Dynamic damage laws of sandstone under different water bearing conditions based on nuclear magnetic resonance
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摘要: 為研究不同含水狀態巖石的動態損傷特性，制備干燥、半飽和、飽和3種不同含水狀態的砂巖試樣.采用分離式霍普金森壓桿（SHPB），以4種不同的低入射能對巖石進行損傷沖擊試驗.通過核磁共振測試實驗對巖石試樣進行孔隙掃描，獲取巖石孔隙的T2譜曲線、孔隙度以及孔隙成像等數據.通過試驗發現：（1）沖擊能量的增加導致巖石的平均應變率和強度的增大；（2）不同含水狀態的巖石受到沖擊后，孔隙度與孔隙度變化率均有不同程度的增加；（3）與沖擊前相比，巖石的T2譜曲線有明顯右移趨勢，同時出現譜峰增加的現象，而且沖擊能量越大，孔隙譜峰增加越明顯；（4）核磁共振成像顯示巖石孔隙數量和尺寸有明顯的增加，展現出巖石內部孔隙擴展和演化的過程.Abstract: To study the dynamic damage characteristics of sandstone under different water bearing conditions, three different kinds of samples with different moisture states (dry, semi-saturated, and saturated) were prepared. The impact damage of the rock was tested using a split Hopkinson pressure bar (SHPB) with four values of low incident energy. The T2 spectrum curves, porosity, and pore image of the samples were obtained by scanning the samples by nuclear magnetic resonance test. The results show the following:(1) an increase in the impact energy led to increased average strain rate and strength; (2) after impact, the porosity and porosity variation rate of every sample under different water bearing conditions increase with different amounts; (3) compared with the test before impact, T2 spectrum curve has obvious right movement trend and large pore peaks increase. The greater the impact energy increase, more obvious the large pore peaks increased are; (4) nuclear magnetic resonance images show that the number and size of pores increase, which show the expansion and evolution of pores in the rocks.
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Key words:
- water bearing condition /
- dynamic damage /
- impact test /
- nuclear magnetic resonance /
- porosity /
- T2 spectrum curves
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參考文獻
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