摘要
围岩冻融损伤劣化加剧了寒区隧道衬砌结构破坏,为探究新疆高寒隧道强风化炭质板岩围岩冻融损伤劣化规律及各向异性特征,制取层理倾角θ=0°、45°、90°3种板岩试样,在开放饱水的条件下进行了0次、10次、20次、30次、40次冻融循环试验,并对冻融循环后的试样进行宏观力学性能试验及断裂面扫描电镜测试。结果表明:在冻融循环作用下,强风化板岩的冻融损伤多集中于节理裂隙等软弱结构处,损伤模式主要为顺层理裂隙萌生、顺层理剥落及顺层理断裂,板岩自然饱和质量呈现先缓慢增加后迅速递减的趋势;不同层理倾角板岩强度特征差异较大且受风化作用与冻融循环作用影响显著,伴随着冻融循环次数的增加,板岩抗压强度、弹性模量均呈现非线性衰减趋势,冻融受荷损伤变量逐渐增大,3种层理倾角板岩抵抗冻融损伤作用的关系为0°>90°>45°;扫描电镜图像观察到板岩层理断裂表现出显著的脆性特征,但多次的冻融循环作用使板岩受荷破坏破裂面表现出一定的塑性特征。研究发现倾角为0°层理构造的板岩受冻融环境的影响相对较小,具有更加稳定的力学性质,研究揭示了强风化定向层理板岩各向异性冻融损伤劣化规律,可为定向产状结构围岩背景下的寒区隧道工程冻害风险评估提供参考。
This paper aims to explore the degradation law and anisotropic characteristics of freeze-thaw damage of strongly weathered carbonaceous slate surrounding rock in Xinjiang s high-cold tunnel.The authors obtained three types of slate rock samples with bedding angles of 0°,45°,and 90°,and conducted 0,10,20,30,and 40 freeze-thaw cycles under open saturated conditions.After the freeze-thaw cycles,the author conducted macroscopic mechanical performance tests and fracture surface scanning electron microscopy tests.The results show that under the action of freezing and thawing cycles,the freeze-thaw damage of strongly weathered slate is mostly concentrated at the weathered joint fissures,and the main damage modes are the initiation of bedding cracks,detachment of bedding,and fracture of bedding,the natural saturated mass of slate shows a trend of slow increase followed by rapid decrease.The strength characteristics of slate with different bedding angles vary greatly and are significantly affected by weathering and freeze-thaw cycles.With the increase of freeze-thaw cycles,the compressive strength and elastic modulus of slate rock samples exhibit a nonlinear attenuation trend,and the damage variable under freeze-thaw loading gradually increases,the relationship between the resistance to freeze-thaw damage of slate with three different bedding angles is 0°>90°>45°.Scanning electron microscopy images show that the bedding fracture of the slate exhibits significant brittle characteristics,but multiple freeze-thaw cycles cause the fracture surface of the slate to exhibit certain plastic characteristics under load.Research has found that slate with a dip angle of 0°bedding structure is less affected by the freeze-thaw environment and has more stable mechanical properties.The study has revealed the deterioration laws of anisotropic freeze-thaw damage in strongly weathered directional layered slate,which can provide reference for the risk assessment of freezing damage in cold region tunnel engineering under the background
作者
包卫星
卢汉青
郭强
尹严
BAO Weixing;LU Hanqing;GUO Qiang;YIN Yan(School of Highway,Chang an University,Xi an 710064,China;Xinjiang Transportation and Construction Administration Bureau,Urumqi 830049,China)
出处
《工程地质学报》
CSCD
北大核心
2023年第4期1213-1224,共12页
Journal of Engineering Geology
基金
新疆重大科技专项(资助号:2020A03003-7)
陕西省自然科学基础研究计划面上项目(资助号:2021JM-180)
中央高校基本科研业务费自主项目(领军人才计划)(资助号:300102211302).
关键词
寒区隧道
强风化板岩
冻融损伤机制
扫描电镜
损伤变量
Cold region tunnel
Strongly weathered slate
Freezethaw damage mechanism
Scanning electron microscope
Damage variable
