本文選題：巖石力學(xué)　切入點(diǎn)：凍融循環(huán)　出處：《中南大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：摘要：巖石凍融損傷研究因其極強(qiáng)的寒區(qū)工程應(yīng)用背景,已經(jīng)成為巖石力學(xué)學(xué)科的研究熱點(diǎn)。開展多因素耦合作用下巖石凍融損傷機(jī)理試驗(yàn)研究,對高海拔寒區(qū)礦業(yè)開發(fā)等巖體工程中凍融災(zāi)害的分析和防治,具有重要的理論價(jià)值和現(xiàn)實(shí)意義。 論文以砂巖為研究對象,通過開展加卸載作用后巖石的凍融損傷試驗(yàn)和復(fù)雜環(huán)境下巖石凍融損傷試驗(yàn),綜合運(yùn)用力學(xué)分析和核磁共振測試技術(shù)等手段,對多因素耦合作用下凍融巖石的物理力學(xué)性質(zhì)變化和內(nèi)部細(xì)觀結(jié)構(gòu)變化進(jìn)行了觀測和分析,并基于試驗(yàn)結(jié)果對巖石凍融損傷機(jī)理進(jìn)行了研究。 取得的主要成果如下： (1)加卸載作用后巖石在凍融0-135次時(shí),試件質(zhì)量無顯著變化,整體形狀完好,單軸抗壓強(qiáng)度隨凍融次數(shù)增加略微下降,試件泊松比變化規(guī)律不顯著。彈性模量隨著加卸載中卸荷點(diǎn)的增大而有所降低,凍融作用使試件脆性有所增強(qiáng)。 (2)化學(xué)環(huán)境對巖石試件損傷影響非常大,溶液內(nèi)試件隨凍融次數(shù)的增加,質(zhì)量和抗拉強(qiáng)度顯著減小,試件表面出現(xiàn)不同程度的剝落和掉塊。 (3)黃砂巖試件的孔隙度隨凍融次數(shù)增加總體呈緩慢上升態(tài)勢,內(nèi)部損傷模式為：初始階段微小尺寸的新孔隙產(chǎn)生較快,后續(xù)小孔隙的擴(kuò)展緩慢。加卸載操作未對試件內(nèi)凍融損傷模式和孔隙結(jié)構(gòu)演變造成顯著影響。(4)紅砂巖試件孔隙度隨凍融次數(shù)增加基本呈線性增加態(tài)勢,化學(xué)溶液顯著加速了巖石試件的孔隙擴(kuò)展。內(nèi)部損傷模式為：巖石在凍融初期原生小孔隙擴(kuò)展為大尺寸孔隙,隨后巖石內(nèi)部又產(chǎn)生新的次生小孔隙,小孔隙會(huì)迅速擴(kuò)展為大孔隙直至坍塌破壞。 結(jié)果表明,均勻大孔徑的多孔巖石凍融損傷機(jī)理基本符合靜水壓凍融破壞理論,而非均勻小孔徑的多孔巖石凍融損傷機(jī)理基本符合滲透壓凍融破壞理論。巖石材料孔隙結(jié)構(gòu)不同是凍融損傷作用機(jī)理差異的重要原因。
[Abstract]:Abstract: the research of rock freeze-thaw damage has become a hot topic in rock mechanics because of its strong engineering application background in cold region. It is of great theoretical value and practical significance to analyze and prevent freeze-thaw disasters in rock mass engineering such as mining development in high altitude cold region. In this paper, sandstone is taken as the research object, through the freezing and thawing damage test of rock after loading and unloading and the freezing and thawing damage test of rock under complex environment, the comprehensive use of mechanical analysis and nuclear magnetic resonance testing technology is used. The physical and mechanical properties of freeze-thawed rock and the variation of internal meso-structure were observed and analyzed. The mechanism of freeze-thaw damage of rock was studied based on the experimental results. The main results achieved are as follows:. 1) when the rock is frozen and thawed 0-135 times after loading and unloading, the mass of the specimen has no significant change, the whole shape is intact, and the uniaxial compressive strength decreases slightly with the increase of freezing and thawing times. The change of Poisson's ratio is not obvious. The elastic modulus decreases with the increase of unloading point, and the brittleness of the specimen is enhanced by freezing and thawing. (2) the chemical environment has a great influence on the damage of rock specimen. With the increase of freeze-thaw times, the mass and tensile strength of the specimen decrease significantly, and the surface of the specimen appears different degree of spalling and falling. (3) the porosity of yellow sandstone specimen increases slowly with the increase of freeze-thaw times. The porosity of the red sandstone specimen increases linearly with the increase of freezing and thawing times, and the loading and unloading operation has no significant effect on the damage mode and the evolution of pore structure of the specimen, and the porosity of the red sandstone specimen increases linearly with the increase of freezing and thawing times. The chemical solution significantly accelerates the pore expansion of rock specimens. The internal damage pattern is that the primary small pores in the early stage of freezing and thawing become large pores, and then new secondary small pores occur in the rock interior. Small pores can rapidly expand into macropores until they collapse. The results show that the mechanism of freezing and thawing damage of porous rock with uniform and large pore size basically accords with the theory of hydrostatic freezing and thawing failure. However, the mechanism of freezing and thawing damage of porous rock with non-uniform small pore size basically accords with the theory of osmotic freezing and thawing failure, and the difference of pore structure of rock material is the important reason for the difference of mechanism of freezing and thawing damage.
【學(xué)位授予單位】：中南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU452

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本文編號：1632187