Calculation of periodic roof weighting interval in longwall mining using finite element method

The state of periodic loading and the interval of periodic roof weighting have an important role in geomechanical stability and, hence, in the continuity of longwall mining operations. In this paper, the mechanism of roof caving in longwall mining—together with the effect of engineering and geomechanical properties of surrounding rock masses on the magnitude and timing of periodic loading—is studied. For this purpose, a longwall mine is first modeled using Phase2 software, and then, by simulating the roof caving process, the periodic roof weighting intervals is calculated. Based on the numerical modeling, the first roof weighting interval and the periodic roof weighting interval are calculated as 27.2 and 12.1 m, respectively. Sensitivity analysis is then applied to determine the effect of changes in the mechanical properties of the rock mass, especially in the main roof and immediate roof. The results of the analysis show that as GSI and quality of the immediate roof increases, the periodic roof weighting interval also increases. Hence, the applied algorithm in this research study can effectively be utilized to calculate the periodic roof weighting interval in the longwall mining method.     

Optimizing post-mining land use for pit area in open-pit mining using fuzzy decision making method

Open-pit mining method has severe environmental impacts which should be prevented, monitored, controlled, and reduced by mined-land reclamation process. After mine closure, a permanent post-mining land use should be implemented as an appropriate choice for using different sections of mined land. The most appropriate alternative of post-mining land use for each section of mined land is presented as the optimum post-mining land use. Pit area among different sections of mined land has more significant effects on the environment and also on defining the optimum post-mining land use for other sections of mined land. Though there are several alternatives and criteria for defining the optimum post-mining land use, the multi-attribute decision-making methods can be efficient techniques in this regard. The nature of the effective parameters used for defining the optimum post-mining land use is the same as Fuzzy numbers including incremental changes without definite limits. Thus, application of the Fuzzy multi-attribute decision-making modeling can produce more reliable results than that of other techniques. As well, pair-wise comparisons and judgments through Fuzzy numbers have proper consistency with the nature of the effective parameters; therefore, a model is developed to attain the optimum post-mining land use for pit area through Fuzzy analytical hierarchy processing. As a case study, the model was implemented in Sungun copper mine in the Northwest of Iran. Forestry?Clumber production was defined as the optimum post-mining land use containing the greatest relative importance coefficient 3.019 for the pit area in this mine.     

Application of TOPSIS method for selecting the most appropriate blast design

Blasting operation should be performed satisfying some criteria, such as fragmentation, flyrock, and cost. To reach the most appropriate alternative among previous performed blast designs, all the criteria should be simultaneously considered in the analysis. To do so, rather new emerging approaches such as Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), a branch of multi-criteria decision-making techniques could be applied. Using TOPSIS method, the present study tries to investigate the blasting operation in the Tajareh limestone mine and select the most appropriate blasting pattern. According to the obtained results, alternative ten with hole diameter of 64 mm and staggered pattern designed by Ash formula, was selected to be the best decision. Application of this alternative comparatively satisfies both fragmentation and flyrock.     

Effect of Pile Driving on Ground Vibration in Clay Soil: Numerical and Experimental Study

Geotechnical and Geological Engineering - In this study, peak particle velocity (PPV) values for driving three piles with diameters of 40 cm, 50 cm, and 70 cm in a clayey...