煤样三轴压缩下变形和强度分析

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1、第25卷增1岩石力学与工程学报Vol.25Supp.12006年2月ChineseJournalofRockMechanicsandEngineeringFeb.，2006煤样三轴压缩下变形和强度分析11122苏承东，翟新献，李永明，李仕明，刘中云(1.河南理工大学能源科学与工程学院，河南焦作454000；2.义马煤业集团公司杨村煤矿，河南义马472300)摘要：基于在伺服试验机对煤样的常规三轴压缩和三轴卸围压试验，分析了煤样在不同应力条件下的强度和变形特征。煤样在围压作用下裂隙闭合后利用摩擦仍可以承载，并且所有煤样峰前变形特性基本一致。三轴卸围压试验峰值处出现屈服平台，与常规三轴相比峰后

2、塑性明显增强，煤样破坏时的轴向应变量受常规三轴压缩全程应力–应变曲线控制。常规三轴压缩和三轴卸围压试验的峰值强度与围压均成线性关系，围压影响系数基本相同，内摩擦角能够表征材料力学性质，与加载方式没有关系，但相同围压下三轴卸围压时试样的承载能力比常规三轴加载时明显偏低，表明煤样经历较高轴向载荷作用后存在局部损伤。关键词：岩石力学；三轴压缩试验；卸围压；变形；强度准则中图分类号：TU458文献标识码：A文章编号：1000–6915(2006)增1–2963–06STUDYONDEFORMATIONANDSTRENGTHOFCOALSAMPLESINTRIAXIALCOMPRESSION1112

3、2SUChengdong，ZHAIXinxian，LIYongming，LIShiming，LIUZhongyun(1.SchoolofEnergyScienceandEngineering，HenanPolytechnicUniversity，Jaozuo，Henan454000，China；2.YangcunColliery，YimaCoalGroupCo.Ltd.，Yima，Henan472300，China)Abstract：Thepseudo-triaxialcompressiontestsandconfiningpressurereductiontestswerecarried

4、outforcoalspecimenstrengthsindifferentstressonservo-controlledtestingmachine.Undertheactionofconfiningpressure，coalspecimenswithfissuresclosedcanbeartheweightthroughfissurefriction.Thedeformationpropertiesofcoalspecimensbeforepeakstressarebasicallysimilar.Yieldterracesinthepeakofthestress-straincu

5、rveofcoalspecimensoccurredinconfiningpressurereductiontests，andthepost-peakplasticpropertiesaremoreenhancedthanthatinpseudo-triaxialcompressiontests.Axialdeformationvaluewhilecoalspecimensdamagedaredominatedbytheirpseudo-triaxialcompressionstress-straincurves.Thestrengthsofcoalspecimenunderpseudo-

6、triaxialcompressionandconfiningpressurereductiontestsarebothlinearlinerrelationwiththeirconfiningpressure，andtheconfiningpressureinfluencecoefficientsarebasicallythesame.Theinternalfictionangleofcoalspecimenshavingnorelationwithloadedtypecanbeusedtorepresentmechanicpropertyofmaterial.Thecompressio

7、nstrengthsofcoalspecimensinconfiningpressurereductiontestsarelowerthanthoseinpseudo-triaxialcompressiontestsatthesameconfiningcompression.Thereasonisthatcoalspecimenshaveinnerdamageundertheactionofhigher-axialcom