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针对干湿循环作用下岩石强度劣化引发工程岩体稳定性控制问题,以山西忻州保德煤矿8煤顶板中粒长石石英砂岩为例,对砂岩进行有机硅材料改性试验。通过单轴压缩试验研究改性前、后砂岩经历不同干湿循环作用后的强度损伤劣化规律,采用电泳法对比分析改性前、后砂岩表面ζ电位变化规律,并探讨了有机硅材料改性砂岩的改性机制。结果表明,(1)改性后砂岩的单轴抗压强度、弹性模量和变形模量明显提高,单轴抗压强度提高21.7%,弹性模量提高22.2%,变形模量提高23%;(2)受干湿循环作用砂岩强度劣化效应明显,随干湿循环次数增多,砂岩单轴抗压强度、弹性模量和变形模量均呈负指数关系降低;(3)有机硅材料对砂岩表面的电性有较大影响,随着岩样悬浮液p H值的降低,砂岩表面的负电性逐渐减弱至不带电,最后变为正电。
In order to control the stability of engineering rock mass caused by the deterioration of rock strength under the action of wet and dry cycles, this paper took the example of medium-feldspar quartz sandstone in No.8 coal roof of Baode Coal Mine, Xinzhou, Shanxi Province. The uniaxial compression test was used to study the deterioration rules of strength and damage of sandstone before and after modification under different wetting and drying cycles. The variation of ζ potential of sandstone surface before and after modification was analyzed by electrophoresis, and the modification of silicone material was also discussed Sandstone modification mechanism. The results show that: (1) The uniaxial compressive strength, elastic modulus and modulus of deformation of sandstone obviously increase after unmodified, the uniaxial compressive strength increases by 21.7%, the elastic modulus increases by 22.2% and the deformation modulus increases by 23%. (2) The effect of strength deterioration of sandstone affected by wetting and drying cycles is obvious. With the increase of the number of wetting and drying cycles, the uniaxial compressive strength, elastic modulus and deformation modulus of sandstone decrease in a negative exponential relationship. (3) The electrical properties of the surface have a greater impact, with the p H value of the rock sample decreases, the negative surface of the sandstone gradually weakened to uncharged, and finally become positive.