本文選題：石膏巖　切入點(diǎn)：飽水　出處：《巖土力學(xué)》2017年10期

【摘要】：針對荊門市荊花石膏礦中留作礦柱的新鮮石膏巖進(jìn)行天然和飽水兩種狀態(tài)下的單軸和三軸壓縮試驗(yàn),結(jié)合微觀掃描電鏡試驗(yàn),研究石膏巖的強(qiáng)度和變形軟化特性及機(jī)制。結(jié)果表明:石膏巖遇水會發(fā)生顯著的強(qiáng)度和變形軟化。隨溶液中SO_4~(2-)、Ca~(2+)濃度不同,強(qiáng)度軟化系數(shù)在0.6~0.72之間,彈性模量軟化系數(shù)在0.66~0.75之間,凝聚力c顯著下降而內(nèi)摩擦角φ基本保持不變。石膏巖具有良好的延性,天然狀態(tài)下峰后應(yīng)變軟化轉(zhuǎn)為理想塑性變形的臨界圍壓在2.5~5.0 MPa之間,經(jīng)飽水軟化后臨界轉(zhuǎn)換圍壓低于2.5 MPa。石膏巖遇水軟化機(jī)制與其主要礦物成分二水硫酸鈣的微溶性質(zhì)密切相關(guān)。在蒸餾水中,石膏巖主要因溶解造成礦物流失,弱化內(nèi)部結(jié)構(gòu)而軟化;在硫酸鈣飽和溶液中,石膏礦物溶解-重結(jié)晶的動態(tài)平衡改變了巖石內(nèi)部結(jié)構(gòu),使其疏松化,造成其力學(xué)性質(zhì)發(fā)生軟化。試驗(yàn)結(jié)果加深了對石膏巖遇水軟化力學(xué)特性的認(rèn)識,對石膏礦采空區(qū)穩(wěn)定性分析具有重要意義。
[Abstract]:The uniaxial and triaxial compression tests of fresh gypsum rock in Jingmen Jinghua Gypsum Mine were carried out under natural and saturated conditions, combined with microscopic scanning electron microscopy (SEM) test. The strength and deformation softening characteristics and mechanism of gypsum rock are studied. The results show that the strength and deformation soften of gypsum rock is obvious when it is in water, and the strength softening coefficient is between 0.6 ~ 0.72 with the concentration of so _ 4 ~ + _ 2 ~ (2) in the solution. When the softening coefficient of elastic modulus is between 0.66 and 0.75, the cohesion c decreases significantly and the angle of internal friction 蠁 remains unchanged. Gypsum rock has good ductility, and the critical confining pressure of strain softening after peak to ideal plastic deformation is between 2.5 MPa and 5.0 MPa. The critical conversion circumference depression of gypsum rock is 2.5 MPA after saturated softening. The mechanism of water softening of gypsum rock is closely related to the microsolubility of calcium sulfate dihydrate, the main mineral component of which is calcium sulfate dihydrate. In distilled water, the loss of minerals is mainly caused by dissolution of gypsum rock. In saturated solution of calcium sulfate, the dynamic equilibrium of dissolution and recrystallization of gypsum minerals changes the internal structure of rock and makes it loose. The test results deepen the understanding of the mechanical properties of gypsum rock in water softening, and are of great significance to the stability analysis of the goaf of gypsum mine.
【作者單位】： 中國科學(xué)院武漢巖土力學(xué)研究所巖土力學(xué)與工程國家重點(diǎn)實(shí)驗(yàn)室;長沙理工大學(xué)土木工程學(xué)院;
【基金】：國家自然科學(xué)基金面上項(xiàng)目(No.51274188)~~
【分類號】：TU45

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