本文运用ADINA有限元程序对薄煤层（厚1.15m）开采后底板岩体的破坏深度进行了数什模拟，探讨了断层对破坏深度的影响，其计算结果与地质雷达探测结果是一致的，可作为底板突水预报的依据。

Tongshan area, a part of the floodplain of the abandoned Huanghe River, is one of the popular ndemic fluorosis areas in East China. One of the reasons is high concentration of fluorine in shallow groundwater. Test results of 36 groundwater samples show that fluorine concentration in shallow groundwater is 0.18-6.7mg/L and 50% of the samples exceed the Chinese drinking water quality standard. There exists a significant negative correlation in content between Ca2+ and F-. The correlations between fluorine concentration and other cations (for example Na+, K+, Mg2+) are not significant. The content of dissolved fluorine from the flooding sediments of the Huanghe River that varying from 5.6mg/kg to 15.2mg/kg plays an important role in forming the high fluorine groundwater. Usually, the dissolved fluorine content in silt is much higher than that in silty clay and clay. According to the geological investigation fluorine content in deep groundwater (over 60m) is less than 1.0mg/L and suitable for drinking, so it is an effective measure to prevent endemic fluorosis by extracting deep groundwater in disease areas.