نشریه علوم و فنون سازندگی
سال سوم شماره 1 (پیاپی 7، بهار 1401)

More recently, the demand has been raised for application of segmental tunnel lining in long and deep tunnels in rock beds and also shallow tunnels in soft ground, particularly in urban areas. From technical and economic aspects, proper dimensioning and connecting of the segmental linings have always attracted the interest of many designers in the field of tunneling. The guiding rods are placed in the horizontal joints of the segment to make the segment easier to install and to provide shear strength at the joint. In this article, first, the types of joints in tunnel segments are studied and how the connections in these joints work are discussed. Next, the performance of the guiding rod is examined and the operation of the guide rod in the tunnel is investigated. For this purpose, the tunnel is first modeled with the real geotechnical conditions of the ground from the metro terminal to Abuzar town station in plaxis2D software and the values ​​of axial and shear forces in the tunnel structure are obtained. Based on the outputs of the plaxis2D model, the amount of shear strength borne by the cross section of the segment and the guide rod is presented. Abacus software is used to analyze the behavior of the guide bar and the output of this model shows that the solid and hollow guiding rods have linear behavior and the hollow guiding rod can also be used for this part of the tunnel route, which can effectively reduce construction costs.

Low-temperature cracking is one of the major failures of asphalt surfaces, and is considered as a performance indicator in the mechanistic-empirical design method. Fracture toughness and fracture energy are important parameters for investigating the low-temperature cracking of asphalt concrete. The purpose of this study is to explore the low-temperature fracture parameters of asphalt mixtures containing the recycled asphalt pavement (RAP) and the warm mix asphalt (WMA) additive namely, Sasobit using the semicircular bending (SCB) test. For this purpose, the SCB test is carried out at 0 °C under the load line displacement (LLD) controlled mode. The eight superpave-designed asphalt concretes including hot mix asphalt (HMA), Sasobit-modified asphalt concrete (WMA), HMA containing RAP (HRAP), and WMA containing RAP (WRAP), were prepared with two nominal maximum aggregate sizes of 9.5 and 19 millimeters. The recycled asphalt mixtures (both HRAP and WRAP) showed a sudden and brittle failure, while in the case of HMA and WMA mixtures, the failure was more ductile. The fracture toughness of the RAP mixtures was higher than the other ones (about 100% of mixtures without RAP).  Based on the fracture energy parameter, the recycled asphalt mixtures (HRAP and WRAP) had a better low-temperature cracking performance, in addition to the environmental and economic benefits. The coarse-grained WRAP mixtures showed an increase of about 22% in the fracture energy, followed by the fine-grained WRAP mixture (about 15%), and the coarse-grained HRAP mixture (about 12%). The cracking severity of the RAP mixtures was lower than the RAP-free mixtures (between 25% to 84% of the corresponding RAP-free mixtures)

This article seeks to improve the traffic situation in one of the squares of Kerman. In this article, first the traffic intensity in the objective location is examined in consecutive days and hours, and its traffic node is extracted using visual criteria. The extracted traffic junction is shown to be one of the intersections adjacent to the square, which causes the traffic to bounce back to the square, making the the underpass built in the square useless. In this study, first, regulations are mentioned to improve the general condition of this intersection, and in the next step, traffic simulation is used to improve this specific intersection. To simulate the raw data, the volume of traffic passing through this intersection was required, which was captured using several people and using several video cameras. After capturing this data using video cameras, the required information was extracted using a review of these videos. In the next step, using simulation, 5 solutions were proposed to improve the condition of this intersection, which could improve the traffic parameters of this intersection, including reducing the delay to one third of the non-performance option. The study also examined the economic implications of these options, which showed a 39 percent improvement in the cost imposed by the non-coplanar intersection over the status quo.

In this study, in order to investigate and evaluate the performance of the EPB TBM, the parameters of progress rate and foam consumption for ground improvement have been used. To evaluate the performance of EPB tunnel boring machine in this research, drilling data were used from 4 databases namely Qom metro line one project, Shiraz metro line two project (east and west tunnel), Isfahan metro line two project and Isfahan metro line one project which have been EPB TBM excavated. Based on this database, models based on statistical techniques including regression analysis (simple regression, linear multivariate (MLR) and nonlinear (MNLR) regressions) and support vector machine least squares (LS-SVM) algorithm were developed to evaluate the foam consumption and the advance rate. Then, in order to study more accurately and better the experimental and intelligent models presented to predict the foam consumption and the advance rate, statistical indicators such as the coefficient of determination (R2), the statistical values ​​of the root mean square of the normalized error (NRMSE) and error variance (VAF) for each developed model were calculated using the test data set. Comparison of the calculated values of R2, VAF and NRMSE for the models developed to predict the foam consumption and the advance rate showed that the proposed model based on the LS-SVM algorithm has remarkable accuracy compared to other models, in predicting the amount of foam consumption and the advance rate of the EPB tunnel boring machine. The values of R2, VAF and NRMSE indices for the developed model in the prediction of the amount of foam consumption are 0.945, 94.356 and 0.237 respectively, and in the prediction of the advance rate are equal to 0.741, 74.071 and 0.149, respectively.  Due to the high accuracy of predicting the amount of foam consumption (Qt) and the advance rate (AR), the models which are developed on the LS-SVM algorithm basis, can play a significant role as applied models in the mechanized drilling industry.

Currently the only unit for the production of phosphoric acid by wet chemical method in the country is Arya Phosphoric Jonub Company with the production capacity of 381 thousand tons per year of phosphoric acid solution with a concentration of 50%. Due to the widespread need for this acid in the country, the need to design and build a new unit for the production of phosphoric acid is strongly felt. Designing and constructing industries require knowing the theoretical foundations and having practical and experimental perspectives in accordance with the prevailing economic and cultural conditions and the existing technical knowledge of society, in order to achieve production goals. Technical study and optimization of phosphoric acid production conditions by dihydrate method is done in line with these goals. The discussion of process optimization is always fraught with many difficulties and complexities. One of the most important challenges ahead is access to process information such as purity of raw materials, temperature limits, pressure and flows rate, limitation of the use of equations and laws of transfer phenomena. In this project, we have tried to design and simulate a phosphoric acid production unit according to the needs of the country and the soil used in this unit, using the powerful Aspen Plus software. Various experiments were performed on the sample received from the National Iranian Copper Industries Company and based on the results of these analyses, the process was designed and simulated. Finally, the simulation results were presented.

Remote sensing is one of the novel methods in the field of Earth sciences and environment studies. Despite well-known methods of producing geological maps which are costly and time-consuming, remote sensing techniques are cheap and fast, and are more capable of space resolution. By detecting and identifying various installations, areas and landscape phenomena, the natural resources are investigated with reservation in time, cost and human power. As remote sensing has a much larger field scope than arial photography, it allows the interpreters to determine the alliance between various geological phenomena. Remotely acquired data, although used extensively in many applications, have not been widely used for lineament extraction in tunnel route selection. In this study the main focus is on the applicability of the remote sensing technique as a tool for predicting geological and rock mass conditions by using the Landsat Enhanced Thematic Mapper Plus (ETM+) sensor onboard the Landsat 7 in drilling the Kani Sib tunnel for conveyance of water into the Urmia Lake which is located in the south of West Azerbaijan Province, Iran. For this purpose, in this research the best band assignment, the best band combination, filtering and main component analysis (PCA) based on statistical ratio-findings (OFI) are selected and applied on band numbers 1 to 5 and band 7 ETM+ photos with 30 m resolution power. The results show that ETM+ Landsat satellite’s different data processing methods can be applied for geological studies and structure investigations in vast areas or hardly accessible regions.