南芬露天矿绿泥角闪岩吸水及强度软化规律

Water absorption and strength softening law of chlorite amphibolite in Nanfen open-pit mine

研究表明降雨是诱发矿山边坡失稳变形破坏的重要因素,主要通过降低潜在滑动面(带)岩体强度诱发滑坡。国内外学者对南芬露天铁矿下盘滑坡机理和稳定性评价开展了大量研究,取得了丰富的研究成果。然而,所有研究成果证明该边坡潜在滑动面(带)岩体吸水性较弱,水通过何种途径影响边坡稳定性机理不清晰。采用自主研发的"软岩气态水吸附智能测试系统",对潜在滑动面(带)上分布的绿泥角闪岩进行吸水软化实验,揭示岩石的吸水特性及吸水后的强度衰减规律;运用Image-Pro Plus专业图像处理技术,分析其SEM微观图像;结合绿泥角闪岩的压汞实验结果,揭示其微观孔隙结构特征与岩石吸水特性之间的相互关系。分析结果表明:(1)绿泥角闪岩吸水特性是一个在短时间内快速上升而后下降达到均匀饱和的过程;(2)影响绿泥角闪岩吸水特性的主要因素是岩石样品的孔隙结构特征而非黏土矿物含量;(3)岩石的孔隙累计体积与其吸水特性之间存在正相关关系;(4)集中分布的孔隙直径越小,占据的比例越大,则岩石的吸水能力越差;(5)绿泥角闪岩的吸水率与单轴压缩强度以及弹性模量呈负相关关系。上述研究结果可为南芬露天矿降雨诱发顺层石质滑坡的防治提供理论依据。

Rainfall is an important factor to induce the instability and deformation of pit slope,mainly through the reduction of potential sliding surface(band)rock mass intensity to induce landslides.A large number of studies have been carried out on the mechanism and stability evaluation of bedding landslide along the footwall of Nanfen open-pit iron mine stope,and a lot of achievements have been obtained.However,all the research results show that the potential sliding surface(rock)of the slope is weak in water absorption,and the mechanism of the slope stability affected by water is not clear.In this paper,firstly,the experiment of water absorption and softening of chlorite amphibolite on the potential sliding surface(band)is carried out by using a self-developed“intelligent testing system for vapor water absorption of soft rock”,to reveal the characteristics of water absorption and the change of strength attenuation after absorbing water;then,using Image-pro Plus professional image processing technology,the SEM image is analyzed;finally,the relationship between the micro-pore structure characteristics and the characteristics of water absorption is revealed.The results show that①The water absorption of chlorite amphibolite increases rapidly in a short time and then decreases to uniform saturation;②The main factors affecting the water absorption characteristics of chlorite amphibolite are the pore structure characteristics rather than the content of clay minerals;③There is a positive correlation between the pore accumulative volume(total pore volume)and water absorption characteristics;④The smaller the pore diameter of the concentration distribution,the greater the proportion occupied,the worse the water absorption capacity of the rock is;⑤The water absorption rate of chlorite amphibolite is negatively correlated with uniaxial compression strength and elastic modulus.The above results provide a theoretical basis for the prevention and control of landslide induced by rainfall in Nanfen Open-pit mine.