华北煤矿区岩溶陷落柱特征及成因探讨

岩溶陷落柱是中国北方型石炭二迭纪煤田的一种特殊隐伏垂向构造，广泛分布于20个煤田45个煤矿区。通过对华北煤矿区岩溶陷落柱内部物质特征和外部形态特征的综合分析，认为适当的岩溶及地质构造是岩溶陷落柱形成的基本要素，其形成过程是多种因素影响的复杂动力地质过程。以奥灰岩层中岩溶发育为基础，地下水的强烈交替为条件，岩体自重重力、地应力集中以及溶洞内的真空负压三重作用为动力，经过迅速垮落、溶蚀、搬运、塌陷、冒落等周而复始的过程，分阶段逐步形成陷落柱。向斜轴部的岩层底面受张拉破碎为‘倒楔形’岩块，背斜轴部岩层底面受压破碎为‘正楔形’岩块。在重力作用下向斜轴部有利于岩块整体下移形成陷落柱，从力学上解释了‘华北地区岩溶陷落柱集中发育多在向斜褶曲部位而不是背斜轴部’这一基本规律。

STUDIES ON CHARACTERS AND FORMING MECHANISM OF KARSTIC COLLAPSE COLUMNS AT MINE AREA OF NORTH CHINA

Karstic collapse columns are a kind of vertical structures typically formed at Carboniferous-permian coal fields of north China and widely distributed at 45 coal mines of 20 coal fields. Through characteristics analysis of interior rock masses and exterior shape of karstic collapse columns in the coal mine areas of north China, is concluded that there are several influence factors and dynamic geological actions on forming process of it karstic collapse columns,among which karst and geological structure are the basic factors of their formation. The forming of karstic collapse columns results from repeated processes of collapse,intermission,dissolve erode, convey,subsidence,fall and so on under the dynamical action of rock mass gravity,geo-stress concentration, negative vacuum pressure and other actions on karstic cavity and groundwater violence flow. The bottom of rocks at syncline axis is tensioned and inverse cuneiform-like rock masses are formed. By contraries,cuneiform-like rock masses are formed at anticline axis under compression. So,it is propitious for whole rock mass to move down under gravity at syncline axis and karstic collapse columns are formed. The basic rule is explained in the light of mechanics,following which karstic collapse columns are more likely formed at syncline axis than at anticline axis in north China.