科研之友
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摘要
The existence of micro cracks inside rocks influences the rock strength and deformation significantly and controls the presence of crack closure stage under compression. However typical discrete element method (DEM) fails to model the gradual crack closure behavior of rock due to insufficient consideration for pre-existing micro-cracks. The stress-strain curves simulated in previous DEM are usually linear in initial stage until numerous cracks are induced under stress. Thus a new method implemented in Discrete Element Method is proposed to model the crack closure behavior of rocks under uniaxial compression. The pre-existing micro-cracks inside the rock sample are created and opened by introducing two notional contact surfaces and giving a negative reference gap. These opened cracks are gradually closed under stress as the adjacent discs sustain sufficient relative movement (re-contact). Thus the gradual crack closure behavior of rock under compression is reproduced. The crack distribution respect to the crack orientation is described with the crack tensor analysis to consider the effect of crack density and anisotropy. Three factors including crack intensity, crack orientation and crack gap are discussed with parametric study to study their influence on the crack closure behavior. The effects of pre-existing cracks on the properties of rocks (such as rock strength, Young's modulus, crack closure stress levels) are also analyzed, and are in well agreement with observations by experiment A little modification is made to previous calibration process to consider the crack closure stage of rock. Finally two types of rocks including limestone and granite are calibrated and compared to the experiment results. The simulated stress-strain curves match the curves of experiment, especially the initial crack closure segment perfectly, which validates the proposed method.
- 出版日期2018-12
- 单位武汉大学
