含水饱和度影响下砂岩单轴压缩破碎特征及其弱化机理
Weakening mechanism and fragmentation characteristics under uniaxial compression of sandstone with different saturations
张村 1高敬宜 2吴润泽 2师旭涛 2王方田 3王潇杰 2韩鹏华2
作者信息
- 1. 中国矿业大学(北京)能源与矿业学院,北京 100083;中国矿业大学(北京)厚煤层绿色智能开采教育部工程研究中心,北京 100083;矿业大学(北京)内蒙古研究院,内蒙古鄂尔多斯 017000
- 2. 中国矿业大学(北京)能源与矿业学院,北京 100083
- 3. 中国矿业大学矿业工程学院,江苏徐州 221116
- 折叠
摘要
水岩作用导致岩体强度弱化是采矿工程中常见灾害的诱因,掌握水岩作用弱化特征及其内在机理是防治水岩作用工程问题的关键.基于此,本文借助声发射、扫描电镜、核磁共振等表征手段,研究了不同含水饱和度(含水饱和度分别为0,25％,50％,75％,100％)砂岩水浸弱化破碎特征和内在机理.研究发现,从干燥到饱和岩样抗压强度均值从93.613 4 MPa降至19.255 7 MPa,下降了 79.43％,高饱和度砂岩塑性增强.从干燥到饱和声发射(AE)计数和累计能量分别从23 186和29 495降至8 504和3 695,损伤变量B也从1.00降至0.57,声发射空间分布密度减小.随着饱和度增加,砂岩破碎程度减小,主裂隙面从拉伸破坏逐渐演化为剪切破坏,破碎分形维数从1.716 5下降至1.376 2.核磁共振分析结果表明,随着吸水饱和度的增加,毛细管水比例逐渐上升,造成岩样黏聚力、摩擦力下降,促使岩样生成软弱结构.电镜扫描结果表明,岩样内部矿物成分的溶蚀造成岩样内部孔隙增加,大孔比例上升.上述水岩作用造成岩样破坏时由穿晶裂隙逐渐演化为晶间裂隙,宏观表现为岩样由拉伸破坏演化为剪切破坏,岩样强度降低.
Abstract
Strength weakening of rock mass caused by water rock interaction is a common cause of disasters in mining engineering.Water rock interaction weakening characteristics and its mechanisms are the key to preventing and controlling engineering problems related to water rock interaction.On the basis,the characterization methods such as acoustic emission(AE),scanning electron microscopy(SEM),and nuclear magnetic resonance(NMR)were used to study the characteristics and mechanisms of water immersion weakening in sandstone with dif-ferent saturations(0,25％,50％,75％,100％).It was found that the average uniaxial com-pressive strength of rocks from dry to saturated has decreased from 93.613 4 MPa to 19.255 7 MPa with a decrease of 79.43％.The plasticity of highly saturated sandstone has been enhanced.The AE count and cumulative energy from dry to saturated decreased from 23 186 and 29 495 to 8 504 and 3 695,respectively.The damage variable B also decreased from 1.00 to 0.57,and the spatial distribution density of AE signals decreased.As the saturation increa-ses,the fragmentation degree of sandstone decreases,and the main fracture surface gradually evolves from tensile failure to shear failure.The fractal dimension of fragmentation decreases from 1.716 5 to 1.376 2.NMR results indicate that as the water absorption saturation increa-ses,the capillary water ratio gradually increases,causing a decrease in the cohesion and friction of the rock sample,and promoting the formation of weak structures in the rock sample.SEM results show that the dissolution of mineral components inside the rock sample causes an increase in internal pores and the proportion of macropores.The above-mentioned wa-ter rock interaction causes changes in the form of rock sample failure,it gradually evolves from transgranular cracks to intergranular cracks.The macroscopic manifestation is that the rock sample evolves from tensile failure to shear failure,resulting in a decrease in rock strength.
关键词
水岩作用/声发射/损伤变量/破碎特征/水浸弱化机理Key words
water rock interaction/acoustic emission/damage variable/fragmentation charac-teristics/water weakening mechanism引用本文复制引用
出版年
2024
NETL
NSTL
万方数据