摘要
利用Φ50 mm分离式霍普金森(Hopkinson)压杆(SHPB)试验系统,对煤进行单轴冲击压缩试验,明确煤的力学特性随应变率的变化规律。试验气压等级设计为0.30,0.35,0.40,0.45,0.50,0.55 MPa,为试样提供相应的6组不同应变率。试验结果表明:高应变率下煤应力-应变曲线大致分为压密阶段、弹性变形阶段、微裂纹演化阶段、裂纹非稳定扩展阶段以及卸载阶段;应变率升高缩短压密阶段,延长弹性变形阶段;随着应变率的升高,煤动态弹性模量与峰值应力近似呈对数形式增加,而峰值应变近似呈对数形式降低;煤试样的破坏程度随应变率的升高而增加,应变率由68.666 s-1增加到79.751 s-1,煤破坏程度对应变率的敏感性最为显著。研究结果可为采矿工程割煤参数的确定提供依据。
The mechanical properties of coal changing with the strain rate are proposed by impact uniaxial compression tests on split Hopkinson pressure bar（SHPB） equipment which with a diameter of 50 mm. Six different strain rates are provided for coal by designing test pressure levels with 0.30, 0.35, 0.40, 0.45, 0.50 and 0.55 MPa. Results of the tests are indicated as follows：Stress- strain curves of coal at high strain rates can be roughly divided into compaction phase, elastic deformation stage, micro-cracks evolution stage, crack unstable growth stage and unload stage. What＇s more, increased strain rate can shorten compaction phase and extended elastic deformation stage. With the increase of strain rate, the increment of dynamic elastic modulus and peak stress of coal can be approximately represented by a logarithmic trend, while decrement of the peak strain approximate logarithmic form. The damage extent of coal sample increases with the increasing strain rate, which becomes the most significant when strain rate increases from 68.666 s-1 to 79.751 s-1.The results can be provided the basis for determining the rationalized parameters of cutting coal mining engineering.
出处
《采矿与安全工程学报》
EI
CSCD
北大核心
2015年第2期317-324,共8页
Journal of Mining & Safety Engineering
基金
国家重点基础研究发展计划(973)项目(2013CB227900)
国家自然科学基金项目(51104128
51227003
U1261201
51322401)
教育部博士点基金项目(20120095110013)
江苏省高校研究生创新基金项目(KYLX_1371)
关键词
高应变率
煤力学特性
冲击载荷
采矿工程
high strain rates
mechanical properties of coal
impact load
mining engineering
