深井抽水对地倾斜观测影响的实验研究

Experimental Study on the Effect of Deep Well Pumping on Ground Tilt Observation

采用抽水、放水实验方法,研究地倾斜的变化量与地下水抽取量之间的关系、蓄水池池水变化量与地倾斜变化量之间的关系。通过对抽水实验数据分析研究可知：在放水速率（V放水〈9 m^3/h）、总放水量（T〈82 m^3）有限的前提下,弥渡地震台观测山洞正上方30 m处的蓄水池水量变化不会引起地倾斜观测资料的明显变化;而地下水抽取是造成地倾斜异常变化的主要原因,且地倾斜异常变化在时间上与抽水作业（起止时间）保持高度同步性;抽水活动持续时间与地倾斜变化量是成非线性关系：随抽水时间延长,地倾斜变化速率开始较快,随后减小。但在开始抽水2小时时段内表现为近似线性关系,即NS测向VNS=-0.045 53 ms/min,EW测向VEW=-0.079 71 ms/min。通过频域分析可知：弥渡地倾斜观测受抽水干扰的异常信号的频率在0.001 8-0.003 Hz之间。由此,笔者设计了带阻滤波处理软件对抽水干扰信号频段进行处理,降低了抽水作业对弥渡地倾斜观测的影响。

By using pumping and dewatering test method,we researched the relationship betw een the variation of ground tilt and amount of groundwater extraction,water yield variation of water reservoir. The analysis result of the pumping water test data showed that under the premise of the limited drainage rate（ Vdrainage 〈9 m^3/ h）,the total discharge of water（ T〈 82 m^3）,the water yield variation of water reservoir which was located at 30 m above the observing cave of M idu Station didn＇t cause significant interference to the ground tilt observation. The main reason of the ground tilt anomaly variation was induced by the pumping of the ground water and its variation maintained a high degree of synchrony with the pumping operation（ the date of the start and the end） in time. The duration of pumping water had a non-linear relation with the ground tilt variation,that is,the variation rate of ground tilt was faster at first,and decreased as follow with the pumping time. How ever it showed an approximately linear relationship,that is,VNS=- 0. 045 53 ms / min in NS,VEW=- 0. 079 71 ms / min in EW within the first tw o hours of pumping water. The frequency domain analysis result show s that： The frequency of anomaly signal of ground tilt which was interfered by pumping water was betw een 0. 00 18 Hz and 0. 003 Hz.Thus,we designed a band-stop filter processing program to filter out the frequency of pumping water signal to reduce the influence of pumping water on the ground tilt observation.