動態(tài)荷載下巖石裂紋的擴張機理研究
發(fā)布時間：2018-07-23 21:00
【摘要】：動態(tài)荷載下巖石裂隙的破壞問題是關(guān)系到巖土工程建設(shè)和風險評估等各個方面的重大課題。實際巖土建設(shè)工程中所遇到的巖石裂隙的擴展破壞問題多是由于動態(tài)荷載的作用造成,如地震荷載、爆破荷載等等。在巖石斷裂力學(xué)方面,靜態(tài)荷載和沖擊荷載都有了一定程度的研究。然而對于起銜接作用的低速荷載下巖石裂隙的擴展機理還研究尚少。因此本文將通過嵌入兩大破壞準則的離散有限元程序(EDEM)對不同速度荷載下巖石裂隙的破壞進行數(shù)值模擬計算,并對其破壞的形態(tài)差異和力學(xué)特性差異進行對比分析,從而得出不同加載速度對巖石裂隙破壞的影響。對不同加載速度對巖石裂隙擴展的研究可以更進一步理解為在不同的應(yīng)變率下裂隙擴展的機理,為全面系統(tǒng)地研究巖石裂隙在各種動態(tài)荷載下的擴展特性奠定基礎(chǔ)。同時,可以對工程實踐中的重要巖土工程選址和建筑工程風險評估等有著一定的指導(dǎo)依據(jù)。本文中利用擴展離散元程序,通過對多種加載速度和不同預(yù)制裂隙角度的模型的模擬,對其結(jié)果進行整理分析,發(fā)現(xiàn)加載速度對巖石裂隙擴展產(chǎn)狀和巖體力學(xué)特性兩方面的影響。總結(jié)出了在增大加載速度后模型裂隙擴展產(chǎn)狀與靜載作用下的相似性和差異性。在擴展產(chǎn)狀方面,高速加載下模型的裂隙擴展將會出現(xiàn)更多的次生裂隙,甚至形成破壞帶,最后達到與沖擊破壞相似的“X”形破壞產(chǎn)狀；在模型力學(xué)特性方面,通過統(tǒng)計分析每次計算中加載板的應(yīng)力、位移等數(shù)據(jù),發(fā)現(xiàn)在高速加載下模型在破壞前將會達到更大的應(yīng)力值。同時對在動態(tài)荷載下的模型的力學(xué)響應(yīng)做出了分析,發(fā)現(xiàn)了應(yīng)力波在巖體中傳播的研究在動力學(xué)研究以及實際巖土工程中的重要性。動態(tài)荷載下巖石的裂隙擴展和動態(tài)斷裂力學(xué)將是解決巖土工程中動態(tài)荷載對地層和建筑工程影響的重要理論基礎(chǔ)。在今后的研究中,通過對不同加載速度下巖石裂隙力學(xué)反應(yīng)和破壞產(chǎn)狀的深入探討可以全面地研究巖石的動態(tài)斷裂力學(xué),以求能達到精確地對動態(tài)荷載下巖石裂隙的風險評估和擴展預(yù)測等對實際工程有指導(dǎo)意義的目的。
[Abstract]:The failure of rock fissures under dynamic load is an important subject related to geotechnical engineering construction and risk assessment. In the actual geotechnical construction engineering, the problems of rock crack expansion and failure are mostly caused by dynamic loads, such as earthquake load, blasting load, and so on. In rock fracture mechanics, static load and impact load have been studied to some extent. However, there is little research on the mechanism of rock fracture propagation under low speed load. In this paper, the failure of rock fractures under different velocity loads is simulated by the discrete finite element program (EDEM), which embed two failure criteria, and the difference of fracture morphology and mechanical properties is compared and analyzed. The influence of different loading speed on rock fracture failure is obtained. The study of crack propagation at different loading speeds can be further understood as the mechanism of crack propagation at different strain rates, which lays a foundation for a comprehensive and systematic study of the propagation characteristics of rock fractures under various dynamic loads. At the same time, it can provide some guidance for geotechnical engineering site selection and construction engineering risk assessment in engineering practice. In this paper, the extended discrete element program is used to simulate the models with different loading speeds and different prefabricated fracture angles, and the results are analyzed. The effect of loading speed on the occurrence of crack propagation and mechanical properties of rock mass is found. The similarity and difference between the occurrence of crack propagation and the static load in the model are summarized after increasing the loading speed. In the aspect of propagation occurrence, the crack propagation of the model under high-speed loading will appear more secondary cracks, even form failure zone, and finally achieve the "X" shape failure occurrence similar to the impact failure, and in the mechanical properties of the model, Through the statistical analysis of the stress and displacement data of the loaded plate in each calculation, it is found that the model will reach greater stress value before failure under high-speed loading. At the same time, the mechanical response of the model under dynamic load is analyzed, and the importance of the study of stress wave propagation in rock mass is found in the study of dynamics as well as in the actual geotechnical engineering. Crack propagation and dynamic fracture mechanics of rock under dynamic load will be the important theoretical basis to solve the influence of dynamic load on stratum and building engineering in geotechnical engineering. In the future research, the dynamic fracture mechanics of rock can be studied comprehensively through the deep discussion on the mechanical reaction and failure state of rock fracture under different loading speeds. In order to achieve accurate risk assessment and expansion prediction of rock fractures under dynamic load, it is of guiding significance to practical engineering.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU45
本文編號：2140621
[Abstract]:The failure of rock fissures under dynamic load is an important subject related to geotechnical engineering construction and risk assessment. In the actual geotechnical construction engineering, the problems of rock crack expansion and failure are mostly caused by dynamic loads, such as earthquake load, blasting load, and so on. In rock fracture mechanics, static load and impact load have been studied to some extent. However, there is little research on the mechanism of rock fracture propagation under low speed load. In this paper, the failure of rock fractures under different velocity loads is simulated by the discrete finite element program (EDEM), which embed two failure criteria, and the difference of fracture morphology and mechanical properties is compared and analyzed. The influence of different loading speed on rock fracture failure is obtained. The study of crack propagation at different loading speeds can be further understood as the mechanism of crack propagation at different strain rates, which lays a foundation for a comprehensive and systematic study of the propagation characteristics of rock fractures under various dynamic loads. At the same time, it can provide some guidance for geotechnical engineering site selection and construction engineering risk assessment in engineering practice. In this paper, the extended discrete element program is used to simulate the models with different loading speeds and different prefabricated fracture angles, and the results are analyzed. The effect of loading speed on the occurrence of crack propagation and mechanical properties of rock mass is found. The similarity and difference between the occurrence of crack propagation and the static load in the model are summarized after increasing the loading speed. In the aspect of propagation occurrence, the crack propagation of the model under high-speed loading will appear more secondary cracks, even form failure zone, and finally achieve the "X" shape failure occurrence similar to the impact failure, and in the mechanical properties of the model, Through the statistical analysis of the stress and displacement data of the loaded plate in each calculation, it is found that the model will reach greater stress value before failure under high-speed loading. At the same time, the mechanical response of the model under dynamic load is analyzed, and the importance of the study of stress wave propagation in rock mass is found in the study of dynamics as well as in the actual geotechnical engineering. Crack propagation and dynamic fracture mechanics of rock under dynamic load will be the important theoretical basis to solve the influence of dynamic load on stratum and building engineering in geotechnical engineering. In the future research, the dynamic fracture mechanics of rock can be studied comprehensively through the deep discussion on the mechanical reaction and failure state of rock fracture under different loading speeds. In order to achieve accurate risk assessment and expansion prediction of rock fractures under dynamic load, it is of guiding significance to practical engineering.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU45
【參考文獻】
相關(guān)期刊論文 前1條
1 胡柳青;李夕兵;龔聲武;;沖擊載荷作用下裂紋動態(tài)響應(yīng)的數(shù)值模擬[J];爆炸與沖擊;2006年03期
，本文編號：2140621
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