دانشگاه یزد روش های تحلیلی و عددی در مهندسی معدن 2251-6565 15 42 2025 03 21 Considering Uncertainty for Estimating Shear Strength Parameters of Intact Rock Using Statistical Methods در نظر گرفتن عدم قطعیت برای تخمین پارامترهای مقاومت برشی سنگ بکر با استفاده از روش‌های آماری 1 13 3065 10.22034/anm.2023.19104.1573 FA مهدی محمدی گروه مهندسی معدن، دانشگاه ولی‌عصر (عج) رفسنجان، رفسنجان، ایران محمد فاتحی دانشکده مهندسی معدن و متالوژی، دانشگاه یزد، یزد، ایران Journal Article 2022 10 21 Summary One of the most critical steps in the design process of a rock structure by the limit equilibrium method is to determine the shear strength parameters. Because the prediction of these parameters is always accompanied by uncertainty. In such cases, if the range in which the actual shear strength parameters are located is obtained, the results are more reliable. Hence, in this paper, an applied technique based on probabilistic methods is developed. In the first step, by developing an innovative method for two widely used failure criteria, consist of Mohr-Coulomb and Hoek Brown, statistical samples of shear strength parameters are generated and latter, using the t distribution in which the shear strength parameters are located with confidence 95% are determined separately for the two failure criteria. The available data from the previous research are used for the case study. The results of the case study indicate that the prediction of shear strength parameters with the presented method is more accurate than the conventional methods. Introduction Stability analysis of rock structures in mining and civil structures, such as surface mine walls, dams, or rock slopes, is very necessary and important. Because the instability of each of them will cause damage and costs. Shear strength parameters are required for stability analysis. Estimation of shear strength parameters is a critical and vital step in the design and analysis of rock structures. Because the prediction of these parameters is always accompanied by uncertainty. In practice, for determining the shear strength parameters, two failure criteria consist of Mohr-Coulomb and Hoek-Brown, are widely used. The two criteria results are crisp values. Studies show that these results are affected by the uncertainties due to the heterogeneity of the rock or the mathematical relationship of the failure criterion. On the other hand, to estimate the shear strength parameters, at least the results of 5 triaxial stress tests are needed for determining these parameters based on regression. If the number of samples (number of tests) changes or the ultimate strength of one of the samples changes due to the influence of lateral stress in the experiments, the shear strength parameters vary by the regression of the results. In the past decades, some studies reported the determination of the equivalent parameters of shear strength based on the Hoek- Brown criterion [1-5]. According to Brown, the determination of exact equivalent shear strength parameters is a challenging point due to the inherent uncertainty of rock as well as the failure criterion [6]. In such cases, if the range in which the actual shear strength parameters are located is obtained, the results are more reliable [7-10]. Hence, in this paper, an applied technique based on probabilistic methods is developed. In the first step, by developing an innovative method for two widely used failure criteria, consisting of Mohr-Coulomb and Hoek-Brown, statistical samples of shear strength parameters are generated, and later, using the t distribution in which the shear strength parameters are located with confidence 95% are determined separately for the two failure criteria. The available data from the previous research are used for a case study (Table 1) [11]. Methodology and Approaches The conventional method for determining the shear strength parameters is based on the regression of the results of at least 5 groups of data obtained from samples subjected to triaxial stress, according to the Mohr-Coulomb or Hoek-Brown criteria. But in practice, if there are two different groups of triaxial test results of the same type of rock, in the regression of the test results, the shear strength parameters are also changed, and the results are not reliable. Hence, in the first step, using an innovative method, groups of different triaxial test data are generated for the desired rock, and then the cohesion and internal friction angle are determined for each group, and finally, statistical samples of the shear strength parameters are predicted. By generating statistical samples (from shear strength parameters), the range in which the real shear strength parameters are located is determined using the t distribution. Therefore, the obtained result has the highest level of certainty, and the uncertainty is reduced. Results Figure 1 shows the shear strength parameters based on the developed method and the conventional method. According to the figure, the developed method is superior concerning the conventional method. This is because of the statistical samples that were produced to determine the range in which the real parameters are located are taken from the conventional method. In other words, if the conventional method is used, the results in Figure 1 may be used in the analysis. But by utilizing the developed method, shear strength parameters are determined with higher certainty and in a more realistic range. یکی از چالش‌های موجود در روند تحلیل پایداری و یا طراحی یک سازه سنگی به روش تعادل حدی، تعیین پارامترهای مقاومت برشی شامل چسبندگی و زاویه اصطکاک داخلی است؛ زیرا در عمل با توجه به ناهمگنی موجود در سنگ، پیشبینی این پارامترها همواره با تردید همراه است. در چنین شرایطی اگر بتوان دامنهای از پارامترهای مقاومت برشی واقعی را به دست آورد، قابلیت اعتماد به نتایج بالاتر خواهد بود. در این مقاله برای رسیدن به هدف موردنظر، یک روش کاربردی بر مبنای روشهای احتمالاتی توسعه داده شده است. در گام اول برای تولید نمونه‌های تصادفی از پارامترهای مقاومت برشی با توسعه یک روش ابتکاری، گروه‌هایی از جفت تنش‌های کمینه و بیشینه تولید شده است. در گام بعدی پس از تولید پارامترهای مقاومت برشی با استفاده از دو معیار پرکاربرد، موهرکلمب و هوکبراون و با استفاده از توزیع t، دامنهای که پارامترهای مقاومت برشی در آن قرار دارند با سطح اطمینان 95 درصد برای دو معیار شکست بهصورت جداگانه تعیین شده است. برای بررسی روش ارائه‌شده، مطالعه موردی روی نمونه‌های ماسه‌سنگ پینگ دینگ شان انجام شده است. نتایج حاصل از مطالعه موردی بیانگر این است که پیش‌بینی دامنه پارامترهای مقاومت برشی با روش توسعه داده‌شده در مقایسه با روش مرسوم از قطعیت بیشتری برخوردار است و بنابراین طراح اعتماد بیشتری به نتایج می‌تواند داشته باشد.

https://anm.yazd.ac.ir/article_3065_ba1114fe80c264f158d2407946255fba.pdf

دانشگاه یزد روش های تحلیلی و عددی در مهندسی معدن 2251-6565 15 42 2025 03 21 Joint Interpretation of Electromagnetic in Low Induction Number and Electrical Resistivity Tomography: A Case Study on Data From an Area in South Africa تفسیر توأمان داده‌های الکترومغناطیسی با عدد القای پایین (EM-LIN) و توموگرافی مقاومت‌ویژه الکتریکی (ERT)؛ مطالعه موردی: منطقه‌ای در آفریقای جنوبی 15 23 3445 10.22034/anm.2024.20684.1610 FA حسینعلی قاری دانشکده مهندسی معدن و متالورژی، دانشگاه یزد، یزد، ایران 0000-0001-6299-976X Journal Article 2023 09 27 Summary Quantitative interpretation of electrical resistivity tomography (ERT) and electromagnetic in low induction number (EM-LIN) data sets is possible through inversion. Data inversion of the two methods is confronted with two problems of non-uniqueness and instability, which must be solved by the use of constraints and a priori information. The more important issue is that the implementation of one geophysical method does not lead to a favorable interpretation of the subsurface structure in many cases, so the combination of geophysical data is inevitable. In this paper, the joint interpretation of resistivity and electromagnetic data in low induction number data is used for a site in South Africa. In this area, the identification of dolerite dyke is the most important goal in the exploration of underground water. Here, a 2D forward modeling code for EM-LIN and ERT is developed based on the integral equation (IE) method. Also, a linear relation between model parameters and apparent conductivity values is proposed. To invert both data sets, the weighted minimum length solution algorithm is used, and the depth weighting function is used as the model weighting matrix. The inversion of electromagnetic in low induction number indicates a relatively thick dyke in the depth range of less than 5 to 15 m and with a horizontal extension of 185 to 200 m (thickness is about 15 m). Electrical resistivity tomography recovers a two layered medium, and in the conductive layer close to the surface of the dyke, a resistive dyke is extended to near the surface. The electromagnetic method reconstructs the dyke better, while electrical resistivity tomography can recover the layered structure. Introduction Interpretation of ERT and electromagnetic data requires inverse modeling because direct interpretation of measured data is not possible except for very simple cases, and this can be accomplished qualitatively. Furthermore, unlike seism methods for which data processing provides sufficient information for interpretation, there is no efficient technique available for quantitative interpretation of ERT and electromagnetic data. Individual data inversion has provided successful interpretations of subsurface anomalies for decades [1-4], but there are many cases where individual inversion does not result in a high-resolution image of the subsurface. As a result, a combination of geophysical methods is very important, which may be done in three general ways: 1) joint interpretation [5], 2) sequential or cooperative inversion [6], and 3) joint inversion [7]. In the joint interpretation, the inversion of each method is obtained separately, then the final model of the subsurface is presented based on the inversion models, geological information, and the available a priori information. In this paper, the joint interpretation of ERT and EM-LIN data is used for the site in South Africa. The dolerite dyke in this area is the main anomaly for groundwater exploration. Methodology and Approaches Perez-Flores et. al introduced linear IEs for 3D EM-LIN modeling of horizontal and vertical magnetic dipoles using the Born approximation [8]. These IEs are Fredholm Integral equations of the first kind for which observed apparent resistivities are linearly related to the true conductivities as follows: equations for vertical magnetic dipoles (VMD) [11]: and for horizontal magnetic dipoles (HMD): where s, ω and μ_0 stand in turn for T-R separation, angular frequency, and magnetic permeability, while m_z and m_y are a magnetic momentum around the z and y directions, respectively. σ_a and σ(r) express observed apparent conductivity and conductivity distribution of the subsurface. r_1, r_2 and r represent position vectors of the transmitter, receiver, and subsurface model, respectively. To obtain appropriate expressions for the corresponding 2D problem, we integrate equations (1) and (2) from minus infinity to infinity along the y-axis (strike direction), which can be made analytically or numerically. In this paper, numerical integration is made to achieve the 2D case. Therefore, by implementing numerical integration along the y-axis, we may form the following matrix equations for each configuration of magnetic dipoles: where dE is the vector of measured apparent resistivities, mE contains unknowns (model parameters), and AE is the kernel matrix or forward operator. In fact, ERT forward problem can be considered as a Fred-Holm Integral Equation of the first kind whose 2D form of can be written as [9]: s stands for current and potential electrodes, d refers the logarithm of apparent resistivity values, (x_c.z_c) are coordinates of points of the interested area, G is kernel and m is the model. Like EM-LIN method, the following matrix equation can be obtained from the discretization of equation (4): AR is the 2D forward operator, dR is data vector and mR refers to the model. Since both inverse problems are linear, therefore following damped weighted minimum length solution algorithm is utilized for the inversion process [9]: I and α are the identity matrix and the regularization parameter, respectively. W_m representing depth weighting matrix is defined as [10] z_c is the z coordinate of cell centers, and β is the depth weighting exponent. Results and Conclusions Using the presented algorithm, the results of EM-LIN data inversion for both vertical magnetic dipole (VD) and horizontal magnetic dipole (HD) configurations are shown in Figure 1. These models represent high consistency. Conductivity models indicate a dyke in the horizontal range of 185 to 200 meters. Also, the depth range of the dyke is from less than 5 meters to about 15 meters. In addition, it should be noted that the section of the VD arrangement is somewhat noisy. The curves of calculated data versus measured data for both arrangements are depicted in Figure 2. Computed data fitting is better for the arrangement with horizontal dipoles. The resistivity cross-section recovered from the inversion of the data indicates an almost two-layered earth, where the first layer is more conductive. In the middle of the conductive layer, a resistive anomaly has extended to near the surface, which shows the compatibility of the results of both ERT and EM-LIN methods. The pseudo-sections of measured data and calculated data can be seen in Figure 3. In order to have a better comparison of the obtained models of both methods, we convert the conductivity cross-sections of the EM-LIN into resistivity cross-sections. This issue is easily possible considering that the resistivity=1/conductivity. Indeed, the inversion section of ERT data is displayed only up to a depth of 25 meters (Figure 4), allowing easy comparison. Comparing of these sections clearly shows the higher resolution of the electromagnetic method in the reconstruction of dyke model, while the ERT method represents the layered structure below the surface. تفسیر کمی داده‌های دو روش توموگرافی مقاومت ویژه الکتریکی و الکترومغناطیسی با عدد القای پایین از طریق معکوس‌سازی میسر است. معکوس‌سازی داده‌های دو روش با دو مشکل عدم یکتایی و ناپایداری مواجه است که برای رفع آنها باید از قیدها و اطلاعات اولیه بهره گرفته ‌شود. مسئله مهم‌تر آن است که داده‌های یک روش ژئوفیزیکی در موارد زیادی منجر به تفسیر مطلوبی از ساختار زیر سطح نمی‌شود، بنابراین ترکیب داده‌های ژئوفیزیکی اجتناب‌ناپذیر است. تفسیر توأمان داده‌های دو یا چند روش ژئوفیزیکی یکی از متداول‌ترین راهکارهای شناسایی هر چه بهتر بی‌هنجاری‌های زیر سطح زمین است. در این مقاله از تفسیر توأمان داده‌های توموگرافی مقاومت ویژه الکتریکی و الکترومغناطیس با عدد القای پایین برای منطقهای در کشور آفریقای جنوبی استفاده می‌شود. در این ناحیه شناسایی دایک دولریتی مهم‌ترین هدف در اکتشاف آب زیرزمینی است که آشکارسازی آن از طریق فرآیند معکوس‌سازی دادههای مذکور صورت میگیرد. برای معکوس‌سازی داده‌های دو روش از الگوریتم کمینه طول وزن‌دهی شده استفاده می‌شود و تابع وزن‌دهی عمقی به‌عنوان ماتریس وزن‌دهی مدل بکار گرفته می‌شود. معکوس‌سازی داده‌های الکترومغناطیسی با عدد القای پایین نشانگر دایکی نسبتاً ضخیم در گستره عمقی کمتر از 5 تا 15 متر و با گسترش افقی از 185 تا 200 متر (ضخامتی نزدیک به 15 متر) است. روش توموگرافی مقاومت ویژه الکتریکی محیطی لایهای را بازیابی می‌کند و در لایه رسانای نزدیک به سطح دایک مقاومی تا نزدیک سطح قابل‌مشاهده است. درواقع روش الکترومغناطیس دایک را بهتر بازسازی می‌کند و تنها روش توموگرافی مقاومت‌ویژه الکتریکی ساختار لایه‌ای را نشان می‌دهد.

https://anm.yazd.ac.ir/article_3445_a63c97c5fb97e3b2108829518c8758ee.pdf

دانشگاه یزد روش های تحلیلی و عددی در مهندسی معدن 2251-6565 15 42 2025 04 17 Providing an Analytical Relationship Between the Froth Color on the Cell Surface and the Copper Mineral Grade in Flotation ارائه رابطه تحلیلی بین رنگ کف سلول و عیار ماده معدنی مس در عملیات فلوتاسیون 25 36 3399 10.22034/anm.2024.20444.1605 FA رضا ﻋﻠﻰ ﭘﻮر ﻗﺎﺳﻤﻰ ﻧﮋاد دانشکده فنی و مهندسی، گروه مهندسی برق، دانشگاه ولی‌عصر (عج) رفسنجان، رفسنجان، ایران محمدحسین قلی زاده دانشکده فنی و مهندسی، گروه مهندسی برق، دانشگاه ولی‌عصر (عج) رفسنجان، رفسنجان، ایران 0000-0003-4337-5067 حسین قیومی زاده دانشکده فنی و مهندسی، گروه مهندسی برق، دانشگاه ولی‌عصر (عج) رفسنجان، رفسنجان، ایران 0000-0002-5390-3938 Journal Article 1402 05 16 Summary In this paper, by preparing a film with a digital camera from the surface of a flotation cell in the Miduk copper mine in Kerman province, the relationship of the mean color components of existing film frames, Haralick textural features including entropy, image uniformity and energy, as well as the texture complexity feature in three color spaces RGB, YCbCr and HSI with the mineral grade is analyzed. Introduction Flotation control is usually performed by observing the surface of cells by humans. The cell surface is mainly adjusted by the operators using the color of the bubble and the texture characteristics. The color of the froth on the surface of cells includes essential information about the mineral content, which is revealed by long-term observation during the flotation process on an industrial scale. Hence, the surface of froth is a fundamental element to evaluate the flotation performance. In this paper, the relationship between the texture color related to the froth on the surface of the flotation cell and the mineral grade is investigated based on image processing procedures. The employed samples in the paper are provided by the Miduk copper mine in Kerman province. Methodology and Approaches Taking a movie from the floor surface of the flotation cell was done with a GoPro 6 camera capable of recording 60 frames per second, which was installed at a height of 50 cm from the floor surface. Consistency of the amount of light and the location of the camera is very important for all samples. At the same time as filming, the copper concentrate material is also sampled and sent to the laboratory for copper grading. Filming has been done during 3 months in different weeks and at various times of the day, from an active rougher flotation cell in the concentration section of Miduk copper mine. The result of the work was 109 films of 120 seconds, from each film, 10 frames with a time interval of 12 seconds were extracted as frames of the desired image. Results and Conclusions By analyzing the relationship between the mean color components of existing film frames, Haralick textural features including entropy, image uniformity and energy, as well as the texture complexity feature in three color spaces and the mineral grade separately, it is concluded that the intensity parameters in the three color spaces have a value of the correlation coefficient between 0.8461 and 0.8483 with the mineral grade. Performing the regression to estimate the relationship mathematically, and comparing the performed regression based on theoretical criteria also confirm the closer relationship of the mentioned parameters with the mineral grade, because for the coefficient of determination, a value between 0.6693 and 0.7302, and the adjusted coefficient of determination, a value between 0.6220 and 0.7271 is obtained. The reliability of grade estimation based on the intensity parameters is evaluated by the root mean square error (RMSE) criterion, which resulted in a value between 2.32 to 2.70 percent, which indicates the superiority of the proposed method. کنترل فلوتاسیون عموماً با مشاهده سطح سلولها توسط انسان انجام میشود. سطح سلول عمدتاً توسط رنگ حباب و ویژگی بافت مشاهده‌شده توسط اپراتورها تنظیم میشود. رنگ کف موجود بر روی سطح سلول شامل اطلاعات ضروری از محتوای مواد معدنی است که با مشاهده طولانی‌مدت در طول روند فلوتاسیون در مقیاس صنعتی آشکار میشود. ازاین‌رو، رنگ سطح کف یک عنصر اساسی برای ارزیابی عملکرد فلوتاسیون است. در این مقاله، ارتباط بین رنگ کف موجود در سطح سلول فلوتاسیون و عیار ماده معدنی با تکیه‌بر روشهای پردازش تصویر موردبررسی قرار میگیرد. نمونههای مورداستفاده در اینجا از معدن مس میدوک در استان کرمان به‌صورت واقعی تهیه گردیده است. در این بررسی، با تهیه فیلم از سطح سلول فلوتاسیون با دوربین عکاسی دیجیتال، ارتباط بین میانگین اجزای رنگی فریمهای فیلمهای موجود، ویژگیهای بافتی هارالیک شامل آنتروپی، یکنواختی تصویر و انرژی و ویژگی پیچیدگی بافت در سه فضای رنگی با عیار ماده معدنی مورد تجزیه‌وتحلیل قرار میگیرد. سه فضای رنگی موردبررسی عبارت‌اند از RGB، YCbCr و HSI. با تحلیل ارتباط جداگانه هر یک از پارامترهای فوق با عیار قابل‌مشاهده است که پارامترهای شدت در سه فضای رنگی دارای ضریب همبستگی بین 8461/0 تا 8483/0 با عیار هستند. انجام رگرسیون جهت تخمین ریاضی این ارتباط و همچنین مقایسه رگرسیون انجام‌شده بر اساس معیارهای تئوری نیز مؤید ارتباط نزدیکتر این پارامترها با عیار است، چراکه برای ضریب تعیین مقداری بین 6693/0 تا 7302/0 و برای ضریب تعیین تعدیل‌شده مقداری بین 6220/0 تا 7271/0 حاصل شد. قدرت تخمین عیار نیز توسط پارامترهای شدت با معیار خطای ریشه میانگین مربعات (RMSE) مورد ارزیابی قرار گرفت که مقداری بین 32/2 تا 70/2 درصد را نتیجه داد که حاکی از قدرت روش پیشنهادی است.

https://anm.yazd.ac.ir/article_3399_4b90032b5669f9a2bfa410788b4b4eb6.pdf

دانشگاه یزد روش های تحلیلی و عددی در مهندسی معدن 2251-6565 15 42 2025 03 21 Mineral Prospectivity Mapping of the Hidden Cu-Au Porphyry Mineralization in the Basiran and Kodegan 1:100,000 Sheets بررسی و تهیه نقشه پتانسیل مطلوب کانی سازی پنهان مس-طلادار پورفیری ورقه‌های یکصد هزارم بصیران و کودگان 37 50 3172 10.22034/anm.2023.18917.1568 FA منصور ضیائی گروه معدن، دانشکده مهندسی معدن، نفت و ژئوفیزیک دانشگاه صنعتی شاهرود، شاهرود، ایران علی شبانی گروه معدن، دانشکده مهندسی معدن، نفت و ژئوفیزیک دانشگاه صنعتی شاهرود، شاهرود، ایران مهرداد سلیمانی منفرد گروه معدن، دانشکده مهندسی معدن، نفت و ژئوفیزیک دانشگاه صنعتی شاهرود، شاهرود، ایران 0000-0003-4755-4214 عارف شیرازی دانشکده مهندسی معدن، دانشگاه صنعتی امیرکبیر، تهران، ایران سید امیر علی حامدی دانشکده مهندسی معدن، دانشگاه صنعتی امیرکبیر، تهران، ایران Journal Article 2022 09 19 Summary This study was carried out in the eastern area of the Lut block and sheets of Basiran and Kodegan. Due to the existence of numerous vein copper deposits in this area, the possibility of porphyry copper mineralization was evaluated by using the zonality indicators related to porphyry copper deposits and the singularity method, and tectonic and geological maps. In this research, after modifying the censored data, the histogram of the abundance of elements related to the used zonality index, including copper, lead, zinc, and molybdenum, was drawn, and after software processing of the data using logarithmic images of grade-area, the amount of anomalous grade and background. is identified. The dispersion map of lead, zinc, and copper elements was prepared and analyzed, and the dispersion elements were used as one of the weighting layers in the hierarchical integration method of AHP. Also, the distribution map of the index of supra-mineral and sub-mineral zonality was prepared, and by combining the two maps, the layer of areas rich in lead, zinc, copper, and molybdenum was obtained and used in the AHP method. The singularity method related to the surface production of the zonality index in windows with an area of 2,500 square meters was used to prepare one of the weighting layers in the hierarchical method. In the geological map of the region, the Oligo-Miocene intrusive masses were integrated as a suitable substrate for hosting copper deposits with the tectonic evidence layer and were used as one of the main weighting parameters in the AHP method. The use of the geological layer in the AHP matrix led to the removal of alluvial areas or Quaternary sediments in the detection of promising porphyry copper mineralization areas. The desired layers were combined with each other in the GIS software environment by the AHP add-on, and a favorable potential map for porphyry copper mineralization was prepared. In the final result of hierarchical integration, the area of 490 square kilometers out of 5200 square kilometers of the investigated area was introduced as a promising area. In this research, using quantitative variables, a qualitative and functional map was prepared to advance the preliminary explorations of the region. In order to validate the processing, 22 known mineral indices related to copper mineralization were used, of which 17 indices, equivalent to 77% of them, were found in the areas identified in this study. این مطالعه در کمربند متالوژنی قلعه زری - ده سلم متعلق به ورقه اصلی بصیران و کودگان صورت پذیرفت. نقشه پتانسیل مطلوب خاص ذخایر پنهان مس طلادار پورفیری با استفاده از داده‌های ژئوشیمیایی رسوبات آبراهه‌ای، ساختاری، زمین‌شناسی و پراکندگی اندیس‌ها تهیه شد. از روش‌های ترکیبی زونالیته ژئوشیمیایی، سینگولاریتی و سلسله مراتبی فازی (AHP) استفاده گردید. در این تحقیق از روش کلان داده‌های ژئوشیمیایی برای ارزیابی منظرهای ژئوشیمیایی خشک و کویری جهت آشکارسازی آنومالی‌های پنهان و عمیق که دگرسانی ضعیف دارند استفاده گردید از 5200 کیلومترمربع 490 کیلومتر پتانسیل دار جدا شد و 17 اندیس از 22 اندیس کانی سازی شده در مناطق پتانسیل دار واقع شده‌اند.

https://anm.yazd.ac.ir/article_3172_a7f98b674fbe9bae2dff6c113e5f6fb6.pdf

دانشگاه یزد روش های تحلیلی و عددی در مهندسی معدن 2251-6565 15 42 2025 03 21 Predicting the Intensity of the Vulnerability of the Building due to Tunneling-Induced Settlement by Studying the Geomechanical Behavior of the Surrounding Medium پیش‌بینی شدت آسیب‌پذیری ساختمان‌ها در اثر نشست ناشی از تونل‌سازی با مطالعه رفتار ژئومکانیکی محیط دربرگیرنده 51 67 3557 10.22034/anm.2024.21632.1634 FA فرشاد کولیوند گروه مهندسی معدن، دانشکده فنی مهندسی، دانشگاه لرستان، خرم‌آباد، ایران 0000-0002-6396-3360 Journal Article 2024 05 18 Summary This paper investigates the effect of geotechnical parameters on the prediction of building damage severity due to tunneling-induced settlement. The influence of soil elastic modulus, cohesion, and internal friction angle on ground displacement and building deformation was studied using the numerical finite element method in the Tehran Metro Line 7 tunnel project. The severity of the building damage was analyzed based on an assessment of building deformation parameters. The results indicate that building damage severity is significantly sensitive to changes in soil elastic modulus. Minor changes in elastic modulus can lead to a shift in damage severity from structural and severe (damage grades 4 and 5) to non-structural and minor (damage grades 0 and 1). In contrast, changes in internal friction angle do not have a significant impact on damage severity. However, an increase in cohesion can be somewhat effective in reducing damage severity. Introduction One of the major challenges in urban tunneling is the occurrence of settlement and its detrimental effects on buildings [1]. Proper understanding of ground behavior in geotechnical projects, particularly tunneling, requires a sound comprehension of the relationship between soil strength characteristics and the surrounding environment, which enables accurate prediction of tunneling-induced building damage severity. Researchers have proposed various approaches for the evaluation and control of tunneling-induced settlement, including experimental methods [2], numerical modeling [3], physical and laboratory modeling [4], in-situ monitoring and measurements [5], and analytical methods [6]. However, adjacent buildings still suffer from minor and structural damage due to settlements [7]. Some researchers have also analyzed the tunnel-building interaction using analytical [8] and semi-analytical [9] methods. Methodology and Approaches In this study, the tunnel construction process was modeled using the three-dimensional finite element method. Numerical models were validated based on the results of the instruments' data deployed in the Tehran Metro Line 7 tunnel project. After reviewing the building damage criteria, five out of nine building deformation parameters induced by tunneling-induced settlement, namely maximum settlement (Sv,max), maximum differential settlement (δSv,max), maximum building slope (θmax), maximum tensile strain (εmax), and maximum angular distortion (βmax), were selected as evaluation criteria for damage severity. Then, to investigate the effect of elastic modulus changes on damage severity, numerical models were constructed by assigning a range of elastic modulus values to the soil layers. The 5 deformation parameters were analyzed based on different elastic moduli, and the damage severity level was determined. The same procedure was followed for internal friction angle and cohesion, and the results were analyzed. Results and Conclusions The results show that changes in the geomechanical behavior of soil layers caused by variations in geotechnical parameters affect building damage severity. Building damage severity is significantly sensitive to changes in elastic modulus, and minor changes in soil elastic modulus can lead to a shift in damage severity from structural and severe (damage classes 4 and 5) to minor and negligible (damage classes 0 and 1). This sensitivity is minimized for internal friction angle, and changes in internal friction angle do not have a significant impact on ground displacement and consequently on damage severity to buildings. The effect of increased cohesion on reducing damage severity is more pronounced than that of internal friction angle and less than that of elastic modulus, leading to a shift in damage severity from structural (damage class 4) to moderate (damage class 3). Figure 1 illustrates the impact of each geotechnical parameter on tunneling-induced building damage severity. The area of each parameter's surface represents its influence on building damage severity changes. As can be observed, building damage severity is highly sensitive to elastic modulus changes, and with increasing and decreasing elastic modulus, damage severity shifts from classes 4 and 5 to classes 0 and 1. This can be attributed to the significant impact of elastic modulus on soil cohesion and integrity. Increased soil elastic modulus reduces ground displacement and movement caused by tunneling, resulting in less severe building damage. مهم‌ترین چالش تونل‌سازی شهری مواجهه با نشست و اثرات مخرب ان بر ساختمانهای اطراف است که ممکن است پیامدهای مالی و اجتماعی نامطلوب فراوانی داشته باشد. پارامترهای ژئوتکنیکی محیطهای آبرفتی تأثیر قابل‌توجهی بر جابجاییها و حرکت خاک و درنتیجه نشست سطح زمین دارد. بنابراین مطالعه ارتباط پارامترهای ژئوتکنیکی و چگونگی رفتار تغییر شکل محیط راهکار مفیدی برای پیش‌بینی شدت آسیب وارد بر ساختمانها است. در این مقاله تأثیر پارامترهای ژئوتکنیکی بخش شرقی-غربی تونل خط 7 مترو تهران بر نشست ناشی از تونل‌سازی و اثرات متعاقب آن بر شدت آسیب وارد بر ساختمانهای مجاور بررسی شد. شدت آسیب ساختمانها به ازای پارامترهای ژئوتکنیکی بر اساس پارامترهای تغییر شکل ساختمان ارزیابی شد. نتایج نشان میدهد شدت آسیب ساختمان‌ها بهطور قابل‌توجهی به تغییرات مدول الاستیسیته خاک حساس است و تغییرات اندک مدول الاستیسیته منجر به تغییر آسیب ساختمان از آسیبهای ساختاری شدید (آسیب ردههای 4 و 5) به آسیب‌های غیرساختاری و جزئی (آسیبهای رده 0 و 1) میشود. تغییرات زاویه اصطکاک داخلی تأثیر کمی بر پارامترهای تغییر شکل ساختمان دارد و شدت آسیبهای ساختمان را بهطور قابل‌توجهی تغییر نمیدهد. همچنین افزایش تأثیر چسبندگی لایههای خاک بر شدت آسیب ساختمان بیشتر از زاویه اصطکاک داخلی و کمتر از مدول الاستیسیته خاک است که میتواند رده آسیبهای ساختمان را از آسیبهای نسبتاً شدید تا آسیبهای متوسط کاهش دهد.

https://anm.yazd.ac.ir/article_3557_cbfe88bcb61f55c9087bd8bcaa9975a2.pdf

دانشگاه یزد روش های تحلیلی و عددی در مهندسی معدن 2251-6565 15 42 2025 03 21 Wellbore Stability Analysis Using Ground Reaction Curve and Mohr-Coulomb Failure Criterion تحلیل پایداری چاه با استفاده از منحنی اندرکنش زمین و معیار مور-کولمب 69 76 3265 10.22034/anm.2023.20594.1609 FA امیرمحمد احمری دانشکده مهندسی معدن، دانشکدگان فنی، دانشگاه تهران، تهران، ایران ابوالفضل عبدالهی پور دانشکده مهندسی معدن، دانشکدگان فنی، دانشگاه تهران، تهران، ایران 0000-0003-2687-4470 علیرضا کارگر دانشکده مهندسی معدن، دانشکدگان فنی، دانشگاه تهران، تهران، ایران Journal Article 2023 09 05 Summary This research adapts the ground reaction curve (GRC) method, traditionally used in tunnel engineering, to analyze wellbore stability and determine the optimal drilling fluid weight in oil and gas operations. The objectives are to assess wellbore stability under varying conditions and establish a safe drilling fluid pressure window. The methodology employs analytical solutions based on the Mohr-Coulomb failure criterion and numerical modeling using FLAC software. Results demonstrate that parameters such as pore pressure, in-situ stress ratios, and wellbore radius influence wellbore convergence, with the numerical GRC method providing a larger safe drilling fluid pressure window compared to the analytical approach, potentially enhancing drilling efficiency and reducing operational risks. Introduction Wellbore stability is increasingly critical in the oil and gas industry as drilling operations target complex geological formations to meet rising energy demands. Conventional analytical methods for determining safe drilling fluid weights often rely on simplifying assumptions that may not fully address the challenges posed by these environments. This study introduces a novel approach by adapting the ground reaction curve (GRC), a concept from tunnel engineering, to wellbore stability analysis. The GRC relates internal pressure to radial displacement, offering a framework to evaluate rock mass behavior under varying conditions. Pertinent literature highlights diverse approaches to wellbore stability, including elastoplastic and poroelastic models, and failure criteria such as Mohr-Coulomb, Mogi-Coulomb, and Hoek-Brown [1-2]. Building on these foundations, this research employs two methods: an analytical approach using the Mohr-Coulomb criterion with Kirsch equations to calculate stress distributions and critical pressures, and a numerical approach using FLAC software to simulate wellbore excavation and generate the GRC. The study investigates the effects of pore pressure, stress anisotropy, and wellbore radius on stability. The main findings indicate that the numerical method yields a broader safe drilling fluid pressure window, offering potential operational advantages over the analytical method. Methodology and Approaches The methodology integrates analytical and numerical techniques to assess wellbore stability. Analytically, stress distributions around the wellbore are computed using the Kirsch equations, which describe radial and tangential stresses as functions of drilling fluid pressure, in-situ stresses, and Poisson’s ratio. The Mohr-Coulomb failure criterion is then applied to determine the minimum pressure preventing shear failure (collapse) and the maximum pressure avoiding tensile failure (fracturing), establishing the safe pressure window. Numerically, the FLAC software (version 8) simulates wellbore excavation in a two-dimensional model under hydrostatic and anisotropic stress fields. The GRC is generated by monitoring radial displacement as internal pressure varies. The lower limit of the safe pressure window is identified when the wellbore stabilizes (e.g., at 75% of in-situ stress in the hydrostatic case), while the upper limit is determined by minimizing the plastic zone around the wellbore (e.g., at 42 MPa). The study also examines the sensitivity of the GRC to pore pressure, stress ratios, and wellbore radius, with parameters detailed in the original paper’s Table 1. This dual approach provides a comprehensive stability analysis, with sufficient detail to replicate the methods or refer to cited works [3-4]. Results and Conclusions The GRC analysis shows that increased pore pressure, stress anisotropy, and wellbore radius amplify convergence. Table 1 compares the safe drilling fluid pressure windows from both methods in a hydrostatic field (σH = σh = 30 MPa). The numerical GRC method consistently provides a larger window across conditions, enhancing drilling flexibility. Fig. 1 visually contrasts these windows, confirming that the numerical GRC method generally provides a larger safe range across conditions, enhancing drilling flexibility. This principle suggests that integrating displacement-based numerical analysis with failure-based analytical methods improves stability assessment. An exception occurs in specific hydrostatic cases where the numerical window narrows slightly, possibly due to differing criteria emphasis. Theoretically, this approach refines wellbore mechanics understanding; practically, it suggests cost and risk reductions. Validation with field data remains necessary. The study concludes that the GRC method is a promising tool for optimizing drilling fluid design, recommending further testing across diverse formations. امروزه با افزایش نیاز بشر به تأمین انرژی و مشتقات نفتی، استخراج این ماده روزبه‌روز در حال افزایش است. بااین‌وجود مخازنی که ازنظر عملیات حفاری و پایداری چاه پیچیدگی و مشکلات اندکی داشتند، در حال اتمام هستند. مهندسان برای پاسخ به این نیاز باید به استخراج منابعی که دارای پیچیدگی و مشکلات بیشتری در حفاری و پایداری نسبت به قبل هستند بپردازند. لذا مبحث پایداری چاه، وزن بهینه و پنجره ایمن سیال حفاری بیش‌ازپیش مورد اهمیت قرار میگیرد. در این پژوهش با تعمیم و اصلاح منحنی اندرکنش زمین که یکی از مهمترین روشها در تحلیل پایداری فضاهای زیرزمینی است، به تحلیل پایداری چاه و انتخاب وزن بهینه سیال حفاری با استفاده از روش حل تحلیلی و عددی پرداخته میشود. در ابتدا منحنی اندرکنش زمین برای پنج حفره دایرهای شکل در میدان تنشهای هیدرواستاتیک و ناهمسانگرد رسم شده و تأثیر پارامترهایی همچون فشار منفذی، نسبتهای مختلف تنشهای افقی به قائم و شعاع حفره روی منحنی اندرکنش زمین برسی میشود. مشخص شد تغییرات این پارامترها با میزان همگرایی دیواره حفره رابطه مستقیم داشته و با افزایش آنها میزان همگرایی دیواره حفره افزایش مییابد. سپس با استفاده از روابط تحلیلی مور-کلمب و روش منحنی اندرکنش زمین در مدل‌سازی عددی تفاضل محدود، حدود پنجره ایمن سیال حفاری محاسبه گردید. طبق نتایج به‌دست‌آمده در روش عددی با استفاده از منحنی اندرکنش زمین حد پایین و بالای فشار سیال حفاری به ترتیب کمتر و بیشتر از حد پایین و بالای فشار سیال حفاری با استفاده از روش تحلیلی مور-کلمب بوده و روش عددی مبتنی بر منحنی اندرکنش زمین پنجره ایمن بزرگ‌تری نسبت به روش تحلیلی مور-کلمب ارائه میدهد.

https://anm.yazd.ac.ir/article_3265_730da6f1b456d5759c9f3c2bc3d19650.pdf