(中南大學(xué) 資源與安全工程學(xué)院，長(zhǎng)沙 410083)
摘 要: 通過(guò)對(duì)花崗巖進(jìn)行不同圍壓損傷控制的三軸等幅循環(huán)荷載試驗(yàn)，采用核磁共振技術(shù)，對(duì)巖石損傷變形和細(xì)觀結(jié)構(gòu)特征進(jìn)行了分析。結(jié)果表明：1) 當(dāng)圍壓從50 MPa增大到120 MPa時(shí)，試樣累計(jì)塑性應(yīng)變和應(yīng)變損傷參數(shù)整體上呈增大趨勢(shì)；2) 隨著循環(huán)次數(shù)增加，試樣軸向累計(jì)塑性應(yīng)變逐漸增大，徑向和體積累計(jì)塑性應(yīng)變呈階段增長(zhǎng)趨勢(shì)，而塑性應(yīng)變?cè)隽砍氏燃眲∷p后趨于穩(wěn)定的階段現(xiàn)象；3) 在圍壓一定條件下，隨著循環(huán)次數(shù)增加，試樣軸向應(yīng)變損傷參數(shù)減小，體積應(yīng)變損傷參數(shù)增大，徑向應(yīng)變損傷參數(shù)先增大后減小；4) 循環(huán)加卸載后，試樣的T2譜曲線由三峰結(jié)構(gòu)變?yōu)殡p峰結(jié)構(gòu)，其細(xì)觀結(jié)構(gòu)主要表現(xiàn)出大孔隙數(shù)量增多、孔徑增大以及整體孔隙度大幅升高的特征。
關(guān)鍵字: 花崗巖；循環(huán)荷載；圍壓；循環(huán)次數(shù)；塑性應(yīng)變；損傷參數(shù)
（School of Resources and Safety Engineering, Central South University, Changsha 410083, China）
Abstract:Through triaxial constant amplitude cyclic loading tests of granite under different confining pressures and nuclear magnetic resonance technology, the damage deformation and meso-structural characteristics of rock specimens were analyzed. The results show that: 1) When the confining pressure increases from 50 MPa to 120 MPa, the cumulative plastic strain and strain damage parameters of specimens increase as a whole; 2) With the increase of the number of cycles, the axial cumulative plastic strain of specimens increases gradually, while the radial and volumetric cumulative plastic strains increase in stages. The increment of plastic strain decreases sharply first and then tends to be stable; 3) Under a certain confining pressure, the axial strain damage parameters of specimens decrease, the volume strain damage parameters increase, and the radial strain damage parameters first increase and then decrease with the increase of the number of cycles; 4) After cyclic loading and unloading, the T2 spectrum distribution curves of specimens change from three-peak structure to two-peak structure, and the meso-structure mainly shows the characteristics of increasing the number of large pores, pore size and overall porosity.
Key words: granite; cyclic loading; confining pressure; number of cycles; plastic strain; damage parameter
