土体含水状态对黄土边坡剥落病害产生的影响
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摘要
对不同含水状态下的土试样开展宏观裂缝分析及室内直剪试验,研究黄土试样在不同含水状态下裂隙发育扩展过程,分析在不同干湿循环次数、不同增湿、减湿变化幅度条件下剪切强度的变化规律,探讨黄土体含水状态对边坡剥落病害的影响。结果表明:洛川黄土粘粒含量大,土体吸水性强,崩解性强;在增湿、减湿过程土体内部均会产生裂隙,土体结构发生不同程度的破坏;随着干湿循环次数及循环幅度的增加,土试样表面裂隙不断扩展、延伸,内部结构破坏程度增加;当土体内部某个优势面贯通时,沿着优势面发生剥落病害。
Based on macroscopic crack analysis and laboratory direct shear test of different loess moisture states,the development of loess fissure under different loess moisture states was researched.Through analysing the different loess dry-wet circle test times and the variation law of shear strength under different conditions of humidification and dehumidification amplitude,the influence of loess moisture state on loess slope spalling hazards was discussed.The results show that the loess samples collected from Luochuan are composed of larger clay contents,with stronger water absorption ability and stronger disintegration.During the process of humidification and dehumidification,cracks occur on the loess samples,which causes damage of loess structure at different degrees.With the increase of dry-wet circle time and amplitude,the cracks in sample surface undergo continuous expansion and the loess internal structure damage increases seriously.Once the preferred plane of the loess perforates,spalling hazards will occur along the preferred plane.
Based on macroscopic crack analysis and laboratory direct shear test of different loess moisture states,the development of loess fissure under different loess moisture states was researched.Through analysing the different loess dry-wet circle test times and the variation law of shear strength under different conditions of humidification and dehumidification amplitude,the influence of loess moisture state on loess slope spalling hazards was discussed.The results show that the loess samples collected from Luochuan are composed of larger clay contents,with stronger water absorption ability and stronger disintegration.During the process of humidification and dehumidification,cracks occur on the loess samples,which causes damage of loess structure at different degrees.With the increase of dry-wet circle time and amplitude,the cracks in sample surface undergo continuous expansion and the loess internal structure damage increases seriously.Once the preferred plane of the loess perforates,spalling hazards will occur along the preferred plane.
引文
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[2]方鹏.黄土边坡剥落病害处治技术研究[D].西安:长安大学,2007.FANG Peng.Study on the Punishment Technology of Flake in Loess Side Slope[D].Xi’an:Chang’an University,2007.
[3]叶万军,杨更社,彭建兵,等.冻融循环导致洛川黄土边坡剥落病害产生机制的试验研究[J].岩石力学与工程学报,2012,31(1):199-205.YE Wan-jun,YANG Geng-she,PENG Jian-bing,et al.Test Research on Mechanism of Freezing and Thawing Cycle Resulting in Loess Slope Spalling Hazards in Luochuan[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(1):199-205.
[4]吕海波,曾召田,赵艳林,等.膨胀土强度干湿循环试验研究[J].岩土力学,2009,30(12):3797-3802.LU Hai-bo,ZENG Zhao-tian,ZHAO Yan-lin,et al.Experimental Studies of Strength of Expansive Soil in Drying and Wetting Cycle[J].Rock and Soil Mechanics,2009,30(12):3797-3802.
[5]张芳枝,陈晓平.反复干湿循环对非饱和土的力学特性影响研究[J].岩土工程学报,2010,32(1):41-46.ZHANG Fang-zhi,CHEN Xiao-ping.Influence of Repeated Drying and Wetting Cycles on Mechanical Behaviors of Unsaturated Soil[J].Chinese Journal of Geotechnical Engineering,2010,32(1):41-46.
[6]李国玉,马巍,李宁,等.冻融对压实黄土工程地质特性影响的试验研究[J].水利与建筑工程学报,2010,8(4):5-7.LI Guo-yu,MA Wei,LI Ning,et al.Experimental Research on Impact of Freezing and Thawing on Geotechnical Properties of Compacted Loess[J].Journal of Water Resources and Architectural Engineering,2010,8(4):5-7.
[7]曾仲毅,徐帮树,胡世权,等.增湿条件下膨胀土隧道衬砌破坏数值分析[J].岩土力学,2014,35(3):871-880.ZENG Zhong-yi,XU Bang-shu,HU Shi-quan,et al.Numerical Analysis of Tunnel Liner Failure Mechanism in Expansive Soil Considering Water-increased State[J].Rock and Soil Mechanics,2014,35(3):871-880.
[8]齐吉琳,马巍.冻融作用对超固结土强度的影响[J].岩土工程学报,2006,28(12):2082-2086.QI Ji-lin,MA Wei.Influence of Freezing-thawing on Strength of Overconsolidated Soils[J].Chinese Journal of Geotechnical Engineering,2006,28(12):2082-2086.
[9]刘奉银,张昭,周冬,等.密度和干湿循环对黄土土-水特征曲线的影响[J].岩土力学,2011,32(增2):132-137.LIU Feng-yin,ZHANG Zhao,ZHOU Dong,et al.Effects of Initial Density and Drying-wetting Cycle on Soil Water Characteristic Curve of Unsaturated Loess[J].Rock and Soil Mechanics,2011,32(S2):132-137.
[10]赵天宇,王锦芳.考虑密度与干湿循环影响的黄土土水特征曲线[J].中南大学学报:自然科学版,2012,43(6):2445-2453.ZHAO Tian-yu,WANG Jin-fang.Soil-water Characteristic Curve for Unsaturated Loess Soil Considering Density and Wetting-drying Cycle Effects[J].Journal of Central South University:Science and Technology,2012,43(6):2445-2453.
[11]周志军,吕大伟,宋伟,等.基于含水率和温度变化的冻融黄土性能试验[J].中国公路学报,2013,26(3):44-49.ZHOU Zhi-jun,LU Da-wei,SONG Wei,et al.Experiment on Loess Characteristics After Freeze-thaw Circle Based on Changes of Moisture Content and Temperature[J].China Journal of Highway and Transport,2013,26(3):44-49.
[12]胡俊,胡怀雯.水库地区公路边坡加固及土质大坝防渗处理[J].筑路机械与施工机械化,2013,30(3):48-50,55.HU Jun,HU Huai-wen.Highway Slope Reinforcement and Impermeable Treatment of Earth Dam in Reservoir Area[J].Road Machinery &Construction Mechanization,2013,30(3):48-50,55.
[13]彭建兵,李庆春,陈志新,等.黄土洞穴灾害[M].北京:科学出版社,2008.PENG Jian-bing,LI Qing-chun,CHEN Zhi-xin,et al.Loess Cave Disaster[M].Beijing:Science Press,2008.