摘要
寒区断续节理岩体受冻融作用影响易发生失稳破坏。为探究冻融作用下节理特征对岩体损伤与力学特性的影响,使用相似材料制备不同节理倾角、岩桥长度的断续节理试样,并开展冻融循环试验。通过对冻融试样进行损伤分析与单轴压缩试验,得到了各类试样的劣化损伤特性及其对抗压强度与破坏模式的影响规律。研究表明:冻融作用下,断续节理类岩石试样的劣化模式以片落模式为主,裂纹模式为辅,且不同节理特征试样间存在冻融损伤差异;节理特征与片落损伤的关联较小,但对裂纹扩展的影响显著,节理倾角越大,裂纹发育越不明显,岩桥长度越短,裂纹贯通越迅速,裂纹扩展程度不同是造成试样间冻融损伤差异的主要原因;在差异性冻融损伤的影响下,各类试样的抗压强度普遍降低,并随节理特征的变化表现出不同的强度损失规律;试样破坏过程中延性增强,节理尖端的拉伸裂纹减少、剪切裂纹增多,部分类型试样的破坏模式与岩桥贯通模式发生改变。
The intermittent jointed rock mass in the cold region is prone to instability and failure under the influence of freezing and thawing.In order to investigate the influence of joint characteristics on the damage and mechanical properties of rock under freeze-thaw action,intermittent jointed samples with different joint dips and rock bridge lengths were prepared using similar materials,and freeze-thaw cy-cle tests were conducted.Through damage analysis and uniaxial compression test on the samples after freeze-thaw tests,the deterioration characteristics of various samples and their influence on the com-pressive strength and failure mode were obtained.The results show that the degradation modes of rock samples with intermittent joints are dominated by flake shedding,supplemented by sample cracking.There are differences in freeze-thaw damage between samples with different joint characteristics.The joint characteristics have little relationship with the shedding but significantly impact the crack propaga-tion.The larger the joint inclination,the less the crack development,and the shorter the rock bridge length,the faster the crack penetration.The different crack propagation degrees are the main reasons for the difference in freeze-thaw damage between samples.Under the influence of differential freeze-thaw damage,the compressive strength of all specimens generally decreases and shows different strength loss laws with the change of joint characteristics.In the process of specimen failure,the ductil-ity is enhanced.The tensile cracks at the joint tip are reduced,and the shear cracks are increased.The failure mode of some types of specimens and the rock bridge penetration mode changes.
作者
龙士国
徐继同
李日进
刘雪儿
陈劲杰
LONG Shiguo;XU Jitong;LI Rijin;LIU Xueer;CHEN Jinjie(College of Civil Engineering,Xiangtan University,Xiangtan 411105,China)
出处
《防灾减灾工程学报》
CSCD
北大核心
2024年第1期137-145,共9页
Journal of Disaster Prevention and Mitigation Engineering
基金
国家自然科学基金项目(51908481)资助。
关键词
冻融循环
断续节理
损伤
力学特性
破坏模式
freeze-thaw cycle
intermittent joint
damage
mechanical characteristics
failure mode
