观测室环境对水汞观测结果的影响

对观测室环境和观测时间改变对水汞观测数据产生的影响进行了实验研究和分析,详细介绍了一次水汞测值异常的核实过程,得出以下结论:(1)观测环境及观测时间的改变不会对水汞观测结果产生明显影响;(2)由于观测室内会残存汞蒸汽,应将观测室随时保持通风状态以降低观测室残存汞蒸气对水汞测值的影响;(3)要加强对试剂、观测室空气中汞含量的监测,避免外界条件变化对水汞观测结果带来的影响。     

一起非地震前兆的水质测项突跳异常

针对郑州市地震局测井水质测项的大幅度突跳异常变化的分析,主要通过观测井连续抽水对水质观测的影响试验,研究抽水时间的长短对水质观测影响的定量关系。分析认为,抽水时间的长短对水质观测的各测项的影响很大,且符合y=ae^b／x函数关系,尤其在抽水持续2～3小时内,水质观测各测项测值变化梯度最大,之后在影响后的高(低)值附近小幅度起伏。因此,该测井水质测项大幅度突跳变化是由于连续抽水影响所致,不属于地震前兆事件。     

下关温泉水汞整点观测变化与日测值关系研究

进行每天一次定点、定时、定量人工取样观测的下关温泉水汞进行24小时整点人工加密取样观测实验,研究并讨论人工取样水汞24小时日变化与日测值的关系,为汞量异常时的人工加密观测提供预研究依据,以期更好、更充分地捕获水汞前兆异常信息。     

王3井水氡、水汞观测资料分析

对王3井水氡、水汞开始观测以来的资料进行了系统清理,针对近几年该井水氡观测资料出现的年动态和下降变化、水汞观测值较低的现象进行了分析,认为王3井水氡观测值出现的年动态变化和水汞观测值2001年的下降与增上数字化观测项目而进行的井-排水系统的改造有关;而2004年下半年水氡、水汞观测值的下降与周良1井的开采有关。文中提出了对王3井的一些改造措施,同时提出了天津水化观测井的重新选井问题。     

山西忻州奇村水汞观测干扰因素浅析

为进一步明确山西忻州奇村水汞观测过程中存在的干扰因素,分别对硫酸单一试剂、综合试剂、空气湿度、同一个水样多次观测等项进行了试验。试验表明,现用硫酸及其他试剂的汞污染均不明显,对水汞观测构不成于扰;观测室内空气高湿度对水汞观测有一定干扰,且湿度越大,干扰越强,高湿度导致测值大幅突跳;通常所测的水汞含量实为在鼓泡延续时间及空气流量固定不变特定情况下的相对含量,两者的改变会对测值的可比性产生人为干扰。     

保护剂添加时间对水汞测值影响的实验研究

为考察保护剂添加时间的不同是否对水汞测值有影响,通过实验的方法,对比分析了相同水样不同时间添加保护剂后水汞含量测值存在的差异,结果表明:保护剂的添加时间差异对水汞测值不会产生较大的影响。该结论对台站实际工作中的样品处理以及特殊条件下的短临跟踪工作具有一定的借鉴意义。     

抽水对地下水位、汞、氡的影响——以古城试验为例

介绍了在内蒙古古城进行的同层抽水对水位、水温(地热)、气氡、气汞、水氡与水汞影响的观测试验及其结果。结果表明,抽水对井水位影响最大,影响距离可达近1 km;对水温影响较为明显;对气氡、气汞的影响不明显;水氡与水汞的动态可能有一定影响,但影响幅度不大。     

东古楼抽水试验对地下流体动态影响研究

为了研究抽水对水位、水温(地热)、气氡、气汞、水氡与水汞的影响,在内蒙古呼和浩特市东南的东古楼村进行了相关试验观测。结果表明,抽水对井水位的影响最大,影响距离可达680m;对水温影响也较为明显;对气氡与气汞动态的影响不明显;对水氡与水汞动态可能有一定影响,但影响幅度很小。     

保护剂和还原剂对水汞观测结果的影响分析

在定量测试分析的基础上,讨论了保护剂和还原剂对水汞观测数据的影响。指出,分析纯硫酸的汞含量因生产厂家的不同而不同,有时可达地下水中汞含量的几百倍。对水汞微量分析而言,优级纯硫酸比分析纯硫酸更好。建议先用无汞蒸馏水做空白对照,然后再观测泉水,并以水样测值减去空白对照值,所得才是真正的泉水汞含量。     

山西忻州奇村井水汞高值原因分析

通过对比观测实验,对水汞观测中出现的大幅度高值异常变化原因进行分析,认为汞标准源长时间置于观测室,造成室内汞污染;捕汞管、取样瓶、还原器等长时间不清洗受到污染等是造成水汞高值的主要原因。对观测过程中存在的问题提出几点建议,以利于提高水汞观测质量及在地震分析预报中的作用。     

栾城王家庄井水位异常分析

2012年8月栾城王家庄井水位短时间内多次出现快速、大幅下降变化,调研发现,下降异常由距离该井约860 m的新井抽水引起.利用抽水试验模型,定量模拟抽水对王家庄井水位的变化影响,模拟结果与实际变化量相当,进一步确定该井水位下降异常为抽水影响.     

INFLUENCE OF PUMPING ON FOUR-COMPONENT BOREHOLE STRAIN AT TAI'AN SEISMIC STATION AND ITS INTERFERENCE MECHANISM

Four-component borehole strainmeter (FCBS) is one kind of high-precision borehole strain observation instruments invented in China. As a kind of near-surface deformation observation instrument, FCBS is also easily disturbed by the external environment factors. As a common factor, pumping has significant influence on FCBS observation. Existing studies mostly identify the pumping interference from the perspective of observation curve morphology, relatively few studies focus on its interference mechanism. In order to truly capture earthquake precursor information, it is necessary to study the interference mechanism. In recent years, RZB-3 type FCBS at Tai'an seismic station has been seriously affected by pumping, so it is necessary and also feasible to study the interference mechanism of pumping. Since the influence of pumping interference on borehole strainmeter is common, this work would be very practical and be used for reference by other borehole strain observation stations. We find that the original observation curves and observed surface strain, shear strain from RZB-3 type FCBS at Tai'an seismic station have the characteristics of synchronous change with the borehole water level, in which the linear correlation coefficient between the two observed shear strain curves and borehole water level reached 0.70 and 0.82 respectively. We further find that the principal strain direction of borehole and borehole water level after normalization meet the nonlinear function as y=1.217arctan(x)^0.224-0.284. The above phenomenon indicates that the observation of RZB-3 type FCBS at Tai'an seismic station is significantly affected by the borehole water level, and the influence is more obvious and the gradient is larger at the stage of low water level. Pumping interference often appears in low water level stage and changes the rock pore pressure state. Statistics show that pumping interference affects the borehole strain state. To investigate the interference mechanism of pumping to RZB-3 type FCBS at Tai'an seismic station, we take a known pumping as an example, in which we study the principal strain state of the borehole in three periods of normal pumping, interruption of pumping and resuming pumping respectively. During each period, we solve 3 parameters of the principal plane strain state, i.e. the maximum principal strain rate, the minimum principal strain rate and the maximum principal strain direction from four observation equations of FCBS by nonlinear iterative least squares algorithm. On the other hand, concentrated load model (CLM) is used to simulate the mechanical mechanism of pumping. Firstly, the depth of FCBS relative to pumping source and the concentrated load at pumping source are inversed, then, the strain state surrounding the pumping well, including the state at RZB-3 borehole, is simulated by forward modeling. By comparing these results, we find that: (1)The concentrated load at pumping source inversed by CLM during periods of normal pumping and resuming pumping are both located at or near the bottom of the pumping well, which is consistent with the actual situation, indicating that mechanism and degree of the influence of pumping on borehole strain are well simulated by CLM. (2)The observed strain state is consistent with the simulation result of pumping interference by forward modeling, indicating that the principal strain state of borehole calculated based on observation of FCBS reflects the true strain state of borehole under different pumping states.(3)The inversed concentrated load at pumping source during pumping periods is significant greater than the load of the pumped water, indicating that the pumping process has more significant influence on the pore pressure of rocks than the load of the pumped water. Even though CLM is an approximate simulation since it's based on some elastic assumptions, the interference mechanism of pumping on RZB-3 type FCBS at Tai'an seismic station is well explained, which is maybe very helpful for studying the influence of pumping interference on other deformation instruments, locating the unknown pumping source and studying the characteristics of pore pressure of rocks.     

重庆大足井水位对邻井抽水的奇异响应及其机理

大足井位于重庆市大足县拾万镇,井深108.7m,观测含水层为J_2S泥岩夹砂层的风化裂隙潜水层。多年的观测结果表明,每当相距仅14.6m的邻井抽水时,该井水位不仅不降,反而上升,是国内外罕见的奇异现象。通过对这一现象进行的观测资料分析、井区地质-水文地质条件调查、现场试验观测及理论分析等得出,大足井水位对邻井抽水的奇异响应是在特定的水文地质条件下,抽水降落漏斗外边界带上因水流速度较大引起的动水压力使该处的观测井产生的特殊井水位动态。     

福建永安井水位大幅度异常变化原因的研究

2001年7月18日起,永安井水位出现持续的大幅度上升变化。经调查落实,这是由于该井附近的另一口多年开采的井孔,于2001年7月17日突然停止抽水,从而使永安井的地下水补给量增大,造成水位大幅度上升。深入分析该井水位变化的成因,为研究邻井抽水对地震地下水动态观测井水位动态的影响提供了一个实例,对于识别地下水前兆异常与抽水干扰有一定的参考意义。     

怀来地震台线应变测项群井抽水干扰分析

怀来地震台伸缩仪观测曲线年变形态每年出现2次较大幅度的阶跃型上升,且变化幅度大小不同。对该地震台观测山洞周边4 km范围内抽水井的分布、2016-2017年季节性抽水时间、抽水量、群井开抽数量等进行调查,并与伸缩仪观测曲线异常变化进行对比分析,发现在时间及变化幅度上,二者同步性较好,分析认为形变观测的周期性大幅度上升变化应与观测山洞周边群井抽水有关,非地震前兆异常变化;并对抽水引起的形变观测机理进行初步分析,提出干扰消除方法。     

2016年衡水冀16井水位变化分析

衡水冀16井水位2016年经常出现有规律的大幅度异常波动变化,具有小幅下降—持续上升—小幅上升—持续下降变化形态,日变最大幅度0.73 m。通过现场核实,发现观测仪器工作正常,附近鱼场地下水开采量增加。增加辅助观测仪器同井对比水位观测,并对鱼场2口冷水井进行抽水试验,分析衡水冀16井水位异常变化原因。结果显示,衡水冀16井水位大幅波动异常变化可能因冷水井1抽水所致,冷水井2无影响。     

Monitoring of drawdown pattern during pumping in an unconfined physical aquifer model

In this study, we attempted to analyse a drawdown pattern around a pumping well in an unconfined sandy gravelly aquifer constructed in a laboratory tank by means of both experimental and numerical modelling of groundwater flow. The physical model consisted of recharge, aquifer and discharge zones. Permeability and specific yield of the aquifer material were determined by Dupuit approximation under steady‐state flow and stepwise gravitational drainage of groundwater, respectively. The drawdown of water table in pumping and neighbouring observation wells was monitored to investigate the effect of no‐flow boundary on the drawdown pattern during pumping for three different boundary conditions: (i) no recharge and no discharge with four no‐flow boundaries (Case 1); (ii) no recharge and reservoir with three no‐flow boundaries (Case 2); (iii) recharge and discharge with two no‐flow boundaries (Case 3). Based on the aquifer parameters, numerical modelling was also performed to compare the simulated drawdown with that observed. Results showed that a large difference existed between the simulated drawdown and that observed in wells for all cases. The reason for the difference could be explained by the formation of a curvilinear type water table between wells rather than a linear one due to a delayed response of water table in the capillary fringe. This phenomenon was also investigated from a mass balance study on the pumping volume. The curvilinear type of water table was further evidenced by measurement of water contents at several positions in the aquifer between wells using time domain reflectometry (TDR). This indicates that the existing groundwater flow model applicable to an unconfined aquifer lacks the capacity to describe a slow response of water table in the aquifer and care should be taken in the interpretation of water table formation in the aquifer during pumping. Copyright © 2001 John Wiley & Sons, Ltd.     

高温腐蚀性抽水控制系统在怀4井的应用

由于近年来水位普遍降低以及地热资源的不断开发,造成河北怀4井水位严重下降,几近断流。为了延长该井的观测年限,2007年怀4井进行了降低取水口的改造。由于改造后出水口低于地面,必须将泄流出的水抽走,由此必须抽水进行控制。由于怀4井水温达到85℃以上,并且富含矿物质,对金属具有强腐蚀性,因此对排水控制系统提出了很高的要求。通过在怀4井的实践,给出了一种在高温和腐蚀性等条件下长期正常运行的抽水控制系统。     

Multivariate approaches optimize locations of groundwater pumping facilities for different hydrogeological scales

A number of optimization approaches regarding the design location of groundwater pumping facilities in heterogeneous porous media have elicited little discussion. However, the location of groundwater pumping facilities is an important factor because it affects water resource usage. This study applies two optimization approaches to estimate the best recharge zone and suitable locations of the pumping facilities in southwestern Taiwan for different hydrogeological scales. First, for the regional scale, this study employs numerical modelling, MODFLOW‐96, to simulate groundwater direction and the optimal recharge zone in the study area. Based on the model's calibration and verification results, this study preliminarily utilizes the simulated spatial direction of groundwater and compares the safe yield for each well group in order to determine the best recharge zone. Additionally, for the local scale, the micro‐hydrogeological characteristics are considered before determining the design locations of the pumping facilities. According to drawdown record data from six observation wells derived from pumping tests at the best recharge area, this study further utilizes the modified artificial neural network approach to improve the accuracy of the estimation parameters as well as to analyse the direction and anisotropy of the hydraulic conductivities of an equivalent homogeneous aquifer. The results suggested that the best locations for the pumping facilities are along the more permeable major direction. Copyright © 2011 John Wiley & Sons, Ltd.