摘要
预拉应力作用下脆性岩石的动态直接拉伸破坏力学特性,对于深部岩石工程的安全稳定性评价具有重要意义。然而,由于预拉岩石的动力直接拉伸试验条件较为苛刻,该方面的试验研究相对欠缺,关于宏-细观力学机制的理论研究更是缺乏。基于准静态直接拉伸荷载作用下的翼型裂纹扩展模型、准静态与动态断裂韧度关系模型、动静耦合的应变率与应变关系函数,通过引入与预拉应力相关的断裂韧度修正参数λ,提出了一个脆性岩石在预拉伸作用下动态直接拉伸破坏的本构关系模型,建立了预拉岩石动态断裂韧度增强效应与动态直接拉伸强度提升之间的联系。当预拉应力小于岩石内部裂纹启裂应力时,预拉应力的增大强化了脆性岩石的动态直接拉伸强度。通过比较轴向预拉应力σ_(1pre)与裂纹启裂应力σ_(1ci)的大小关系,将预拉岩石动态直接拉伸断裂本构关系分为3种工况。重点分析了预拉应力对脆性岩石力学特性影响,讨论了岩石初始状态参数(初始损伤、裂纹初始尺寸、角度)对预拉岩石力学特性影响。研究结果为深部地下工程施工与设计提供一定理论参考。
The mechanical characterization of dynamic direct damage in brittle rock under pre-tension stress is crucial for evaluating the safety and stability of deep rock engineering.However,due to the harsh experimental conditions associated with dynamic direct tension of pre-tensioned rocks,experimental studies in this area are relatively scarce,and theoretical investigations into the macro-micro mechanisms are even rarer.Based on the wing crack extension model under quasi-static direct tensile loading,the static and dynamic fracture toughness relationship models,and the dynamic-static coupling function of strain rate and strain,a constitutive relationship model for dynamic direct tensile damage of brittle rock under pre-tension is proposed by introducing the fracture toughness modification parameterλrelated to pre-tension stress.The relationship between the enhancement of dynamic crack fracture toughness and dynamic direct tensile strength in pre-tensioned rock is established.The dynamic direct tensile strength increases with pre-tension stress,provided that the pre-tension stress does not exceed the crack initiation stress in rocks.By comparing the magnitude of axial pre-tension stressσ_(1pre) with the crack initiation stressσ_(1ci),the expansion of wing cracks is categorized into three cases,each corresponding to a different constitutive relationship.The effects of pre-tension stress on the mechanical properties of brittle rock are analyzed,along with the influence of the rock’s initial state(initial damage,crack size,density,and angle)on the mechanical properties of pre-tensioned brittle rock.The findings provide theoretical references for the construction and design of deep underground engineering.
作者
李晓照
闫怀蔚
李连杰
戚承志
LI Xiao-zhao;YAN Huai-wei;LI Lian-jie;QI Cheng-zhi(School of Civil and Transportation Engineering,Beijing University of Civil Engineering and Architecture,Beijing 100044,China)
出处
《岩土力学》
北大核心
2025年第S1期217-227,237,共12页
Rock and Soil Mechanics
基金
国家自然科学基金(No.51708016,No.12172036)
北京市教委科研项目(No.KM202110016014)
北京建筑大学研究生创新项目(No.PG2024035)
关键词
脆性岩石
预拉应力
动态直接拉伸
本构关系
宏细观力学模型
brittle rock
pre-tension
dynamic direct tension
constitutive relationship
macro-micro model
