فهرست مطالب حسن بخشنده امنیه

Short term mine scheduling aims to provide a constant amount of material to the milling facility. Among the available approaches, mathematical modeling is reliable in determining an optimum solution. Cut and fill mining is conducted in mineral reserves with weak surroundings. In this paper, a new mathematical model is introduced to production scheduling of drift and fill mining method while the special constraints of cut and fill mining is considered. The model is capable to consider mining operation in several levels. The model is applied for stope sequencing in Anguran mining project. The data from the +2721, +2733 and +2737 levels are used for production scheduling and stope sequencing. The Anguran underground project is a cut and fill mining project. In this mine the levels are separated into 2 northern and southern panels. The results show that simultaneous mining of +2721 and +2737 levels is capable of reaching the predetermined production level with a maximum deviation of 2.4%.

Pile movement is one of the rock blasting outcomes that, considering the type of haulage machines, has a direct effect on the efficiency of the loading process. In this study, using UDEC discrete element software, the pile movement of fragmented material caused by the blasting operation is modeled. Since UDEC is not capable of modeling the whole process of rock blasting, to accurately model the pile movement of fragmented material, the damping coefficients must be changed in a way to allow the move freely out of the split blocks after the blast, be modeled. The numerical modeling results show that implementing a negative exponential function with three (the initial, threshold, and power) eigenvalues, as the fish-function to the damping coefficient, can model the results pile movement. With the help of this damping function, three blasting blocks with one and two rows of blast holes were modeled. The results of these modeling show that the pile movement for the two rows of blast holes depends on the inter-row delay time, and for the delay times of 17 ms and 50 ms, the maximum horizontal movement of the pile was 30 m and 55 m, respectively. These values show good agreement with the values measured in an actual blast operation. The results of this study show that by changing the negative exponential function eigenvalues defined for damping, the velocity of the fragmented blocks, the displacement, and the geometry of the pile, could be modeled. This shows the capability of the discrete element method in the modeling of the results of rock blasting.

Nowadays, duo to mining and construction activities' progression, the need to utilize blasting has been increasing in order to reduce time and cost. The use of blast for drilling and crushing rock, in addition to its advantages, has disadvantages, the most important of which is ground vibration. Vibration caused by the blast is an important and significant part of the blast process and controling its amount in order to reduce possible damage to the surrounding areas, is always necessary. In this paper, the field data of the blast in the second line of the Tabriz water pipeline project have been collected using three-component Blast Recorder seismographs. By modeling the process of blast in ANSYS-Autodyn finite element software, the behavior of the blast zone environment is simulated. The average of numerical modeling errors compared to field surveys is estimated at about 20%. According to the numerical modeling, the most critical state of velocity entering the pipeline is less than the allowable blast standards near the pipeline, and the maximum stress, strain, and displacement in the boundary of pipe and soil are equal to 17.24 MPa, 135 μmm /mm, and 0.18 mm, respectively.

The present work aims at implementing Response Surface Methodology (RSM) in order to generate a statistical model for Minimum Required Caving Span (MRCS) and estimate both the individual and mutual effects of the rock mass parameters on rock mass cavability. The adequate required data is obtained from the result of numerical modeling. In this work, various arrays of numerical simulations (480 models) are carried out using the UDEC software in order to study the rock mass cavability thoroughly. The effect of each individual parameter and their mutual effect on MRCS are investigated by means of ANOVA. ANOVA indicates that all the chosen parameters (depth, dip of the joint, number of joints, angle of friction of the joint surface, and joint spacing) highly affect MRCS. In other words, the results of ANOVA are in high agreement with the results of the conventional sensitivity analysis. Moreover, a combination of joint spacing and joint inclination has the highest mutual effect on MRCS, and a combination of undercut depth and joint spacing has the lowest effect on MRCS.

Determining the hydraulic radius of the undercut in the block caving method is one of the key issues in this method. The hydraulic radius is directly related to the minimum caving span. In this research work, the rock mass cavability is investigated using the UDEC and 3DEC software. Since the factors affecting the cavability are very diverse and numerous, firstly, by 2D modeling in the UDEC software and examining the trend of changes in the minimum caving span, the most important factors including the depth, dip of the joint, number of joints, angle of friction of the joint surface, and joints spacing are selected for the final study. The variation trend of each variable is investigated by keeping the other variables constant (single-factor study) among various factors. In the second step, the minimum caving span for the five main factors and values is ​​determined in the single-factor study using the SPSS software and the multivariate regression method. Then the power function of the minimum caving span is chosen based on the selected variables with a coefficient of determination of 0.76. In continuation, a simple 3D model is built from the undercut. A linear equation is achieved between the results of the 3D and 2D modeling results in similar conditions. In a model with certain conditions, using the equation obtained from the numerical method, the calculated hydraulic radius of caving is 22.5 m, which is close to the result obtained from the Laubscher's empirical method with the same condition (24 m).

One of the major problems related to blasting operations in open-pit mines is the formation of cracks on the benches behind the last row of blast holes or back breakes. Power Deck blasting has been introduced as a new and alternative method for conventional blasting, which improves blasting results by explosive energy utilization enhancement. In this technique, there is an air deck at the end of the blasting hole which decreases or eliminates sub-drilling. Power Deck blasting reduces charge per delay in the same conditions as conventional blasting and charge per delay is one of the most effective parameters of back break. In this study, back break caused by conventional and Power Deck blasting was evaluated in the Mishdovan iron ore mine. Back break in Power Deck blasting was reduced by 16.4% and 55% in iron ore and stone waste respectively as compared to back break in conventional blasting. Power Deck blasting could therefore be effectively used as a controlled blasting technique to obtain stable faces. Also after loading and hauling the fragment size, it was found that both methods have no significant differences in flat floors. Eventually, the Power Deck method reduced powder factor and specific drilling by 28.5% and 9%, respectively. In addition, holes productivity improved by 9% in Power Deck blasting compared to conventional blasting.

Summary In this paper, the capability of foundation and support for the Sardasht dam is investigated. Finally, according to the results of numerical modeling in UDEC software, the diameter and distance of grout injection boreholes and dimensions and angle of seal curtain of the dam foundation dam have been suggested.   Introduction The injection is a process whereby a cement slurry is pushed into rock formations through a borehole, thereby reducing the permeability and deformation of the rock mass and increasing its resistance. The rocks are almost impermeable and rock mass permeability is often a function of discontinuity systems. Due to the different and unpredictable behavior of rock masses, there is no specific law for determining the distance of injection holes and generally relies on the experience and judgment of the design engineer when deciding on the borehole distance. So, it is proposed to use numerical methods in predicting the radii of injection for grouting material and also determining the ideal spacing between adjacent holes. As the main results of this study, the optimum pattern for drilling sealing systems for different locations of the Sardasht dam was determined and compared to the empirical models using the discrete element method in UDEC. The optimum deviation angle of the holes was investigated, too.   Methodology and Approaches The Sardasht dam is a trench with a clay core with a height of about 106 meters and a length of 280 meters. The total embankment volume of the dam body is estimated to be about 3 million cubic meters and the volume of clay core is about 516000 cubic meters. The water diversion system consists of two tunnel strings with an inner diameter of 7m and lengths of 627m and 682m in the right support and its height is about 46m. The right tunnel is used as the lower evacuator during the operation period. In order to investigate the in-situ condition of rock mass in Sardasht Dam area, rock mechanical parameters including rock mass quality index (RQD), specific gravity, uniaxial compressive strength, and geometry and resistive properties of discontinuities have been determined and measured. Then, the quality of grout injection in walls and foundation of the Sardasht dam was modeled, using numerical modeling in UDEC discrete element software.   Results and Conclusions The results of this study show that the appropriate borehole spacing for the walls and the foundation should be taken as 3m and 5m, respectively. Also, the results obtained from the numerical modeling of the optimum injection pressure in the construction area of the Sardasht dam were determined for different depths. Based on the numerical modeling results in order to minimize water leakage from the Sardasht dam foundation, the optimum angle of curtain installation should be 17 degrees.

When a tunnel passes through weak soil with different conditions, or there is a thin layer of soil on top of the tunnel, the mass of soil or rock must be stabilized. In addition, an excavation method must be chosen and applied in order to control the amount of subsidence and convergence which are among the most significant factors in excavation a tunnel especially in urban area, since the soil between the tunnel and the ground moves due to changes in the shape of the tunnel through excavation, and progression of these movements toward the ground is manifested in subsidence of the surface structures. Therefore, in order to choose an excavation method based on the conditions of the project site, providing a decision-making model is essential. The ultimate goal is to select the most suitable subway tunnel excavation method among all available alternatives based on some determining criteria for Isfahan subway tunnel (Line 1). These criteria along with Multi-Criteria Decision Making (MCDM) models helped prioritize suitable alternatives. This model was designed based on technical, financial, executive, social, political and geo-mechanical features of the research site each of which subsumes a number of criteria. On the one hand, alternatives include Open Shield (full face) method, Slurry method, NATM method and excavate twin tunnel with TBM method which are used in the model. Finally, alternative D (excavate twin tunnel with TBM method) was selected as the best alternative of the site in both AHP(D=0.225) and TOPSIS(D=0.676391).

Providing a fresh and cool airflow in underground mines is one of the main concerns during mining. Destruction of support systems, the presence of undesirable objects in the airway and distortion of airflow are the parameters involved that would result in pressure loss, which would affect the ventilation network. There are a lot of research works about the ventilation network planning that consider the confidence in the planning but how reliable are these designs? These questions can be answered using the quantitative reliability evaluation. For the reliability evaluation of mine ventilation network, tunnel resistance and flow rate changes for all branches are considered as the reliability indices and criteria. This paper describes a stepwise method for evaluation of the underground coal mine network reliability associated with major losses using the cut set method. The reliability of the entire network is achieved by the reliability of every single component. The proposed model is implemented by the Takht coal mine. The Takht mine ventilation network probability of failure is in the range of 19-100% so reliability is in the range of 0-81% for the entire ventilation network.

In the urban tunneling project, one of the most important parameters to be considered is the subsidence level. Metro tunnels are one of the most important urban transportation infrastructures. Due to shallow depth of drilling, the most important factors to prevent the maximum subsidence and subsequent damage of surface and subsurface structures are deformation control and shear forces. The various methods of estimating the subsidence are divided in three categories, namely; Empirical, analytical and numerical methods. In this research, according to the geotechnical conditions of the study area using the data collected from the monitoring during the excavation of twin tunnels of metro by TBM, the empirical methods for the subsidence ( s=A_2+s_max/2 ), the maximum subsidence (s_max=A_1-A_2 ) and the inflection point (ⅈ=x_0 ) are presented by using Boltzmann function for Isfahan twin metro tunnel.

Sequencing and timing of project activities with limited resources is one of the important issues related to the field of project management that With proper management can reduce the high costs of projects. One of the projects that could be mentioned, Extraction project of a block of Choghart iron ore mining is located in Yazd province that with accurate identification of its activities, WBS charts and AOA with prerequisite relationships between the activities and resources required are derived. Mathematical model of a particular issue with the aim to minimize overtime costs and delays in project delivery, has been developed. Mathematical model implemented by the GAMS.9 software and results of activities optimization sequencing and scheduling is estimated. The results show that the optimal number 5 sources there is in order to extract a block of Choghart iron ore mine. - - - - - - - - - - - - -

Risk management is today known as one of the nine major project management bodies of knowledge science. An effective risk management allows decision makers to identify the project's strengths, weaknesses, and opportunities. Also, they will be ready to respond if they arise. It includes identifying, recording, ranking and recognizing of response actions and also allocation of actions to corresponding risks. An appropriate risk management of a project helps project managers in getting safe conditions for project design and implementation. Therefore, one area in which there is a necessary need for decision making is project risk management. One of the main steps in risk management is risk assessment and risk ranking, which are important parts of risk management. On the other hand, tunneling projects are now risk-prone activities in mining engineering context. Missing or incomplete risk management in tunneling projects leads to negative consequences, such as longer project time and increased costs. Due to the multiplicity of risk factors in an urban mechanized tunneling project by Earth Pressure Balance ( EPB ) machine, ranking risk is a complex convoluted procedure. So, it is necessary to use multi-criteria decision-making ( MCDM ) methods. Hence, in this paper, in order to analyze the risks of a tunneling project in Tehran Metro-Line 7, we suggest to use Technique for Order of Preference by Similarity to Ideal Solution ( TOPSIS ) method. It is a method for aggregation that compares a set of alternatives by identifying weights for each criterion. It then normalizes scores for each criterion and calculates the geometric distance between each alternative and the ideal alternative. The obtained results show that financial and human resource factors get the first high risk ranks. Furthermore, the risk of dealing with a network of aqueducts is the most well-known problems of the Tehran Metro-Line 7 project. Conducted field studies of the project and visiting the workshop site confirmed the validity of analysis.

Assessment and prediction of rock fragmentation by drilling and blasting operations, the most basic and most critical parameters affecting the economy of mine is considered. Choghart mine had one of the largest Iran iron ore mine that annual eight million tons of iron ore is extracted from it. In the mine mining operations, including drilling, blasting, loading, transportation and processing is done on a daily basis. Distribution of aggregation from blasting operations and resulting machinery production, mining costs may be reduced. There are several methods to determine the blasting fragmentation and currently, the use of image processing systems is appropriate and effective method for evaluating of blasting fragmentation. In this study, sieve analyzes of three patterns of explosive in Choghart mine and fragmentation curve obtained by the image processing method is compared and then this method for more accurate predictions in mine by factors of α and β is correct. The correction factors value respectively is 0.81108 and 0.82087.

One of the properties that evaluate in geotechnical reviews at rock mass, is the amount of permeability, that determine from water pressure test (WPT) and lugeon number. From the results of these test, use in determining of the amount of groutability in tunnel and dam site. Logical and practical relationship between amount of water penetration in Sections and cement grout take, leads to find prediction model of take amount in sections and so, necessity and the amount of grouting defined and will Cause to optimization of grouting operation in terms of technical and economic. In this study, using the Seymareh dam site data, relationship between lugeon number and grout take analysed. Then the effect of rock mass quality and depth of the grouting section to this relationship were studied. The results showed that in surface and much deep sections, penetration of water and grout, with correlation coefficients 0/86 and 0/82 have more relationship than central and deep sections, with coefficients 0/62 and 0/58. also in terms of quality of rock mass (according to RQD coefficient), in sections with very good and poor quality, these two parameters with correlation coefficients, respectively, 0/82 and 0/75, are closer together than good and medium sections with the coefficients 0/54 and 0/58. In central sections with state average quality, because of existence karst cavities and filling of joints and happening of hydraulic fracture, this correlation reduce.

T‌u‌n‌n‌e‌l f‌a‌c‌e s‌u‌p‌p‌o‌r‌t d‌u‌r‌i‌n‌g b‌o‌r‌i‌n‌g o‌p‌e‌r‌a‌t‌i‌o‌n‌s i‌s g‌a‌i‌n‌i‌n‌g m‌o‌r‌e i‌n‌t‌e‌r‌e‌s‌t a‌s t‌u‌n‌n‌e‌l‌i‌n‌g d‌e‌v‌e‌l‌o‌p‌m‌e‌n‌t e‌x‌p‌a‌n‌d‌s t‌o‌w‌a‌r‌d‌s g‌e‌o-t‌e‌c‌h‌n‌i‌c‌a‌l‌l‌y l‌e‌s‌s a‌p‌p‌r‌o‌p‌r‌i‌a‌t‌e z‌o‌n‌e‌s w‌i‌t‌h h‌e‌a‌v‌y t‌r‌a‌f‌f‌i‌c. G‌o‌o‌d t‌u‌n‌n‌e‌l f‌a‌c‌e s‌u‌p‌p‌o‌r‌t i‌s a p‌r‌e-r‌e‌q‌u‌i‌s‌i‌t‌e f‌o‌r s‌u‌c‌c‌e‌s‌s‌f‌u‌l s‌a‌f‌e b‌o‌r‌i‌n‌g, a‌n‌d e‌v‌a‌l‌u‌a‌t‌i‌n‌g o‌p‌t‌i‌m‌u‌m p‌r‌e‌s‌s‌u‌r‌e i‌s a‌n i‌m‌p‌o‌r‌t‌a‌n‌t f‌a‌c‌t‌o‌r i‌n t‌h‌e p‌e‌r‌f‌o‌r‌m‌a‌n‌c‌e o‌f t‌h‌e E‌a‌r‌t‌h P‌r‌e‌s‌s‌u‌r‌e B‌a‌l‌a‌n‌c‌e (E‌P‌B) m‌a‌c‌h‌i‌n‌e i‌n u‌r‌b‌a‌n t‌u‌n‌n‌e‌l‌i‌n‌g. A‌p‌p‌l‌y‌i‌n‌g p‌r‌e‌s‌s‌u‌r‌e‌s l‌o‌w‌e‌r t‌h‌a‌n e‌q‌u‌i‌l‌i‌b‌r‌i‌u‌m r‌e‌s‌u‌l‌t‌s i‌n f‌a‌c‌e s‌u‌b‌s‌i‌d‌e‌n‌c‌e, w‌h‌i‌l‌e h‌i‌g‌h‌e‌r t‌h‌a‌n e‌q‌u‌i‌l‌i‌b‌r‌i‌u‌m c‌a‌u‌s‌e‌s a‌n u‌p-l‌i‌f‌t i‌n g‌r‌o‌u‌n‌d s‌u‌r‌f‌a‌c‌e, l‌e‌a‌d‌i‌n‌g i‌n e‌i‌t‌h‌e‌r c‌a‌s‌e, t‌o o‌p‌e‌r‌a‌t‌i‌o‌n d‌i‌s‌r‌u‌p‌t‌i‌o‌n, f‌l‌o‌o‌r s‌u‌b‌s‌i‌d‌e‌n‌c‌e a‌n‌d d‌a‌m‌a‌g‌e t‌o n‌e‌a‌r‌b‌y b‌u‌i‌l‌d‌i‌n‌g‌s. O‌p‌t‌i‌m‌u‌m p‌r‌e‌s‌s‌u‌r‌e f‌o‌r f‌a‌c‌e s‌u‌p‌p‌o‌r‌t i‌s e‌v‌a‌l‌u‌a‌t‌e‌d h‌e‌r‌e u‌s‌i‌n‌g a‌n‌a‌l‌y‌t‌i‌c‌a‌l a‌n‌d n‌u‌m‌e‌r‌i‌c‌a‌l m‌e‌t‌h‌o‌d‌s, a‌n‌d p‌a‌r‌a‌m‌e‌t‌e‌r‌s s‌u‌c‌h a‌s s‌o‌i‌l p‌h‌y‌s‌i‌c‌a‌l a‌n‌d m‌e‌c‌h‌a‌n‌i‌c‌a‌l c‌h‌a‌r‌a‌c‌t‌e‌r‌i‌s‌t‌i‌c‌s, h‌e‌i‌g‌h‌t o‌f o‌v‌e‌r-b‌u‌r‌d‌e‌n, w‌a‌t‌e‌r t‌a‌b‌l‌e l‌e‌v‌e‌l, t‌u‌n‌n‌e‌l g‌e‌o‌m‌e‌t‌r‌y, a‌n‌d t‌r‌a‌f‌f‌i‌c a‌n‌d s‌t‌r‌u‌c‌t‌u‌r‌a‌l l‌o‌a‌d‌s. A‌s t‌h‌e t‌u‌n‌n‌e‌l f‌o‌r l‌i‌n‌e 7 o‌f t‌h‌e T‌e‌h‌r‌a‌n s‌u‌b‌w‌a‌y (E‌a‌s‌t‌e‌r‌n-W‌e‌s‌t‌e‌r‌n p‌i‌e‌c‌e) w‌a‌s e‌x‌c‌a‌v‌a‌t‌e‌d i‌n a‌n u‌r‌b‌a‌n z‌o‌n‌e, i‌n t‌h‌i‌s w‌o‌r‌k, t‌h‌e J‌a‌n‌c‌s‌e‌c‌z a‌n‌a‌l‌y‌t‌i‌c‌a‌l m‌e‌t‌h‌o‌d w‌a‌s u‌s‌e‌d t‌o m‌e‌a‌s‌u‌r‌e t‌h‌e r‌e‌q‌u‌i‌r‌e‌d p‌r‌e‌s‌s‌u‌r‌e f‌o‌r t‌h‌e t‌u‌n‌n‌e‌l f‌a‌c‌e s‌u‌p‌p‌o‌r‌t. T‌h‌e t‌u‌n‌n‌e‌l w‌a‌s b‌o‌r‌e‌d u‌s‌i‌n‌g a 9/164m d‌i‌a‌m‌e‌t‌e‌r g‌r‌o‌u‌n‌d p‌r‌e‌s‌s‌u‌r‌e b‌a‌l‌a‌n‌c‌i‌n‌g m‌a‌c‌h‌i‌n‌e. T‌h‌e f‌i‌n‌a‌l t‌u‌n‌n‌e‌l c‌o‌v‌e‌r w‌a‌s t‌e‌t‌r‌a‌g‌o‌n‌a‌l i‌n g‌e‌o‌m‌e‌t‌r‌y, 35c‌m t‌h‌i‌c‌k a‌n‌d 1.50m w‌i‌d‌e, m‌a‌k‌i‌n‌g a‌n o‌u‌t‌s‌i‌d‌e d‌i‌a‌m‌e‌t‌e‌r o‌f 8.85m f‌o‌r t‌h‌e t‌u‌n‌n‌e‌l. D‌a‌t‌a o‌b‌t‌a‌i‌n‌e‌d f‌o‌r t‌h‌i‌s s‌t‌u‌d‌y w‌a‌s o‌b‌t‌a‌i‌n‌e‌d f‌r‌o‌m 13 b‌o‌r‌e‌h‌o‌l‌e‌s a‌n‌d 5 w‌e‌l‌l‌s e‌x‌c‌a‌v‌a‌t‌e‌d d‌e‌l‌i‌b‌e‌r‌a‌t‌e‌l‌y a‌l‌o‌n‌g t‌h‌e t‌u‌n‌n‌e‌l. T‌h‌e f‌l‌o‌w d‌i‌r‌e‌c‌t‌i‌o‌n o‌f u‌n‌d‌e‌r‌g‌r‌o‌u‌n‌d w‌a‌t‌e‌r a‌b‌o‌u‌t t‌h‌e t‌u‌n‌n‌e‌l‌i‌n‌g z‌o‌n‌e w‌a‌s f‌o‌u‌n‌d t‌o b‌e n‌o‌r‌t‌h-e‌a‌s‌t t‌o s‌o‌u‌t‌h-w‌e‌s‌t. C‌o‌n‌s‌i‌d‌e‌r‌i‌n‌g t‌h‌e a‌v‌e‌r‌a‌g‌e w‌a‌t‌e‌r l‌e‌v‌e‌l o‌b‌t‌a‌i‌n‌e‌d f‌r‌o‌m t‌h‌e b‌o‌r‌e‌h‌o‌l‌e‌s, o‌n‌l‌y 35\% o‌f t‌h‌e t‌u‌n‌n‌e‌l r‌e‌m‌a‌i‌n‌s a‌b‌o‌v‌e w‌a‌t‌e‌r a‌n‌d 65\% i‌s b‌e‌l‌o‌w w‌a‌t‌e‌r l‌e‌v‌e‌l. T‌o i‌l‌l‌u‌s‌t‌r‌a‌t‌e w‌a‌t‌e‌r p‌r‌e‌s‌s‌u‌r‌e f‌l‌u‌c‌t‌u‌a‌t‌i‌o‌n, t‌h‌i‌s w‌a‌s c‌o‌n‌s‌i‌d‌e‌r‌e‌d i‌n t‌h‌e a‌n‌a‌l‌y‌t‌i‌c‌a‌l m‌e‌t‌h‌o‌d, b‌u‌t i‌g‌n‌o‌r‌e‌d i‌n t‌h‌e n‌u‌m‌e‌r‌i‌c‌a‌l o‌n‌e, w‌h‌i‌c‌h e‌m‌p‌l‌o‌y‌e‌d $P‌L‌A‌X‌I‌S^{3D}$ s‌o‌f‌t‌w‌a‌r‌e. W‌h‌e‌n c‌o‌m‌p‌a‌r‌i‌n‌g t‌h‌e r‌e‌s‌u‌l‌t‌s, a p‌r‌e‌s‌s‌u‌r‌e d‌i‌f‌f‌e‌r‌e‌n‌c‌e o‌f 20-25 k‌P‌a w‌a‌s n‌o‌t‌e‌d, i‌n‌d‌i‌c‌a‌t‌i‌n‌g a‌c‌c‌e‌p‌t‌a‌b‌l‌e c‌o‌n‌f‌o‌r‌m‌a‌n‌c‌e o‌f t‌h‌e d‌a‌t‌a.

Constructing underground spaces causes chaos in the ground stress field and its deformation. Due to settlement، construction of such urban underground spaces as subway tunnels is of utmost importance. In this research، the boring process of Tehran subway tunnel، line 7، has been studied and ground settlements، under Greenfield conditions، have been estimated for 2 sections (km 5+100 and km 9+900). The numerical analyses of the settlements of these 2 sections have been done with the Plaxis 3D software and compared with those recorded on the tunnel axis. It has been shown، through measuring ground settlement of the tunnel nearby buildings، that a relatively symmetrical settlement has been occurred around the tunnel axis. Settlements in these 2 sections، estimated by analytical and numerical methods، were not found to be in the permissible range. Therefore، to control settlement، it is necessary that improving measures be taken; at km 5+100، a coefficient of 1. 6 for the chamber room pressure would suffice and at km 9+900، the tunnel route needs regional improvement to make the work face stable and cause settlements to occur in the permissible limits. The values found by infography confirm those found by this research

During recent years، mining engineering is considered as one of the crucial fields of risk evaluation and assessment. Blasting is a common technique for rock excavation in mining projects. However، blasting has several undesirable effects on surrounding area. Ground vibration is one of the most important undesirable effects of blasting operation and may cause substantial damage to nearby structures as well as human beings. The Shur river dam is in the vicinity of Sar-cheshmeh copper mine، in Kerman province، Iran. The core of this dam is affected by ground vibrations resulting from blasting operations in this area and therefore، the risk evaluation in this dam is necessary. In this paper، based on the basic concepts of rock engineering systems (RES) approach، a new model for the risk evaluation of ground vibrations at the Shur river dam area is developed. The evaluation risk on the proposed model is based on interaction matrix، vulnerability index and effective parameters on the level of ground vibrations. For the risk evaluation of ground vibration in this area، a database comprising of 20 blast events were prepared and utilized. The obtained results showed that overall risk of ground vibrations for the studied blasting operations is at the medium level. The developed model in this study may be useful for a preliminary stage of blasting design.

Stability analysis of the support systems in tunnels is an important designing issue. Convergence-confinement method is used to estimate the applied load to the installed support system. The behavior of encountered jointed rockmass (which reduces the strength) could be studied, having established the degree of their convergence. Carranza-Torres and Fairhurst having used the latest version of Hoek-Brown correlation presented an analytical method to determine the relationship between factors describing the rockmass strength and mechanical reflections concerning the cylindrical underground spaces. In this article, using similar approach, the ground reaction curve was obtained for Sardasht long tunnel. Having compared the results with those prepared from a numerical method using FLAC 3D, it was clear that the above approach could be used for this tunnel where a safety factor of 3.14 was obtained for the stability of the segmented lining in the face of the applied loads.

In recent years، tunneling with the Earth Pressure Balance (EPB) shield has been applied in urban areas in different soils types. The most common technology in the mechanized tunneling is using the EPB machine. Soil conditioning operation can be carried out through the screw conveyor. Knowing different soil conditioning agents and their affects in different soils types is quite important in selection of the most appropriate foam-polymer to be used. Selecting the most appropriate soil conditioning set needs different precise studies so that the properties of the conditioned soil can be determined and the measurable data can be specified. Selection an appropriate strategy (for soil conditioning during boring) highlights the importance of the ground risks involved so that conclusive decisions can be made regarding the type of the physical behavior of the foam and other additives. Methodology and Approaches: The soil layers in this project were divided into 6 units (ET-1 to ET-6). In this study، It was revealed that every unit needed specific additives depending on its geological and geotechnical specifications and the soil conditioning parameters for every unit would be different. The optimum amount of conditioning agents and types of additives to be used in the tunnel route (considering the geological risks that needed conditioning، and the presence and expanse of different soil units) were studied in 3 separate stages based on the guiding tables، standards، and laboratory and field tests. Results and For soil conditioning، used material was made of 3 different foam types (A، B and C: A & B for ordinary soils with medium stability and C for adhesion and impermeable soils with high stability) for respectively 60% and 30% of the tunnel route. The FIR change amplitude in the project has been estimated to be 20% to 80%; maximum consumption has been in the interval of 20% to 40% and FER has been equal to 4 to 7.

Controlled blasting is commonly employed in civil and mining engineering developments. This reduces maintenance and supporting system costs and improves the bench appearance. Safe maintenance of the wall and avoidance of damage caused by blasting is therefore important in all subsequent underground and surface excavations. Different types of controlled blasting nowadays include trim blasting, line drilling, cushion blasting, pre-split blasting, fracture controlled method and linear shaped charge. Although these approaches incur additional operational costs, but considering benefits associated with the safety condition necessary for such operations, increased production and faster progress resulting from more stable walls, improved waste/ore ratio, controlled ore concentration and the required size reduction of the rock for haulage and loading, these additional costs are justifiable. Controlled blasting is also common in open-pit mining, quarry mining, trenching and shaft drilling. In case spacing and charge quantity are evaluated based on engineering design principals, a uniform fracture with narrow width would result. This would dampen the transfer of the explosion wave outside the explosion block, when production blast holes are fired. In pre-split blasting, which is a more common technique often used in such operations, blast holes with smaller diameters and lesser spacing than normal production sizes, are applied in the last drilling row. The method could easily be applied to all types of rocks. However, drilling patterns and the required explosive charges should be determined based on rock mass characteristics, such as stiffness, roughness, existence of discontinuities. Also, in pre-split blasting, contrary to other methods, the controlled blast holes are fired 50ms sooner than the main production blast holes. In case this delay exceeds 50ms for whatever reason, the fracture produced by the controlled blast holes will be filled with post-explosion fragments and their ability in cushioning the explosive transmitted wave is seriously hampered. Hence, in applications of this technique for hard rock mass, it is customary to leave a proportion of the blast holes without charge. The blast holes diameter in this technique varies from 51 to 102 mm, with the diameter of charge ranging from 17 to 32 mm, hence decoupling is less than one. The explosive connection is often carried out by detonating cord and if wire and electric detonators are used, they should be fast triggered type of milli-second delay or better. Superposition of compression waves due to adjacent blasting holes lead to tension stresses, perpendicular to the direction of blast-hole lines. This results in tensional fractures within the rock mass. In this study, using UDEC distinct element software, the mechanism of crack propagation and superposition of pre-split blasting waves in three holes are investigated, and the data are compared with field data obtained on the conglomerate rock mass at Gotvand Olya dam. Blast holes of 76mm in diameter, 3m height, 8 cm spacing were drilled at the rock mass and charging included 7 Emulite cartridges with cortex blasting. Ground vibrations of 175.24 mms-1 and 77.33 mms-1 were recorded by two VIBROLOC seismometers, placed at 8m and 13m away from the blast hole centre, respectively. The results suggest that numerical simulation could be employed with sufficient accuracy for predicting presplit blasting.

Segment joints of the lining should be capable of withstanding a certain amount of bending moment, axial and shear forces, and considering that the force-displacement correlation may behave linearly within a certain range of the applied load, the bending moment applied on the lining might be reduced. Hence, the lining thickness could be reduced once smaller internal forces are involved. In the structural analysis of the lining segment, joints could be modeled as elastic tubes and their stiffness could be expressed in terms of rigidity.