本文選題：石灰?guī)r　切入點(diǎn)：損傷　出處：《山東農(nóng)業(yè)大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：巖石是由多種礦物晶粒組成的集合體,其內(nèi)部結(jié)構(gòu)中隨機(jī)分布著大量的微裂紋和微孔隙。它不是離散介質(zhì),也不是連續(xù)介質(zhì),因此存在著宏、細(xì)觀的不連續(xù)性。傳統(tǒng)的研究方法往往把巖石均化為宏觀的連續(xù)體,從而忽略了巖石材料中的微缺陷或微裂紋的形成及其發(fā)展對材料力學(xué)性能的影響。然而巖石的破壞機(jī)制是在外力作用下,其內(nèi)部微裂紋萌生、擴(kuò)展及貫通,直至宏觀裂紋形成,促使式樣破裂的整個過程。 眾所周知,巖石破壞后的斷口記錄著其斷裂過程,斷口上蘊(yùn)藏著關(guān)于斷裂機(jī)理的信息。通過對斷口表面的分析可以追溯巖石斷裂產(chǎn)生的機(jī)理。然而斷口表面是粗糙不平的,其表面的幾何形態(tài)難以用經(jīng)典的幾何語言進(jìn)行描述。分形理論的研究表明：巖石斷裂表面的幾何形態(tài)具有分形特征,用分維數(shù)可以定量地描述巖石斷口表面的粗糙程度。通過分維值可以追溯到巖石斷裂時的宏觀力學(xué)行為。 本文利用SAW-2000微機(jī)控制電液伺服巖石三軸試驗機(jī),對鑫安煤礦所取的石灰?guī)r試件進(jìn)行一般力學(xué)性質(zhì)試驗,得到石灰?guī)r單軸、三軸試驗下的全應(yīng)力應(yīng)變曲線、巖石斷口及其宏觀圖像。利用JSM-6510LV高低真空掃描電子顯微鏡,對石灰?guī)r試件斷口進(jìn)行電鏡掃描,獲得試件斷口的細(xì)觀掃描圖像。借助Photoshop將石灰?guī)r斷口圖像處理成灰度圖,利用分形理論,采用盒子計數(shù)法計算獲得石灰?guī)r斷口的分形維數(shù)。 從損傷力學(xué)的角度出發(fā),根據(jù)Weibull統(tǒng)計分布理論,結(jié)合分形幾何,在連續(xù)損傷力學(xué)的基本關(guān)系式中引入約化參數(shù),推導(dǎo)出石灰?guī)r在單軸、三軸壓縮試驗下的損傷模型,并與試驗結(jié)果進(jìn)行比較,驗證了理論模型的合理性。 巖石由微裂紋的萌生、發(fā)育、擴(kuò)展到貫通的過程,都伴隨著能量的吸收與釋放。因此,從能量的角度,研究分析巖石試件斷裂破壞耗散能量的分形特征,將分維值與巖石斷裂的宏觀特征聯(lián)系起來。
[Abstract]:Rock is an aggregate composed of a variety of mineral grains, in which a large number of microcracks and micropores are randomly distributed in its internal structure. It is not a discrete medium nor a continuum medium, so there are macros. Mesoscopic discontinuities. Traditional research methods tend to transform rocks into macroscopic continuum, Therefore, the formation and development of microdefects or microcracks in rock materials have been neglected. However, the failure mechanism of rock is the initiation, propagation and penetration of internal microcracks under external force, until the formation of macroscopic cracks. The whole process of causing patterns to break. It is well known that the fracture process is recorded on the fractured surface of rock, and there is information about the fracture mechanism on the fracture surface. The mechanism of rock fracture can be traced by analyzing the fracture surface. However, the fracture surface is rough and uneven. It is difficult to describe the geometric shape of rock surface by classical geometric language. The study of fractal theory shows that the geometric morphology of rock fracture surface has fractal characteristics. The roughness of rock fracture surface can be quantitatively described by fractal dimension, which can be traced back to the macroscopic mechanical behavior of rock fracture. In this paper, SAW-2000 microcomputer controlled electro-hydraulic servo triaxial testing machine is used to test the general mechanical properties of limestone samples taken from Xinan Coal Mine, and the total stress-strain curves of limestone under uniaxial and triaxial tests are obtained. The fracture surface of limestone is scanned by electron microscope with JSM-6510LV high and low vacuum scanning electron microscope, and the meso-scanning image of fracture surface of limestone specimen is obtained. The image of limestone fracture surface is processed into grayscale image by means of Photoshop. Based on fractal theory, the fractal dimension of limestone fracture surface is calculated by box counting method. From the point of view of damage mechanics, according to the Weibull statistical distribution theory and fractal geometry, the reduced parameters are introduced into the basic relational formula of continuous damage mechanics, and the damage model of limestone under uniaxial and triaxial compression tests is derived. Compared with the experimental results, the rationality of the theoretical model is verified. The initiation, development and expansion of microcracks in rock are accompanied by the absorption and release of energy. Therefore, from the angle of energy, the fractal characteristics of energy dissipation for fracture failure of rock specimens are studied and analyzed. The fractal dimension is associated with the macroscopic characteristics of rock faults.
【學(xué)位授予單位】：山東農(nóng)業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU45

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本文編號：1611049