黄土饱和度与B值关系试验研究
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摘要
黄土由于结构不同于一般岩土体,三轴试验的饱和阶段,利用抽气饱和极易导致黄土结构扰动而发生破坏。而试样饱和是三轴试验中的重要步骤之一,且饱和度直接影响后期黄土力学性质的准确性。为研究不引起黄土结构破坏的饱和方法,利用天水和兰州所取原状黄土试样,在GDS三轴仪上开展了8组共33个试样的三轴饱和试验,基于体变传感器实时监测试样在饱和中所产生的体积变化,结合精确控制器测得试样中滞水质量,进行饱和度计算。同时利用GDS三轴仪进行B值检测,如此反复获得黄土试样饱和度与B值关系曲线。分析了不同饱和方式对黄土饱和效果的影响,并对黄土饱和度与B值关系进行非线性拟合,获得其定量关系:饱和度和B值存在指数函数关系。
Loess is a special soil because of its large pore structure and vertical joints. The structure of loess is unique, so the structure of loess will be destroyed if the loess is vacuum saturated. The saturation of soil is one of the important steps in the triaxial test. It is known that the saturation degree of specimen closely correlates with the accuracy of the loess mechanical properties. Eight groups of loess samples from Lanzhou and Tianshui, Gansu province, China, were used in the triaxial tests of saturation by GDS triaxial apparatus. A total volume change sensor was used during the saturation of loess samples. Later the total volume change tested by the sensor and the quantity of water in the sample tested by the controller. The saturation degrees of loess samples were calculated by the parameters of loess. After that, the B value would be collected by the computer at the same time. The relationship between the saturation degree and the B value was obtained at the same time. The influence of different methods of saturation on the loess was discussed. The nonlinear fitting on the saturation degree and B value was also conducted so that an empirical formula with exponential form was produced.
Loess is a special soil because of its large pore structure and vertical joints. The structure of loess is unique, so the structure of loess will be destroyed if the loess is vacuum saturated. The saturation of soil is one of the important steps in the triaxial test. It is known that the saturation degree of specimen closely correlates with the accuracy of the loess mechanical properties. Eight groups of loess samples from Lanzhou and Tianshui, Gansu province, China, were used in the triaxial tests of saturation by GDS triaxial apparatus. A total volume change sensor was used during the saturation of loess samples. Later the total volume change tested by the sensor and the quantity of water in the sample tested by the controller. The saturation degrees of loess samples were calculated by the parameters of loess. After that, the B value would be collected by the computer at the same time. The relationship between the saturation degree and the B value was obtained at the same time. The influence of different methods of saturation on the loess was discussed. The nonlinear fitting on the saturation degree and B value was also conducted so that an empirical formula with exponential form was produced.
引文
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[18]中华人民共和国水利部,GB/T50123―1999.土工试验方法标准[S].北京:中国计划出版社,1999.The Ministry of Water Resources of the People’s Republic of China.GB/T50123―1999 Standard for soil test method[S].Beijing:China Planning Press,1999.
[19]GU X Q,YANG J,HUANG M S.Laboratory investigation on relationship between degree of saturation,B-value and P-wave velocity[J].Journal of Central South University,2013,20(7):2001-2007.
[20]黄博,汪清静,凌道盛,等.饱和砂土三轴试验中反压设置与抗剪强度的研究[J].岩土工程学报,2012,34(7):1313-1319.HUANG Bo,WANG Qing-jing,LIN Dao-sheng,et al.Effects of back pressure on shear strength of saturated sand in triaxial tests[J].Chinese Journal of Geotechnical Engineering,2012,34(7):1313-1319.
[2]周永习,张得煊,罗春泳,等.饱和黄土稳态强度特性的试验研究[J].岩土力学,2010,31(5):1486-1490.ZHOU Yong-xi,ZHANG De-xuan,LUO Chun-yong,et al.Experimental research on steady strength of saturated loess[J].Rock and Soil Mechanics,2010,31(5):1486-1490.
[3]庞旭卿,胡再强,李宏儒,等.黄土剪切损伤演化及其力学特性的CT-三轴试验研究[J].水利学报,2016,47(2):180-188.PANG Xu-qing,HU Zai-qiang,LI Hong-ru,et al.Structure damage evolution and mechanical properties of loess by CT-triaxial test[J].Journal of Hydraulic Engineering,2016,47(2):180-188.
[4]李加贵,陈正汉,黄雪峰.原状Q3黄土湿陷特性的CT-三轴试验[J].岩石力学与工程学报,2010,29(6):1288-1296.LI Jia-gui,CHEN Zheng-han,HUANG Xue-feng.CT-triaxial test for collapsibility of undisturbed Q3 loess[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(6):1288-1296.
[5]方瑾瑾,邵生俊,冯以鑫.真三轴条件下Q3原状黄土的吸力变化特性研究[J].岩土力学,2017,38(4):934-942.FANG Jin-jin,SHAO Sheng-jun,FENG Yi-xin.Suction changes of intact Q3 loess based on true triaxial tests[J].Rock and Soil Mechanics,2017,38(4):934-942.
[6]陈昌禄,邵生俊,罗爱忠,等.结构性对原状黄土强度影响规律的真三轴试验研究[J].岩土工程学报,2013,35(12):2322-2327.CHEN Chang-lu,SHAO Sheng-jun,LUO Ai-zhong,et al.True triaxial tests on structural effects on strength of intact loess[J].Chinese Journal of Geotechnical Engineering,2013,35(12):2322-2327.
[7]张玉,邵生俊,陈菲,等.不同应力路径条件下原状Q3黄土的强度特性及破坏方式试验研究[J].岩土力学,2017,38(增刊2):99-106.ZHANG Yu,SHAO Sheng-jun,CHEN Fei,et al.Experimental study of strength characteristics and failure modes of Q3 intact loess under different stress paths[J].Rock and Soil Mechanics,2017,38(Suppl.2):99-106.
[8]王军海,刘亚明.基于动三轴试验的压实黄土动强度特性研究[J].地震工程学报,2016,38(3):439-444.WANG Jun-hai,LIU Ya-ming.Dynamic strength properties of compacted loess based on dynamic triaxial test[J].China Earthquake Engineering Journal,2016,38(3):439-444.
[9]WANG G,ZHANG D,FURUYA G,et al.Pore-pressure generation and fluidization in a loess landslide triggered by the 1920 Haiyuan earthquake,China:a case study[J].Engineering Geology,2014,174(1):36-45.
[10]ZHANG D,WANG G,LUO C,et al.A rapid loess flowslide triggered by irrigation in China[J].Landslides,2009,6(1):55-60.
[11]SHAHNAZARI H,REZVANI R.Effective parameters for the particle breakage of calcareous sands:an experimental study[J].Engineering Geology,2013,159(9):98-105.
[12]YILMAZ Y,MOLLAMAHMUTOGLU M,OZAYDIN V,et al.Experimental investigation of the effect of grading characteristics on the liquefaction resistance of various graded sands[J].Engineering Geology,2008,100(3):91-100.
[13]DAOUADJI A,ALGALI H,DARVE F,et al.Instability in granular materials:experimental evidence of diffuse mode of failure for loose sands[J].Journal of Engineering Mechanics,2010,136(5):575-588.
[14]CHEN X,ZHANG J,LI Z.Shear behaviour of a geogrid-reinforced coarse-grained soil based on large-scale triaxial tests[J].Geotextiles and Geomembranes,2014,42(4):312-328.
[15]金艳丽,戴福初.饱和黄土的静态液化特性试验研究[J].岩土力学,2008,29(12):3293-3298.JIN Yan-li,DAI Fu-chu.Experimental investigation of static liquefaction of saturated loess[J].Rock and Soil Mechanics,2008,29(12):3293-3298.
[16]王平,王谦,王兰民,等.黄土室内液化试验饱和方法的研究现状及前景展望[J].世界地震工程,2011,27(4):86-90.WANG Ping,WANG Qian,WANG Lan-min,et al.Status quo and prospect of research on saturated methods in loess liquefaction test[J].World Earthquake Engineering,2011,27(4):86-90.
[17]谌文武,刘伟,孙冠平,等.重塑黄土饱和与固结时间三轴试验研究[J].工程地质学报,2014,22(5):839-844.CHEN Wen-wu,LIU Wei,SUN Guan-ping,et al.Triaxial test on saturation and consolidation of remolded loess[J].Journal of Engineering Geology,2014,22(5):839-844.
[18]中华人民共和国水利部,GB/T50123―1999.土工试验方法标准[S].北京:中国计划出版社,1999.The Ministry of Water Resources of the People’s Republic of China.GB/T50123―1999 Standard for soil test method[S].Beijing:China Planning Press,1999.
[19]GU X Q,YANG J,HUANG M S.Laboratory investigation on relationship between degree of saturation,B-value and P-wave velocity[J].Journal of Central South University,2013,20(7):2001-2007.
[20]黄博,汪清静,凌道盛,等.饱和砂土三轴试验中反压设置与抗剪强度的研究[J].岩土工程学报,2012,34(7):1313-1319.HUANG Bo,WANG Qing-jing,LIN Dao-sheng,et al.Effects of back pressure on shear strength of saturated sand in triaxial tests[J].Chinese Journal of Geotechnical Engineering,2012,34(7):1313-1319.