نشریه علوم و فنون سازندگی
سال سوم شماره 4 (پیاپی 10، زمستان 1401)

Determining the type and characteristics of the distribution functions for orientation and location of discontinuities in rock mechanics and engineering geology is important. Generally, the distribution functions of orientation parameters, including the dip and dip direction, are either hypothetically determined or determined independently and the spatial dependence of these parameters is ignored in determining their distribution functions. This creates uncertainty in determining the distribution functions for orientation and location of discontinuities. In this study, using statistical, probabilistic and reliability methods, an algorithm for determining the distribution functions is presented. Studies show the high ability of this algorithm to determine the orientation distribution functions and spatial location of discontinuities. Then distribution functions of orientation and location for discontinuities were determined in the western wall of Sarcheshmeh copper mine. Stability of the wall was investigated using the identified distribution functions. The results showed that the Log Logistic – 3 parameter Weibull combined distribution function is the best distribution function for describing orientation and location of discontinuities. Instability was investigated using the combined distribution function detected and under different dips of the final wall. The results showed that the probability of occurrence of instability in the western wall is maximum under the 45 ° of the final wall dip and final wall is completely stable under the 30 ° of wall dip. The optimal dip of the western wall of the Sarcheshmeh copper mine is 29 °.

According to statistics, the construction industry is one of the most dangerous industries in the world, and many people are injured or die in this industry every year. Therefore, it is necessary to develop and comply with HSE guidelines and standards for the protection of human resources and material resources in all construction projects. One of the most important effective measures in this field is to use a comprehensive model to assess the level of safety and environmental hazards in accordance with the existing standards, in the design phase and site layout planning. By reviewing past studies, the lack of this model that supports decision-making and includes the entire evaluation process and a suitable choice is felt. In this research, in order to solve this research gap, a comprehensive framework including five phases of reviewing HSE regulations, designing workshop equipment layout options, safety index evaluation, traffic index evaluation, and the final decision phase as a decision support system has been developed. In this regard, new technologies such as building information modeling (BIM) and multi-criteria decision-making methods (MCDM) have been used and its performance has been measured by developing the proposed framework in the form of a web application on a case study.

Roadheaders are one of those machines that have a unique capability and flexibility in mechanical excavation of soft to moderate rock formations, therefore they are widely used in underground mining and tunneling projects. Performance prediction and evaluation of roadheaders are considered crucial factors in successful applications of such machines. The main objective of this research work is to provide a model for predicting the pick consumption index (PCI), an index indicating pick consumption rate, based on the characteristics of the excavated rock formations. For this purpose, a comprehensive database with high reliability of pick consumption indexes (PCI), as well as the geomechanical properties of the rock formations were prepared during the detailed evaluation of the roadheaders’ performance through field and operational observations in the main tunnels and access galleries of the Tabas coal mine project and were then analyzed and examined carefully. The results of the analysis finally yeild a model for predicting the pick consumption index (PCI). The results show that there is a very good correlation between the peak cutting force (PCF) and the pick consumption index (PCI ) with the coefficient of determination (R²=0.94). The results of the research also demonstrated that this new series of equations can be successfully used to predict the pick consumption index (PCI) in coal mines.

Superplasticizers are among the most important concrete additives that will improve the flow of fresh concrete by reducing its viscosity and yield stress. One of the most commonly used superplasticizers in the concrete industry are polycarboxylate-based superplasticizers. As a result of being absorbed on the surface of cement particles, these materials prevent particles from sticking together in concrete with the mechanism of spatial hindrance and improve its flow. In the conducted research, the effect of five types of superplasticizers on the properties of fresh and hardened mortar and concrete was investigated. The obtained results show that based on chemical tests, all five types of polycarboxylate superplasticizers are the same with functional groups and their differences are in molar mass and the length of their side branches. Is. Finally, according to the performance of all five types of superplasticizers, it was found that with the increase in the length of the polymer chain and the length of the side branches, as well as the increase in the percentage of superplasticizer solids, the viscosity of plastic mortar and concrete decreases. Because the steric hindrance of polymer chains absorbed on the surface of cement particles increases and the possibility of accumulation of these particles, which reduces the flow of concrete, decreases. Due to the use of anti-foam additive, the air trapped in the concrete is reduced, but by increasing its amount from an optimal value, the water permeability of concrete increases and its efficiency decreases.

In the present paper, owing to importance of seeking a proper hydraulic response evaluation of the rubble mound structure against the incident waves, a systematic study has been carried out to investigate the wave overtoping on rubble mound breakwater. To gain this goal, numerical simulation was conducted an apposite range of sea state condition and geometrical parameters to investigate wave overtopping on rubble mound breakwater. In the current research, the effects of environmental parameters such as wave height, wave period, water depth and also a diversity of geometrical parameters including berm width, front slope and crest freeboard over the overtopping discharge, have been individually scrutinized and studied. The Flow-3D software has been used to simulate and solve the governing equations on the flow. The numerical results have been validated using experimental results. The computed results of wave overtopping discharge over parsian breakwater agree well with the physical model results. The present study, results showed that an increase in wave height, wave period and water depth would increase the wave overtopping on crest breakwater. Also, results outlined by enhancing the structural parameters like berm width and crest freeboard would increase the wave overtopping. As the slope gets steeper, the wave overtopping will be on a striking increase and strongly run-up level will be increased.

Opposition-based learning (OBL) is an effective approach to improve the performance of meta-heuristic optimization algorithms that are commonly used to solve complex engineering problems. In this paper, an opposite learning strategy is presented to combine with the Grasshopper Optimization Algorithm (GOA). In this proposed algorithm (OGOA), the solutions generated by the GOA algorithm are sorted and divided into good and bad solutions, then the bad solutions are selected to generate new solutions using opposition-based learning. To verify the performance of the proposed algorithm, some benchmark mathematical functions were tested. In addition, the performance of the OGOA algorithm was evaluated by implementing an optimal design of a real-scale reinforced concrete bridge. To identify the effective parameters in the design of structural components of reinforced concrete bridges, sensitivity analysis has been performed. In addition, the total cost of materials in the foundation columns and bridge deck was defined as an objective function. Also, the dimensions of sections and longitudinal steel bars are selected as design variables. The simulation results show the stability and robustness of the proposed OGOA method compared to the standard GOA. Also, the proposed OGOA is an efficient method for the optimal design of columns and decks of reinforced concrete bridges.