陇西地区黄土陷穴成因分析及形成机理

摘要

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 type, the water erosion - underground erosion - breakthrough type, the collapsility - underground erosion - breakthrough type, the water erosion - underground erosion - collapsibilty - underground erosion - breakthrough type and the composite type.%研究目的:黄土陷穴是陇西地区工程建设经常遇到的问题,容易导致斜坡变形失稳、隧道坍塌、泥石流等地质灾害.本文为解决这些工程地质问题,分析研究陇西地区黄土陷穴的成因及形成机理,为陇西地区工程建设提供地质依据.研究结论:陇西地区黄土具有颗粒大、疏松多孔、易崩解、渗透性强,黄土厚度大,湿陷性强,土体构造裂隙发育等特点,是陇西地区黄土陷穴形成的主要原因；陇西地区黄土陷穴是通过黄土地层中发育的垂直节理、构造节理、卸荷节理等优势渗流通道或径流通道,主要以水的冲蚀作用和潜蚀作用为主作用方式,兼有湿陷作用、崩解作用、重力作用、生物作用等一系列综合因素的影响形成的,其形成机理概括为:冲蚀—贯通型、冲蚀—潜蚀—贯通型、湿陷—潜蚀—贯通型、冲蚀—潜蚀—湿陷—潜蚀—贯通型以及复合型模式等五大类型.