摘要
为了描述深部煤体开采过程中扰动特征,提出基于采动应力的扰动强度判别表达式。根据深部煤体开采实际条件,采用应变软化本构关系,建立深部煤体在保护层开采及蠕变条件下数值模型,得出保护层开采后煤体应力场演化规律及受扰动强度特征,并分析出在受扰动影响及蠕变条件下变形场规律,最终将现场实测应力与模拟结果进行对比,说明数值模拟的合理性。研究表明:(1)深部煤岩体强度差异大,岩体强度高,破坏时应力衰减快,而煤体强度较低,呈现弹塑性破坏。(2)采用基于采动应力的扰动因子表征煤体受扰动程度;保护层采空区下煤体卸压范围大,表现出区域性扰动特征,而未受保护层开采影响但受本煤层回采巷道影响的局部区域,扰动因子在0.7以上,呈现高强度扰动特征;采动应力扰动因子与扰动强度呈正相关,扰动因子越大,煤体受扰动程度越强。(3)深部煤体受扰动及蠕变影响,保护层采空区下煤体体积应变增加明显,而未受保护层开采扰动的煤体由于蠕变影响,其体积应变也随时间而增加。
In order to describe the disturbance characteristics in the process of coal mining at depth,an expression of disturbance intensity based on mining stress is proposed.Mohr-Coulomb strain softening constitutive model is determined to describe the failure process of the coal and rock at depth.According to the actual conditions of coal mining,the numerical model under the conditions of mining protective layer and creep deformation at depth is built to analyze the evolution law of stress field and disturbance intensity of coal when the protective layer was extracted.Finally,the influence law of the disturbed stress field and creep deformation field is analyzed.The numerical results of vertical stress in coal are in good agreement with those of the in-situ test,which prove that the numerical simulation has certain rationality.The results show that:(1)the uniaxial compressive strength of coal and rock is significant difference.The stress attenuation rate of post peak is fast for high strength rock,while low strength coal shows the elastoplastic failure.(2)The disturbance factor based on the induced stress of coal mining is used to characterize the disturbance level of coal.The coal seam in the gob of the protective layer has extensive area of pressure relief range and shows the regional disturbance characteristics.The disturbance factor of local area without protective layer mining but affected by the roadways of the working is above 0.7,and shows high intensity disturbance characteristics.The mining stress disturbance factor has a positive correlation with the disturbance intensity,and the greater the disturbance factor,the stronger disturbance degree of the coal.(3)under the effect of disturbing and creep conditions,volume strain of coal under the gob of protective layer increases obviously,while undisturbed coal also increases over time due to the influence of creep deformation.
作者
王路军
周宏伟
荣腾龙
任伟光
WANG Lujun;ZHOU Hongwei;RONG Tenglong;REN Weiguang(School of Mechanics and Civil Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China;State Key Laboratory of Coal Resources and Safe Mining,China University of Mining and Technology(Beijing),Beijing 100083,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2019年第A01期2944-2954,共11页
Chinese Journal of Rock Mechanics and Engineering
基金
国家重点研发计划(2016YFC0600704)
国家自然科学基金资助项目(51674266)~~
关键词
采矿工程
深部煤体
扰动因子
采动应力场
体积应变
mining engineering
coal at depth
disturbance factor
mining stress field
volumetric strain
