北京房山张坊岩溶区节理发育特征及其对岩溶作用的影响

北京张坊岩溶区是北方岩溶的典型代表.通过野外地质调查、节理与岩溶特征观测、地表节理数据统计分析和应力解析,对节理发育特征、节理形成时期及节理对岩溶作用的影响进行研究,发现节理构造对本区岩溶发育具有重要影响:1)节理的延伸方向不仅影响溶洞的延伸方向,而且控制洞穴的平面形态;2)地表斜向节理利于溶蚀裂隙和溶蚀破碎带的发育,而地表层间节理则更利于中小型层间溶洞的发育;3)节理的疏密影响岩溶的发育程度;4)节理充填不易溶蚀物质时抑制了岩溶的发育,而节理充填软弱物质时则有利于岩溶的发育;5)早期形成的节理比晚期形成的节理更有利于岩溶洞穴的发育.

Characteristics of joints in karst area and their influence on karstification in Zhangfang in Fangshan region of Beijing

Zhangfang area of Beijing is a typical example of the North China karst area, and the research on characteristics of joints and their impacts on karst and water enrichment is of great significance. In this paper, we attempt to study the characteristics of joints and discuss their influence on karstification with the method of probability and structural analysis. The earth's surface joint data that we use are got from geological surveys. Joints in this region have great influences on the karst development:1) the development extension of joints controls the extension and plane shape of karst development; 2) the oblique joints are favourable to the development of grikes and karst fracture zones while the intraformational joints are beneficial to the development of small and medium-sized interlayer karst caves; 3) the density of joints affects the degree of karst development; 4) joints filling with hard corrosion substance will restrain karst development while joints that filling with easy corrosion substance will be conducive to karst development; and 5) joints which formed early are more advantageous to the development of karst caves than the late joints.