Abstract：Research purposes: The loess sinking hole is the problem often encountered in the engineering construction in the Longxi region，and it can cause a series of geological disasters，such as the slope unstability，tunnel collapse，debris flow and so on． To solve these engineering geological problems，the cause and formation mechanism for the loess sinking hole in the Longxi region was analyzed and studied for provide the geological basis to the engineering construction in the Longxi region．
Research conclusions: The loess featured with coarse particles， porousness， disintegration， relatively strong permeability，thick soil layer，strong collapsiblility，structural fracture development are main reasons for the loess sinking hole in the Longxi region． Under the main effects of water erosion and underground erosion and the auxiliary effects of the saturated yielding，disintegration，gravity and living things，the loess sinking hole is formed by the preferential seepage channel and the runoff channel of the vertical bedding joint，structural joint and unloading joint．The formation mechanism of the loess sinking hole includes the following five types: the water erosion － breakthrough
胡永占. 陇西地区黄土陷穴成因分析及形成机理[J]. 铁道工程学报, 2013, 30(3): 1-4.
HU Yong － zhan. Analysis of Cause and Formation Mechanisms for Loess Sinking Hole in Longxi Region. 铁道工程学报, 2013, 30(3): 1-4.
Peng Jianbing，Li Xi ’ an． Study of Distribution Regularities on Highway Loess Hidden Holes ［J］． Journal of Highway and Transportation Research and Development，2005( 6) : 1 － 5．
Jiang Xiyan，Lu Peiyi． Analysis of the Collapsible Mechanism and Effect Factor of Loess［J］． Journal of Hebei Institute of Architectural Engineering，2004 ( 3) : 25 － 27．
Ding Jianqiang． Study on Formation and Distribution Law of Loess Sinkhole in Gansu ［J］． Scienfic and Technical Information of Gansu，2009( 1) : 92 － 96．
2013, Vol. 30 
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