黄土垂直节理细微观特征及发育机制探讨
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摘要
风积黄土垂直节理发育,在黄土塬边或岸边容易观测,受水环境变化影响极易诱发黄土灾害。以黄土垂直节理为研究对象,从黄土垂直节理细微观发育特征入手,总结了黄土垂直节理在横纵方向上发育规律,研究了黄土垂直节理在不同评价尺度上的展现形式、转换机制及形成垂直节理的微细观结构基础。从黄土的沉积动态出发,探讨了垂直节理的垂向发育机制。研究结果表明:垂直节理是黄土在历史沉积过程逐渐形成的,是成岩过程的产物,提出了黄土中存在的孔隙集中带及垂直管状通道是能够发育垂直节理的微细观结构基础,三维CT扫描试验结果为其提供了强有力的证据;其在不同评价尺度上的展现形式不同,在外部作用下(干湿循环作用及黄土堆厚)其垂直节理在微-细-中观是可以向上尺度(扩张特征)或者向下尺度(衰退特征)发育、发展转换的,即尺度转换机制;并借此提出了黄土垂直节理的垂向发育机制。
It is easy to observe the development of vertical joints of aeolian loess on the edge or shore of a plateau, and these vertical joints can readily induce loess disasters due to changes in the water environment. The vertical joints of loess were investigated in this study. The developmental laws of vertical joints of loess in horizontal and vertical directions were summarized based on their meso-microscopic developmental characteristics. The display forms, transformation mechanisms and the micro-mesoscopic structural basis for forming vertical joints of loess were observed on different evaluation scales. Based on the sedimentary dynamics of loess, the vertical developmental mechanism of vertical joints was discussed. Studies had shown that vertical joints formed gradually during the historical sedimentary process and were the product of diagenesis. It was proposed that the pore concentration zone and vertical tubular channel in loess were the micro-mesoscopic structural basis for the development of vertical joints, for which the results of a three-dimensional CT scanning test provided strong evidence. The vertical joints exhibit different forms on different evaluation scales. Under external actions(wet and dry cycling and loess pile thickening), the vertical joints in the micro-meso-sub-macro point of view can be developed in an upward scale(expansion characteristics) or downward scale(decay characteristics), and they can transform between the two scales. This is referred as the scale conversion mechanism. The vertical developmental mechanism of vertical joints of loess was also proposed based on this.
It is easy to observe the development of vertical joints of aeolian loess on the edge or shore of a plateau, and these vertical joints can readily induce loess disasters due to changes in the water environment. The vertical joints of loess were investigated in this study. The developmental laws of vertical joints of loess in horizontal and vertical directions were summarized based on their meso-microscopic developmental characteristics. The display forms, transformation mechanisms and the micro-mesoscopic structural basis for forming vertical joints of loess were observed on different evaluation scales. Based on the sedimentary dynamics of loess, the vertical developmental mechanism of vertical joints was discussed. Studies had shown that vertical joints formed gradually during the historical sedimentary process and were the product of diagenesis. It was proposed that the pore concentration zone and vertical tubular channel in loess were the micro-mesoscopic structural basis for the development of vertical joints, for which the results of a three-dimensional CT scanning test provided strong evidence. The vertical joints exhibit different forms on different evaluation scales. Under external actions(wet and dry cycling and loess pile thickening), the vertical joints in the micro-meso-sub-macro point of view can be developed in an upward scale(expansion characteristics) or downward scale(decay characteristics), and they can transform between the two scales. This is referred as the scale conversion mechanism. The vertical developmental mechanism of vertical joints of loess was also proposed based on this.
引文
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[9]王永焱,林在贯.中国黄土的结构特征及物理力学性质[M].北京:科学出版社,1990.WANG Yong-yan,LIN Zai-guan.Structural characteristics and physical mechanical properties of loess in China[M].Beijing:Science Press,1990.
[10]TU X B,KWONG A K I,DAI F C,et al.Field monitoring of rainfall infiltration in a loess slope and analysis of failure mechanism of rainfall-induced landslides[J].Engineering Geology,2009,105(1-2):134-150.
[11]王正贵,康国瑾,马崇武,等.关于黄土垂直节理形成机制的探讨[J].中国科学(B辑),1993,23(7):765-770.WANG Zheng-gui,KANG Guo-jin,MA Chong-wu,et al.Discussion on the formation mechanism of loess vertical joints[J].Science in China(Series B),1993,23(7):765-770.
[12]李同录,王红,付昱凯,等.黄土垂直节理形成机理的试验模拟[J].地球科学与环境学报,2014,36(2):127-134.LI Tong-lu,WANG Hong,FU Yu-kai,et al.Test simulation on the forming mechanism of loess vertical joints[J].Journal of Earth Sciences and Environment,2014,36(2):127-134.
[13]FOOKES P G,PARRISH D G.Observational studies on fissures pattern in cretaceous sediments of south-east England[J].Geotechnique,1969,19(4):453-477.
[14]SKEMPTON A W.Joints and fissures in the London clay at Wraysbury and Edgeware[J].Geotechnique,1969,19(2):205-217.
[15]孔德坊,张慧英,胡卸文,等.裂隙性黏土[M].北京:地质出版社,1994.KONG De-fang,ZHANG Hui-ying,HU Xie-wen,et al.Fissured clay[M].Beijing:Geological Press,1994.
[16]卢全中,彭建兵,陈志新,等.黄土高原地区黄土裂隙发育特征及其规律研究[J].水土保持学报,2005,19(5):193-196.LU Quan-zhong,PENG Jian-bing,CHEN Zhi-xin,et al.Research on characteristics of cracks and fissures of loess and their distribution in Loess Plateau of China[J].Journal of Soil Water Conservation,2005,19(5):193-196.
[17]卢全中,彭建兵.黄土体结构面的发育特征及其灾害效应[J].西安科技大学学报,2006,26(4):446-450.LU Quan-zhong,PENG Jian-bing.Characteristics of structural planes of loess mass in Loess Plateau of China and its hazard effect[J].Journal of Xi’an University of Science and Technology,2006,26(4):446-450.
[18]马鹏辉,彭建兵,王启耀,等.泾阳南塬典型黄土滑坡成因、堆积及运动特征分析[J].工程地质学报,2018,26(4):930-938.MA Peng-hui,PENG Jian-bing,WANG Qi-yao,et al.Formation mechanism,deposits and motion characteristics of the typical loess landslide in south Jingyang platform[J].Journal of Engineering Geology,2018,26(4):930-938.
[19]姚志华,连杰,陈正汉,等.考虑细观结构演化的非饱和原状Q3黄土弹塑性本构模型[J].岩土力学,2018,39(5):1553-1563.YAO Zhi-hua,LIAN Jie,CHEN Zheng-han,et al.An elastic-plastic constitutive model for unsaturated Q3undisturbed loess considering meso-structured evolution[J].Rock and Soil Mechanics,2018,39(5):1553-1563.
[20]雷祥义.陕北陇东黄土孔隙分布特征[J].科学通报,1985,30(3):206-209.LEI Xiang-yi.Pore distribution characteristics of loess in Eastern Shaanxi Province[J].Chinese Science Bulletin,1985,30(3):206-209.
[21]潘德杨.黄土[M].北京:地质出版社,1958.PAN De-yang.Loess[M].Beijing:Geological Press,1958.
[22]王铁行,王娟娟,房江锋,等.垂直节理影响的黄土隧道洞口段稳定性分析[J].地下空间与工程学报,2012,8(1):65-70.WANG Tie-xing,WANG Juan-juan,FANG Jiang-feng,et al.Stability analysis of loess tunnel entrances section considering the impact of vertical joints[J].Chinese Journal of Underground Space and Engineering,2012,8(1):65-70.
[2]李姝,许强,张立展,等.黑方台地区黄土强度弱化的浸水时效特征与机制分析[J].岩土力学,2017,38(7):2043-2048.LI Shu,XU Qiang,ZHANG Li-zhan,et al.Time effect and mechanism of strength weakening of loess soaked in water in Heifangtai area[J].Rock and Soil Mechanics,2017,38(7):2043-2048.
[3]冯连昌,郑晏武.中国湿陷性黄土[M].北京:中国铁道出版社,1982.FENG Lian-chang,ZHENG Yan-wu.Collapsible loess in China[M].Beijing:China Railway Press,1982.
[4]钟世航.黄土中的构造斜节理及其对黄土隧道稳定性的影响[J].岩土工程学报,1983,5(4):68-77.ZHONG Shi-hang.Influence of inclined tectonic joints on stability of tunnels in the loess[J].Chinese Journal of Geotechnical Engineering,1983,5(4):68-77.
[5]王景明,王江帅,刘金峰,等.地裂缝及其灾害的理论与应用[M].西安:陕西科学技术出版社,2000.WANG Jing-ming,WANG Jiang-shuai,LIU Jin-feng,et al.Theory of ground fissures hazards and its application[M].Xi’an:Shaanxi Science and Technology Press,2000.
[6]ZUME J,TARHULE A.Simulating the impacts of groundwater pumping on stream-aquifer dynamics in semiarid northwestern Oklahoma,USA[J].Hydrogeology Journal,2008,16(4):797-810.
[7]孙广忠.西北黄土的工程地质力学特性及地质工程问题研究[M].兰州:兰州大学出版社,1989.SUN Guang-zhong.Study on engineering geo-mechanics and geological engineering problems of loess in Northwest China[M].Lanzhou:Lanzhou University Press,1989.
[8]张茂省.引水灌区黄土地质灾害成因机制与防控技术--以黄河三峡库区甘肃黑方台移民灌区为例[J].地质通报,2013,32(6):833-839.ZHANG Mao-sheng.Formation mechanism as well as prevention and controlling techniques of loess geo-hazards in irrigated areas:a case study of Heifangtai immigration area in the Three Gorges Reservoir of the Yellow River[J].Geological Bulletin of China,2013,32(6):833-839.
[9]王永焱,林在贯.中国黄土的结构特征及物理力学性质[M].北京:科学出版社,1990.WANG Yong-yan,LIN Zai-guan.Structural characteristics and physical mechanical properties of loess in China[M].Beijing:Science Press,1990.
[10]TU X B,KWONG A K I,DAI F C,et al.Field monitoring of rainfall infiltration in a loess slope and analysis of failure mechanism of rainfall-induced landslides[J].Engineering Geology,2009,105(1-2):134-150.
[11]王正贵,康国瑾,马崇武,等.关于黄土垂直节理形成机制的探讨[J].中国科学(B辑),1993,23(7):765-770.WANG Zheng-gui,KANG Guo-jin,MA Chong-wu,et al.Discussion on the formation mechanism of loess vertical joints[J].Science in China(Series B),1993,23(7):765-770.
[12]李同录,王红,付昱凯,等.黄土垂直节理形成机理的试验模拟[J].地球科学与环境学报,2014,36(2):127-134.LI Tong-lu,WANG Hong,FU Yu-kai,et al.Test simulation on the forming mechanism of loess vertical joints[J].Journal of Earth Sciences and Environment,2014,36(2):127-134.
[13]FOOKES P G,PARRISH D G.Observational studies on fissures pattern in cretaceous sediments of south-east England[J].Geotechnique,1969,19(4):453-477.
[14]SKEMPTON A W.Joints and fissures in the London clay at Wraysbury and Edgeware[J].Geotechnique,1969,19(2):205-217.
[15]孔德坊,张慧英,胡卸文,等.裂隙性黏土[M].北京:地质出版社,1994.KONG De-fang,ZHANG Hui-ying,HU Xie-wen,et al.Fissured clay[M].Beijing:Geological Press,1994.
[16]卢全中,彭建兵,陈志新,等.黄土高原地区黄土裂隙发育特征及其规律研究[J].水土保持学报,2005,19(5):193-196.LU Quan-zhong,PENG Jian-bing,CHEN Zhi-xin,et al.Research on characteristics of cracks and fissures of loess and their distribution in Loess Plateau of China[J].Journal of Soil Water Conservation,2005,19(5):193-196.
[17]卢全中,彭建兵.黄土体结构面的发育特征及其灾害效应[J].西安科技大学学报,2006,26(4):446-450.LU Quan-zhong,PENG Jian-bing.Characteristics of structural planes of loess mass in Loess Plateau of China and its hazard effect[J].Journal of Xi’an University of Science and Technology,2006,26(4):446-450.
[18]马鹏辉,彭建兵,王启耀,等.泾阳南塬典型黄土滑坡成因、堆积及运动特征分析[J].工程地质学报,2018,26(4):930-938.MA Peng-hui,PENG Jian-bing,WANG Qi-yao,et al.Formation mechanism,deposits and motion characteristics of the typical loess landslide in south Jingyang platform[J].Journal of Engineering Geology,2018,26(4):930-938.
[19]姚志华,连杰,陈正汉,等.考虑细观结构演化的非饱和原状Q3黄土弹塑性本构模型[J].岩土力学,2018,39(5):1553-1563.YAO Zhi-hua,LIAN Jie,CHEN Zheng-han,et al.An elastic-plastic constitutive model for unsaturated Q3undisturbed loess considering meso-structured evolution[J].Rock and Soil Mechanics,2018,39(5):1553-1563.
[20]雷祥义.陕北陇东黄土孔隙分布特征[J].科学通报,1985,30(3):206-209.LEI Xiang-yi.Pore distribution characteristics of loess in Eastern Shaanxi Province[J].Chinese Science Bulletin,1985,30(3):206-209.
[21]潘德杨.黄土[M].北京:地质出版社,1958.PAN De-yang.Loess[M].Beijing:Geological Press,1958.
[22]王铁行,王娟娟,房江锋,等.垂直节理影响的黄土隧道洞口段稳定性分析[J].地下空间与工程学报,2012,8(1):65-70.WANG Tie-xing,WANG Juan-juan,FANG Jiang-feng,et al.Stability analysis of loess tunnel entrances section considering the impact of vertical joints[J].Chinese Journal of Underground Space and Engineering,2012,8(1):65-70.