| 砂岩的I/III复合型断裂试验研究 |
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| 引用本文： | 李一凡,董世明,潘 鑫,李念斌,原 野.砂岩的I/III复合型断裂试验研究[J].岩土力学,2018,39(11):4063-4070. |
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| 作者姓名： | 李一凡 董世明 潘 鑫 李念斌 原 野 |
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| 作者单位： | 四川大学 建筑与环境学院，四川 成都 610065 |
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| 基金项目： | 四川省科技计划（No. 2018JY0024）；国家自然科学基金（No.11872042） |
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| 摘 要： | 为了了解砂岩的I/III复合型断裂力学性能，采用含有裂纹面垂直于底面但倾斜于正背面的三点弯曲（TPB）试件实现面外断裂。使用Abaqus通过有限元法研究了不同裂纹面倾斜角下沿着试件厚度的I型、II型与III型无量纲应力强度因子。通过讨论可知，在靠近试件厚度中点处I型与III型无量纲应力强度因子取得较大值，而II型无量纲应力强度因子取得接近于0的可以忽略的极小值，且靠近自由面处的应力强度因子不作考虑。故该种试件可用于测量材料的I/III复合型断裂性能。数值计算结果与常规TPB试件的解析公式及倾斜裂纹面TPB试件的近似计算公式的结果进行对比，证明了数值模拟结果的准确性并讨论了近似公式存在的问题。使用7组共28个该种三点弯曲试件，研究砂岩的I/III复合型断裂特性，结果表明：砂岩的I型与III型临界应力强度因子随着裂纹面倾斜角的增大先增大后减小，但其变化趋势不同；砂岩的I/III复合型等效断裂韧度随着裂纹面倾斜角的增大先增大后减小，在倾斜角接近20°时取得最大值。裂纹扩展时裂纹面将发生扭转，倾斜角θ越大则扭转角度越大。
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| 关 键 词： | 三点弯曲 砂岩 数值分析 I/III复合型 |
| 收稿时间： | 2017-03-03 |
Experimental study of mixed-mode I/III fracture of sandstone |
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| LI Yi-fan,DONG Shi-ming,PAN Xin,LI Nian-bin,YUAN Ye.Experimental study of mixed-mode I/III fracture of sandstone[J].Rock and Soil Mechanics,2018,39(11):4063-4070. |
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| Authors: | LI Yi-fan DONG Shi-ming PAN Xin LI Nian-bin YUAN Ye |
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| Institution: | College of Architecture and Environment, Sichuan University, Chengdu, Sichuan 610065, China |
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| Abstract: | Three-point bending (TPB) specimens can realise out-of-plane fracture through pre-establishing a crack surface which is perpendicular to the under-surface while inclined to the front and back surfaces. The finite element method (FEM) software ABAQUS is applied to calculate stress intensity factors (SIFs) of mode I, mode II and mode III crack front along the thickness of the specimen with different inclined angles θ. It is clear that mode I and mode III dimensionless SIFs can get a larger value, while mode II dimensionless SIF is insignificant when it is close to the mid-point of the specimen thickness. As a result, this kind of specimen can be used to investigate mixed-mode I/III of materials. Numerical results are compared with the analytical formula of the conventional TPB specimen and the approximate formula of the TPB specimen with the inclined crack surface. The accuracy of numerical results is proved and the problems of the approximate formula are discussed. Mixed-mode I/III fracture behaviour of sandstone is studied in 7 groups of 28 specimens. The results show that the critical SIFs of mode I and mode III increase with the increase of inclined angle then decrease, while the variation tends are different; mixed-mode I/III effective fracture toughness also changes with the inclined angle and reaches the maximum value when θ=20°. The crack surface tilts when the crack propagates, and the lager θ is, the greater tilted angle can get. |
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| Keywords: | three-point bending (TPB) sandstone numerical analysis mixed-mode I/III |
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