粗粒土二维模型试验研究
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摘要
粗粒土是土石坝的主要填坝材料,其力学特性研究是土力学热点之一,一般采用三轴试验来研究粗粒土的力学性质,由于试验方法的限制,很难观察到三轴试验过程中颗粒的运动。为了获得试验过程中颗粒的运动规律,研究粗粒土的细观变形机理,设计并开展了粗粒土二维模型试验。二维模型试验过程中可以清楚地观察到颗粒的运动,能定性地分析试样的受力变形特征。试验结果表明:①峰值偏应力随侧压力的增大而增大,峰后略有软化现象,体变随应变的发展先剪缩后剪胀,侧压力越小剪胀性越明显;②抗剪强度包线呈很好的线性关系;③颗粒破碎率随侧压力的增大而增大,在很小的侧压力下,就有颗粒破碎发生;④试样破坏时有较明显的剪切带。模型试验的上述规律和三轴试验成果具有很好的一致性,说明二维模型试验能够反映三轴试验过程。
Coarse-grained soil is the main material constructed in rockfill dams,and the research of mechanics properties is a focus of soil mechanics,which is generally obtained by triaxial test.Particle movement is difficult to observe in triaxial test due to shortcomings of test means.Two-dimensional model test for coarsegrained soil was designed and carried out in order to get particle movement laws in test process and to research the meso-deformation mechanism of coarse-grained soil.This paper primarily deals with two-dimensional tests.Particle movement can be observed clearly in test process,and the deformation characters of specimen can also be analyzed qualitatively.The test results indicate:(1) the peak deviatoric stress increases with the increase of lateral pressure,the soften phenomenon occurs after peak stress,the specimen is compressed at first stage and then dilates,and the dilatancy property decreases with the increases of lateral pressure;(2) the Mohr-Coulomb failure envelope shows good linear relationship;(3) the particle breakage increases with the increase of lateral pressure,and particle breakage occurs even at very low lateral pressure;(4) the shear zone occurs when the specimen comes to failure.The above laws on stress-strain relationship,shear strength,particle breakage and specimen failure mode are in good agreement with the results of triaxial test,which indicates that the model test can reflect triaxial test process.
Coarse-grained soil is the main material constructed in rockfill dams,and the research of mechanics properties is a focus of soil mechanics,which is generally obtained by triaxial test.Particle movement is difficult to observe in triaxial test due to shortcomings of test means.Two-dimensional model test for coarsegrained soil was designed and carried out in order to get particle movement laws in test process and to research the meso-deformation mechanism of coarse-grained soil.This paper primarily deals with two-dimensional tests.Particle movement can be observed clearly in test process,and the deformation characters of specimen can also be analyzed qualitatively.The test results indicate:(1) the peak deviatoric stress increases with the increase of lateral pressure,the soften phenomenon occurs after peak stress,the specimen is compressed at first stage and then dilates,and the dilatancy property decreases with the increases of lateral pressure;(2) the Mohr-Coulomb failure envelope shows good linear relationship;(3) the particle breakage increases with the increase of lateral pressure,and particle breakage occurs even at very low lateral pressure;(4) the shear zone occurs when the specimen comes to failure.The above laws on stress-strain relationship,shear strength,particle breakage and specimen failure mode are in good agreement with the results of triaxial test,which indicates that the model test can reflect triaxial test process.
引文
[1]郭庆国.关于粗粒土抗剪强度特性的试验研究[J].水利学报,1987,(5):59-65.
[2]齐吉琳,谢定义,石玉成.土结构性的研究方法及现状[J].西北地震学报,2001,23(1):99-103.
[3]刘爱平,崔春龙.岩土体显微组构与力学性能关系研究现状与展望[J].西南科技大学学报,2003,18(2):75-78.
[4]刘汉龙,秦红玉,高玉峰,等.堆石粗粒料颗粒破碎试验研究[J].岩土力学,2005,26(4):562-566.
[5]陈希哲.粗粒土的强度与咬合力的试验研究[J].工程力学,1994,11(4):56-63.
[2]齐吉琳,谢定义,石玉成.土结构性的研究方法及现状[J].西北地震学报,2001,23(1):99-103.
[3]刘爱平,崔春龙.岩土体显微组构与力学性能关系研究现状与展望[J].西南科技大学学报,2003,18(2):75-78.
[4]刘汉龙,秦红玉,高玉峰,等.堆石粗粒料颗粒破碎试验研究[J].岩土力学,2005,26(4):562-566.
[5]陈希哲.粗粒土的强度与咬合力的试验研究[J].工程力学,1994,11(4):56-63.
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