某大型建设场地覆盖型岩溶发育规律及成因的探讨

Discussion on Development Regularity and Genesis of Covered Karst in a Large Construction Site

为研究株洲地区的覆盖型岩溶发育规律及成因,以株洲某大型建设场地为例,采用钻探和物探相结合的方法,从岩溶的规模、形态特征、空间分布及发育程度分区等方面对岩溶发育规律进行了分析,从地层岩性、地质构造等方面分析了岩溶发育的内在成因,并构建了间歇性隆升条件下覆盖型岩溶发育的概化模型。研究结果表明:1)溶洞主要发育于基岩面附近,深部岩溶不发育,且以小规模及较小规模的浅层溶洞为主,大规模及较大规模的溶洞呈纵向尺度大于横向尺度的似椭球状;2)溶洞在平面上主要展布于沟谷区域,以东侧沟谷最甚,为强烈或极强烈岩溶发育区;3)在不均匀隆起过程中受压剪、张扭综合作用形成以高倾角裂隙或者裂隙带为主的构造特征的灰岩,易形成空间上呈似椭球状、纵向尺寸大于横向尺寸的溶洞。本研究成果对岩溶勘察具有指导意义。

In order to study the development regularity and genesis of covered karst in Zhuzhou,taking a large construction site in Zhuzhou as an example,the method of combining drilling and geophysical exploration is used to analyze the development regularity of karst from the aspects of the scale,morphological characteristics,spatial distribution and development degree zoning of karst,analyzes the internal causes of karst development from the aspects of stratum lithology and geological structure,and constructs a generalized model of karst development under intermittent uplift.The results show that:1) karst caves are mainly developed near the bedrock surface,and deep karst is not developed,and small-scale and smaller-scale shallow karst caves are the main types,large-scale and larger-scale karst caves are ellipsoid-like with longitudinal scale larger than transverse scale;2) karst caves are mainly distributed in the valley area on the plane,and the valley on the east side is the most,which is a strong or very strong karst development area;3) in the process of uneven uplift,the limestone with high dip angle fracture or fracture zone is formed by the combined action of compression,shear and tension,which is easy to form ellipsoid-like caves with longitudinal size larger than transverse size.The research results have guiding significance for karst exploration.