摘要
高温热处理后脆性岩石的蠕变断裂特性研究对深部地下资源开发具有重要意义。热处理后脆性岩石的长期蠕变力学特性,在不同围压下随热处理温度增加可能会出现不同的变化趋势,该方面的机理解释尚不清晰,且该现象的宏细观力学机理研究欠缺。基于细观裂纹扩展模型,引入了通过独立试验确定的5个温度相关的细观裂纹模型参数:初始裂纹损伤D_(0)、裂纹断裂韧性K_(IC)、裂纹扩展应力侵蚀指数n、特征裂纹速率v、初始裂纹摩擦系数μ随温度的演化规律。建立了高温热处理作用后脆性岩石蠕变宏细观断裂力学模型。同时也得到了热处理温度影响下岩石的应力应变本构关系,其为蠕变变形机理的应力状态选取提供重要依据。研究了不同温度及围压对岩石启裂应力、峰值强度、长期强度、蠕变失效时间的影响,试验验证了模型的合理性。重点讨论了初始裂纹摩擦系数随温度变化的不同趋势下,围压对岩石蠕变断裂特性随温度变化规律的影响。研究结果从细观力学角度分析了热处理后脆性岩石短期及长期力学特征,更加清晰地阐释了热处理脆性岩石的力学机理。
The creep behavior of brittle rocks after high-temperature heat treatment holds significant implications for the advancement of deep subsurface resource utilization.The long-term creep mechanical responses of rocks post-heat treatment may manifest diverse tendencies amid varying confining pressures accompanying temperature escalation;However,the underlying causalities remain obscured and the research focusing on the macro-meso mechanical mechanism is scant.Based on a microcrack crack propagation model,five temperature-dependent microcrack model parameters deduced via independent experiments,including initial crack damage(D_(0)),fracture toughness(K_(IC)),crack extension stress corrosion index(n),characteristic crack propagation rate(v),and initial crack friction coefficient(μ),are introduced.A macro-meso fracture mechanics model for creep behavior of brittle rock after high-temperature heat treatment has been established.The stress-strain constitutive relationship of rock under the influence of heat treatment temperature is also obtained,which provides an important basis for the selection of stress states of creep deformation mechanism.The influences of temperatures and confining pressures on parameters such as rock initiation stress,peak strength,long-term strength,and creep failure time are studied.Empirical validation substantiates the rationale of the model.Particular emphasis is vested in delineating the impact of confining pressure on the creep fracture attributes of rocks,as temperature undergoes variations.This emphasis arises from the divergent trends characterizing the evolution of the initial crack friction coefficient with temperature fluctuation.The research findings analyze the short-term and long-term mechanical characteristics of heat-treated brittle rocks from a meso-mechanical perspective.This offers a clearer and more profound understanding of the mechanical mechanisms underlying the behavior of heat-treated brittle rocks.
作者
李晓照
柴博聪
戚承志
邵珠山
Li Xiaozhao;Chai Bocong;Qi Chengzhi;Shao Zhushan(School of Civil and Transportation Engineering,Beijing University of Civil Engineering and Architecture,Beijing 100044,P.R.China;School of Science,Xi'an University of Architecture and Technology,Xi'an 710055,P.R.China)
出处
《地下空间与工程学报》
北大核心
2025年第5期1514-1524,共11页
Chinese Journal of Underground Space and Engineering
基金
国家自然科学基金(51708016,12172036)
北京市教委科研项目(KM202110016014)
北京建筑大学金字塔人才工程(JDYC20200307)。
关键词
脆性岩石
宏细观力学关系
蠕变断裂
热处理
围压
brittle rocks
macro-micro mechanical relation
creep fracture
heat treatment
confining pressure
