Numerical Simulation of Stress Field Induced Groundwater Level Change in Confined Aquifer

doi:10.13209/j.0479-8023.2017.013

Abstract

Abstract:

The aquifer can be treated as poroelastic media in current research. An ideal 2D confined aquifer model was founded to calculate the response of the groundwater level to the variation of stress field. Then the dissipation law of abnormity of groundwater level was discussed. A deconvolution method to invert stress-strain field from groundwater level data when considering the dissipation process was also discussed. Results from forward calculation and earth tide data of Huili Chuan-06 well were analyzed to confirm the deconvolution method. At last, the mechanism of co-seismic step variation in groundwater level was analyzed. It was concluded that a simple poroelastic model cannot explain the amplitude of variation.

Key words: groundwater level, permeation, variation of stress field

摘要：

将含水层看成孔隙弹性介质, 建立二维承压含水层理想模型, 计算周围应力场变化引起的井水位变化的分布和量级, 讨论井水位突变的消散规律。根据消散过程, 用反褶积的方法, 从井水位数据计算周围应力应变场的变化, 并用数值方法和会理川06井的固体潮数据验证这种方法的可行性。应用数值模拟结果探讨同震井水位阶变的机制, 认为简单的孔隙弹性模型不能解释同震井水位变化特征。

关键词: 井水位, 渗流, 应力场变化

CLC Number:

P553

Yuqing XIE, Yonghong ZHAO. Numerical Simulation of Stress Field Induced Groundwater Level Change in Confined Aquifer[J]. Acta Scientiarum Naturalium Universitatis Pekinensis, 2017, 53(4): 683-691.

谢雨晴, 赵永红. 承压含水层应力场与井水位变化的数值模拟[J]. 北京大学学报自然科学版, 2017, 53(4): 683-691.

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URL: https://xbna.pku.edu.cn/EN/10.13209/j.0479-8023.2017.013

https://xbna.pku.edu.cn/EN/Y2017/V53/I4/683

Figures/Tables 15

Table 1 Response of water level to different disturbance of stress and strain in the earth’s crust[7]

应力?应变来源	体应变/mm^-1
潮汐效应	6.6×10^-9
地表水体荷载效应	9.6×10^-7
列车荷载效应	1.0×10^-2

Fig. 1 Ideal model of a 2D confined aquifer

Table 2 Parameters used in the ideal model

参数	取值
Biot-Willis耦合系数α_B	0.79
渗透率κ/m²	2.894×10^-11
动力黏滞系数μ/Pa · s^-1	10^-3
泊松比	0.2
水密度/kg · m^-3	10³
岩石密度/kg · m^-3	2750
杨氏模量/Pa	1.44×10¹⁰
孔隙度	0.19

Fig. 2 Relation between transient variation of groundwater and the variation of stress

Fig. 3 Distribution of hydraulic head and Darcy’s velocity field of two epochs

Fig. 4 Variation of hydraulic head with time of point A under loading force of different value

Fig. 5 Variation of Darcy’s velocity with time of point B under loading force of different value

Fig. 6 Distribution of Darcy’s velocity along line an under loading force of different value

Fig. 7 Variation of groundwater level with time in variable pressure test[15]

Fig. 8 Variation of loading force with time (a), dissipation curve (b), variation of groundwater with time (c),

Fig. 9 Theoretical volume strain of earth tide and recorded water level Huili Sichuan-06 well

Fig. 10 Dissipation curve from deconvolution

Fig. 11 Comparison between water level calculated from dissipation curve and theoretical volume strain of earth tide and recorded water level

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