مخاطرات حفاری مکانیزه تونل در بافت فرسوده شهری

نوع مقاله: مقاله پژوهشی

نویسنده

. استادیار گروه علوم زمین­، دانشکده علوم طبیعی، دانشگاه تبریز

چکیده

ایجاد فضاهای زیرزمینی و حفاری‌های تونل در زیر مناطق شهری که عمدتاً دارای سازه­هایی متراکم با بافت فرسوده و غیرمهندسی هستند حتی علیرغم استفاده از ماشین‌آلات حفاری پیشرفته با چالش­هایی همراه است. در این مقاله، مخاطراتی که در حفاری مکانیزه تونل‌ها با استفاده از ماشین حفار نوع سپر تعادلی در محیط­های شهری باعث آسیب­پذیری سازه­ها و ساختمان‌های مجاور می­شوند مورد بررسی قرار گرفته­اند.
خط یک متروی تبریز به طول 2/17 کیلومتر از میدان ائل‌گلی آغاز و پس از عبور از مرکز و بافت فرسوده شهری در کوی لاله خاتمه می­یابد. حدود 8 کیلومتر از مسیر به صورت تونل عمیق با دو دستگاه ماشین حفار از نوع سپر تعادلی در حال حفاری می‌باشد. بررسی مخاطرات حفاری در بافت شهری نشان می­دهد ایجاد ترک‌های بزرگ و جزئی در ساختمان­ها به ترتیب حدود 13 و 31 درصد را بخود اختصاص داده و نفوذ فوم حفاری و دوغاب تزریقی از طریق حفرات مدفون با فروانی 11 درصد، از آسیب‌هایی هستند که در زمان حفاری با آنها مواجه شده است. وجود حفره­های مدفون در شهرهای تاریخی و با سابقه زلزله‌خیزی مثل تبریز از عوامل تشدید کننده آسیب­های حفاری تونل می­باشد. بر اساس نتایج ابزار دقیق، بیشترین نشست در زمان عبور ماشین حفار اتفاق افتاده و مقدار آن با عمق افزایش پیدا می­کند. نتایج این مقاله می­تواند در پیش­بینی و کاهش مخاطرات حفاری سایر خطوط متروی تبریز و یا شهرهای مشابه نقش مؤثری داشته باشد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Mechanized tunneling hazards in urban area with old structures

نویسنده [English]

  • Ghodrat Barzegari
Assistant professor, Department of Earth Sciences, University of Tabriz
چکیده [English]

Using of underground spaces for transportation have been inevitable with considering to population growth, energy saving and environmental polluting issues especially in metropolis and its need to have modern systems. Tunneling under urban environment which involves old residential building with high density, different infrastructures, monuments and unknown buried subterranean has a specific challenges in spite of using modern tunneling machines. There are different parameters which determine the influence to adjacent structures due to mechanized tunneling. Risk assessment procedures form a key component of pre-construction studies for underground projects.
In this paper, main parameters which cause to hazards and damage to adjacent structures in tunneling by using of pressurized TBM (EPB) in urban areas have been presented and classified corresponding to their abundance on the Tabriz metro line 1.
The project is 17.2 kilometers long which is includes 8 kilometers twin tunnel is part of metropolitan transportation development of Tabriz city. This line is consisted of 17 underground stations and passes underneath the historical city center. Mechanical tunneling of Tabriz metro line 1 twin tunnels with 6.88m in diameter is under construction by using of two EPB-TBM under special urban area including of old residential buildings, different infrastructures and geological challenges (mix faced condition, buried holes, disturbed ground during varies earthquakes, abrasive ground) and continuous needs for TBMs maintenance in hyperbaric condition.
For evaluation of varies hazards on the Tabriz metro line 1 in the studied area, different events have been registered. In order to measurement of settlements in adjacent building, targets along the tunneling line on building walls installed and their movements have been monitored. The variation of displacement in depth were monitored via installation of extensimeter in the tunnel line.
It was found that as well as surface subsidence and other parameters which accounting to tunneling risk assessment efforts, there are some hazards which could enhance the risks in tunneling works in urban area. As experienced in Tabriz metro line 1, presence of wells and unknown buried underground spaces could be enhance the tunneling influence and risks to the adjacent structures. It was conclude that cracks in building due to surface subsidence with 45 percent is the main hazard. The permeation and flow of foam (soil conditioner additives) and grouts to adjacent buildings via holes and unknown spaces with 11 percent was the other hazard which has experienced on the Tabriz metro L1. It was seen that maximum displacement occured during passing of first TBM in tunneling crown level.

کلیدواژه‌ها [English]

  • Urban Tunneling
  • Risk Assessment
  • Tunneling hazards
  • Mechanized tunneling
  • Tabriz Metro
  • Settlement

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