تحلیل پایداری ساختگاه تونل حاجی آباد با استفاده از روش‌های تجربی و تعادل حدی

نویسندگان

1 کارشناس‌ارشد زمین‌شناسی، دانشکده علوم‌زمین، دانشگاه دامغان، دامغان، سمنان، ایران

2 دانشیار گروه زمین‌شناسی، دانشکده علوم‌زمین، دانشگاه دامغان، دامغان، سمنان، ایران

چکیده

در این پژوهش، ویژگی‌های زمین‌شناسی مهندسی ساختگاه تونل حاجی‌آباد در استان هرمزگان بررسی شده و تحلیل پایداری آن با روش‌های تجربی و تعادل حدی صورت گرفته است. ساختگاه این تونل با استفاده از روش BGD به ده واحد ژئوتکنیکی تقسیم شده که شامل T1 تاT8  و دو زون خردشده در واحدهای 5 (Tf1) و 9 (Tf2) می‌باشند. ناپیوستگی‌‌های در توده­سنگ‌های ساختگاه تونل دارای مواد پرکننده کلسیتی و رسی هستند، سطح آن­ها خشک تا مرطوب با میزان هوازدگی کم است. زاویه اصطکاک داخلی سطوح این ناپیوستگی‌‌ها بین 15 تا 45 درجه، پیوستگی آن­ها بین 3 تا بیش از 20 متر، فاصله‌داری آن­ها بین 15/0 تا 4 متر و بازشدگی آن­ها بین 1/0 و 5 میلی‌متر است. مقاومت فشاری سنگ‌های ساختگاه به‌ جزء دو زون خردشده که شرایط متفاوتی دارند، از 20 تا 120 مگاپاسکال متغیر است. درصد رطوبت نمونه‌های حاصل از گمانه‌های ساختگاه تونل بین 87/2 و 12/0 و تخلخل آن­ها بین 33/7 و 32/0 درصد بوده است. با استفاده از نتایج RQD، سنگ‌های ساختگاه تونل در رده بسیار ضعیف (کمتر از 25) تا خوب (حدود 90) قرار می‌گیرند. با نتایج بدست آمده از روش RMR به سنگ‌های بخش‌های مختلف تونل امتیاز 18 یعنی رده خیلی‌ضعیف تا 62 یعنی رده خوب تعلق گرفت. همچنین با استفاده از روش ‌Q، این سنگ‌ها دارای امتیاز 04/0 یعنی رده بی‌نهایت ضعیف و 83/2 یعنی رده ضعیف می‌باشند. نتایج روش GSI نشان داد که سنگ‌های ساختگاه از امتیاز 15 (رده خیلی‌ضعیف) تا 61 (رده خوب) قرار دارند. با استفاده از نرم­افزار Unwedge.v.3.0 حداکثر و حداقل وزن گوه‌های تشکیل شده 5875 و 076/0 تن بدست آمد. همچنین، ضریب اطمینان از حدود 040/0 تا 112 متغیر بوده که گوه‌هایی دارای ضریب اطمینان کمتر از 5/1، با نصب پیچ‌سنگ به ضریب اطمینان قابل‌قبول خواهند رسید.

کلیدواژه‌ها


عنوان مقاله [English]

Stability analysis of the Haji-Abad tunnel site using experimental and limit equilibrium methods

نویسندگان [English]

  • B. Margan 1
  • D. Fereidooni 2
1 M. Sc. of Geology, Earth Sciences Faculty, Damghan University, Damghan, Semnan, Iran
2 Assoc. Prof., Dept., of Geology, Earth Sciences Faculty, Damghan University, Damghan, Semnan, Iran
چکیده [English]

In this research, engineering geological characteristics of the Haji-Abad tunnel site in Hormozgan province have been assessed and its stability analysis is carried out using experimental and limit equilibrium methods. The tunnel site was divided into ten geotechnical units including T1–T8 and two crushed zones in Units 5 (Tf1) and 9 (Tf2) using the BGD method. The rock discontinuities in the tunnel site have filled by calcite and clay, with dry to wet surface conditions, and low degree of weathering. The internal friction angle of the discontinuities surfaces ranges 15º–45º, their persistence is from about 3 to more than 20m, their spacing is 0.15–4m, and their opening is 0.1–5mm. The compressive strength of the site rocks, except for the two crushed zones that have different conditions, varies 20–120MPa. The moisture content of the samples obtained from the boreholes of the tunnel site were 0.12–2.87%, and their porosity were 7.33–0.32%, respectively. The tunnel site rocks are placed in the very poor to good classes with RQD values from 25 to 90. According to the RMR classification, the rocks in the tunnel site have a score of 18–62 (very poor to good). Also, by using the Q method, the rocks of different unites of the tunnel site were given a score rang of 0.04–2.83 (extremely weak to weak). The GSI method indicated that the site constructing rocks range is 15–61 (very poor to good). By using Unwedge.v.3.0 software, the maximum and minimum weight values of the formed wedges were obtained 5875 and 0.076 tons, with heights of 100.94 and 0.12m, respectively. Also, the safety factor is 0.04–112 and the wedges that had a safety factor less than 1.5 will be reached an acceptable safety factor by installing rockbolt.

کلیدواژه‌ها [English]

  • Engineering geology
  • Site
  • Haji-Abad tunnel
  • Stability analysis
  • Limit equilibrium
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