土石混合填料大型三轴剪切试验研究
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摘要
为研究土石混合填料在不同土石混合比情况下的力学响应,以国道316旬阳至安康二级公路改建工程中的填石高路堤工程为依托,利用大型三轴剪切试验仪,在4种不同围压条件下,分别对土石混合质量比为3∶7和3∶2的试样进行固结不排水剪切试验。发现当土石混合比为3∶7时,在低围压(200 kPa)条件下,试样应力-应变曲线为应变硬化型,在高围压(400,600和800kPa)条件下,试样应力-应变曲线在达到峰值应力后有所下降,表现为弱应变软化。在4种围压条件下,试样体应变均表现为随轴向应变先增大后减小,即试样先剪缩后剪胀,且表现为随着围压的增大,剪缩量不断增大,然后达到峰值,随后体应变减小,表现出剪胀趋势,且随着围压的增大,剪胀趋势减弱。当土石混合比为3∶2时,在4种围压条件下,试样应力-应变曲线均表现为应变硬化,无明显的峰值强度。试样体应变均随轴向应变增大而增大,即试样一直表现为剪缩,且围压越大,剪缩趋势越明显,剪缩量越大。体变速率(dεv/dε1)能较好地反映试样变形特性和应力-应变特性。结果表明:土石混合比的变化对土石混合料剪胀性影响很大,对应力-应变特性的影响主要体现在加载后期。
To study the mechanical response of embankment fillings under different soil-rock mixing ratios,based on the project of high rockfill embankment in the reconstruction project of the Xunyang-Ankang secondary road of the National Highway 316,large-scale triaxial consolidated undrained shear tests were carried out on samples with mass ratios of soil-rock mixing of 3∶ 7 and 3∶ 2 under four different confining pressures. It is pointed out that when the soil-rock mixing ratio is 3 ∶ 7,the stress-strain curve shows strain hardening under low confining pressure( 200 k Pa),and under high confining pressure( 400,600 and 800 kPa),the stress-strain curves decreases after reaching the peak stress,which is characterized by weak strain softening. Under four confining pressures,the volumetric strain first increases and then decreases with the axial strain,that is,the sample shearing shrinkage at first,then dilatancy later,and with the increase of confining pressure,the amount of shearing shrinkage increases continuously,then reaches the peak value,and afterwards the volumetric strain decreases,showing the dilatancy trend,which is weakened with the increase of confining pressure. When the soil-rock mixing ratio is 3∶ 2,under four confining pressures,the stress-strain curves show strain hardening without obvious peak strength.The volumetric strain increases with the increase of axial strain,i. e.,the sample shows shearing shrinkage,and as the confining pressure increase,the shearing shrinkage trend becomes apparent and the amount of shearing shrinkage becomes greater. The volumetric rate could well reflect the deformation and stress-strain characteristics of the samples. The results indicate that the change of soil-rock mixing ratio has great influence on the dilatancy of soil-rock mixture,and the influence on stress-strain characteristics is mainly reflected in the later stage of loading.
To study the mechanical response of embankment fillings under different soil-rock mixing ratios,based on the project of high rockfill embankment in the reconstruction project of the Xunyang-Ankang secondary road of the National Highway 316,large-scale triaxial consolidated undrained shear tests were carried out on samples with mass ratios of soil-rock mixing of 3∶ 7 and 3∶ 2 under four different confining pressures. It is pointed out that when the soil-rock mixing ratio is 3 ∶ 7,the stress-strain curve shows strain hardening under low confining pressure( 200 k Pa),and under high confining pressure( 400,600 and 800 kPa),the stress-strain curves decreases after reaching the peak stress,which is characterized by weak strain softening. Under four confining pressures,the volumetric strain first increases and then decreases with the axial strain,that is,the sample shearing shrinkage at first,then dilatancy later,and with the increase of confining pressure,the amount of shearing shrinkage increases continuously,then reaches the peak value,and afterwards the volumetric strain decreases,showing the dilatancy trend,which is weakened with the increase of confining pressure. When the soil-rock mixing ratio is 3∶ 2,under four confining pressures,the stress-strain curves show strain hardening without obvious peak strength.The volumetric strain increases with the increase of axial strain,i. e.,the sample shows shearing shrinkage,and as the confining pressure increase,the shearing shrinkage trend becomes apparent and the amount of shearing shrinkage becomes greater. The volumetric rate could well reflect the deformation and stress-strain characteristics of the samples. The results indicate that the change of soil-rock mixing ratio has great influence on the dilatancy of soil-rock mixture,and the influence on stress-strain characteristics is mainly reflected in the later stage of loading.
引文
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[16]夏加国,胡瑞林,祁生文,等.含超径颗粒土石混合体的大型三轴剪切试验研究[J].岩石力学与工程学报,2017,36(8):2031-2039.XIA Jia-guo,HU Rui-lin,QI Sheng-wen,et al. Largescale triaxial shear testing of soil rock mixtures containing oversized particles[J]. Chinese Journal of Rock Mechanics and Engineering,2017,36(8):2031-2039.
[17]王强,胡新丽,徐迎,等.软岩土石混合体的击实特性与细观机理研究[J].浙江大学学报(工学版),2018,52(12):2995-2305.WANG Qiang,HU Xin-li,XU Ying,et al. Investigation on compaction characteristics and meso-mechanismof soil-rock mixture with soft rock blocks[J]. Journal of Zhejiang University(Engineering Science),2018,52(12):2995-2305.
[18] ZHANG Hai-yang,XU Wen-jie,YU Yu-zhen. Triaxial tests of soil–rock mixtures with different rock block distributions[J]. Soils and Foundations,2016,56(1):44-56.
[19] SHAN Peng-fei,LAI Xing-ping. Mesoscopic structure PFC2D model of soil rock mixture based on digital image[J]. Journal of Visual Communication and Image Representation,2019,58(1):407-415.
[20] Li X,Liao Q L,He J M. Insitu tests and a stochastic structural model of rock and soil aggregate in the three gorges reservoir area,China[J]. Journal of Rock Mechanics and Mining Science,2005,41(3):494-495.
[2]曹文贵,黄文健,王江营,等.土石混填体变形力学特性大型三轴试验研究[J].湖南大学学报(自然科学版),2016,43(3):142-148.CAO Wen-gui,HUANG Wen-jian,WANG Jiang-ying,et al. Large-scale triaxial test study on deformation and intensity characteristics of soil-rock aggregate mixture[J].Journal of Hunan University(Natural Sciences),2016,43(3):142-148.
[3]丁自伟,钱坤.基于原位直剪试验的岩土体力学特性研究[J].西安科技大学学报,2017,37(1):32-37.DING Zi-wei,QIAN Kun. Mechanic characteristics of rock and soil mass based on in-situ direct shear test[J]. Journal of Xi’an University of Science and Technology,2017,37(1):32-37.
[4]宁金成,孙久民.土石混合体的力学性能影响因素研究[J].中外公路,2012,32(2):207-210.NING Jin-cheng,SUI Jiu-min. Study on influence factors of mechanical properties of soil-rock mixture[J]. Journal of China&Foreign Highway,2012,32(2):207-210.
[5]刘丽萍,折学森.土石混合料压实特性试验研究[J].岩石力学与工程学报,2006,25(1):206-210.LIU Li-ping,SHE Xue-sen. Study on compaction property of earth-rock mixture[J]. Chinese Journal of Rock Mechanics and Engineering,2006,25(1):206-210.
[6]赵川,石晋旭,唐红梅.三峡库区土石比对土体强度参数影响规律的试验研究[J].公路,2006(11):32-35.ZHAO Chuan,SHI Jin-xu,TANG Hong-mei. Test and research on influence law of soil-rock ratio in Three Gorges Reservoir Region on soil strength parameters[J].Highway,2006(11):32-35.
[7]董云.土石混合料强度特性的试验研究[J].岩土力学,2007,28(6):1269-1274.DONG Yun. Experimental study on intensity character of rock-soil aggregate mixture[J]. Rock and Soil Mechanics,2007,28(6):1269-1274.
[8]田恒蛟,薛亚东.路用土石混合料的剪切特性试验研究[J].地下空间与工程学报,2014,10(1):30-35,50.TIAN Heng-jiao,XUE Ya-dong. Experimental research on shear behavior of soil-rock mixture for road construction[J]. Chinese Journal of Underground Space and Engineering,2014,10(1):30-35,50.
[9]孙文君,宋杨,路维,等.黄土-碎石混合体的力学性质试验研究[J].公路,2016,(5):178-181.SUN Wen-jun,SONG Yang,LU Wei,et al. Experimental study on mechanical properties of loess-crushed stone mixture[J]. Highway,2016,(5):178-181.
[10]王江营,曹文贵,蒋中明,等.不同应力路径下土石混填体变形力学特性大型三轴试验研究[J].岩土力学,2016,37(2):424-430.WANG Jiang-ying,CAO Wen-gui,JIANG Zhong-ming,et al. Large-scale triaxial tests on deformation and mechanical behavior of soil-rock aggregate mixture under different stress paths[J]. Rock and Soil Mechanics,2016,37(2):424-430.
[11]金磊,曾亚武,张森.块石含量及形状对胶结土石混合体力学性能影响的大型三轴试验[J].岩土力学,2017,38(1):141-149.JIN Lei,ZENG Ya-wu,ZHANG Sen. Large scale triaxial tests on effects of rock block proportion and shape on mechanical properties of cemented soil-rock mixture[J]. Rock and Soil Mechanics,2017,38(1):141-149.
[12]闫云明,王雯璐.粗粒掺量对土石混合料强度特性的影响[J].科技通报,2017,33(9):142-145.YAN Yun-ming,WANG Wen-lu. Effects of coarse fraction content and grain size on strength properties of soil and rock mixtures[J]. Bulletin of Science and Technology,2017,33(9):142-145.
[13]舒志乐,刘新荣,刘保县,等.基于分形理论的土石混合体强度特征研究[J].岩石力学与工程学报,2009,28(增1):2651-2656.SHU Zhi-le,LIU Xin-rong,LIU Bao-xian,et al. Study of strength properties of earth-rock aggregate based on fractals[J]. Chinese Journal of Rock Mechanics and Engineering,2009,28(S1):2651-2656.
[14]杨忠平,雷晓丹,王雷,等.含石量对土石混合体剪切特性影响的颗粒离散元数值研究[J].工程地质学报,2017,25(4):1035-1045.YANG Zhong-ping,LEI Xiao-dan,WANG Lei,et al. Impact of stone content to shear properties of soil-rock mixture using particle flow code simulation[J]. Journal of Engineering Geology,2017,25(4):1035-1045.
[15]詹永祥,姚海林.块石含量对土石混合体抗剪强度特性的影响[J].公路,2018(2):20-25.ZHAN Yong-xiang,YAO Hai-lin. Effect of stone content on shear strength characteristics of soil-rock mixture[J]. Highway,2018(2):20-25.
[16]夏加国,胡瑞林,祁生文,等.含超径颗粒土石混合体的大型三轴剪切试验研究[J].岩石力学与工程学报,2017,36(8):2031-2039.XIA Jia-guo,HU Rui-lin,QI Sheng-wen,et al. Largescale triaxial shear testing of soil rock mixtures containing oversized particles[J]. Chinese Journal of Rock Mechanics and Engineering,2017,36(8):2031-2039.
[17]王强,胡新丽,徐迎,等.软岩土石混合体的击实特性与细观机理研究[J].浙江大学学报(工学版),2018,52(12):2995-2305.WANG Qiang,HU Xin-li,XU Ying,et al. Investigation on compaction characteristics and meso-mechanismof soil-rock mixture with soft rock blocks[J]. Journal of Zhejiang University(Engineering Science),2018,52(12):2995-2305.
[18] ZHANG Hai-yang,XU Wen-jie,YU Yu-zhen. Triaxial tests of soil–rock mixtures with different rock block distributions[J]. Soils and Foundations,2016,56(1):44-56.
[19] SHAN Peng-fei,LAI Xing-ping. Mesoscopic structure PFC2D model of soil rock mixture based on digital image[J]. Journal of Visual Communication and Image Representation,2019,58(1):407-415.
[20] Li X,Liao Q L,He J M. Insitu tests and a stochastic structural model of rock and soil aggregate in the three gorges reservoir area,China[J]. Journal of Rock Mechanics and Mining Science,2005,41(3):494-495.