关键词: 稀有气体异常, 岩层孔隙压力, 华北

Abstract: Recently, remarkable rare gas anomalies have been observed in the water of Baolong and Tai-ping-zhuang wells in Beijing area, and Xialiao No.1 well in Xiaxian County, Shanxi Province. All these three wells are located in North China. According to the characteristics of rare gas anomalies in the three wells and the relationship between the anomalies and groundwater levels, theoretical analysis and experimental study have been carried out to gain an insight into the genesis of the anomalies. The results of experiments show that the volume of gases in the pores and fractures varies significantly with the evolution of groundwater dynamic condition. We find that the gas volume will expanse about 0.009 0% when the water level drops for 100mm. This may indicate that the anomalies of rare gases in these three wells are resulted from the expansion of gas volume and escape of gases due to the drop of groundwater level and the decrease of pore fluid pressures. It is proposed, therefore, that the rare gas anomalies discussed in this paper should not be earthquake precursor, but are anomalies caused by interference factors.

Key words: Rare gas anomaly, Pore pressure, North China