三轴试样径向变形激光量测系统的改进
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摘要
利用激光光电检测技术和高精度位置敏感探测器(PSD)的优点,对三轴试样径向变形的激光量测系统进行相关改进。共做了3个方面的改进工作:(1)将圆形压力室改为方形压力室,可解决光垂直入射时发生的光线偏折现象。(2)由于原系统使用1个PSD,无法解决三轴剪切试验中试样容易发生偏心的问题,使用2个PSD分别对试样径向左右两侧进行量测,可提高量测的精度。(3)将控制传感器升降的微动机械控制单元的普通电机转换成由计算机指令控制的步进电机,每一行程都能回到同一初始位置。运用该套系统对标准件、压力室中的标准件和压力室加水的标准件进行标定,得出电信号变化与直径变化的函数关系,并对饱和含黏砂土试样进行固结试验,将测试结果同计算结果相比较,证明该套系统测试三轴试验试样的体变结果较为可靠。该系统可用于研究三轴试样的局部变形和端部约束等问题,并对当前土体本构关系中的应变局部化、剪切带形成以及非饱和土体变量测等方面也有比较广泛的应用前景。
Taking advantages of laser photoelectricity measurement technique and position sensing detector(PSD) with high precision,the laser measurement system for measuring radial deformation of triaxial specimens is improved. Three aspects of improvement have been done as follows:(1) In order to avoid the deflection of vertical incident light,the square pressure chamber is adopted instead of the circular one. (2) Two PSDs are used to measure radial deformation in left and right sides of specimen instead of one PSD in original system,which couldn′t take into account the specimen eccentricity in triaxial shear tests. So the measuring precision would be enhanced. (3) A stepper motor of controlling transducer lift and down is used instead of common motor. It can ensure the transducer goes back to the same initial position. This system is used to measure standard specimen,standard specimen in the pressure chamber and standard specimen in the pressure chamber full of water. The function relationship between change in electrical signal and change in diameter is obtained. The consolidation tests on saturated sand containing clay are carried out. The comparison of measured and calculated results indicates that the volumetric changing results obtained by the improved triaxial measurement system are reliable. This system can be applied to study the problem of triaxial specimens,such as local deformation and end restraint;it also has great prospect to study deformation localization,formation of shear zone and volumetric changing measurement of unsaturated soils.
Taking advantages of laser photoelectricity measurement technique and position sensing detector(PSD) with high precision,the laser measurement system for measuring radial deformation of triaxial specimens is improved. Three aspects of improvement have been done as follows:(1) In order to avoid the deflection of vertical incident light,the square pressure chamber is adopted instead of the circular one. (2) Two PSDs are used to measure radial deformation in left and right sides of specimen instead of one PSD in original system,which couldn′t take into account the specimen eccentricity in triaxial shear tests. So the measuring precision would be enhanced. (3) A stepper motor of controlling transducer lift and down is used instead of common motor. It can ensure the transducer goes back to the same initial position. This system is used to measure standard specimen,standard specimen in the pressure chamber and standard specimen in the pressure chamber full of water. The function relationship between change in electrical signal and change in diameter is obtained. The consolidation tests on saturated sand containing clay are carried out. The comparison of measured and calculated results indicates that the volumetric changing results obtained by the improved triaxial measurement system are reliable. This system can be applied to study the problem of triaxial specimens,such as local deformation and end restraint;it also has great prospect to study deformation localization,formation of shear zone and volumetric changing measurement of unsaturated soils.
引文
[1]孙树国,陈正汉,冷文,等.基于高精度PSD的三轴试样径向变形激光量测系统的研制[J].岩土工程学报,2007,29(10):1587–1590.(SUN Shuguo,CHEN Zhenghan,LENG Wen,et al.Development of laser measuring system to measure radial displacement of triaxia1specimens based on high precision PSD[J].Chinese Journal of Geotechnical Engineering,2007,29(10):1587–1590.(in Chinese))
[2]黄文熙.土的工程性质[M].北京:水利电力出版社,1983.(HUANG Wenxi.Engineering properties of soil[M].Beijing:Hydraulic and Power Press,1983.(in Chinese))
[3]邵龙谭,王助贫,韩国城,等.三轴试验土样径向变形的计算机图像测量[J].岩土工程学报,2001,23(3):337–341.(SHAO Longtan,WANG Zhupin,HAN Guocheng,et al.Digital image processing technique for measurement of the radial deformation of specimen intriaxial test[J].Chinese Journal of Geotechnical Engineering,2001,23(3):337–341.(in Chinese))
[4]陈正汉,孙树国,方祥位,等.非饱和土与特殊土测试技术新进展[J].岩土工程学报,2006,28(2):147–169.(CHEN Zhenghan,SUN Shuguo,FANG Xiangwei,et al.Recent advances of the measuring technology for unsaturated soils and special soils[J].Chinese Journal of Geotechnical Engineering,2006,28(2):147–169.(in Chinese))
[5]DRUMRIHGT E.The contribution of matric suction to the shear strength of unsaturated soils[Ph.D.Thesis][D].Colorado,USA:University of Colorado,1989.
[6]SUN D A,MATSUOKA H.Collapse of compacted clays using triaxial tests[C]//Proceedings of the3rd International Conference on Unsaturated Soils.[S.l.]:A.A.Balkema,2002:631–634.
[7]MATSUOKA H,SUN D A.The SMP concept-based3D constitutive models for geomaterials[M].London:Taylor and Francis Group,2006.
[8]SUN D A,MATSUOKA H,XU Y F.Elastoplastic model for unsaturated compacted soils and its verification[C]//Proceedings of the1st Worldwide Chinese Geotechnical Forum.Shanghai:[s.n.],2003:60–70.
[9]ROMERO E,LORET A,GENS A.Development of a new suction and temperature controlled oedometer cell[C]//Proceedings of the1st International Conference on Unsaturated Soils.Paris:[s.n.],1995:553–559.
[10]SOPHIE M,ERNST B,ADRIAN Z,et al.Displacement measurement with laser scanning in triaxial testing apparatuses[C]//Proceedings of European Young Geotechnical Engineers Conference.[S.l.]:[s.n.],2004:1–10.
[11]JUCA J F T,FRYDMAN S.State of the art—experimental techniques[C]//Proceedings of the1st International conference on unsaturated soils.[S.l.]:A.A.Balkema,1995:76–111.
[12]RIFAI A,LALOUI L,VULLIET L.Volume measurement in unsaturated triaxial test using liquid variation and image processing[C]//Proceedings of the3rd International Conference on Unsaturated Soils.[S.l.]:A.A.Balkema,2002:441–445.
[13]ELKADY Y T,HOUSTON W N,HOUSTON S L.Calibrated image processing for unsaturated soils testing[C]//Proceedings of the3rd International Conference on Unsaturated Soils.[S.l.]:A.A.Balkema,2002:447–451.
[14]吕海宝.激光光电检测[M].长沙:国防科技大学出版社,2004.(LU Haibao.Laser photoelectricity detect technique[M].Changsha:University of Defense Technology Publishing House,2004.(in Chinese))
[15]李昆.激光非接触位移传感器的研制及其应用[博士学位论文][D].哈尔滨:中国地震局工程力学研究所,2004.(LI Kun.Development and application of noncontact laser type sensor for displacement measurement[Ph.D.Thesis][D].Harbin:Insititute of Engineering Mechanics,China Seismological Bureau,2004.(in Chinese))
[16]MATHEWS J H,FINK K K.Numerical methods using MATLAB[M].Beijing:Publishing House of Electronics Industry,2002.
[2]黄文熙.土的工程性质[M].北京:水利电力出版社,1983.(HUANG Wenxi.Engineering properties of soil[M].Beijing:Hydraulic and Power Press,1983.(in Chinese))
[3]邵龙谭,王助贫,韩国城,等.三轴试验土样径向变形的计算机图像测量[J].岩土工程学报,2001,23(3):337–341.(SHAO Longtan,WANG Zhupin,HAN Guocheng,et al.Digital image processing technique for measurement of the radial deformation of specimen intriaxial test[J].Chinese Journal of Geotechnical Engineering,2001,23(3):337–341.(in Chinese))
[4]陈正汉,孙树国,方祥位,等.非饱和土与特殊土测试技术新进展[J].岩土工程学报,2006,28(2):147–169.(CHEN Zhenghan,SUN Shuguo,FANG Xiangwei,et al.Recent advances of the measuring technology for unsaturated soils and special soils[J].Chinese Journal of Geotechnical Engineering,2006,28(2):147–169.(in Chinese))
[5]DRUMRIHGT E.The contribution of matric suction to the shear strength of unsaturated soils[Ph.D.Thesis][D].Colorado,USA:University of Colorado,1989.
[6]SUN D A,MATSUOKA H.Collapse of compacted clays using triaxial tests[C]//Proceedings of the3rd International Conference on Unsaturated Soils.[S.l.]:A.A.Balkema,2002:631–634.
[7]MATSUOKA H,SUN D A.The SMP concept-based3D constitutive models for geomaterials[M].London:Taylor and Francis Group,2006.
[8]SUN D A,MATSUOKA H,XU Y F.Elastoplastic model for unsaturated compacted soils and its verification[C]//Proceedings of the1st Worldwide Chinese Geotechnical Forum.Shanghai:[s.n.],2003:60–70.
[9]ROMERO E,LORET A,GENS A.Development of a new suction and temperature controlled oedometer cell[C]//Proceedings of the1st International Conference on Unsaturated Soils.Paris:[s.n.],1995:553–559.
[10]SOPHIE M,ERNST B,ADRIAN Z,et al.Displacement measurement with laser scanning in triaxial testing apparatuses[C]//Proceedings of European Young Geotechnical Engineers Conference.[S.l.]:[s.n.],2004:1–10.
[11]JUCA J F T,FRYDMAN S.State of the art—experimental techniques[C]//Proceedings of the1st International conference on unsaturated soils.[S.l.]:A.A.Balkema,1995:76–111.
[12]RIFAI A,LALOUI L,VULLIET L.Volume measurement in unsaturated triaxial test using liquid variation and image processing[C]//Proceedings of the3rd International Conference on Unsaturated Soils.[S.l.]:A.A.Balkema,2002:441–445.
[13]ELKADY Y T,HOUSTON W N,HOUSTON S L.Calibrated image processing for unsaturated soils testing[C]//Proceedings of the3rd International Conference on Unsaturated Soils.[S.l.]:A.A.Balkema,2002:447–451.
[14]吕海宝.激光光电检测[M].长沙:国防科技大学出版社,2004.(LU Haibao.Laser photoelectricity detect technique[M].Changsha:University of Defense Technology Publishing House,2004.(in Chinese))
[15]李昆.激光非接触位移传感器的研制及其应用[博士学位论文][D].哈尔滨:中国地震局工程力学研究所,2004.(LI Kun.Development and application of noncontact laser type sensor for displacement measurement[Ph.D.Thesis][D].Harbin:Insititute of Engineering Mechanics,China Seismological Bureau,2004.(in Chinese))
[16]MATHEWS J H,FINK K K.Numerical methods using MATLAB[M].Beijing:Publishing House of Electronics Industry,2002.
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