摘要
裂隙是造成岩体力学性能劣化的关键因素,针对非闭合裂隙对岩体的损伤作用与裂纹扩展问题,在考虑T应力的前提下,基于Mohr-Coulomb强度准则推导了非闭合裂隙的尖端弹塑性边界方程解析解,以裂隙尖端塑性核区为评价指标,分析了应力环境与裂隙角度α对岩体损伤的影响;通过离散元数值模拟分析,探讨了非闭合裂隙的细观裂纹扩展特性与岩体损伤演化规律。研究表明:当侧压系数λ<0.4,随着λ减小,塑性核区在[π/2,π]范围内扩张速度大于其他区域,导致其形态在裂隙表面呈不均匀分布;当λ<0.7,以α=45°为分界,分界点以下α减小则塑性核区面积缓慢减小,反之则快速增大;随着α增大,塑性核区面积呈缓增长―急增长―稳定的S形曲线变化规律,λ越小,曲线变化越陡峭;非闭合裂隙岩体的单轴抗压强度与塑性核区面积呈负相关关系,塑性核区面积增加,裂纹扩展所需应力增量减小且扩展长度增加,岩体抗压强度减小。研究揭示了非闭合裂隙对岩体损伤的力学机制,为岩体稳定性评估提供了依据。
Fractures are critical factors causing the degradation of mechanical properties in rock mass.In this study,addressing the damage effects and crack propagation problems induced by open fracture on rock mass,an analytical solution for the elastoplastic boundary equation at the tips of open fracture was derived under the consideration of the T-stress effect,based on the Mohr-Coulomb strength criterion.Using the plastic core region at the fracture tips as the evaluation indicator,we analyzed the influences of stress environment and fracture inclination angle(a)on rock mass damage.Through discrete element numerical simulations,the mesoscopic crack propagation characteristics and damage evolution patterns of open fracture were investigated.The obtained results indicate that:(1)When the lateral pressure coefficient(λ)is less than 0.4,the expansion rate of the plastic core region within the range[π/2,π]exceeds that of other regions asλdecreases,resulting in its morphology exhibiting an uneven distribution on the fracture surface;(2)Forlλ<0.7,witha=45°as the critical threshold,the plastic core region area decreases gradually whenadecreases below the threshold,while it increases rapidly whenaexceeds this value;(3)Asaincreases,the plastic core region area exhibits an S-shaped growth curve characterized by“slow growth–rapid growth–stabilization”,with steeper curve transitions observed at lowerlvalues;(4)A negative correlation exists between the uniaxial compressive strength of open-fractured rock mass and the plastic core region area.Specifically,an increase in plastic core region area reduces the required stress increment for crack propagation,extends crack length,and consequently decreases the compressive strength of the rock mass.The study reveals the mechanical mechanisms of rock mass damage caused by open fracture and provides a theoretical basis for rock mass stability assessment.
作者
王炳文
刘臣毅
康明超
李乾龙
杨雷
周森林
钱垒
WANG Bing-wen;LIU Chen-yi;KANG Ming-chao;LI Qian-long;YANG Lei;ZHOU Sen-lin;QIAN Lei(School of Energy and Mining Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China)
出处
《岩土力学》
北大核心
2025年第8期2409-2420,共12页
Rock and Soil Mechanics
基金
国家重点研发计划(No.2018YFC0808403)。
关键词
非闭合裂隙
岩体损伤
T应力
塑性核区
细观裂纹
open fracture
rock mass damage
T-stress
plastic core region
mesoscopic cracks
