مدلسازی عددی فرونشست زمین ناشی از استخراج آب های زیرزمینی با لحاظ کردن اثرات غیر اشباع و به روش بدون المان گالرکین (EFG)

نوع مقاله : پژوهشی

نویسندگان

1 دانشکده مهندسی عمران، دانشگاه صنعتی شریف

2 دانشکده ی مهندسی عمران - دانشگاه صنعتی خواجه نصیرالدین طوسی

چکیده

در پژوهش حاضر، به کمک یک مدل عددی کاملاً همبسته‌ی هیدرومکانیکال، پدیده‌ی فرونشست ناشی از استخراج آب‌های زیرزمینی از آبخوان‌ها با درنظرگرفتن آثار غیراشباع به روش بدون‌المان‌گالرکین (EFG) شبیه‌سازی شده است. به کمک مدل اخیر می‌توان یک پیش‌بینی مناسب برای تغییرات هد هیدرولیکی و میزان فرونشست زمین ارائه کرد. پس از حل مسائل محک، مدل نهائی برای حل مسئله‌ی‌ فرونشست استفاده شد. نتایج پژوهش حاضر با نتایج روش المان‌محدود (FEM) برای یک آبخوان همسان و با درنظرگرفتن شرایط غیراشباع مقایسه و خطای فرونشست زمین 51/5٪ و خطای افت هدهیدرولیکی 35/13٪ محاسبه شد، که نشان از تطابق مناسب بین نتایج دو روش اخیر است. نتایج نشان می‌دهند که روش EFG قابلیت مدل‌سازی پدیده‌ی فرونشست را دارد. همچنین آثار غیرخطی استخراج آب‌های زیرزمینی در کاهش هد هیدرولیکی و افزایش فرونشست قابل تعیین است. درنهایت، یک مطالعه‌ی پارامتری به‌منظور بررسی میزان تأثیر ویژگی‌های ژئوتکنیکی آبخوان در میزان فرونشست انجام شد. پارامترهای مدول کشسان و ضریب پواسون بیشترین تأثیر را در میزان فرونشست زمین دارند و لازم است پیش از اجرای پروژه‌های برداشت آب‌های زیرزمینی، پارامترهای مذکور با دقت قابل قبول درنظر گرفته ‌شوند.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Numerical modeling of land subsidence induced by groundwater extraction considering unsaturated effects and using element-free Galerkin (EFG) method

نویسندگان [English]

  • A. Tourei 1
  • A. Pak 1
  • M. A. Iranmanesh 2
1 Civil Engineering Department, Sharif University of Technology, Tehran, Iran
2 Civil Engineering Department, Khajeh Nasir Toosi University of Technology, Tehran, Iran
چکیده [English]

This study aims to provide a coupled flow-deformation model for simulating land subsidence associated with groundwater extraction in aquifers. For this simulation, we have adopted the element-free Galerkin (EFG) method and considered the unsaturated effects in the aquifers based on the aquifer's hydrologic and geotechnical characteristics. This model gives us a better understanding of the aquifer's hydrogeological characteristics, enabling us to forecast changes in the hydraulic head and land subsidence. To ensure the credibility of our model and to verify the code, we modeled unsaturated hydromechanical benchmark problems. Then, using the EFG method as a numerical tool, we modeled an isotropic aquifer to investigate the effects of groundwater pumping on land subsidence and hydraulic changes in the aquifer. To ascertain the reliability of the modeling, we compared the results obtained from the EFG method with those from the Finite Element Method (FEM). The comparative analysis of EFG and FEM models demonstrates discrepancies of 5.51% in land subsidence and 13.35% in hydraulic head reduction, which are satisfying. The land subsidence and hydraulic head profiles demonstrate that the EFG method is capable of land subsidence simulation caused by water pumping. Furthermore, our findings highlight the nonlinear correlation between groundwater extraction and the subsequent decrease in hydraulic head and land subsidence augmentation. Finally, we conducted a parametric study to better understand the effect of various characteristics of aquifers and observe the effect of the aquifer's parameters, such as hydraulic conductivity, elastic modulus, and Poisson's ratio. We investigated the effect of each parameter on land subsidence increase and hydraulic head decline. The results show that elastic modulus and Poisson's ratio have the most significant effect on land subsidence. Although hydraulic conductivity controls the hydraulic decrement and land subsidence increase time, it slightly affects the ultimate hydraulic head and land subsidence at the steady-state stage. These results highlight the importance of in-situ measurement of elastic modulus and Poisson's ratio paraeters with acceptable accuracy for groundwater extraction projects, as these parameters play a significant role in the feasibility studies.

کلیدواژه‌ها [English]

  • Land subsidence
  • Groundwater extraction
  • Numerical modeling
  • Coupled hydromechanical analysis
  • Element-free Galerkin (EFG)
  • Unsaturated effects

مراجع

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