从地下水变化分析临汾地震台短水准异常的成因

Analysis of Short-Leveling Anomaly in Linfen Seismic StationBased on the Groundwater Change

利用深水井水位数据、龙子祠泉流量资料及临汾地震台短水准所在区域内的长观孔水位资料,分析临汾地震台及周边地区地下水整体变化状态,根据区域水位变化特征对临汾地震台短水准近年来出现的异常进行分析。结果表明,临汾地震台短水准测量场地周边区域地下水位在2011~2013年发生明显变化,与水准观测曲线变化趋势较为一致,水准异常时间滞后于水位变化2~3 a;而大范围水位上升尤其是浅水井水位明显上升主要是因为地下水开采量减少,非构造所致。水位上升引起平原区地面回弹的现象符合Terzaghi有效应力原理,即水位回升使孔隙水压力得到恢复,砂层回弹进而引起地面回弹,并引起短水准高差测值的变化。

Based on water level data from the deep well,the flow data of Longzici spring,and water level data of some long-term observation holes in the structural area of Linfen seismic station,we analyze the overall change of groundwater state at Linfen seismic station and its surrounding areas.We further analyze the short level anomalies at Linfen seismic station in recent years according to the characteristics of regional water level change.The results show that the groundwater level of Linfen short-leveling site and surrounding areas changes significantly from 2011 to 2013,which is consistent with the change of the leveling observation curve.The time of leveling anomalies lags behind the change of water level by 2-3 a.The rising water level in a large range,especially in shallow water wells,which is caused by the decrease of groundwater exploitation not by structure.The ground rebound caused by water level rise accords with the principle of Terzaghi effective stress;that is to say,the water level rise recovers the pore-water pressure,the sand layer rebound and then causes the ground rebound,which further causes the change of the short-leveling height difference measurement value.