فهرست مطالب صالح قادرنژاد

One of the most crucial factors involved in the optimum design and cost estimation of rock sawing process is the rock abrasivity that could result in a significant cost increase. Various methods including direct and indirect tests have been introduced in order to measure rock abrasivity. The Schimazek’s F-abrasiveness factor ( ) is one of the most common indices to assess rock abrasivity.  is the function of three rock parameters including the Brazilian tensile strength ( ), median grain size ( ), and equivalent quartz content ( ). By considering its formulation, it has been revealed that the coefficient of each parameter is equal, which is not correct because each parameter plays a different role in the rock abrasion process. This work aims to modify the original form of  by introducing three correction factors. To calculate these correction factors, an integrated method based on a combination of the statistical analysis and probabilistic simulation is applied to a dataset of 15 different andesite rocks. Based on the results obtained, the values of -0.36, 0.3, and -0.89 are suggested as the correction factors of ,  and , respectively. The performance of the modified Schimazek’s F-abrasiveness factor ( ) is checked not only by the wear rate of diamond wire but also by the cutting rate of the wire sawing process of Andesite rocks. The results obtained indicate that the wear rate and cutting rate of andesite rocks can be reliably predicted using . However, it should be noted that this work is a preliminary one on the limited rock types and further studies are required by incorporating different rock types.

The longwall method is the most commonly method used in extraction of coal layers. The mining review records shows that the majority of the dangers of coal underground mines related to the sudden and uncontrolled roof fall-out of the stopes. Predicting the behavior and the ability to destroy the roof rock is very important for the successful execution of longwall method and reducing its risks. In this study, we will present a new fuzzy classification system by using the theory of fuzzy sets and fuzzy multi-criteria approach to evaluate the roof quality of the coal mines. 

In the first step, 8 parameters were selected as effective factors in the classification system. This selection was performed after reviewing the parameters affecting the roof quality of coal mines. The parameters include: Uniaxial Compressive Strength (UCS), Brazilian Tensile Strength (BTS), moisture sensitivity, spacing and continuity of discontinuities, thickness of layers, joints slope and difference of stopes’ and critical joints’ orientation.
 

Fuzzy classification system was presented after determining the parameters weight. The fuzzy classification system can evaluate and categorize the roof quality of coal mines. The classification qualitatively classified the quality of roofs in 3 classes (good, fair and poor). 

In order to evaluate the performance of the fuzzy classification system data of to 15 stopes in Eastern Alborz coal mines were evaluated. The results of this study showed that we can evaluate the quality of the roof rock with fuzzy classification system with high reliability in for coal mines roofs.

Grouting operations as one of the main methods of ground improvement play a key role in tunneling quality. Grouting reduces the amount of surface subsidence, maximum loads on the support systems and on tunnel convergence by improving strength parameters of ground. On the other hand, grouting operation causes an increase in time and cost, and also reduces the continuity of tunneling operations. According to positive and negative effects of grouting operations in tunneling projects, selecting the optimum grouting radius is very important. Vertical displacement of the crown and the roof of the tunnel, the horizontal displacement of walls, subsidence at the surface, axial forces, shear forces and bending moment on support systems and also time and costs were selected as main parameters in determining an optimum grouting radius. It was primarily aimed to calculate parameters of the Qazvin-Rasht railway tunnels using Finite Difference Method FLAC2D. In the next step, the values of selected parameters in various radiuses of grouting were calculated; then, the degrees of importance of each parameter were determined using Analytical Hierarchy Process. Finally, optimum grouting radius was selected among different alternatives by using VIKOR technique. In this study, 100 cm was selected as an optimal grouting radius for improving geomechanical and design parameters in KOUHIN tunnel.