强震区泥石流启动机制
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摘要
地震区的泥石流物源主要来源于滑坡、崩塌等松散体,具有结构疏松,密实度低,堆积时间短等特点,与非地震环境中的滑坡、崩塌堆积体的结构有所不同,堆积体的物理力学性质发生了改变,堆积体转换为泥石流所需的外界条件也相应的改变。以汶川地震区都江堰市龙池镇典型泥石流灾害为例,分析了地震滑坡、崩塌松散体的堆积形态和堆积体的应力环境。从静力学和动力学角度分析堆积体在强降雨条件下的起动特征,探讨了降雨作用形成的地表径流水深与堆积体失稳时的应力极限状态的关系。分析得出沟道岸坡滑坡堆积体发生侵蚀时的地表径流力为F=(τ1f-f1sinα)/cos(α-26.65),并建立径流水深与地表径流力的关系:H=F/4ρsgJ。分析在动量守恒条件下,堆积体单位时间内的侵蚀体积dV=dM/γs模型。为了进一步探讨在实际现场的应用,以汶川地震区都江堰市的水打沟泥石流为例,分析发生泥石流时的地表径流水深为0.011 m,其结论与实际调查结果基本一致。
Sediment supply for debris flow occurrence in the seismic zone mainly derived from loose deposits of seismic landslides and rockfalls.Normally the sediment supply in debris flow basin has some features such as loose structure,low density,and quick accumulation.It is much different from that in non-seismic zone.Due to change of physical property in the landslide deposits,it results in relevant change of external conditions for landslide debris transmitting in to debris flows.This paper analyzed depositional morphology and the stress environment of loose accumulation of the seismic landslides based on debris flow investigation in a study area of Longchi Town,Dujianyang City that located in the Wenchuan earthquake area.Debris flow initiation mechanism under the condition of rainstorm is discussed in a basis of an analysis of statics and danamics.The relationship between the runoff water depth and the ultimate stress state during landslide deposit failure in saturated condition was showed in the formula as following:F=(τ1f-f1sinα)/cos(α-26.65).And The relationship between the runoff water depth and surface runoff capacity was established as the formula:H=F/4ρsgJ.Under the conditions of the conservation of mechanical energy,erosive volume model with an unit time of landslide deposit failure was established as the formula:dV=dM/γs.In order to apply the proposed model in actual situation,a study area in Shuida debris flow gully of Dujiangyang city of the Wenchuan earthquake area was selected.Result indicated that surface runoff depth when debris flow initiated reached 0.011 m,which is consistent with the result of field survey.
Sediment supply for debris flow occurrence in the seismic zone mainly derived from loose deposits of seismic landslides and rockfalls.Normally the sediment supply in debris flow basin has some features such as loose structure,low density,and quick accumulation.It is much different from that in non-seismic zone.Due to change of physical property in the landslide deposits,it results in relevant change of external conditions for landslide debris transmitting in to debris flows.This paper analyzed depositional morphology and the stress environment of loose accumulation of the seismic landslides based on debris flow investigation in a study area of Longchi Town,Dujianyang City that located in the Wenchuan earthquake area.Debris flow initiation mechanism under the condition of rainstorm is discussed in a basis of an analysis of statics and danamics.The relationship between the runoff water depth and the ultimate stress state during landslide deposit failure in saturated condition was showed in the formula as following:F=(τ1f-f1sinα)/cos(α-26.65).And The relationship between the runoff water depth and surface runoff capacity was established as the formula:H=F/4ρsgJ.Under the conditions of the conservation of mechanical energy,erosive volume model with an unit time of landslide deposit failure was established as the formula:dV=dM/γs.In order to apply the proposed model in actual situation,a study area in Shuida debris flow gully of Dujiangyang city of the Wenchuan earthquake area was selected.Result indicated that surface runoff depth when debris flow initiated reached 0.011 m,which is consistent with the result of field survey.
引文
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[17]Chen Yizhi,Zhuang Xicheng.Preliminary Approach to the solutionfor the Kinematic Wave of saturation overland flow[J].Journal ofFuzhou University:Natural Sciences Edtion,1987,(3):55-61[陈异植,庄希澄.饱和坡面流运动波解初探[J].福州大学学报:自然科学版,1987,(3):55-61]
[18]Jin Changxing.A theoretical study on critical erosion slope gradient[J].Acta Geographica Sinica,1995,(50):234-239[靳长兴.论坡面侵蚀的临界坡度[J].地理学报.1995,(50):234-239]
[19]Tian Kai,Li Xiaoqing,Shen Zhenzhou,et al.Experimental study onhydraulic characteristic of shallow flow under dDifferent bed materi-al[J].Journal of Soil and Water Conservation,2010,(24):70-73[田凯,李小青,申震洲,等.不同床沙下的坡面流水力学特性试验研究[J].水土保持学报.2010,(24):70-73]
[20]Sichuan Geological Engineering Survey Court.Emergency explora-tion report shuida gully,Dujiangyan[R].2010[四川省地质工程勘察院.都江堰市龙池镇水打沟泥石流应急勘查报告[R].2010]
[21]Pia Rosella Tecca,Rinaldo Genevois.Field observations of the June30,2001 debris flow at Acquabona(Dolomites,Italy)[J].Land-slides,2009,(6):39-45
[22]Matteo Berti,Rinaldo Genevoisb,Alessandro Simoni.Field obser-vations of a debris flow event in the Dolomites[J].Geomorphology,1999,(29):265-274
[23]Yu Bin.Research on the calculating density by the deposit of debrisflows[J].Acta Sedimentologica Sinica,2008,(26):789-796[余斌.根据泥石流沉积物计算泥石流重度的方法研究[J].沉积学报,2008,(26):789-796]
[2]Yu Bin.Study on the mean velocity of viscous debris flows[J].Ad-vances in Earth Science,2008,23(5):524-532
[3]Zhuang Jianqi,Cui Peng1,Hu kaiheng,et al.Research on debris flowinitiation due to bed failure after Wenchuan Earthquake[J].Journalof Sichuan University:Engineering Science Edition,2010,(5):231-235[庄建琦,崔鹏,胡凯衡,等.沟道松散物质起动形成泥石流实验研究[J].四川大学学报:工程科学版,2010,(5):231-235]
[4]Emmanuel J Gabet,Simon M Mudd.The mobilization of debris flowsfrom shallow landslides[J].Geomorphology,2006,(74):207-218
[5]Zhang Ming1,Hu Ruilin,Yin Yueping,et al.Study of transformmechanism of landslides-debris flow with ring shear text[J].ChineseJournal of Rock Mechanics and Engineering,2010,(4):822-832[张明,胡瑞林,殷跃平.滑坡型泥石流转化机制环剪试验研究[J].岩石力学与工程学报,2010,(4):822-832]
[6]He Wenshe,Cao Shuyou,Liu Xingnian,et al.Critical shear stress ofincipient motion of sediment[J].Acta Mechanica Sinica,2003,(3):326-331[何文社,曹叔尤,刘兴年,等.泥沙起动临界切应力研究,力学学报[J].2003,(3):326-331]
[7]He Wenshe,Cao Shuyou,Yuan Jie,et al.Incipient motion of non-u-niform sediment particles on sloping fluvial beds[J].Journal of Hy-droelectric Engineering,2004,(4):78-87[何文社,曹叔尤,袁杰.斜坡上非均匀沙起动条件初探[J].水力发电学报,2004,(4):78-87]
[8]Xie Renzhi,Cheng Zhujun.The formula of strong nonlinear logarithmflood peak reasoning[J].Journal of China Hydrology,1988,(4):21-23[谢任之,程祖均.非线性对数雨强公式的洪峰推理公式计算[J].水文,1988,(4):21-23]
[9]Liang Guangmo,Yaolingkan.Sure rainstorm debris flow of the criticalrainfall[J].Subgrade Engineering,2008,(6):3-4[梁光模,姚令侃.确定暴雨泥石流临界雨量的研究[J].路基工程,2008,(6):3-4]
[10]Qi Xing,Yu Bin,Ma Yu,et al.Characteristics of Longchi 8.13 Ma-liu gully debris flow disasters of in Dujiangyan,Sichuan Province[J].The Chinese Journal of Geological Hazard and Control,2011,(22):17-21[亓星,余斌,马煜,等.四川省都江堰龙池8.13麻柳沟泥石流灾害特征[J].中国地质灾害与防治学报.2011,(22):17-21]
[11]Ma Yu,Yu Bin,Wu Yufu,et al.Research on the disaster of debrisflow of Bayi Gully,Longchi,Dujiangyan,Sichuan on August 13,2010[J].Journal of Sichuan University:Engineering Science Edi-tion,2011(43),92-92[马煜,余斌,吴雨夫,等.四川都江堰龙池“8.13”八一沟大型泥石流灾害研究[J].四川大学学报,工程技术版,2011(43),92-92]
[12]Zhushoumin.Soil mechanics(second edition)[M].China Architec-ture&Building Press,2005:86-105[朱首明.土力学(第二版)[M].中国建筑工业出版社.2005:86-105]
[13]Li Jixiang,Peng Shusheng,Zhao Sanqing,et al.Critical erosion gra-dient of freeway cutting slope[J].Journal of Liaoning Technical U-niversity:Natural Science,[2009,(28):56-58李继祥,彭书生,赵三青.高速公路路堑边坡的侵蚀临界坡度[J].辽宁工程技术大学学报:自然科学版,2009,(28):56-58]
[14]Liu Beili,She Xuesen,Yu Wei.Optimizing Analysis of calculationmethod for runoff amount on loess slope[J].Journal of Water Re-sources and Architectural Engineering,2006,(4):60-63[刘倍利,折学森,于伟.黄土坡面径流量计算方法的优化分析[J].水利与建筑工程报.2006,(4):60-63]
[15]Zhang Xiaona,Feng Jie,Gao Yongbo,et al.Influences of slope onrunoff and concentration and solute transport under different rainfallintensities[J].Bulletin of Soil and Water Conservation,2010,(30):119-123[张小娜,冯杰,高永波.不同雨强条件下坡度对坡地产汇流及溶质运移的影响[J].水土保持通报.2010,(30):119-123]
[16]He Siming,Wu Yong,Li Xinpo.Research on eroded start mecha-nism of channel debris flow[J].Rock and Soil Mechanics,2007,(28):155-159[何思明.黏性泥石流沟道侵蚀启动机制研究[J].岩土力学.2007,(28):155-159]
[17]Chen Yizhi,Zhuang Xicheng.Preliminary Approach to the solutionfor the Kinematic Wave of saturation overland flow[J].Journal ofFuzhou University:Natural Sciences Edtion,1987,(3):55-61[陈异植,庄希澄.饱和坡面流运动波解初探[J].福州大学学报:自然科学版,1987,(3):55-61]
[18]Jin Changxing.A theoretical study on critical erosion slope gradient[J].Acta Geographica Sinica,1995,(50):234-239[靳长兴.论坡面侵蚀的临界坡度[J].地理学报.1995,(50):234-239]
[19]Tian Kai,Li Xiaoqing,Shen Zhenzhou,et al.Experimental study onhydraulic characteristic of shallow flow under dDifferent bed materi-al[J].Journal of Soil and Water Conservation,2010,(24):70-73[田凯,李小青,申震洲,等.不同床沙下的坡面流水力学特性试验研究[J].水土保持学报.2010,(24):70-73]
[20]Sichuan Geological Engineering Survey Court.Emergency explora-tion report shuida gully,Dujiangyan[R].2010[四川省地质工程勘察院.都江堰市龙池镇水打沟泥石流应急勘查报告[R].2010]
[21]Pia Rosella Tecca,Rinaldo Genevois.Field observations of the June30,2001 debris flow at Acquabona(Dolomites,Italy)[J].Land-slides,2009,(6):39-45
[22]Matteo Berti,Rinaldo Genevoisb,Alessandro Simoni.Field obser-vations of a debris flow event in the Dolomites[J].Geomorphology,1999,(29):265-274
[23]Yu Bin.Research on the calculating density by the deposit of debrisflows[J].Acta Sedimentologica Sinica,2008,(26):789-796[余斌.根据泥石流沉积物计算泥石流重度的方法研究[J].沉积学报,2008,(26):789-796]
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