مدل‌سازی عددی سه‌بعدی سامانه پیش نگهداری در جلوی سینه‌کار تونل با رویکردهای مختلف، مطالعه موردی | ||
| روش های تحلیلی و عددی در مهندسی معدن | ||
| مقاله 2، دوره 14، شماره 38، فروردین 1403، صفحه 21-33 اصل مقاله (2.65 M) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22034/anm.2023.19518.1587 | ||
| نویسندگان | ||
| سعید صبور؛ مرتضی جوادی اصطهباناتی* ؛ شکرالله زارع | ||
| دانشکده مهندسی معدن، نفت و ژئوفیزیک، دانشگاه صنعتی شاهرود، شاهرود، ایران | ||
| چکیده | ||
| مدل‌سازی سامانه‌های پیش نگهداری به‌عنوان یکی از چالش‌های طراحی و بازطراحی تونل‌ها محسوب می‌شود. به‌طورکلی، سامانه‌های پیش نگهداری تونل با استفاده از دو دیدگاه مختلف شامل رویکرد مبتنی بر المان‌های سازه‌ای خطی و رویکرد مبتنی بر زون معادل مدل‌سازی می‌شوند. هدف از این مقاله، بررسی تأثیر رویکردهای مختلف اعمال سامانه پیش نگهداری در مدل‌سازی عددی اندرکنش تونل و زمین درون‌گیر است. بدین منظور، یکی از مجموعه تونل‌های پروژه آزادراه تهران شمال به‌عنوان مطالعه موردی انتخاب‌شده و مدل‌سازی عددی اندرکنش تونل و زمین درون‌گیر با رویکردهای مختلف و با استفاده از نرم‌افزار FLAC3D انجام‌شده است. به‌منظور اعتبارسنجی و ارزیابی کارایی مدل عددی، بخشی از نتایج مدل عددی و یکی از ریزش‌های حادث‌شده در حین عملیات حفاری تونل مورد مقایسه قرار گرفت. درنهایت، مقایسه بین نتایج مدل‌سازی سامانه پیش نگهداری با رویکردهای مختلف انجام شد. نتایج حاصل از این مطالعه نشان می‌دهد که مدل عددی مورداستفاده بخش مهمی از شواهد و رخدادهای حادث‌شده در واقعیت را به‌طور مناسبی ارزیابی نموده و از این نظر، استفاده از این مدل عددی برای سایر اهداف عملی به‌ویژه تحلیل پارامتریک با دقت موردنیاز امکان‌پذیر خواهد بود. جابجایی‌های قائم پیش‌بینی‌شده مدل‌های عددی با رویکردهای مختلف هم ازنظر توزیع فضایی و مقادیر جابجایی دارای شباهت‌های بسیار زیادی بوده و میزان خطای نسبی بین مقادیر پیش‌بینی‌شده جابجایی تاج تونل با روش‌های مختلف به‌طور متوسط برای مجموعه تونل‌های موردبررسی در حدود 7/2 درصد و 1/5 درصد است. همچنین، با توجه به اختلاف نسبتاً اندک‌بین نتایج حاصل از مدل‌های عددی با رویکردهای مختلف اعمال سامانه پیش نگهداری به‌صورت المان سازه‌ای و مدل‌های مبتنی بر زون معادل، استفاده از هر یک از این دیدگاه‌ها برای مقاصد مدل‌سازی امکان‌پذیر خواهد بود. | ||
| کلیدواژه‌ها | ||
| پیش نگهداری؛ مدل‌سازی عددی؛ المان سازه‌ای خطی؛ زون معادل؛ تونل | ||
| عنوان مقاله [English] | ||
| Three-Dimensional Numerical Modelling of Pre-Support System in front of Tunnel by Different Approaches, Case Study | ||
| نویسندگان [English] | ||
| Saeed Sabour؛ Mortaza Javadi؛ Shokrollah Zare | ||
| Dept. of Mining, Petroleum and Geophysics Engineering, Shahrood University of Technology, Shahrood, Iran | ||
| چکیده [English] | ||
| Summary This paper investigates the effect of the method of applying pre-support in the numerical modeling of tunnel and ground interaction. Two main numerical approaches of linear pile and equivalent zone elements were considered for the modeling of pre-support in front of the advancing tunnel face. Both of these approaches were applied for one of the Tehran-Shomal Freeway as the case study of numerical modeling. The results of numerical models were compared to investigate the effect of pre-support modeling approaches. The vertical deformation of numerical models with different approaches shows a meaningful consistency; therefore, it is concluded that both of these methods of linear pile element and equivalent zone element can be applied to numerical modeling demands for other studies. Introduction This study focuses on the numerical modeling of the umbrella arc in front of the tunnel crown as one of the pre-support or head ground reinforcement techniques of tunneling in weak grounds. The pre-support method consists of installing a set of sub-horizontal pipes above the tunnel crown face from the inside of the tunnel before the excavation advancement. This method is practically and widely applied for ground improvement ahead of tunnel face to manage and control the induced deformation (i.e. settlement), instability risks, and operation safety. Wide practical implementation of the umbrella arc demonstrates the requirement of a standard design method, which cannot be found in scientific literature. In this regard, several previous studies utilized the numerical modeling of ground-umbrella arc interaction. The method of modeling the umbrella arc through numerical models can be classified into two different methods of a linear structural element (i.e. pile, cable, and beam) [1-3], and an equivalent ground element around the tunnel boundary [4-6]. Each of these methods has different advantages and disadvantages respecting simplicity in numerical modelling, efficiency of numerical calculation, and applicability in 2D numerical models. However, the comparison of these methods concerning the accuracy of calculation results has been not studied yet. This issue is the main subject of the present study. Methodology and Approaches Three-dimensional finite difference numerical models by FLAC3D software were utilized to investigate the effect of pre-support element type on induced displacement by tunnel face advance. The numerical model was generated based on the topography of the study area and the as-built construction procedure of a real case study in the Tehran-Shomal freeway, Lot 1. The numerical modeling of tunneling advance was performed for different cases of pre-support element types including 1) no pre-support, 2) linear pile element for pre-support, and 3) equivalent zone around tunnel crown for pre-support. These models are shown in Fig. 1. In addition to these models, an intermediate model of the second type with little changes in the application of pre-support in the limited length of the tunnel (as experienced in the real work advances of construction) was utilized for verification of the numerical model. Results and Conclusions Results and Conclusions should include (1) the principles and generalizations inferred from the results, (2) any exceptions to, or problems with these principles and generalizations, (3) theoretical and/or practical implications of the work, and (5) conclusions drawn and recommendations. Figures, Tables, and Images The results of this study show that applying the pre-support on the numerical model meaningfully improves the state of tunnel-induced deformation around the face. In the case of no pre-support applied in the numerical model, the vertical displacement of the tunnel crown reaches more than 65 cm. In this case, the vertical displacement gradually decreases from the tunnel crown to the ground surfaces, which causes a notable and unacceptable induced ground settlement (more than 50 cm). In this case, the pre-support shall be reasonably applied to control the ground surface settlement and stability of the tunnel crown at the face. In addition, the results of numerical without local pre-support (in short distances of tunnel length) indicate a sudden increase of tunnel induced deformation in front of the tunnel face and the support installed near the face. These prediction results of the numerical model consist of the instability locations and other evidence of instability near the tunnel face in the area without pre-support application during the tunnel construction. Therefore, the proposed numerical model can be utilized for parameter study demands. The results of numerical models with different approaches for pre-support applied in the calculations in the format of vertical displacement induced by tunnel are very similar (both values and spatial variation). The predicted vertical displacements of numerical models with different approaches show a meaningful consistency, where the average relative error is obtained at about 2.7% and 5.1% for right and left tunnels, respectively. Due to the negligible relative error between different approaches of linear pile element and equivalent zone element, it is concluded that both of these methods can be applied for numerical modeling demands for other studies. | ||
| کلیدواژه‌ها [English] | ||
| Pre-Support, Numerical model, Structural element, equivalent zone, tunnel | ||
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