矿产资源伴生含层理、节理、裂隙等结构面的层状岩体,其中层状板岩在我国分布广泛,因抗拉性能差会导致多样工程灾害并影响资源开采.基于此,本文以木寨岭隧道软弱层状炭质板岩为研究对象,通过直缝半圆盘三点弯断裂试验(SCB),深入分析了层状板岩的张拉断裂特性,同时基于数字图像相关方法分析了不同层理倾角层状板岩裂纹起裂、扩展态势下的表面位移场演化特征.结果表明:① 层状板岩在试验时均表现出典型脆性断裂破坏,SCB试验荷载—位移曲线发展态势较为相似,主要包含裂隙压密变形、线弹性变形、塑性弱屈服和瞬时跌落破坏 4 个阶段.但力学响应及峰值荷载差异极大;② 受层理影响,不同层理倾角下的层状板岩呈现出显著各向异性力学性质,SCB试验试样峰值荷载受层理面影响差异巨大,divider试样为竖直层理试样峰值荷载的 1.97 倍;③ 层状板岩张拉断裂破坏形态复杂多变,虽然均从直缝尖端起裂,但其裂纹扩展态势随层理变化而呈现出巨大差异,具体如台阶型、链式折线型和笔直型等断裂形态;④ 基于DIC测取不同层理层状板岩试样缝尖至加载端散斑关注区表面水平位移场,进而揭示了由试样尖端起裂至裂纹扩展贯通形成的表面位移场断裂演化特征.相关研究成果可为层状岩体矿山掘进及开采的灾害防治奠定坚实理论和应用基础.
Mineral resources are often accompanied by layered rock masses with structural planes such as bedding,joints,and fine cleftiness.Among them,layered slate is widely distributed in China,and its poor tensile performance can lead to various engineering disasters and affect resource extraction.Based on this,we take the weak layered carbonaceous slate of Muzhailing tunnel as the research object,and conduct deep analysis of the tensile fracture characteristics of the layered slate through semi-circular bending(SCB)test.Meanwhile,based on digital image correlation(DIC)methods,the evolution charac-teristics of the surface displacement field under the initiation and propagation of cracks in layered slate with different bedding angles are analyzed.The results indicate that:Layered slate exhibits typical brittle fracture failure during testing,and the devel-opment trend of load-displacement curves in SCB test is relatively similar,mainly including four stages:crack compaction de-formation,linear elastic deformation,plastic weak yield,and instantaneous drop failure.However,there is a significant differ-ence in mechanical response and peak load;Due to the influence of weak bedding planes,layered slate with different bedding angles exhibits significant anisotropic mechanical properties.The peak load of SCB test varies greatly due to the influence of bedding planes,with the divider specimen being 1.97 times the peak load of the vertical bedding specimen;The tensile fracture failure modes of layered slate are complex and varied.Although they all crack from the tip of the straight tip,the crack propaga-tion trend varies greatly with the changes in bedding,such as step type,chain type broken line type,and straight type;Based on DIC measurement of the horizontal displacement field on the surface of the speckle area from the crack tip to the loading end of different layered slate specimens,the fracture evolution characteristics of the surface displacement field formed from the crack tip initiation to crack propagation and penetration were revealed.The relevant research results can lay a solid theoretical and practical foundation for disaster prevention and control in the excavation and mining of layered rock mines.