Journal of Engineering Geology
نشریه زمین شناسی مهندسی
Journal of Engineering Geology
Basic Sciences
http://jeg.khu.ac.ir
1
admin
2228-6837
2981-1600
doi
fa
jalali
1396
5
1
gregorian
2017
8
1
11
1
online
1
fulltext
fa
مهندسی ارزش بر اساس رفتارنگاری تونل طی مرحلۀ حفاری (مطالعۀ موردی تونل حکیم)
Value Engineering Based on Monitoring During Tunnel Excavation Phase-a Case Study of Hakim Tunnel
ژئوتکنیک (مکانیک خاک و سنگ)
Geotecnic
مقاله پژوهشی
Original Research
<p>ارائه یک مدل زمینشناسی، تخمین پارامترهای طراحی و انتخاب کلاس حفاری و نگهداری با حداقل کردن ریسک، تامین ایمنی و کاهش هزینه، چالش اصلی فرآیند ساخت تونل در زمینهای نرم است. بنابراین انجام مطالعات کافی، تفسیر، تحلیل و پردازش این دادهها در یک مدل واحد با قابلیت بهروز رسانی برای برنامهریزی فرآیند ساخت یک تونل، از اهمیت به سزایی در موفقیت یک پروژه تونلزنی برخوردار است. بزرگراه حکیم یکی از بزرگراههای اصلی کلان شهر تهران به 9 طول کیلومتر است که از محل اتصال بزرگراه رسالت و بزرگراه کردستان بعد از تونل رسالت آغاز میشود و در بزرگراه لشگری به پایان میرسد. غرب این بزرگراه از منطقه پارک جنگلی چیتگر عبور میکند. با توجه به محدودیتها و الزامات زیست محیطی طرح، تونل دوقلو حکیم با سطح مقطع حفاری 186 مترمربع و طول کلی 3256 متر به روش تونلزنی جدید اتریشی در امتداد مسیر این بزرگراه در محدوده عبوری از پارک چیتگر در حال ساخت است. در فاز اولیه طراحی یک کلاس حفاری و نگهداری پیشنهاد شد. طی مراحل حفاری با استفاده از مشاهدات میدانی، نتایج رفتارنگاری و ابزاربندی و بررسی مدلهای زمینشناسی، رفتار و طبقهبندی زمین مورد بررسی و بازبینی مجدد قرار گرفت و کلاس حفاری و نگهداری بهینهسازی شد. بهینهسازی طرح باعث شد که در هزینههای ساخت حدود 10 درصد صرفهجویی شود.</p>
<strong><a href="./files/site1/files/3Extended_Abstract.pdf">./files/site1/files/3Extended_Abstract.pdf</a>Extended Abstract</strong><br>
(Paper pages 51-72)<br>
<strong>Introduction</strong><br>
Value engineering is considered an efficient alternative to improve design and construction process of urban tunneling projects. Application of value engineering techniques can provide investigating all aspects of a project in a team work, creative and short-time manner which contribute to precisely identify a project’s quality improvement issues, construction time and costs.<br>
Hakim Expressway one of the capital's main highways in Tehran metropolis with 9 Km in length, starts from the junction of Resalat expressway and Kurdistan expressway after Resalat tunnel and ends in Lashgari expressway. The west extended this highway passing through the area of Chitgar forest park. Due to environmental constraints, the Hakim twin tunnels with cross-section of 186 m<sup>2</sup> excavation areas and total length of 3256 m to the NATM/SEM method in this area were excavated (Figure 1).<br>
In preliminary design of Hakim tunnel project, on category of excavation and support system was suggested. During the tunnel<sup>’</sup>s excavation operation, the behavior and classification of the tunnel were investigated from field observation, instrumentation and monitoring of geological models and subsequently, further excavation process was modified in accordance with value engineering. The aim of using value engineering approach in this project was to reduce the costs without any decrease in quality, employer satisfaction along with minimum risk and as well as improving operational and practical aspects. Ultimately, establishment of the value engineering approach on Hakim tunneling project leads to 10% reduction in construction costs as well as relevant quality with the least challenges (Figure 2).<br>
<strong>General Geology</strong><br>
The city of Tehran is founded on Quaternary alluvium, which has been geologically classified by Rieben [1]. The city is located at the foot of the Alborz mountain range, which is basically composed of Eocene pyroclastic deposits (green tuff) and other volcanic rocks. The geology and the morphology of the Tehran region is similar to that for other cities located at the foot of mountains.<br>
Rieben (1966) divided the Tehran coarse-grained alluvia into four categories, identified as A, B, C and D, where A is the oldest and D the youngest (Figure 3).<br>
Hakim tunnel project locates on foothills of northern Tehran, crossing the hills of Chitgar forest park. Results of field surveys indicate that alluvial deposits in tunnel track belong to C (ramps and tunnel portal) and A formations (in most parts of tunnel track).<br>
<br>
<br>
<img alt="" src="./files/site1/images/1.jpg" style="width: 352px; height: 512px; " ><br>
<strong>Geotechnical characterization</strong><br>
Table1 summarizes soil input parameters. Two soil types were considered for the model with 8- meter-height overburden. First layer (No.1) starts from surface with a 1 meter thickness. Second layer (No. 2) has 7 meter thickness.<br>
<strong>Table1. Summary of the geotechnical parameters</strong>
<table align="center" border="1" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td>Parameter</td>
<td>Unit</td>
<td>Layer No. 1</td>
<td>Layer No. 1</td>
</tr>
<tr>
<td>Internal friction angle (CU)</td>
<td>Deg.</td>
<td>29</td>
<td>33</td>
</tr>
<tr>
<td>Cohesion (CU)</td>
<td>Kg/cm<sup>2</sup></td>
<td>0.15</td>
<td>0.45</td>
</tr>
<tr>
<td>Density</td>
<td>Kg/cm<sup>3</sup></td>
<td>18.5</td>
<td>20</td>
</tr>
<tr>
<td>Poisson ratio of unloading/reloading</td>
<td>Kg/cm<sup>2</sup></td>
<td>0.2</td>
<td>0.2</td>
</tr>
<tr>
<td>Secant deformation modulus</td>
<td>Kg/cm<sup>2</sup></td>
<td>550</td>
<td>900</td>
</tr>
<tr>
<td>Power of stress level of stiffness</td>
<td></td>
<td>0.5</td>
<td>0.5</td>
</tr>
<tr>
<td>Stiffness unloading</td>
<td>Kg/cm<sup>2</sup></td>
<td>1650</td>
<td>2700</td>
</tr>
</tbody>
</table>
<div style="clear:both;"></div>During tunnel excavation using field observations, the results of the monitoring and reviewing the geological model, ground behavior and classification were re-examined to optimization of the excavation and support class (Figures 4, 5).<br>
Detailed analysis before excavation and continuation of studies led to two excavation and support classes purposed for Hakim tunnel. Both classes of excavation and support due to ground conditions are modeled and analyzed using software Plaxis. For verification, the results of numerical analysis using monitoring and field observations were compared during the tunnel excavation. The results of monitoring compliance with the results of numerical analysis were appropriate.<br>
Implementation and construction costs were calculated for different sections of two excavation and support classes in accordance to contraction documents to evaluate the effect of optimization in design (Figures 6, 7)<br>
<br>
<img alt="" src="./files/site1/images/2(1).jpg" style="width: 355px; height: 281px; " ><br>
<strong>Figure4. Excavation sequence in excavation and support class “A”</strong><br>
<br>
<br>
<img alt="" src="./files/site1/images/3.jpg" style="width: 357px; height: 419px; " ><br>
<strong>Results</strong><br>
Results indicate that in both classes maximum costs are related to excavation section while minimum costs are for invert and mucking. In all concrete spray operations there was just a %3.5 increase in costs. Overall savings in excavation and support was about %10 which is significant (Figure 8).<br>
<br>
<img alt="" src="./files/site1/images/4.jpg" style="width: 278px; height: 178px; " ><br>
<strong>Figure8. Savings percentage comparison in excavation and support classes A and B</strong><br>
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<br>
<br>
تونل حکیم, کلاس حفاری و نگهداری, رفتارنگاری, حفاری مرحلهای, مهندسی ارزش
Hakim tunnel, Excavation and support class, Monitoring, Sequential excavation, Value engineering
51
72
http://jeg.khu.ac.ir/browse.php?a_code=A-10-549-3&slc_lang=fa&sid=1
Majid
Taromi
مجید
طارمی
majid.taromi@yahoo.com
10031947532846001665
10031947532846001665
Yes
باشگاه پژوهشگران جوان و نخبگان، واحد تهران جنوب، دانشگاه آزاد اسلامی، تهران، ایران
Maziar
Hosseini
مازیار
حسینی
10031947532846001666
10031947532846001666
No
دانشگاه آزاد اسلامی، واحد تهران جنوب
Seyed Mahdi
Pourhashemi
سید مهدی
پورهاشمی
10031947532846001667
10031947532846001667
No
سازمان مهندسی و عمران شهر تهران
Majid
Sadeghi
مجید
صادقی
10031947532846001668
10031947532846001668
No
سازمان مهندسی و عمران شهر تهران