基于角度量测的岩土圆柱试件环向变形测试方法及系统应用
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摘要
为精确获取和深入研究岩土力学试验中标准圆柱试件在全应力–应变过程中环向变形规律与峰后扩容力学特性,借鉴MTS链式环向引伸计,提出一种基于角度量测的岩土圆柱试件环向变形测试方法,阐明测试方法原理并研发仪器系统。系统采用链式滚带环绕标准圆柱试件,角位移传感器通过加持锁定机构与链式滚带连接,DAQ数据采集卡和配套LABVIEW编制的采集程序实现了环向位移的实时采集与记录,测量精度0.004 mm,量程30mm,可适用于气固耦合、三轴加载等多种加载环境。与MTS链式引伸计和近景摄影测量的对比试验验证了系统可靠性和重复精度,开展不同气体对煤体的吸附劣化试验应用,试验对相同预制强度的型煤试件充入相同压力的He,N_2,CH_4和CO_2,待充分吸附后进行轴向加载,获取加载过程中煤体变形和失稳破坏规律,对比分析气体性质对体积扩容、煤体强度和裂隙发育的影响规律,试验结果表明:随着气体吸附性能的提高,煤体更早的由压密阶段进入扩容阶段,达到极限承载值与体积扩容点的位置不断提前,先后顺序为:CO_2>CH_4>N_2>He;充入无吸附性的He对煤体无劣化作用,充入吸附性的CO_2显著降低了煤体强度,其中1.0 MPa气压CO_2吸附后煤体强度降低了32.05%。整套系统采用模块化设计,测试方法原理清晰,可与轴向LVDT位移计实现同步采集,对于丰富岩石力学试验方法和实现对老旧试验机的改造升级具有重要意义。
In order to obtain the accurate circumferential deformation and the mechanical characteristics of post-peak dilation of the standard cylindrical specimen during the whole process of stress-strain test,a new type of circumferential deformation test method for standard specimens was proposed with the angle measurement based on the MTS chain circumferential extensometer.The principle of measurement was described in the paper.A chain rolling belt connected with the angle sensor is used in the system to twine around the standard circular specimen.The data acquisition system programmed by LABVIEW is used to achieve the automatic high precision acquisition and rapid recording.The measurement accuracy is 0.004 mm and the measurement range is 30 mm,which is adequate for many loading environments such as the gas-solid coupling loading and the tri-axial loading.The reliability and accuracy of this system were verified by the MTS chain extensometer and the close-range photogrammetry.The adsorption degradation test of coal with different gases was carried out.The briquettes with the same prefabricated strength were filled with the gases under the same pressure(He,N_2,CH_4 and CO_2),and then the axial loading test was carried out after the full adsorption.The deformation and instability of coal body during loading were obtained.The effects of gas properties on the volume expansion,the strength and fracture development of coal were compared and analyzed.The experimental results show that with the improvement of gas adsorption,the coal enters the expansion stage from the compaction stage earlier,and the position of the ultimate load value and volume expansion point reached earlier with the sequence for gases:CO_2>CH_4>N_2>He.The impregnation of He without adsorption does not degrade the coal,but the coal body strength is significantly reduced by adding the adsorptive CO_2.The peak strength decreases by 32.05%after the CO_2 adsorption under the pressure of 1.0 MPa.The whole system is made of modules and can work synchronously with the axial LVDT displacement meter.
In order to obtain the accurate circumferential deformation and the mechanical characteristics of post-peak dilation of the standard cylindrical specimen during the whole process of stress-strain test,a new type of circumferential deformation test method for standard specimens was proposed with the angle measurement based on the MTS chain circumferential extensometer.The principle of measurement was described in the paper.A chain rolling belt connected with the angle sensor is used in the system to twine around the standard circular specimen.The data acquisition system programmed by LABVIEW is used to achieve the automatic high precision acquisition and rapid recording.The measurement accuracy is 0.004 mm and the measurement range is 30 mm,which is adequate for many loading environments such as the gas-solid coupling loading and the tri-axial loading.The reliability and accuracy of this system were verified by the MTS chain extensometer and the close-range photogrammetry.The adsorption degradation test of coal with different gases was carried out.The briquettes with the same prefabricated strength were filled with the gases under the same pressure(He,N_2,CH_4 and CO_2),and then the axial loading test was carried out after the full adsorption.The deformation and instability of coal body during loading were obtained.The effects of gas properties on the volume expansion,the strength and fracture development of coal were compared and analyzed.The experimental results show that with the improvement of gas adsorption,the coal enters the expansion stage from the compaction stage earlier,and the position of the ultimate load value and volume expansion point reached earlier with the sequence for gases:CO_2>CH_4>N_2>He.The impregnation of He without adsorption does not degrade the coal,but the coal body strength is significantly reduced by adding the adsorptive CO_2.The peak strength decreases by 32.05%after the CO_2 adsorption under the pressure of 1.0 MPa.The whole system is made of modules and can work synchronously with the axial LVDT displacement meter.
引文
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[9]YAMAGUCHI I. A laser-speckle strain gauge[J]. Journal of Physics E Scientific Instruments,2000,14(11):1 270–1 273.
[10]郭文婧,马少鹏,康永军,等.基于数字散斑相关方法的虚拟引伸计及其在岩石裂纹动态观测中的应用[J].岩土力学,2011,32(10):3 196–3 200.(GUO Wenjing,MA Shaopeng,KANG Yongjun,et al.Virtual extensometer based on digital speckle correlation method and itsapplicationtodeformationfieldevolutionofrockspecimen[J].Rock and Soil Mechanics,2011,32(10):3 196–3 200.(in Chinese))
[11]马永尚,陈卫忠,杨典森,等.基于三维数字图像相关技术的脆性岩石破坏试验研究[J].岩土力学,2017,38(1):117–123.(MA Yongshang,CHEN Weizhong,YANG Diansen,et al. Experimental studyof brittlerockfailurebased on three-dimensionaldigitalimage correlation technique[J]. Rock and Soil Mechanics,2017,38(1):117–123.(in Chinese))
[12]王波,吴亚波,郭洪宝,等. 2D-C/SiC复合材料偏轴拉伸力学行为研究[J].材料工程,2017,45(7):91–96.(WANG Bo,WU Yabo,GUOHongbao,etal.Investigationonoff-axistensilemechanical behaviorsof2D-C/SiCcomposites[J].JournalofMaterials Engineering,2017,45(7):91–96.(in Chinese))
[13]第五强强,张伟伟.基于应变片的弹性体分布式位移测量方法[J].西北工业大学学报,2017,35(3):422–427.(DIWU Qiangqiang,ZHANGWeiwei.Measurementofdistributeddisplacementfor elastic[J]. Journal of Northwestern Polytechnical University,2017,35(3):422–427.(in Chinese))
[14]李顺群,高凌霞,冯慧强,等.一种接触式三维应变花的工作原理及其应用[J].岩土力学,2015,36(5):1 513–1 520.(LI Shunqun,GAO Lingxia,FENG Huiqiang,et al. Principle and application of a three-dimensionalcontactingstrainrosette[J].RockandSoil Mechanics,2015,36(5):1 513–1 520.(in Chinese))
[15]CODP.Standardtestmethodforpoisson′sratioatroom temperature[c]//American Society for Testing and Materials. Philadelphia:[s.n.],1984:266.
[16]MTSSystemsCorporation.Circumferentialextensometerstrain calculation[R].[S.l.]:MTS Systems Corporation,2005.
[17]王伟,题正义,张宏岩.改进型岩石试验机检测系统的研究[J].矿山机械,2008,36(4):63–65.(WANG Wei,TI Zhengyi,ZHANG Hongyan.Studyondetectionsystemofmodifiedrocktesting machine[J].MiningandProcessingEquipment,2008,36(4):63–65.(in Chinese))
[18]李铀.利用电容原理测量试件的横向变形[J].岩土力学,1990,11(3):75–78.(LI You. Measuring lateral deformation of samples with e Iectric-capacity principle[J]. Rock and Soil Mechanics,1990,11(3):75–78.(in Chinese))
[19]PAEPGEMWV,BAEREID,LAMKANIE,etal.Monitoring quasi-staticandcyclicfatiguedamageinfibre-reinforcedplasticsby Poisson′s ratio evolution[J]. International Journal of Fatigue,2010,32(1):184–196.
[20]YILMAZC,AKALINC,KOCAMANES,etal.Monitoring Poisson′sratioofglassfiberreinforcedcompositesasdamageindex using biaxial Fiber Bragg Grating sensors[J]. Polymer Testing,2016,53(8):98–107.
[21]汪斌,朱杰兵,邬爱清.MTS815系统变形测试技术的若干改进[J].长江科学院学报,2010,27(12):94–98.(WANG Bin,ZHU Jiebing,WUAiqing.Someimprovementsofdeformationmeasurement techniques on MTS815 system[J]. Journal of Yangtze River Scientific Research Institute,2010,27(12):94–98.(in Chinese))
[22]ZHANG Q B,ZHAO J. A review of dynamic experimental techniques andmechanicalbehaviourofrockmaterials[J].RockMechanicsand Rock Engineering,2014,47(4):1 411–1 478.
[23]李元海,贾冉旭,杨苏.基于岩土渐进变形特征的数字散斑相关优化分析法[J].岩土工程学报,2015,37(8):1490–1496.(LI Yuanhai,JIA Ranxu,YANG Su. Optimized method for DSCM based onprogressivedisplacementcharacteristicsofgeotechnical materials[J].ChineseJournalofGeotechnicalEngineering,2015,37(8):1 490–1 496.(in Chinese))
[24]王汉鹏,张庆贺,袁亮,等.含瓦斯煤相似材料研制及其突出试验应用[J].岩土力学,2015,36(6):1 676–1 682.(WANG Hanpeng,ZHANGQinghe,YUANLiang,etal.Developmentofasimilar materialformethane-bearingcoalanditsapplicationtooutburst experiment[J]. Rock and Soil Mechanics,2015,36(6):1 676–1 682.(in Chinese))
[25]李清川,王汉鹏,李术才,等.可视化恒容气固耦合试验系统的研发与应用[J].中国矿业大学学报,2018,47(1):148–156.(LI Qingchuan,WANGHanpeng,LIShucai,etal.Developmentand applicationofagas-solidcouplingtestsysteminthevisualand constantvolumeloadingstate[J].JournalofChinaUniversityof Mining and Technology,2018,47(1):148–156.(in Chinese))
[26]中华人民共和国国家标准编写组.GB/T50266—99工程岩体试验方法标准[S].北京:中国计划出版社,1999:15–16.(The National StandardsCompilationGroupofPeople′sRepublicofChina.GB/T50266—99 Standard for test method of engineering rock mass[S].Beijing:China Planning Press,1999:15–16.(in Chinese))
[27]刘力源,朱万成,魏晨慧,等.气体吸附诱发煤强度劣化的力学模型与数值分析[J].岩土力学,2018,39(4):1500–1508.(LIU Liyuan,ZHU Wangcheng,WEI Chenhui,et al. Mechanical model and numericalanalysisforgasadsorption-inducedcoalmechanical property alterations[J]. Rock and Soil Mechanics,2018,39(4):1 500–1 508.(in Chinese))
[2]李晓照,邵珠山.脆性岩石渐进及蠕变失效特性宏细观力学模型研究[J].岩土工程学报,2016,38(8):1 391–1 398.(LI Xiaozhao,SHAOZhushan.Macro-micromechanicalmodelfor progressiveand creepfailureofbrittlerock[J].ChineseJournalofGeotechnical Engineering,2016,38(8):1 391–1 398.(in Chinese))
[3]夏开文,徐颖,姚伟,等.静态预应力条件作用下岩板动态破坏行为试验研究[J].岩石力学与工程学报,2017,36(5):1 122–1 132.(XIAKaiwen,XUYing,YAOWei,etal.Experimentalstudyof dynamicfracturebehaviorofbrittlerockplateunderstatic pre-loading[J]. Chinese Journal of Rock Mechanics and Engineering,2017,36(5):1 122–1 132.(in Chinese))
[4]MOUSTABCHIRH, ARBAOUIJ, AZARIZ, etal.Experimental/numericalinvestigationofmechanicalbehaviourof internally pressurized cylindrical shells with external longitudinal and circumferentialsemi-ellipticaldefects[J].AlexandriaEngineering Journal,2017,(6):1–13.
[5]唐浩,李天斌,陈国庆,等.水力作用下砂岩三轴卸荷试验及破裂特性研究[J].岩土工程学报,2015,37(3):519–525.(TANG Hao,LI Tianbin,CHEN Guoqing,et al. Triaxial unloading tests on rupture characteristicsofsandstoneunderhydro-mechanicalcoupling conditions[J].ChineseJournalofGeotechnicalEngineering,2015,37(3):519–525.(in Chinese))
[6]尤明庆,华安增.岩样三轴压缩过程中的环向变形[J].中国矿业大学学报,1997,26(1):1–4.(YOUMingqing, HUAAnzeng.Circumferentialdeformationofrocksampleinpseudo-triaxial compression[J].JournalofChinaUniversityofMiningand Technology,1997,26(1):1–4.(in Chinese))
[7]种照辉,李学华,鲁竞争,等.基于数字图像与数值计算的节理岩体锚固效应研究[J].岩土工程学报,2017,39(7):1225–1233.(CHONGZhaohui,LIXuehua,LUJingzheng,etal.Anchorage behaviourofspecimenscontainingasinglefissurebasedondigital image correlation and numerical method[J]. Chinese Journal of Geotechnical Engineering,2017,39(7):1 225–1 233.(in Chinese))
[8]ANGELIDI M,VASSILOPOULOS A P,KELLER T. Displacement rateandstructuraleffectsonPoissonratioofaductilestructural adhesiveintensionandcompression[J].InternationalJournalof Adhesion and Adhesives,2017,78(10):13–22.
[9]YAMAGUCHI I. A laser-speckle strain gauge[J]. Journal of Physics E Scientific Instruments,2000,14(11):1 270–1 273.
[10]郭文婧,马少鹏,康永军,等.基于数字散斑相关方法的虚拟引伸计及其在岩石裂纹动态观测中的应用[J].岩土力学,2011,32(10):3 196–3 200.(GUO Wenjing,MA Shaopeng,KANG Yongjun,et al.Virtual extensometer based on digital speckle correlation method and itsapplicationtodeformationfieldevolutionofrockspecimen[J].Rock and Soil Mechanics,2011,32(10):3 196–3 200.(in Chinese))
[11]马永尚,陈卫忠,杨典森,等.基于三维数字图像相关技术的脆性岩石破坏试验研究[J].岩土力学,2017,38(1):117–123.(MA Yongshang,CHEN Weizhong,YANG Diansen,et al. Experimental studyof brittlerockfailurebased on three-dimensionaldigitalimage correlation technique[J]. Rock and Soil Mechanics,2017,38(1):117–123.(in Chinese))
[12]王波,吴亚波,郭洪宝,等. 2D-C/SiC复合材料偏轴拉伸力学行为研究[J].材料工程,2017,45(7):91–96.(WANG Bo,WU Yabo,GUOHongbao,etal.Investigationonoff-axistensilemechanical behaviorsof2D-C/SiCcomposites[J].JournalofMaterials Engineering,2017,45(7):91–96.(in Chinese))
[13]第五强强,张伟伟.基于应变片的弹性体分布式位移测量方法[J].西北工业大学学报,2017,35(3):422–427.(DIWU Qiangqiang,ZHANGWeiwei.Measurementofdistributeddisplacementfor elastic[J]. Journal of Northwestern Polytechnical University,2017,35(3):422–427.(in Chinese))
[14]李顺群,高凌霞,冯慧强,等.一种接触式三维应变花的工作原理及其应用[J].岩土力学,2015,36(5):1 513–1 520.(LI Shunqun,GAO Lingxia,FENG Huiqiang,et al. Principle and application of a three-dimensionalcontactingstrainrosette[J].RockandSoil Mechanics,2015,36(5):1 513–1 520.(in Chinese))
[15]CODP.Standardtestmethodforpoisson′sratioatroom temperature[c]//American Society for Testing and Materials. Philadelphia:[s.n.],1984:266.
[16]MTSSystemsCorporation.Circumferentialextensometerstrain calculation[R].[S.l.]:MTS Systems Corporation,2005.
[17]王伟,题正义,张宏岩.改进型岩石试验机检测系统的研究[J].矿山机械,2008,36(4):63–65.(WANG Wei,TI Zhengyi,ZHANG Hongyan.Studyondetectionsystemofmodifiedrocktesting machine[J].MiningandProcessingEquipment,2008,36(4):63–65.(in Chinese))
[18]李铀.利用电容原理测量试件的横向变形[J].岩土力学,1990,11(3):75–78.(LI You. Measuring lateral deformation of samples with e Iectric-capacity principle[J]. Rock and Soil Mechanics,1990,11(3):75–78.(in Chinese))
[19]PAEPGEMWV,BAEREID,LAMKANIE,etal.Monitoring quasi-staticandcyclicfatiguedamageinfibre-reinforcedplasticsby Poisson′s ratio evolution[J]. International Journal of Fatigue,2010,32(1):184–196.
[20]YILMAZC,AKALINC,KOCAMANES,etal.Monitoring Poisson′sratioofglassfiberreinforcedcompositesasdamageindex using biaxial Fiber Bragg Grating sensors[J]. Polymer Testing,2016,53(8):98–107.
[21]汪斌,朱杰兵,邬爱清.MTS815系统变形测试技术的若干改进[J].长江科学院学报,2010,27(12):94–98.(WANG Bin,ZHU Jiebing,WUAiqing.Someimprovementsofdeformationmeasurement techniques on MTS815 system[J]. Journal of Yangtze River Scientific Research Institute,2010,27(12):94–98.(in Chinese))
[22]ZHANG Q B,ZHAO J. A review of dynamic experimental techniques andmechanicalbehaviourofrockmaterials[J].RockMechanicsand Rock Engineering,2014,47(4):1 411–1 478.
[23]李元海,贾冉旭,杨苏.基于岩土渐进变形特征的数字散斑相关优化分析法[J].岩土工程学报,2015,37(8):1490–1496.(LI Yuanhai,JIA Ranxu,YANG Su. Optimized method for DSCM based onprogressivedisplacementcharacteristicsofgeotechnical materials[J].ChineseJournalofGeotechnicalEngineering,2015,37(8):1 490–1 496.(in Chinese))
[24]王汉鹏,张庆贺,袁亮,等.含瓦斯煤相似材料研制及其突出试验应用[J].岩土力学,2015,36(6):1 676–1 682.(WANG Hanpeng,ZHANGQinghe,YUANLiang,etal.Developmentofasimilar materialformethane-bearingcoalanditsapplicationtooutburst experiment[J]. Rock and Soil Mechanics,2015,36(6):1 676–1 682.(in Chinese))
[25]李清川,王汉鹏,李术才,等.可视化恒容气固耦合试验系统的研发与应用[J].中国矿业大学学报,2018,47(1):148–156.(LI Qingchuan,WANGHanpeng,LIShucai,etal.Developmentand applicationofagas-solidcouplingtestsysteminthevisualand constantvolumeloadingstate[J].JournalofChinaUniversityof Mining and Technology,2018,47(1):148–156.(in Chinese))
[26]中华人民共和国国家标准编写组.GB/T50266—99工程岩体试验方法标准[S].北京:中国计划出版社,1999:15–16.(The National StandardsCompilationGroupofPeople′sRepublicofChina.GB/T50266—99 Standard for test method of engineering rock mass[S].Beijing:China Planning Press,1999:15–16.(in Chinese))
[27]刘力源,朱万成,魏晨慧,等.气体吸附诱发煤强度劣化的力学模型与数值分析[J].岩土力学,2018,39(4):1500–1508.(LIU Liyuan,ZHU Wangcheng,WEI Chenhui,et al. Mechanical model and numericalanalysisforgasadsorption-inducedcoalmechanical property alterations[J]. Rock and Soil Mechanics,2018,39(4):1 500–1 508.(in Chinese))