calibration procedure was proposed to ease the calibration of mechanical parameters and crack-closure behaviour. Through the proposed numerical method and calibration procedure, the basic mechanical parameters and crack-closure behaviour of sandstone were well matched.

中文翻译:

岩石非线性裂纹闭合行为的三维 DEM 模拟

岩石材料的裂缝闭合行为是众所周知的,而裂缝闭合行为的三维离散元法(DEM)模拟仍然是一个挑战。因此,提出了一种将概念曲面法与平面联合模型相结合的数值方法。通过本方法可以将有限宽度的预先存在的微裂纹插入到三维数值样本中。由于模拟中包括了两种物理机制,即预先存在的微裂纹的闭合和平面接头的断裂,因此可以通过本方法捕获裂纹闭合阶段的各种演变趋势。由于平接头模型计算效率高,可以实现裂纹闭合行为的三维DEM模拟。参数化研究结果表明,裂纹强度决定了裂纹闭合行为,裂纹宽度显着影响了裂纹闭合阶段的演变趋势。模拟的无侧限抗压强度(UCS)和抗拉强度(TS)随着裂纹强度的增加而显着降低。裂纹宽度显着影响变形参数,如弹性模量、泊松比和裂纹闭合应变。提出了一种校准程序,以简化机械参数和裂纹闭合行为的校准。通过所提出的数值方法和校准程序,砂岩的基本力学参数和裂缝闭合行为得到了很好的匹配。
更新日期:2022-05-13
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