【摘要】：本文根據(jù)峰后砂巖CT試驗，對峰后砂巖在不同圍壓下進行加載，通過CT圖像研究峰后砂巖的損傷特征。目前CT技術(shù)為研究峰后巖石的損傷提供了十分有效的技術(shù)手段，但是現(xiàn)有的CT圖像分析并沒有充分地利用峰后巖石的CT圖像資料。文中基于峰后砂巖CT圖像的數(shù)字圖像處理技術(shù)，對峰后砂巖的CT圖像進行圖像降噪，圖像偽彩色增強，及邊緣檢測等處理，得到了峰后砂巖內(nèi)部損傷的清晰圖像，且分析了峰后砂巖內(nèi)部損傷裂隙的分布特征。 本文在一些專家學(xué)者研究的基礎(chǔ)上，對峰后砂巖試驗后的力學(xué)參數(shù)進行了分析，以損傷力學(xué)與細觀力學(xué)為理論依據(jù)，建立了峰后砂巖損傷理想數(shù)學(xué)模型，對其損傷進行定義，通過CT圖像計算求得峰后砂巖的CT數(shù)與方差，，由CT數(shù)的定義推導(dǎo)出了巖石峰后損傷變量與CT數(shù)之間的關(guān)系，求得峰后砂巖在不同軸壓下的損傷變量，發(fā)現(xiàn)從開始加壓到荷載達到極限前，試件的體積都是減小的，這樣使得峰后砂巖的平均密度實際上在增大，這樣掃描圖像的平均CT數(shù)也就增大了，這其實會抵消由于微裂隙的出現(xiàn)所引起CT數(shù)減小的事實，其損傷也不是很大，不過在峰值以后由于試件破壞嚴重，裂隙變寬，導(dǎo)致峰后砂巖的體積增加，密度變小，使得掃描圖像的平均CT數(shù)也就開始變小，相對于初始掃描圖像的平均CT數(shù)減小的幅度很大，損傷度卻增大了，這充分說明在峰值以后的試件已完全破裂，失去支撐能力，能夠定量的研究其損傷程度及損傷演化過程。 文中最后以分形理論及分形模型為理論基礎(chǔ)，獲得了峰后砂巖裂隙的分形維數(shù)，并根據(jù)獲得的相關(guān)分形維數(shù)來描述峰后砂巖裂隙的分布情況，根據(jù)自定義的峰后巖石損傷建立了與分形維數(shù)的關(guān)系，用分形維數(shù)來定量的描述峰后砂巖的損傷，發(fā)現(xiàn)隨著荷載的增大，峰后砂巖裂隙分布分維數(shù)F越來越大，這是因為隨著荷載的加大，砂巖內(nèi)部逐漸有新裂隙產(chǎn)生并且原裂隙也在變大，使得統(tǒng)計的區(qū)域內(nèi)裂隙數(shù)量越來越多的緣故。揭示了峰后砂巖裂隙分布具有分形分布特征及其損傷演化規(guī)律，補充了謝和平在巖石峰后的研究。
[Abstract]:Based on the CT test of post-peak sandstone, the damage characteristics of post-peak sandstone under different confining pressures were studied by CT image. At present, CT technology provides a very effective technical means to study the damage of post-peak rock, but the existing CT image analysis has not fully utilized the CT image data of post-peak rock. Based on the digital image processing technology of post-peak sandstone CT image, the CT image of post-peak sandstone is processed by image denoising, image pseudo-color enhancement and edge detection, and a clear image of interior damage of post-peak sandstone is obtained. The distribution characteristics of the damage fractures in the sandstone behind the peak are also analyzed. Based on the research of some experts and scholars, the mechanical parameters of post-peak sandstone test are analyzed in this paper. Based on the theory of damage mechanics and meso-mechanics, an ideal mathematical model for damage of post-peak sandstone is established and its damage is defined. The CT number and variance of sandstone behind peak are calculated by CT image, and the relation between damage variable after peak and CT number is deduced from the definition of CT number, and the damage variable of sandstone behind peak under different axial pressures is obtained. It is found that the volume of the specimen decreases from the beginning of the compression to the limit of the load, so that the average density of the sandstone behind the peak is actually increasing and the average CT number of the scanned image is also increased. This will actually counteract the fact that the number of CT decreases due to the appearance of micro-cracks, and the damage is not very great. However, after the peak value, due to the serious damage of the specimen, the crack becomes wider and the volume of the sandstone behind the peak increases and the density of the sandstone decreases. The average CT number of the scanned image begins to decrease, and the average CT number of the scanned image decreases greatly compared with the initial scan image, but the degree of damage increases, which fully indicates that the specimen after the peak value has completely cracked and lost its supporting capacity. It can quantitatively study the damage degree and damage evolution process. Finally, on the basis of fractal theory and fractal model, the fractal dimension of post-peak sandstone fracture is obtained, and the distribution of post-peak sandstone fracture is described according to the obtained correlation fractal dimension. The relationship between rock damage after peak and fractal dimension is established. The fractal dimension is used to describe the damage of sandstone behind peak quantitatively. It is found that with the increase of load, the fractal dimension F of fracture distribution in post-peak sandstone becomes larger and larger. This is because with the increase of load, there are new cracks in the interior of sandstone and the original cracks are also increasing, which makes the number of cracks in the statistical area more and more. It is revealed that the fracture distribution of sandstone behind the peak has the characteristics of fractal distribution and its damage evolution, which complements the study of Xie Heping after the peak of rock.
【學(xué)位授予單位】：內(nèi)蒙古科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TD313

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