基于内摩擦角的砂岩脆性评价指标分析  

Analysis of sandstone brittleness evaluation index based on internal friction angle

作　　者：陈俊龙 余乔娟 吕原君 CHEN Junlong;YU Qiaojuan;LÜYuanjun(Rock Mechanics Institute,Ningbo University,Ningbo 315211,China)

机构地区：[1]宁波大学岩石力学研究所,浙江宁波315211

出　　处：《宁波大学学报(理工版)》2025年第1期19-26,共8页Journal of Ningbo University:Natural Science and Engineering Edition

基　　金：国家自然科学基金(42277147);宁波市自然科学基金(2023J085)。

摘　　要：脆性是岩石力学的一个重要指标,对地下工程与边坡稳定性分析有重要作用.当前岩石脆性的评估方法虽然很多,但业内尚未形成统一的认识.为了探究以内摩擦角作为岩石脆性评估方法的可行性,以青砂岩、灰黑砂岩和米白砂岩为研究对象,通过常规三轴压缩试验,获取围压为0、15、30、45 MPa时3种不同类型砂岩的基本力学参数,用内摩擦角表征砂岩脆性特征,并将基于内摩擦角的砂岩脆性评价方法与其他方法进行对比.结果表明:(1)随着围压的增大,砂岩的峰值强度表现出显著的线性增长,但是不同类型砂岩的抗压强度差异较大;(2)砂岩内摩擦角越大,峰值强度越大,两者呈现正比关系;(3)青砂岩、灰黑砂岩和米白砂岩的脆性程度表现为依次减小,破坏时的峰值应变则为依次增大,出现应变越低脆性程度越大的现象;(4)评估结果与目前常用的以脆性破坏时的破裂角度作为评估脆性指标的结果相一致.Rock brittleness is a crucial indicator in rock mechanics,playing a significant role in the stability analysis of underground engineering and slopes.Currently,research on rock brittleness is still incomplete,and there is no unified method for its evaluation.To explore the feasibility of using the internal friction angle as an assessment method for obtaining rock brittleness indices,this study takes green sandstone,gray-black sandstone,and beige sandstone as research objects.Through conventional triaxial compression tests,the basic physical and mechanical parameters were obtained at confining pressures of 0,15,30,and 45 MPa.The internal friction angle was used as an evaluation method to derive the brittleness characteristics of sandstone,and the results were compared with those from the other methods.The experimental results indicate that:(1)As the confining pressure increases,the peak strength of sandstone exhibits a significant linear growth relationship,but the compressive strength varies greatly among different types of sandstone;(2)The greater the internal friction angle of the sandstone,the higher the peak strength,showing a positive proportional relationship;(3)The brittleness degree of green sandstone,gray-black sandstone,and beige sandstone decreases sequentially,while their peak strain at failure increases sequentially,indicating that lower strain corresponds to higher brittleness;(4)The evaluation results are consistent with those when the commonly used brittle fracture angle is used as an indicator for assessing brittleness.

关 键 词：砂岩 内摩擦角 三轴压缩试验 脆性评价指标 

分 类 号：TU458.3[建筑科学—岩土工程]