砂巖Ⅰ型斷裂的尺寸效應試驗研究

彭劍文; 李長洪; 苗勝軍

doi:10.13374/j.issn2095-9389.2017.10.003

砂巖Ⅰ型斷裂的尺寸效應試驗研究

doi: 10.13374/j.issn2095-9389.2017.10.003

北京科技大學金屬礦山高效開采與安全教育部重點實驗室, 北京 100083

基金項目:

國家基礎研究發展計劃資助項目(973計劃)(2015CB060200)

詳細信息

中圖分類號: TU458.3
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出版歷程
- 收稿日期: 2017-01-05

Experimental investigation for effect of size on sandstone Mode I fracture

Key laboratory of High-Efficient Mining and Safety of Metal Mines, University of Science and Technology Beijing, Beijing 100083, China

摘要

摘要: 通過對尺寸成等比例的砂巖試樣進行三點彎曲試驗,研究了I型斷裂問題中試樣尺寸對砂巖斷裂參數的影響.結果表明:隨著試樣尺寸的增大,名義張拉強度減小,名義斷裂韌度和破裂過程區長度增大,三者均為試樣尺寸的函數.基于試驗結果,引入有效破裂過程區長度cf,建立等效線彈性斷裂力學尺寸效應模型,通過理論分析,發現其尺寸效應曲線介于理想脆性和理想塑性材料之間,體現出準脆性材料的尺寸效應特點,并計算得到了不同尺寸試樣的破裂過程區長度等斷裂參數.為驗證該尺寸效應模型在砂巖中的正確性,采用數字圖像匹配技術(DIC)測定相應尺寸砂巖試樣的破裂過程區長度,測定結果和理論模型計算值相符.
- 巖石力學 /
- 尺寸效應 /
- I型斷裂 /
- 破裂過程區 /
- 數字圖像匹配技術
Abstract: To study the effect of specimen size on fracture parameters in Mode I fracture issue, a group of geometrically similar sandstone specimens were tested by three-point bending. The result shows that as the size of specimen increases, apparent tensile strength decreases and the apparent fracture toughness and length of the process zone increase. These three factors are a function of size. Based on these test results, equivalent linear elastic fracture mechanics (ELEFM) was used to calculate fracture parameters such as the length of the process zone in rock material. The fracture mechanism of sandstone was identified to be between the perfectly plastic and perfectly brittle limits and the effect of size on quasi-brittle material was shown. To verify the correctness of ELEFM, the length of the process zone was obtained by digital image correlation (DIC) test and the experimental and theoretical results were found to fit well.
- rock mechanics /
- size effect /
- Mode I fracture /
- process zone /
- digital image correlation

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