有机硅材料改性砂岩强度与ζ电位变化规律

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。

Change rules of strength and zeta potential of sandstone with organic silicon material modification

In light of the present situation of engineering rock mass stability control problem caused by strength deterioration of rock under wetting-drying cycles, taking the coal seam roof No.8 medium grained feldspar quartz sandstone of Baode coal mine in Xinzhou, Shanxi province, China, for example, modified tests by organic silicon material were carried out. The strength damage and deterioration rules of sandstone for modified and unmodified under different wetting-drying cycles were studied by uniaxial compression tests; the change rules of surface zeta potentials of sandstone for modified and unmodified were comparatively analyzed by electrophoresis; and modification mechanism of organic silicon material modified sandstone is discussed. The results show that: (1) The uniaxial compression strength (UCS), elastic modulus (E) and deformation modulus (Ed) of sandstone samples are increased obviously by modification, and raising the UCS, E and Ed of sandstone samples by 2.17%, 22.2% and 23% respectively. (2) The strength deterioration effect is obvious under wetting-drying cycles; and the UCS, E and Ed of sandstone samples decrease by negative exponent relationship with wetting-drying cycle times increase. (3) Organic silicon material greatly affects the surface of electrical behavior of sandstone; with the pH values of sandstone suspension samples decreasing, the surface electrical potential of sandstone varies from electronegative to electrically neutral and to electropositive in the end.