2018年大理岩试样的长度对单轴压缩试验的影响.doc

大理岩试样的长度对单轴压缩试验的影响 　　岩石力学与工程学报 23(22)：3754～3760 　　2004年11月 Chinese Journal of Rock Mechanics and Engineering Nov . ，2004 　　　　第23卷 第22期 　　　　大理岩试样的长度对单轴压缩试验的影响 　　　　＊ 　　尤明庆 苏承东 　　(河南理工大学资源与材料工程系 焦作 454159) 　　　　摘要 相同直径试样的单轴压缩强度随长度的减小而增加，而使用柔性垫片强度则随长度的减小而减小，表明试验机压头与试样端面之间存在摩擦，其影响程度随岩性而变化。2块粒径为0.5～1 mm 的细晶大理岩，试样长度对强度的影响相同，长径比为1时强度是标准长度试样的130%，长径比为0.6时增大到150%以上。但两者的强度、杨氏模量不同，且强度较高者存在圆锥破裂面，强度较低者呈平面剪切破裂，破坏形式都与试样长度无关。粒径为5 mm的粗晶大理岩，试样强度随长度变化不很明显，长径比小于2.5的试样的峰后应力降低过程大体相似。这与裂纹扩展受晶粒影响较大、缺少明显的主控破裂面有关。利用厚度为0.5 mm 的聚四氟乙烯垫片(使用前预压两次) ，直径为50 mm 、长度小于50 mm 的试样也能得到标准试样的单轴压缩强度。不过，试样长度减小时端面质量对强度和杨氏模量的影响增大。 　　关键词 岩石力学，单轴压缩，试样长度，端部效应，强度，柔性垫片 　　分类号 TU 458+.3 文献标识码 A 文章编号 1000-6915(2004)22-3754-07 　　EFFECT OF LENGTH OF FINE AND COARSE CRYSTAL MARBLE 　　SPECIMENS ON UNIAXIAL COMPRESSION TESTS 　　　　You Mingqing，Su Chengdong 　　(Department of Resource and Material Engineering，Henan Polytechnic University， Jiaozuo 454159 China ) 　　　　Abstract The uniaxial compression strength of marble specimens with diameter of 50 mm increases with their length shortening，but the strength will decrease when soft cushions are used between the specimen ends and loading heads of testing machine. It shows that there is friction at the specimen ends. However the friction effect varies with characteristics of rock. For the two marble blocks of fine crystal with grain size of 0.5～1 mm，the relations of specimen lengths to the uniaxial strength are the same. The strength increases to 130% when the ratio of length to diameter decreases from 2 to 1，and the strength increases to more than 150% when the ratio decreases to 0.6. But the two marble blocks have different strength and Young′s modulus. The specimen with higher strength has failure crack in cone shape and the other has failure crack in plane. For the marble blocks of coarse crystal with grain size of 5 mm，the influence of their length on the strength is not apparent. The stress-strain curves a