张玉坑磷石膏集中库岩溶水文地质调查与示踪

Karst hydrogeological survey and tracing ofZhangyukeng phosphogypsum repository

磷石膏是生产磷酸过程中产生的废弃物,对其最有效的处理方法就是采取集中堆填处理。张玉坑磷石膏集中库就是一个典型的磷石膏堆填场所,建造磷石膏集中库对地质环境要求严格,涉及磷石膏堆填体稳定性问题,同时还涉及对地下水可能造成的污染。文章在野外地质调查、钻井岩心观察、地球物理剖面解释的基础上,利用示踪评价技术,对研究区岩溶发育及岩溶水的径流、排泄特征进行评价,得出如下结论:①张玉坑磷石膏集中库所在冲沟与临谷无任何水力联系,不会发生向临谷的地下水渗漏;②NE向岩溶管道的存在控制着张玉坑地区岩溶水的径流和排泄,排泄通道唯一,地质点(D5)是该区存在的接触式下降泉——岩溶地下水的排泄通道;③示踪曲线具有拖尾特征的单峰式曲线,地下岩溶管道类型单一,相对简单,同时也说明试验区地下岩溶较为发育,存在着由地质点(D2)到地质点(D5)的主流径通道,且通道畅通;④磷石膏堆填场地的理想要求就是具有相对独立的地下水文地质单元,与临谷没有水力联系,排泄通道单一清楚,张玉坑磷石膏集中库岩溶水文地质条件基本满足上述要求,满足建库水文地质条件。

The most effective treatment of phosphogypsum—the waste generated in the production of phosphoric acid—is centralized landfill.Given the stability of phosphogypsum landfill and possible pollution to groundwater,Zhangyukeng phosphogypsum repository,a typical phosphogypsum landfill site,should be established in accordance with strict requirements on the geological environment.In this study,based on the field geological survey,observation of drilling cores and interpretation of geophysical profiles,the tracer evaluation technology was used to evaluate karst development and to analyze characteristics of karst water runoff and discharge in the study area.The following conclusions are drawn as follows.Firstly,the gullies where Zhangyukeng phosphogypsum repository is located have no hydraulic connection with the adjacent valley;therefore,there will be no groundwater leakage to the adjacent valley.Secondly,NE karst pipelines control the runoff and discharge of karst water in Zhangyukeng area.The discharge channel is unique and the geological point(D5)is the contact-type descending spring existing in this area—the discharge channel of karst groundwater.Thirdly,the tracer curve is a unimodal one with trailing characteristics,and the type of underground karst pipeline is single with relatively simple structures,which shows that the underground karst in the experimental area is developed and there is a main path channel with smooth flow between two geological points from D2 to D5.In conclusion,from the perspective of hydrogeological conditions,the building of a phosphogypsum landfill should meet the requirements that there exists a relatively independent underground geological unit without the hydraulic connection with the adjacent valley,and the discharge channel is single and clear.The karst hydrogeological conditions of Zhangyukeng phosphogypsum repository basically satisfy the above requirements and meet the hydrogeological conditions for its construction.