【摘要】：巖石內(nèi)部存在大量微裂紋,在外荷載作用下微裂紋擴(kuò)展形成損傷發(fā)展,最終導(dǎo)致巖石材料破壞,微裂紋是巖石最重要的損傷機(jī)制�？紫端畷�(huì)促使微裂紋擴(kuò)展,建立損傷模型時(shí)需考慮孔隙水壓對(duì)損傷發(fā)展的影響。利用MTS815巖石力學(xué)試驗(yàn)系統(tǒng),開(kāi)展了致密砂巖的單軸壓縮實(shí)驗(yàn)和多種圍壓下的三軸壓縮實(shí)驗(yàn)以及多種孔隙水壓下的水滲流全應(yīng)力應(yīng)變實(shí)驗(yàn)。實(shí)驗(yàn)結(jié)果表明砂巖在自然狀態(tài)下的抗壓強(qiáng)度高于飽水狀態(tài)下的抗壓強(qiáng)度,而其有效彈性模量沒(méi)有明顯的差異;圍壓會(huì)顯著提高砂巖試件的抗壓強(qiáng)度,二者之間存在線性相關(guān)性,飽水試件的抗壓強(qiáng)度隨著孔隙水壓的增大而顯著降低�？紤]孔隙水壓對(duì)微裂紋演化行為的影響,引入能量平衡原理描述微裂紋擴(kuò)展,分別研究微裂紋張開(kāi)、摩擦滑移、面內(nèi)擴(kuò)展、偏折擴(kuò)展以及微裂紋匯合對(duì)巖石變形的影響,建立了飽水砂巖的統(tǒng)計(jì)損傷模型。基于該理論模型編寫(xiě)了計(jì)算程序,對(duì)不同孔隙水壓下砂巖的三軸壓縮實(shí)驗(yàn)進(jìn)行了數(shù)值計(jì)算,其計(jì)算結(jié)果與實(shí)驗(yàn)結(jié)果基本吻合。計(jì)算表明該細(xì)觀損傷模型也適用于含瓦斯煤巖。研究了微裂紋相互作用對(duì)巖石變形的影響,有限元計(jì)算結(jié)果表明當(dāng)微裂紋平均間距參數(shù)低于2時(shí)微裂紋相互作用對(duì)微裂紋變形有明顯的影響�；贛ori-Tanaka方法,建立了能考慮橢圓形微裂紋之間相互作用效果和微裂紋擴(kuò)展的細(xì)觀損傷模型,理論計(jì)算結(jié)果表明,當(dāng)微裂紋間距參數(shù)小于2時(shí)應(yīng)當(dāng)采用考慮微裂紋相互作用的理論模型,而微裂紋間距參數(shù)大于3時(shí)則無(wú)需考慮微裂紋相互作用對(duì)巖石變形的影響。
[Abstract]:There are a large number of microcracks in the rock, and the microcracks under external load form damage and development, which leads to the failure of rock materials. Microcracks are the most important damage mechanism of rock. Pore water can promote microcrack propagation, and the influence of pore water pressure on damage development should be taken into account in establishing damage model. Using MTS815 rock mechanics test system, uniaxial compression experiments of tight sandstone, triaxial compression experiments under various confining pressures and full stress strain experiments of water seepage under various pore water pressures have been carried out. The experimental results show that the compressive strength of sandstone in natural state is higher than that in saturated state, but there is no obvious difference in effective modulus of elasticity, the confining pressure can significantly increase the compressive strength of sandstone specimen, and there is a linear correlation between them. The compressive strength of saturated specimen decreases significantly with the increase of pore water pressure. Considering the influence of pore water pressure on the evolution behavior of microcracks, the energy balance principle is introduced to describe the microcrack propagation. The effects of microcrack opening, friction slip, in-plane propagation, deflection propagation and micro-crack convergence on rock deformation are studied, respectively. The statistical damage model of saturated sandstone is established. Based on the theoretical model, a computer program is developed to calculate the triaxial compression experiments of sandstone under different pore water pressures. The calculated results are in good agreement with the experimental results. The calculation shows that the meso-damage model is also suitable for gas-bearing coal rocks. The effect of microcrack interaction on rock deformation is studied. The finite element calculation results show that the microcrack interaction has a significant effect on the microcrack deformation when the average distance parameter of microcrack is less than 2. Based on the Mori-Tanaka method, a meso-damage model considering the interaction effect between elliptical microcracks and the propagation of microcracks is established. The theoretical results show that, When the parameter of microcrack spacing is less than 2, a theoretical model should be adopted to consider the microcrack interaction, but the effect of microcrack interaction on rock deformation should not be considered if the microcrack spacing parameter is greater than 3.
【學(xué)位授予單位】：湖南科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類(lèi)號(hào)】：TU45

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