不等厚互层顺层磷矿高边坡变形机制研究

以云南晋宁磷矿东采区顺层高边坡为研究对象,通过现场勘察,对现场滑坡形态、破坏情况、滑面及滑体特征等进行分析,并从地质、力学角度上分析滑坡变形破坏特征、力学机制及滑坡演化形成过程。最后采用离散元分析验证。研究结果表明:滑坡变形破坏模式为滑移—拉裂破坏,降雨及磷矿开采是滑坡滑动的重要诱因。磷矿层开采坡前缘切断岩层,形成临空面,岩体卸荷松弛发育裂隙,雨水下渗到全风化粘土层面附近富集,层间含水化强的物质,在长期浸泡软化、不等厚互层差异风化等作用下,岩体力学性质大幅衰减,滑体沿软弱层面向临空方向滑动,坡体后缘岩体被拉开,形成张拉裂缝,软弱滑动面贯通,边坡发生变形破坏,主要是以岩石的拉张破坏为主,拉应力对岩石的破坏起主导作用。从计算的位移、滑动形态、变形速率及应力分布判断,滑坡的变形机制为滑移—拉裂破坏模式。其研究成果为矿区高边坡稳定性分析及加固设计提供一定参考依据。

Research on Deformation Mechanism of the Bedding High Rock Slope with Different Interbed Thickness at Jinning Phosphorus Mine

Taking the bedding high rock slope of the eastern mining area in Jinning Phosphorus Mine, Yunnan Province as the research object, based upon the geotechnical exploration, this paper makes statistics and analysis on configuration, failure condition, the slide plane, and the slip mass of the landslides. And the deformation characters, mechanical mechanism, formation and evolution of these landslides were analyzed by geological and mechanical methods. Then, the deformation mechanism was checked by means of distinct element method. The results indicate that the main deformation and destruction mode of the bedding landslide is sliding-tension failure. The rainfall and phosphate rock mining is the important cause of landslide sliding. The exploitation of the phosphorus mine led to formation of some free faces due to cutting off the rock, it caused relax and cracking of the rock mass, and the completely-weathered clay layer gathered plenty of water due to that the rainwater infiltrated along cracks, and there is strong hydrate material, under long-term softening and different weathering, the rock mass strength was attenuating. The landslip slides along the soft slide plane, and the back rocks are pulled, the extension fractures and the soft slide plane appeared, and then the slope deformation appeared, and the main formation mechanism of the sliding-tension cracks was the rock’s tension destruction, the main role of rock destruction is the tensile stress σ₃. Analysis of the deformation mechanism of the slope from the displacement variation, deformation rate, sliding plane and stress distribution by discrete element method shows that the deformation is of sliding-tension type. The results can provide some reference for stability analysis and strengthening design of the slope at the mine.