Knowledge to geology conditions and its hazards, have an important role to selection support and suitable excavation method in underground structures. Water transport tunnel is the most important such this structures. Golab water transition tunnel with 11 kilometers lengths and 4.2 meters diameter is a part of water transporting project from the Zayanderood dam to Esfahan and Kashan cities. With regard to high, calcitic and weak overburden for this tunnel, the research on probability geology hazards such as squeezing and rock burst are compared and studied. In this Research, at first, the tunnel is zoned by using of geophysics studies and boreholes, then the squeezing and rock burst potential have been discussed and comprised. Results of our studies, low to moderate squeezing potential and low Rock burst potential have been predicted for some panels of the tunnel. Finally, primary support has been suggested for this tunnel based on probable geological hazards and using numerical methods.

During construction of underground openings, such as: tunnels, shafts and caverns stress concentrations increase near these openings and instability problem occur in these underground excavations. Tests on thick-walled hollow cylinders of rock are a relatively easy, economical and realistic means to better understand stability and the mechanisms associated to underground openings failure. The mode of rupture observed in the tests was a pair of radial rupture planes. These rupture planes correspond to a compacting failure mechanism, because, these planes are perpendicular to major principal stress (tangential stress). This kind of rupture usually occurs in very porous material.

From these factors the tunnel form, dimensions, depth, the tunnel drilling method, presence of water, etc. can be mentioned. Achieving an optimized design requires identification of effective parameters and the relationships among them. Effective design parameters include stability of the tunnel face, horizontal and vertical displacement, seismic wave, and shrinkage phenomenon, etc. Also considering the importance of the structural stability on the ground surface above the tunnel, especially in the urban tunnels, the settlement level of the ground surface must be considered. In this study the stability of an 8m width and height horseshoe sectioned tunnel located in Tehran alluvium having been projected for water transmission has been technically analyzed using the FLAC 2D‎‏ software and the comparison wad made using empirical and analytical methods. The results showed that the maximum settlement resulting from design step using software is 14.9 mm which is almost consistent with the value obtained from the empirical relationship, and the difference estimation lies within the acceptable range (0.7%). Also the obtained horizontal displacement shows that the maximum displacement within the 25m distance from the tunnel axis (on both sides) is 2mm and the values obtained from the empirical relationship showed that the maximum horizontal displacement occurs on the 25m distance from the tunnel axis.

Facilities built in areas affected by earthquake activity, such as tunnels, which have always been an integral part of human life, must withstand both dynamic and static loading. It has led to the need for practical studies on the effects of earthquakes on underground structures and the factors affecting their destruction. For this purpose, in this research, at first different patterns of tunnel’s excavation were investigated and by using Plaxis 2D software and based on Tabas earthquake in Iran, sensitivity analysis on geotechnical parameters of the soil surrounding tunnel such as cohesion, friction angle, unit weight and modulus of elasticity was carried out, and the parameters whose changes have the greatest and least effects on the bending moment changes on the tunnel lining are introduced. The results show that tunnel excavation patterns significantly affect the bending moment, axial forces, displacements, and surface settlement of the tunnel. Often, by dividing tunnel excavation area to small parts, the values of bending moment, axial forces, displacements, and surface settlement of the tunnel decreases in static analysis. Also, outputs of sensitivity analysis on geotechnical parameters of the soil surrounding tunnel showed that modulus of elasticity of the soil surrounding tunnel has the most effect and cohesion changes have the least effect on bending moment induced on tunnel lining..

Seismic methods have gained significant attention for locating seismic sources caused by large explosions and enhancing the signal-to-noise ratio. Most studies focus on large-scale scenarios where the seismic source is assumed to be far from the seismic array. In military applications, underground excavations are often conducted to create passages for transferring forces and equipment. Hence, seismic methods can be employed to determine the location of such excavations as seismic sources. This study investigates the feasibility of estimating the planar position of low-energy underground excavations, which are not detectable using conventional seismic techniques. To this end, a tool based on triangular seismic arrays is developed, and a simple mechanism utilizing cross-correlation analysis is proposed for estimating the planar position of the source. The efficiency of this method is compared with existing approaches. Since the received signals are significantly affected by local noise due to the low energy of the source, a noise reduction algorithm based on the similarity of received signals is introduced, yielding favorable results compared to conventional methods.

Drilling and blasting operation is performed simultaneously with mechanical and electrical jobs in phase one of the development project of Masjed Solaiman Dam power plant. To avoid any damage to structures and facilities, precise estimation of land vibration is required. This would help a proper design for blasting operation, too, due to which the level of ground vibration must remain within the permitted limits set up by some well-accepted standards. In this investigation, based on maximum instantaneous charge and the distance from blast locations, vibration is estimated by means of both empirical models and neural network technique. The analysis of recorded data revealed that application of five empirical models resulted in more or less similar results whereas the neural network method showed to be much more accurate technique. Due to non-linearity, flexibility and the ability of accepting variation in the number of impacting factors, the neural network method was observed to be, by far, more capable technique. It is, therefore, concluded that the latter method can be considered as a proper tool for ground vibration estimation.

This paper describes an experimental device which is used for determining radial permeability of rocks around well bore hole according to effective stress.Permeability of rocks is a very important characteristic because it controls the flow of fluid. Laboratory tests on thick-walled hollow cylinders of rock are relatively easy, economical and realistic means to understand better the mechanisms associated with wellbore failure. The experimental device used to carry out tests on thick-walled hollow cylinders under two distinct conditions which are: 1) Tests without pore fluid 2) Tests with convergent radial flow of pore fluid. Two types of tests were carried out in conditions with pore fluid: a) Tests under an increasing external pressure and a constant external pore pressureb) Tests under a constant external pressure and an increasing external pore pressure The tests were carried out on a very porous artificial material (CPIR09). The mode of rupture observed in the tests was a pair of radial rupture planes. The results obtained show that when the external pore pressure is constant the global permeability decreases with increasing external pressure. When the external pore pressure increases the convergent radial flow of pore fluid (due to the imposed pore pressure) slightly increased the global permeability samples. The convergent radial flow of pore fluid acts to remove fractured materials and to erode localization bands, therefore, the global permeability samples brutally increased.

Since two decades ago with the increase in dam construction projects in Iran, a major part of the ancient and historic sites of the country went under water. As mostly, do not exist desirable and sufficient relationship between Iranian Cultural Heritage, Handicraft and Tourism Organization (ICHHTO) and other organizations like Ministry of Energy, the budget allocated to the study of ar­chaeological sites behind dams (that will go under water) has been delayed and postponed. The consequences of this situation reveal as fast and emergency rescue excavations that in some cases certainly this haste greatly will reduce the quality of archaeological studies.From scientific and technical perspective and according to directors of dam excavation projects experience, generally believe that fast and emergency excavation it is not only and surest way to preserve and protect of ancient sites; why, given the little time and lack of adequate funding for dam archaeological projects, of course, excavations excavate only a small parts of the archaeological sites. Archaeological excavation experience carried out in several dams like, Seimareh, Sivand, Got­vand, etc, shows that more than one hundred archaeological sites have been surveyed and intro­duced behind the dams and only a handful of them were excavated in one or two seasons, which is only includes less than 10% of the sites and this method cannot be a good strategy for carrying out research projects. Using the boat for going to the sites for excavation, as well as other serious problems in this regard should be add to emergency excavation projects problems...

Excavation in urban plans influences the adjacent buildings and sometimes creates the irreparable damages. In this regard the effect of adjacent structure stiffness on the ground movement due to excavation is important. However, there are only a few studies in this area of research. In this paper, the interaction of excavation and its adjacent structure is studied using two famous finite elements codes (PLAXIS & SAP) and an elastoplastic constitutive model. For this purpose, the two excavation systems have been considered. The adjacent structure in the first system is a concrete bending frame. In the second system, instead of a real structure, an equivalent (in stiffness) elastic beam has been used. The achieved results indicate the considerable effect of adjacent structure on the ground movement due to excavation. In addition, the remarkable influence of excavation on internal forces of different members of structure is addressed. It is shown that the application of an equivalent elastic beam, which has the characteristic of simplicity and flexibility in consideration of different stiffness for a given building weight, can be used for evaluation of the interaction of excavation and its adjacent structure.

Summary Computer method is one of the ventilation network design methods in underground excavations. Computer method has been designed based on mathematical approximate methods. Methods such as Newton-Raphson method, Hardy Cross method and its modified versions, critical path, linear analysis, non-linear programming and optimization techniques are considered as some mathematical approximate methods. Newton-Raphson method is one of the methods of solving nonlinear equations in numerical calculations. This method is designed based on the definition of derivative and its correction. Using Newton-Raphson method for the analysis of ventilation networks in underground excavations has been common. However, so far, perfect investigation of this method has not been carried out. The purpose of this paper is to investigate Newton-Raphson method and its improvement in the analysis of ventilation networks in underground excavations. The analysis indicates that this method in some models is unable to find the final true answer because instead of convergence, it diverges. Thus, the improvement of this method seems to be necessary. Introduction Ventilation design of underground excavations is done based on preparing underground excavation map, identification of branches and injunctions in ventilation network, calculation of mine resistance for any of branches, calculation of air flow quantity for any of branches, calculation of pressure loss for any of branches, calculation of natural ventilation, network adjustment, selection of regulator doors and selection of main fans. Various methods have been presented such a manual and computer methods for the analysis of ventilation networks of underground excavations. The choice of analysis method depends on the purpose of ventilation network analysis. Methodology and Approaches One of the methods for solving nonlinear equations in numerical calculations is Newton-Raphson method. This method is designed based on the definition of derivative and its correction. In this method, the error amount of the initial guess is calculated for purpose function, and then, the initial guess is corrected. In this method, based on the equation and injunction rules, supposition flow quantity for any of branches. is supposed. Based on the ventilation network fans and mathematical approximate equations, the error of any ring in the ventilation network is calculated, and then, supposition flow quantity is corrected. Based on the mathematical equations, correction operations of air flow quantity are repeated until the calculation accuracy becomes equal to or smaller than the calculation error. Results and Conclusions Newton-Raphson method is one of solution methods in ventilation networks analysis. Convergence to the final solution in this method depends on supposition flow quantity, the direction of supposition flow and the arrangement of ring selection. If the direction of the hypothetical flow in the network is in accordance with the actual flow direction, the fastest method for reaching the final solution in the analysis of underground ventilation networks will be the use of Newton-Raphson method. However, if the direction of the hypothetical flow in the network is not in accordance with the actual flow direction, the validation of this method will indicate that this method in some models becomes divergent. Therefore, improvement of Newton-Raphson method is necessary. The improvement of Newton-Raphson method in this paper is made in two stages. The first stage is the identification of negative flow intensity, and then, the flow direction is reversed. In the second stage, the correction of the equation is performed, and then, the calculations are repeated.