大射电望远镜一平方公里阵(SKA)候选台址核心区岩溶水系发展演化过程及其工程意义研究

大射电望远镜SKA是国际射电天文界提议,并由国际SKA计划办公室(ISPO)和国际SKA操作委员会(ISSC)具体实施的国际性项目,中国SKA工程方案是利用贵州省众多的喀斯特洼地作为大射电望远镜SKA侯选台址,其核心区为平塘县六水洼地群。通过大量的岩溶地质调查,认为,SKA核心区属于贵州省VII剥夷面,与之相对应的地文期为第三期第1亚期,该区强烈岩溶的作用,是坝王河的强烈溯源侵蚀结果。区内垂向岩溶作用强烈,落水洞密布,地表河与地下暗河间频繁转换,岩溶水系发展演化过程可分为3个阶段,而目前处于第3阶段中期,其特征是“高差大、水量大、岩溶作用强烈,槽谷、洼地等负地形量大而密集分布”。大射电望远镜工程建设需处理好洼底岩溶水顺畅排泄、主反射面支撑柱地基局部垮塌和支撑柱地基不均匀沉降等问题。

KARST WATER DEVELOPMENT AND ITS ENGINEERING EFFECTS ON THE SELECTION OF SKA CORE REGION

The project of a square kilometer array(SKA) proposed by many international astronomers has been implemented by the International SKA Project Office(ISPO) and the International SKA Steering Committee(ISSC) since 1992.Taking numerous karst depressions in Guizhou as the SKA sites is a new scheme proposed by China.The SKA core region is located at Liushui Village,Pingtang County,which belongs to the 7~(th) Guizhou stripped plane with the 1~(st) sub-cycle in the III physiographic cycle.Due to the heavy head erosion of the Bawang River,the karstification,especially in the vertical direction in the core region is strong,and downspouts are densely distributed,surface rivers and underground rivers converse multifariously.The development of the karst water system can be divided into 3 stages.At the intermediate stage of the third one various landforms characterized by differential height,plentiful karst water,strong karstification are densely distributed through valleys and depressions.Therefore,unimpeding the karst water's outflow pathways at the bottom of the depression,preventing the supporters' local collapse,decreasing the differential settlement of the supporters' foundation are the main engineering geological tasks for the SKA project.