حسین میرزایی نصیرآباد

Surface settlement induced by tunneling is one of the most crucial problems in urban environments. Hence, accurate prediction of soil geotechnical properties is an important prerequisite in the minimization of it. In this research work, the amount of surface settlement is predicted using three-dimensional numerical simulation in the finite difference method and Artificial Neural Network (ANN). In order to determine the real geotechnical properties of soil layers around the tunnel; back-analysis is carried out using the optimization algorithm and monitoring data. Among the different optimization methods, genetic algorithm (GA) and particle swarm optimization (PSO) are selected, and their performance is compared. The results obtained show that the artificial neural network has a high ability with the amounts of R=0.99, RMSE=0.0117, and MSE= 0.000138 in predicting the surface settlement obtained from 150 simulations from randomly generated data. Comparing the results of back-analysis using the optimization algorithm, the genetic algorithm shows less error than the particle swarm algorithm in different initial populations. In all cases of analysis, the calculation time for both algorithms lasts about 5 minutes, which indicates the applicability of both algorithms in optimizing the parameters in mechanized tunneling in a short time.

This paper presents an integer linear programming (ILP) model for allocating trucks according to their operating performances in a truck-shovel system of an open-pit mine, so as to minimize the total operating cost of trucks. To evaluate the performance of the proposed model, the model was applied with two different strategies, namely independent fleet management and integrated fleet management. The results of the research in a copper mine case study showed that the developed strategies were capable of handling the operation with a fewer number of trucks than the actual mine strategy. In addition, integrated fleet management indicated 2% and 3% cost-savings over the shift compared to strategy 1 and the mine allocation schedule, respectively.

Global sensitivity analysis is one of the beneficial and useful tool to identify the uncertainty of input variables that has been extremely investigated in different science such as simulations. Sensitivity analysis is an essential step in the production of meta-model, which, by identifying effective parameters in tunneling, reduces the time and computations required. In this paper, sensitivity analysis was carried out on geotechnical and operational parameters of EPB mechanized tunneling in soft soil. So, the tunneling processes were modeled using a finite difference method in FLAC 3D software, and the numerical model was validated by the monitoring data obtained from the East-West route of Tehran metro 7 line. The sensitivity analysis by using elementary effect Morris method was performed on the 6 input parameters and three parameters (face pressure, specific gravity and cohesion of the soil layer which the tunnel was excavated) were selected as effective and sensitive parameters in the maximum surface settlement. Then to construction of meta- model, 100 samples were generated from effective parameters using the Latin Hypercube method. After numerical simulation for each sample, the simulation results were used for surface settlement prediction by using artificial neural network. The results showed that the prediction of the meta-model based on the artificial neural network and the numerical model for the data in the design phase corresponded about 98%.

Evaluation of the interaction between a new and the existing underground structures is one of the important problems in urban tunneling. In this work, using FLAC3D, four numerical models of single- and twin-tube tunnels in urban areas are developed, where the horizontal distance between the single- and twin-tube tunnels are varied. The aim is to analyze the effects of the horizontal distances, considering various criteria such as the deformation of linings, the forces and moments exerted on the twin-tube tunnels and their safety factors, the subsidence that occur on the surface and the nearby buildings, the stability of the single-tube tunnel, and the stability of the pillar lying between the single- and twin-tube tunnels. Considering the above-mentioned criteria, the results obtained indicate that the interaction between the single- and twin-tube tunnels is virtually negligible in the distance more than three times the single-tube tunnel diameter. Also the stability of the pillar lying between the tunnels makes the distance to be chosen at least 1.5 times the single-tube tunnel diameter.

One of the main issues involved during tunnel construction with tunnel boring machines is the tail gap grouting. This gap is between the external diameter of tunnel lining and the excavation boundary that is filled with high-pressure grouting materials. In this work, three different approaches of gap grouting modeling in the FLAC3D software are investigated with a special attention to the influence of the grout material hardening process. In the first approach, the grout is modeled as a liquid during injection, and considering the TBM advancement and its hardening time, the grout characteristics are changed to the properties of the solid grouting. In the second approach, the grouting material from the beginning of injection is considered with the properties of solid grouting in the model, and the liquid phase is ignored. In the third approach, without considering the back-filled grouting area in the model geometry, only the injection pressure is applied to the end of the shield and behind the installed segments. The validity of the approaches is evaluated with respect to the maximum ground surface settlement. All the three approaches estimate different surface settlement but the result of the first approach is closer to the monitoring data. Also as a sensitivity analysis, in this work, we investigate the effect of the elastic modulus of liquid and solid grouting materials on the amount of surface settlement that can help to gain a more accurate insight into the effect of grout mixture.

The aim of stope limit optimization is to define an area with maximum economic value, for which, in accordance to the mining method used, all technical and geometrical constraints is considered. Although more than four decades have passed since the first presentation of underground stope optimizatiom algorithm, the development of these algorithms in comparison with similar algorithms used in open pit mines, have been very slow. This may be due to the high variety of underground mining methods and complexity of economic modeling of mining limit. In this paper a 3D comprehensive algorithm, which is called MLOA, is proposed. This algorithm runs on a variable value block models and is able to determine the number, height and optimal layout of levels. To determine the optimum limit of stopes, MLOA has used a heuristic algorithm which is called SOA. In SOA algorithm, Technical and geometrical constraints such as the minimum and maximum of stope dimension and minimum width of rib pillars have been regarded. The optimum location and dimension of stopes within specific level can be determined by using SOA. In order to verify the methods , the results of the application of SOA algorithm on hypothetical economic block model, are compared to similar rigorous algorithm’s results. The results demonstrate the capability of SOA algorithm in determining optimum limit of stopes.

Underground and infrastructure projects are generally complex project with many variables including ground ýand groundwater conditions are variable and uncertain. These ýconditions infliction significant risks in all project components or parts that are indirectly related with the ýproject, and has led to the high costs and time delays to the project. Ranking by providing timely response to risk it all, helpful to the risk management process will be more ýsuccessful. In this paper, prioritize risks are discussed in the mechanized tunneling to using Fuzzy Technique ýfor Order Preferences by Similarity to Ideal Solution (FTOPSIS) in rocky environments. The calculations ýperformed in 19 separate zone and ultimately three risk as the high risk (main) in each zone specified. The ýanalysis results show that leaks of toxic gases in rocks and water leaks and influx into the tunnel in this study ýare respectively most important risks.ý

Evaluation of interaction between new and existing underground spaces is one of the important problems in tunneling in urban areas. In some cases it is necessary to excavate tunnels close to each other’s. This، in turn، will lead to important interaction between these tunnels. In this paper، using 3D numerical modeling of line 1 twin tunnels of Tabriz urban railway، excavation stability of these tunnels، using critical strain of Sakurai، have been studied. Also displacement pattern of lining in both twin tunnels (Sahand & Sabalan) have been investigated. In next step، effect of excavation of these tunnels on the subsidence of surface and adjacent buildings، using Cramer criteria and finite difference method (FLAC 3D)، have been studied. For the purpose of study of the interaction effects between these tunnels، forces and moments that act on the segmental lining of each tunnel and their safety factor have been verified. Eventually، stability of pillar that lies between two tunnels، have also been evaluated. The results show that: 1-twin tunnels of Tabriz metro will be stable during excavation. 2-Surface subsidence due to excavation of these tunnels will have no important effect on existing structures. 3-Safety factors varies between 5-10 on the different positions of segmental lining. 4- Pillar that lies between twin tunnels will be stable

Nowadays، subways and urban tunnels are one of the most important infrastructures of public transportation network in big cities. Since the new tunnel projects should be constructed in under ground in populated urban areas، construction and implementation of this underground systems may cause damages to utilities، surface and subsurface structures. In this article، because of the importance of the issue of crossing the old urban areas and the need to reduce damages as much as possible، the distance between Stations N. 11 and 12 of Line 1 of Tabriz Subway that contains of old and traditional structure with old buildings of low strength has been studied. Due to existence of Cultural Heritage buildings in this distance، the study of settlements was performed using three different methods including Peck’s empirical method، Laganatan & Pollus’ analytical method and finite element method of numerical methods (using PlAXIS3D Tunnel software). Finally، the results of aforementioned methods were compared. The results show that the settlement values ​​obtained from the numerical model are more than the settlement values obtained from Peck’s empirical method and Laganatan & Pollus’ analytical method. Also، since the settlement values obtained from the numerical model are more than the allowable settlement values in urban and residential areas، it is needed to perform the necessary controlling strategies in this distance in order to make the excavating system able to cross this distance safely.

Various underground spaces such as tunnels are constructed in urban areas for different purposes. These spaces are often located in soil media near to ground surface. In EPB tunneling, the face pressure (P) and backfill grouting pressure (G) are the most important factors to prevent the surface settlement. The 7th line of Tehran subway project is excavated by EPB machine. In this paper four section of 7th line tunnel are selected and the influence of face pressure on surface settlement are investigated numerically by PLAXIS Tunnel software. In two section of tunnel the results of numerical models are verified by monitoring instruments. In next two sections of tunnel, four status of face pressure: P=P0 (estimated initial pressure), P=1.5P0, P=2P0 and P=4P0 and for each state, five status of backfill grouting pressure: G=0, G=P, G=P+0.5 bar, G=P+1 bar and G=P+2 bar are considered and surface settlement are analyzed. Results show that an increase of %400 for face pressure lead to a decrease of maximum 5 mm in surface settlement. So in this project the influence of face pressure is trivial but the influence of backfill grouting pressure is more significant.

The Cheraghvays dam is located in 17Km away from the west of Saqez in Kurdistan province. Basically, the arrangement of grout holes was based on the quality of bedrock, so the grout holes were arranged at 2 m intervals and 10.5m final depth. Also, the consolidation grouting process was conducted from the bottom to the top of the grout holes.Particular attention to the geological structures in the initial studies and construction of dams is important which locking of it can be caused some problems. Therefore, in this paper, permeability and cement take of 1438 grouted holes were studied and interpreted by using geological view of the beneath clay core of Cheraghvays dam. Finally two parameters, permeability and cement take of mentioned grouted holes were compared and their nonconformity is interpreted by geological view and imperfection of Lugeon test.

Under various loads، pre-existing cracks (flaws) in rock propagate and leads to crack coalescence and failure. In this paper، crack propagation and coalescence mechanism in rock-like materials (gypsum specimens)، containing two inclined and open flaws (pre-existing cracks) under uniaxial compressive loads are experimentally investigated. The cubic specimens are prepared from the mixture of gypsum and water and the flaws are created by inserting steel shims into modeling material in the mould template. A set of specimens containing two inclined flaws with the fix length of 15 mm، inclination of 45 degree and connection line of 20 mm with various bridge angle of 45، 60، 75، 90، 105 and 120 degrees are subjected to compressive loads and the mechanical behavior of them are monitored. The bridge angle has important role and controls the propagation and coalescence pattern. For different bridge angles، four coalescence modes including shear، shear-tension، tension - shear and tension mode were observed. With the increase of bridge angle، the corresponding coalescence stress increases.

The commonly used failure criterion based on stress intensity factors is compared with new developed stress based failure criterion to predict crack growth trajectory and the advantages and disadvantages of both criteria are discussed using some examples. To obtain displacement vector and strain and stress tensors، the element free Galerkin method (EFGM) is used. The visibility criterion is applied to model cracks and the M-integral method is employed to calculate the stress intensity factors. Two examples are considered to evaluate the mentioned failure criteria. The stress intensity factors obtained from EFGM show good agreement with the results of finite element and analytical solutions. The failure criterion based on stress intensity factors only can predict the initial crack trajectory however the stress based failure criterion can predict the complete crack growth path and its predictions coincide very well with numerical and experimental results.