干湿循环下纤维加筋膨胀土裂隙特性分析
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摘要
为研究纤维加筋膨胀土的效果和机制,抑制膨胀土脆性开裂,以室内模拟膨胀土为研究对象,通过室内试验及数字图像处理技术,分析干湿循环条件下土体的开裂特性及纤维加筋对裂隙发展的影响。结果表明:膨胀土中掺加纤维,能有效提高土体无侧限抗压强度,且掺量为0.7%时,对土体加筋效果最为显著;在干湿循环条件下,土体表面裂隙发育基本沿原有通道继续展开;随循环次数的增加土体表面裂隙面积率、裂隙总长度逐渐增大,而裂隙平均宽度存在递减趋势,掺加纤维能有效抑制裂隙的开展。研究成果可以为纤维在膨胀土路基工程和边坡防护等实际工程中的设计和施工提供参考。
In order to study the effect and mechanism of fiber reinforced expansive soil and inhibit failure,unconfined compression experiment of the expansive soil was carried out.Image processing technique was used to analyze the cracking characteristics of the soil and the effect of fiber reinforcement on the crack development under wetting-drying cycles.Results show that adding fiber in the expansive soil can significantly improve the soil unconfined compressive strength.When the fiber content is 0.7%the soil reinforcement effect is most significant.Under wetting-drying cycles,the development of soil surface cracks continues to expand along the original channel.With the increase in cycle number,the crack area ratio and total crack length on the soil surface gradually increase,while the average crack width decreases.The addition of fiber in expansive soil can effectively restrain the development of fracture.The results of this research can provide reference for fiber reinforced soil in practical engineering,such as the expansive subgrade,slop protection design and construction.
In order to study the effect and mechanism of fiber reinforced expansive soil and inhibit failure,unconfined compression experiment of the expansive soil was carried out.Image processing technique was used to analyze the cracking characteristics of the soil and the effect of fiber reinforcement on the crack development under wetting-drying cycles.Results show that adding fiber in the expansive soil can significantly improve the soil unconfined compressive strength.When the fiber content is 0.7%the soil reinforcement effect is most significant.Under wetting-drying cycles,the development of soil surface cracks continues to expand along the original channel.With the increase in cycle number,the crack area ratio and total crack length on the soil surface gradually increase,while the average crack width decreases.The addition of fiber in expansive soil can effectively restrain the development of fracture.The results of this research can provide reference for fiber reinforced soil in practical engineering,such as the expansive subgrade,slop protection design and construction.
引文
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[9]张艳美,张旭东,张鸿儒.土工合成纤维土补强机理试验研究及工程应用[J].岩土力学,2005,26(8):1323-1326.Zhang Yan-mei,Zhang Xu-dong,Zhang Hong-ru.Test research of geotechnique textile soil reinforcement mechanism and engineering application[J].Rock and Soil Mechanics,2005,26(8):1323-1326.
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[12]吴珺华,杨松.基于湿变量的膨胀土初始裂隙模型及影响因素分析[J].土木工程学报,2016(4):96-101.Wu Jun-hua,Yang Song.Study on initial cracking model of expansive soil based on moisture change and analysis on its influencing factors[J].China Civil Engineering Journal,2016(4):96-101.
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[15]刘汝明.云南昭通膨胀土工程地质特征及路基处理[J].中国地质灾害与防治学报,2006,17(2):23-27.Liu Ru-ming.Engineering geological characteristic and roadbed treatment of the expansive soil in Zhaotong Basin,Yunnan province[J].The Chinese Journal of Geological Hazard and Control,2006,17(2):23-27.
[16]潘国林,吴泊人,李郑.安徽省膨胀土分布及工程地质特征研究[J].地质灾害与环境保护,2012,23(2):54-59.Pan Guo-lin,Wu Bo-ren,Li Zheng.Distribution and engineering geological properties of expansibe soil in Anhui[J].Journal of Geological Hazards and Environment Preservation,2012,23(2):54-59.
[17]交通部公路科学研究院.公路土工试验规程[M].北京:人民交通出版社,2007.
[18]中华人民共和国住房和城乡建设部.膨胀土地区建筑技术规范[M].北京:中国建筑工业出版社,2013.
[19]韩春鹏,何钰龙,申杨凡,等.冻融作用下纤维土抗剪强度影响因素试验研究[J].铁道科学与工程学报,2015,12(2):275-281.Han Chun-peng,He Yu-long,Shen Yang-fan,et al.Experimental study on factors of shear strength of fiber soils under the freeze-thaw cycle[J].Journal of Railway Science and Engineering,2015,12(2):275-281.
[20]唐朝生,王德银,施斌,等.土体干缩裂隙网络定量分析[J].岩土工程学报,2013,35(12):2298-2305.Tang Chao-sheng,Wang De-yin,Shi Bin,et al.Quantitative analysis of soil desiccation crack network[J].Chinese Journal of Geotechnical Engineering,2013,35(12):2298-2305.
[21]Tang C S,Cui Y J,Shi B,et al.Desiccation and cracking behaviour of clay layer from slurry state under wetting-drying cycles[J].Geoderma,2011,166(1):111-118.
[2]姚海林,郑少河,陈守义.考虑裂隙及雨水入渗影响的膨胀土边坡稳定性分析[J].岩土工程学报,2001,23(5):606-609.Yao Hai-lin,Zheng Shao-he,Chen Shou-yi.Analysis on the slope stability of expansive soils considering cracks and infiltration of rain[J].Chinese Journal of Geotechnical Engineering,2001,23(5):606-609.
[3]张国新,武晓峰.裂隙渗流对岩石边坡稳定的影响——渗流、变形耦合作用的DDA法[J].岩石力学与工程学报,2003,22(8):1269-1275.Zhang Guo-xin,Wu Xiao-feng.Influence of seepage on the stability of rock slope-coupling of seepage and deformation by DDA method[J].Chinese Journal of Rock Mechanics and Engineering,2003,22(8):1269-1275.
[4]陈铁林,邓刚,陈生水,等.裂隙对非饱和土边坡稳定性的影响[J].岩土工程学报,2006,28(2):210-215.Chen Tie-lin,Deng Gang,Chen Sheng-shui,et al.Effects of fissures on stability of unsaturated soil slope[J].Chinese Journal of Geotechnical Engineering,2006,28(2):210-215.
[5]虞海珍,李小青,姚建伟.膨胀土化学改良试验研究分析[J].岩土力学,2006,27(11):1941-1944.Yu Hai-zhen,Li Xiao-qing,Yao Jian-wei.Experimental study and analysis of expansive soil improved with chemical medicine[J].Rock and Soil Mechanics,2006,27(11):1941-1944.
[6]孙树林,郑青海,唐俊,等.碱渣改良膨胀土室内试验研究[J].岩土力学,2012,33(6):1608-1612.Sun Shu-lin,Zheng Qing-hai,Tang Jun,et al.Experimental research on expansive soil improved by soda residue[J].Rock and Soil Mechanics,2012,33(6):1608-1612.
[7]Kutara K,Miki H,Horiya S,et al.Mechanical behavior of reinforced soil by continuous threads[J].Geosynthetics Symposium,1991,3:213-221.
[8]Ye H S,Lok T M H.Study of mechanical behavior of fiber reinforced soil with modified direct shear apparatus[J/OL].[2017-12-01],http://umir.umac.mo/jspui/bitstream/123456789/15217/1/4558_0_Sein&Lok.pdf
[9]张艳美,张旭东,张鸿儒.土工合成纤维土补强机理试验研究及工程应用[J].岩土力学,2005,26(8):1323-1326.Zhang Yan-mei,Zhang Xu-dong,Zhang Hong-ru.Test research of geotechnique textile soil reinforcement mechanism and engineering application[J].Rock and Soil Mechanics,2005,26(8):1323-1326.
[10]宫亚峰,申杨凡,谭国金,等.不同孔隙率下纤维土无侧限抗压强度[J].吉林大学学报:工学版,2018,48(3):712-719.Gong Ya-feng,Shen Yang-fan,Tan Guo-jin,et al.Unconfined compressive strength of fiber soil with different porosity[J].Journal of Jilin University(Engineering and Technology Edition),2018,48(3):712-719
[11]孙即超,王光谦,孙其诚.临界状态下非饱和土裂缝开裂间距[J].科学通报,2009,54(9):1311-1314.Sun Ji-chao, Wang Guang-qian, Sun Qi-cheng.Crack spacing of unsaturated soils in the critical state[J].Chinese Science Bulletin,2009,54(9):1311-1314.
[12]吴珺华,杨松.基于湿变量的膨胀土初始裂隙模型及影响因素分析[J].土木工程学报,2016(4):96-101.Wu Jun-hua,Yang Song.Study on initial cracking model of expansive soil based on moisture change and analysis on its influencing factors[J].China Civil Engineering Journal,2016(4):96-101.
[13]李生林,施斌.湖北郧县膨胀土的工程地质特征[C]∥全国第三次工程地质大会论文选集,成都,1988:41-47.
[14]刘特洪.长江流域膨胀土工程地质特征及工程处理[J].人民长江,2005,36(3):13-15.Liu Te-hong.Discussion on coupling relation of new tectonic movement and landslide in the Three Gorges reservoir area[J].Yangtze River,2005,36(3):13-15.
[15]刘汝明.云南昭通膨胀土工程地质特征及路基处理[J].中国地质灾害与防治学报,2006,17(2):23-27.Liu Ru-ming.Engineering geological characteristic and roadbed treatment of the expansive soil in Zhaotong Basin,Yunnan province[J].The Chinese Journal of Geological Hazard and Control,2006,17(2):23-27.
[16]潘国林,吴泊人,李郑.安徽省膨胀土分布及工程地质特征研究[J].地质灾害与环境保护,2012,23(2):54-59.Pan Guo-lin,Wu Bo-ren,Li Zheng.Distribution and engineering geological properties of expansibe soil in Anhui[J].Journal of Geological Hazards and Environment Preservation,2012,23(2):54-59.
[17]交通部公路科学研究院.公路土工试验规程[M].北京:人民交通出版社,2007.
[18]中华人民共和国住房和城乡建设部.膨胀土地区建筑技术规范[M].北京:中国建筑工业出版社,2013.
[19]韩春鹏,何钰龙,申杨凡,等.冻融作用下纤维土抗剪强度影响因素试验研究[J].铁道科学与工程学报,2015,12(2):275-281.Han Chun-peng,He Yu-long,Shen Yang-fan,et al.Experimental study on factors of shear strength of fiber soils under the freeze-thaw cycle[J].Journal of Railway Science and Engineering,2015,12(2):275-281.
[20]唐朝生,王德银,施斌,等.土体干缩裂隙网络定量分析[J].岩土工程学报,2013,35(12):2298-2305.Tang Chao-sheng,Wang De-yin,Shi Bin,et al.Quantitative analysis of soil desiccation crack network[J].Chinese Journal of Geotechnical Engineering,2013,35(12):2298-2305.
[21]Tang C S,Cui Y J,Shi B,et al.Desiccation and cracking behaviour of clay layer from slurry state under wetting-drying cycles[J].Geoderma,2011,166(1):111-118.