天津王3井水位异常机理

Mechanism of abnormal water level changes in the Wang 3 well of Tianjin

  • 摘要: 本文针对2016年6—9月天津王3井出现的井水位高值异常现象进行了异常机理分析。首先,利用频谱分析法提取了水位年动态并与区域降水量进行相关分析,排除降水的影响;其次,采用三阶多项式拟合计算了水位多年动态,定量地识别出王3井的水位年变异常,并取王3井及周边水源进行了水化学分析,结果显示,王3井所处局部区域的地下水主要成因为大气降水,存在一定的水岩作用,与周边水源之间无明显水力联系;最后,结合首都圈地震台站的波速比推测天津王3井所处的局部构造区域内可能存在一次短期应力积累过程。2016年9月10日发生的唐山MS4.2地震缓解了此次局部应力积累,使得王3井内水位逐渐恢复正常年变特征。

     

    Abstract: Water level in the Wang 3 well of Tianjin was higher than its normal annual values during June to September 2016. The possible mechanisms of the abnormal water level changes were analyzed in this study. Firstly, the normal annual variation of water level was extracted using spectral analysis method, and the influence of precipitation was corrected according to the relationship between the well water level and the local precipitation. Secondly, the multi-year values of water level were calculated by using the third-order polynomial fitting, and the abnormal water level in the Wang 3 well was identified quantitatively. Then, the hydrochemical analyses in the well and its surrounding water sources were made. The result shows that the groundwater in the well is mainly derived from the local precipitation, which indicates that there was some water-rock interaction rather than obvious hydraulic relationship between well water and surrounding water sources. Finally, from the wave velocity ratio in Beijing area, it is deduced that there may be a short-term stress accumulation around the Wang 3 well, which is verified by the local stress relief resulted from the Tangshan MS4.2 earthquake on September 10, 2016, and the water level of Wang 3 well gradually returned to its normal annual values.

     

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