加载速率对煤样力学行为影响的试验研究  

Mechanical behavior and mechanism analysis of coal samples based on loading rate effect

作　　者：李海涛[1,2] 蒋春祥[3] 姜耀东[1,4] 王宏伟[1,4] 刘华博[1,4] 

机构地区：[1]中国矿业大学(北京)力学与建筑工程学院,北京100083 [2]北京安科兴业科技股份有限公司,北京100083 [3]连云港市水利局通榆河北延送水工程管理处,江苏连云港222000 [4]中国矿业大学(北京)煤炭资源与安全开采国家重点实验室,北京100083

出　　处：《中国矿业大学学报》2015年第3期430-436,共7页Journal of China University of Mining & Technology

基　　金：国家重点基础研究发展计划(973)项目(2010CB226801);国家自然科学基金项目(51174213);煤炭资源与安全开采国家重点实验室开放基金项目(SKLCRSM11KFB07)

摘　　要：加载速率变化会对介质力学行为产生影响,选用煤进行不同加载速率单轴力学试验.结果表明:对于煤,其强度随加载速率增加表现出先升高后降低的现象,将转折点对应的加载速率称为临界加载速率,低于该值时,煤样强度随加载速率增加而增大,高于该值时加载速率增加强度反而降低.建立"骨架"模型对该现象进行解释,分析表明:较快的加载速率可减少裂隙损伤有利于承载,但同时微元体承载部分将储存更多的弹性能出现局部破坏不利于承载.故必然存在"最优"加载速率使强度出现最大值,此时即对应临界加载速率.以此为基础,提出现场条件下低卸载速率配合均匀弱化介质的手段保证高强度生产的安全.The change of loading rate will affect the mechanical behavior of media. Thus, uni- axial tests with coal samples under different loading rates are carried out. Results show that the strength of coal increases firstly and decreases later with the increase of loading rate, the loading rate corresponding to the turning point is named as ＂critical loading rate＂, below which the coal strength increases with the increase of loading rate, and above which the coal strength decreases with respect to loading rate. A ＂skeleton model＂ is established to explain these phe- nomena. It indicated that higher loading rates will reduce the fracture damage, while the infini- tesimal element will store more elastic energy which may lead to local failure. Thus, there must be an optimal loading rate at which the maximum strength appears, that is, the ＂critical loading rate＂. Based on this theory, techniques with lower unloading rates and uniformly weakening the media were proposed to ensure the safety of mining with high intensity.

关 键 词：率效应 煤样 临界加载速率 损伤 有效加载时间 

分 类 号：TD313[矿业工程—矿井建设]