荆门石膏矿岩遇水软化力学特性试验研究

发布时间：2018-03-29 04:31

本文选题：石膏岩　切入点：饱水　出处：《岩土力学》2017年10期

【摘要】：针对荆门市荆花石膏矿中留作矿柱的新鲜石膏岩进行天然和饱水两种状态下的单轴和三轴压缩试验,结合微观扫描电镜试验,研究石膏岩的强度和变形软化特性及机制。结果表明:石膏岩遇水会发生显著的强度和变形软化。随溶液中SO_4~(2-)、Ca~(2+)浓度不同,强度软化系数在0.6~0.72之间,弹性模量软化系数在0.66~0.75之间,凝聚力c显著下降而内摩擦角φ基本保持不变。石膏岩具有良好的延性,天然状态下峰后应变软化转为理想塑性变形的临界围压在2.5~5.0 MPa之间,经饱水软化后临界转换围压低于2.5 MPa。石膏岩遇水软化机制与其主要矿物成分二水硫酸钙的微溶性质密切相关。在蒸馏水中,石膏岩主要因溶解造成矿物流失,弱化内部结构而软化;在硫酸钙饱和溶液中,石膏矿物溶解-重结晶的动态平衡改变了岩石内部结构,使其疏松化,造成其力学性质发生软化。试验结果加深了对石膏岩遇水软化力学特性的认识,对石膏矿采空区稳定性分析具有重要意义。
[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.
【作者单位】：中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室;长沙理工大学土木工程学院;
【基金】：国家自然科学基金面上项目(No.51274188)~~
【分类号】：TU45

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