Study on crack initiation and propagation in rock mass during unloading based on XFEM
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摘要: 地下和邊坡工程開挖常涉及巖體卸荷問題,采用ABAQUS軟件中的擴展有限單元法(extended finite element method,XFEM)對開挖卸荷過程巖體內部裂紋的起裂擴展進行了模擬,通過計算裂紋尖端應力強度因子研究了其起裂特征,并探討了起裂影響因素,通過記錄裂紋擴展形態研究了其動態演化模式.結果表明,卸荷過程中卸荷速率越快,裂紋長度越長,傾角越大,其起裂越容易;并且裂紋面受到的正應力不斷減小,剪應力不斷增大,裂紋擴展主要由剪應力控制,這與理論分析結果一致.裂紋最終擴展演化形態也與物理試驗相近,充分表明運用擴展有限單元法研究巖體裂紋問題的可靠性.Abstract: Rock-mass unloading often occurs during underground and slope engineering excavations. Here, rock-mass crack initiation and propagation during the excavation unloading progress was simulated using the extended finite element method (XFEM) in ABAQUS. Crack propagation and its influencing factors were studied and discussed after calculating the stress intensity factors at the crack tips, and by recording the crack's shape a dynamic evolution model was produced. The results show that the faster the unloading rate,the longer the crack,and the greater the crack dip angle, the easier the crack initiates. The normal stress on a crack surface decreases while shear stress increases during unloading, and that crack propagation is mainly controlled by shear stress. This is consistent with the theoretical analysis. The final shape of the modeled crack was also close to the result of the physical experiments, indicating the reliability of this study.
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Key words:
- rock-mass unloading /
- crack /
- initiation and propagation /
- extended finite element method
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參考文獻
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