摘要
灰岩地区存在复杂的溶隙网络,其控制着灰岩的破裂特征,作为Griffith断裂准则核心的能量释放率可有效表征岩体裂纹扩展过程。为深入研究溶隙灰岩变形破坏过程中的能量特性和细观裂纹萌生、扩展演化规律,将灰岩溶隙形态概化为裂隙、椭圆孔、类蘑菇孔和类哑铃孔4种类型,并根据非线性动力学理论、Lemaitre应变等效假设和岩体能量理论,推导了溶隙灰岩宏细观耦合损伤能量释放率计算公式,获得了溶隙灰岩破坏过程中的细观裂纹扩展规律。研究结果表明:根据能量耗散理论,类蘑菇孔、裂隙、椭圆孔、完整灰岩和类哑铃孔的灰岩试样能量积聚作用依次减弱;根据能量耗散特征、宏细观耦合损伤能量释放率以及应力应变曲线,灰岩变形破坏阶段可分为应力调整阶段(Ⅰ)、微裂纹或微孔隙稳定闭合阶段(Ⅱ)、细观裂纹低速扩展阶段(Ⅲ)、细观裂纹快速扩展阶段(Ⅳ)以及宏观主断裂形成阶段(Ⅴ)等5个阶段,且第Ⅳ阶段岩样损伤能量释放率突变点可作为岩样破坏前兆识别点。研究结果可为分析岩溶地区地质灾害提供理论指导。
Limestone region is characterized by a complex and extensive karst network,featuring a variety of fracture shapes that can be categorized into four primary types:cracks,elliptical holes,mushroom-like holes,and dumbbell-like holes.Compared with intact limestone,the presence of fissures significantly influences the mechanical properties,energy characteristics and the mechanism of microcracks in limestone.Furthermore,energy release rate,which is the core of the Griffith fracture criterion,effectively characterizes the crack propagation process of rock mass.To investigate energy characteristics and the mechanism of micro-crack initiation and propagation evolution during the deformation and failure of fractured limestone,a formula for the coupled micro-macro damage energy release rate is derived,based on nonlinear dynamic theory,Lemaitre strain equivalent hypothesis,and energy theory.This was followed by the determination of the micro-crack propagation law under Unconfined Compressive Strength(UCS)testing conditions.The results indicate that,according to the energy dissipation theory,the order of energy accumulation is as follows:mushroom-like hole,fissure,elliptic hole,intact limestone,and dumbbell-like hole.Based on energy dissipation characteristics,coupled macro-micro damage energy release rate and stress-strain curve,the deformation and failure stages of fractured limestone and intact limestone can be divided into five stages:stress adjustment stage(StageⅠ),stable closing of micro-cracks or micro-pores(StageⅡ),low-speed propagation of micro-cracks(StageⅢ),rapid propagation of micro-cracks(StageⅣ),and the formation of main macroscopic fractures(StageⅤ).The mutation point of energy release rate in Stage IV prior to the peak can serve as an identification point of failure precursor of rock samples.The research results can provide theoretical guidance for analyzing geological hazards in karst areas.
作者
王润秋
王桂林
张亮
孙帆
WANG Runqiu;WANG Guilin;ZHANG Liang;SUN Fan(School of Civil Engineering,Chongqing University,Chongqing 400045,China;National Joint Engineering Research Center of Geohazards Prevention in the Reservoir Areas,Chongqing 400045,China;Key Laboratory of New Technology for Construction of Cities in Mountain Area(Chongqing University),Ministry of Education,Chongqing 400045,China;School of Architecture and Civil Engineering,Xi'an University of Science and Technology,Xi'an 710054,China;Nanjiang Hydrogeological&Engineering Geology Brigade,Chongqing 401121,China)
出处
《岩土工程学报》
北大核心
2025年第9期1903-1912,共10页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(51978106)
重庆市研究生科研创新项目(CYS21027)
山地城镇建设与新技术教育部重点实验室开放基金项目(LNTCCMA-20230110)
重庆市博士后创新人才支持计划项目(CQBX202208)。
关键词
溶隙灰岩
能量演化
宏细观耦合损伤
能量释放率
裂纹扩展
fractured limestone
energy evolution
micro-macro coupled damage
energy release rate
crack propagation
