摘要
为研究干湿循环作用对节理岩体剪切力学性质的影响,通过倾斜试验筛选出JRC范围为4.95~5.45的节理试样,在恒定法向应力下对不同干湿循环次数的红砂岩节理进行直剪试验。在干湿循环初期,节理峰值剪切位移先增大后减小,8次干湿循环作用后有增大趋势。随着干湿循环次数增加,节理剪切刚度逐渐降低,低法向应力下剪切刚度下降更为明显。在干湿循环作用16次后,砂岩节理的峰值剪切强度降低了12.41%~23.77%,干湿循环作用的影响随着循环次数的增加而减弱,高法向应力下节理峰值剪切强度的劣化程度减小。黏聚力和内摩擦角在干湿循环次数较小时劣化显著,相同循环次数下,黏聚力的劣化程度大于摩擦角。节理表面损伤程度随着干湿循环次数的增加而增大,4次干湿循环作用后,损伤程度趋于稳定。干湿循环作用下,节理剪切力学特性劣化明显,节理表面附近裂纹、裂隙的产生和扩展是剪切力学参数劣化的原因。
In order to study the effect of wetting and drying cycles on the shear mechanical properties of jointed rock mass,joint samples with a JRC range of 5.20±0.25 were selected by tilt test,and the direct shear tests of red sandstone joints with different numbers of wetting-drying cycles were carried out under constant normal stress.At the beginning of the wetting-drying cycle,the peak shear displacement of the joints increased first and then decreased,and increased after 8 wetting-drying cycles.As the number of wetting and drying cycle increased,the shear stiffness of joints gradually decreased,especially under low normal stress.After 16 wetting-drying cycles,the peak shear strength of sandstone joints decreased by 12.41%–23.77%.The influence of wetting and drying cycles weakened with the increase of cycle times,and the deterioration degree of peak shear strength of joints under high normal stress decreased.The cohesion and friction angle deteriorated significantly when the number of wetting and drying cycles is small.Under the same number of cycles,the degree of degradation of the cohesion is greater than the friction angle.The degree of joint surface damage increased with the increase of the number of wetting and drying cycles.After 4 wetting-drying cycles,the degree of damage tended to be stable.Under the action of wetting and drying cycles,the shear mechanical properties of joints are significantly degraded.The generation and expansion of cracks and fissures near the joint surface is the cause of the deterioration of shear mechanical parameters.
作者
刘星
唐志成
李璐
张清照
苏锋
LIU Xing;TANG Zhicheng;LI Lu;ZHANG Qingzhao;SU Feng(Faculty of Engineering,China University of Geosciences,Whan,Hubei 430074,China;Department of GeotechnicalEnginering,Tongi University,Shanghai 2092,China;Northwest Engineering Corporation Limited,Power China,Xi'an,Shaanxi 710065,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2020年第S02期3316-3325,共10页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金面上项目(41672302)。
关键词
岩石力学
干湿循环作用
砂岩节理
剪切强度
节理表面损伤
rock mechanics
wetting-drying cycle
sandstone joint
shear strength
joint surface damage
