مطالعه پتانسیل زمین‌لغزش با استفاده از روش توموگرافی الکتریکی دوبعدی در منطقه چای‌باغ (سوادکوه شمالی، ایران)

نوع مقاله : مقاله پژوهشی‌

نویسندگان

1 دانش آموخته دکترای زلزله شناسی، گروه زلزله شناسی، موسسه ژئوفیزیک دانشگاه تهران، تهران، ایران

2 استاد گروه زلزله شناسی، موسسه ژئوفیزیک دانشگاه تهران، تهران، ایران

3 کارشناس ارشد زمین شناسی مهندسی، کارشناس آزمایشگاه فنی و مکانیک خاک، تبریز، ایران

چکیده

زمین‌لغزش‌ها مخاطراتی طبیعی هستند که باعث تلفات جانی و خسارات مالی شدید می‌شوند. برای تجزیه و تحلیل زمین‌لغزش‌ها از روش‌های مختلفی ازجمله روش‌های ژئوتکنیکی و ژئوفیزیکی به‌ترتیب به دلیل دقت و هزینه بسیار کم استفاده می‌شود. در میان روش‌های ژئوفیزیکی، از توموگرافی مقاومت الکتریکی به‌طور گسترده‌ای برای اکتشاف نزدیک به سطح در مناطق زمین‌لغزش استفاده می‌شود. در این مطالعه از بررسی‌های توموگرافی مقاومت الکتریکی دوبعدی برای بررسی ساختار زیرسطحی و پتانسیل زمین‌لغزش در منطقه چای‌باغ استفاده شده است. در مطالعات اولیه پروژه‌های عمرانی به‌ویژه سازه‌های خطی، بررسی مناطقی که پتانسیل لغزش دارند، از اهمیت بسزایی برخوردار است. به همین منظور پس از ایجاد شکاف بزرگ در قسمتی از جاده ساری- شیرگاه در منطقه چای‌باغ شهرستان سوادکوه شمالی که واژگون شدن قطار باری را در پایین‌دست جاده به دلیل خم شدن ریل راه‌آهن درپی‌داشت، تحقیقات توموگرافی مقاومت الکتریکی دوبعدی برای تشخیص دلیل این حادثه و احتمال وقوع زمین-لغزش گسترده در منطقه صورت گرفت تا در ساخت دوباره جاده تدابیر لازم لحاظ و از بروز خسارت بیشتر جلوگیری شود. در این تحقیق داده‌های حاصل از سه مقطع با آرایه‌های دوقطبی- دوقطبی، قطبی- قطبی و سونداژ الکتریکی (VES) با روش وارون‌سازی دوبعدی در نرم افزار Res2dinv تفسیر شد. نتایج مطالعه نشان داد پتانسیل لغزش در سطح وسیعی از منطقه با سطح لغزشی در عمق 30 تا 35 متری از سطح جاده وجود دارد و تجمع شار آب زیرزمینی می‌تواند محرک اصلی زمین‌لغزش احتمالی در آینده باشد. بر این اساس تمهیدات لازم ازجمله طراحی زهکش برای ساخت دوباره این قسمت از جاده برای افزایش ایمنی پیشنهاد شده است.

کلیدواژه‌ها


عنوان مقاله [English]

Study of landslide potential in Chaybagh region with 2D electrical resistivity tomography method

نویسندگان [English]

  • Reza Emami 1
  • Mehdi Rezapour 2
  • Mohammad Faraji 3
1 Ph.D. in Seismology, Department of Seismology, Institute of Geophysics, University of Tehran, Tehran, Iran
2 Professor of Seismology, Department of Seismology, Institute of Geophysics, University of Tehran, Tehran, Iran
3 M.Sc. in Engineering Geology, Expert of Technical & Soil Mechanics Lab.co., Tabriz, Iran
چکیده [English]

Landslides are natural hazards that cause severe fatalities and financial losses. Various methods are used to analyze landslides. Among those, geotechnical and geophysical methods are used due to their accuracy and low cost, respectively. In geophysical methods, electrical resistivity tomography (ERT) is widely used for near-surface exploration of landslide areas characterized by a complex geological environment. In this study, two-dimensional electrical resistivity tomography (ERT) studies have been used to define the subsurface structure and landslide geometry of Chaybagh. Over the past decade, technological advances in field data acquisition systems and the development of new algorithms for tomographic inversion have made this technique more suitable for studying landslide areas. In order to reduce the possible damages in the preliminary studies of construction projects, especially linear structures, it is very important to study the areas with slip potential.
    Following the widening the road in a part of Sari-Shirgah road in the Chaybagh area of North Savadkuh County, which overturned a freight train downstream due to bending of railway tracks, a large gap was created. In order to determine the cause of this accident and the possibility of landslides in the area, 2D geoelectric tomography was performed and necessary considerations were taken into account for reconstruction of the new road to prevent further damages.According to the geological map of Ghaemshahr 1/100000, the study area includes conglomerate, silty marl, sandstone and siltstone. At the bottom of the landslide area is the Talar River bed, which includes alluvial fans, floodplains, old and young rivers and streams, alluvial floodplains, older coastline deposits, and non-hardened alluvium of the present age in the bed of rivers. In this study, the data obtained from the profiles with Dipole-Dipole and Pole-Pole arrays and geoelectric sounding were interpreted by two-dimensional inversion method in Res2dinv software.
    The results of the study show that on the upper slope of the road, a small landslide surface is observed at a depth of 4 to 5 meters. This landslide occurred at a small level and has nothing to do with landslides and road gaps, but there is a large-scale landslide potential in the area with landslides at a depth of 30 to 35 meters above the road surface in the future so that groundwater flux accumulation can trigger landslides. Therefore, designing of drainage for engineering structures in this part of the road is essential to prevent road collapse, accidents and possible losses. Moreover, the possibility of landslides in the designs should be considered.

کلیدواژه‌ها [English]

  • landslide potential
  • Electrical Resistivity Tomography (ERT)
  • inversion
  • least squares method
  • landslide surface
  • Chaybagh
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