The Specific Length of an Underground Tunnel and the Effects of Rock Block Characteristics on the Inflow Rate

The specific length of a tunnel (STL) and a new analytical model for calculating the block surface area of the rock mass are introduced. First, a method for determining the appropriate length of a tunnel for a numerical simulation is described. The length is then used to examine the correlation between the inflow rate to the tunnel and the block volume, the block surface area, and the fracture intensity (P32) through analytical and numerical modeling. The results indicate that the length of the tunnel should at least be equal to the least common multiple (LCM) of the apparent spacings of the joint sets at the wall of the tunnel to obtain the more reliable and immediate results for the inflow rate to a tunnel that is excavated in a fractured rock mass. A new analytical model was developed to calculate the block surface area and determine the essential joint set parameters, which include the dip, dip direction, and spacing. The determination of the rock block characteristics through numerical modeling requires considering the intact block for calculations. The results indicated that the inflow rate to the tunnel increased with an increase in fracture intensity and a decrease in block volume and surface area. The STL and the analytical model used for calculating the block surface area are validated through numerical simulations with 3DEC software version 7.0.

Field Investigation and Experimentation of Expansive Mortar in Dimension Stone Mining

Nature has blessed Pakistan with huge reserves of dimension stone that are mostly extracted through conventional mining methods. Different mechanized techniques have been tested and some give propitious results but failed to get popularity in the dimension stone sector of Pakistan. One such attempt is made in this work and a non-conventional method expansive mortar (EM) is introduce into this sector, to reduce the waste and cracks that are produced during conventional mining method (drilling and blasting). The results proclaim that expansive mortar efficiently reduced waste production and increased productivity. Through conventional method 470 MTs economical blocks were extracted from a block of 10758 cubic ft, earning $1121.95. In contrast, expansive mortar was applied to a block volume of 6750 cubic ft, in which economical blocks extracted were weighing 489 MTs, earning $5766.46. These encouraging figures replicate more than five-time increase in profit and high reduction in waste production.

PENGEMBANGAN BAHAN AJAR MATEMATIKA DARING UNTUK MENINGKATKAN KEMAMPUAN PEMECAHAN MASALAH

The objectives of this study were (1) to develop online-based mathematics teaching materials for distance learning in the pandemic era, and (2) to determine the level of validation of the development of online-based mathematics teaching materials based on expert validation tests. This R&D research uses the ADDIE model which consists of analysis, design, development, implementation, and evaluation. The subjects of this study were class teachers and 5th grade students of SD Negeri Plumutan, Bancak, Semarang Regency. The results of this study are (1) there are five stages in the development of online-based mathematics teaching materials, namely making indicators, making learning objectives, collecting mathematics learning materials for cube and block volume materials, compiling materials in the form of LKPD, making Weebly Websites, and preparing lesson plans. (2) based on the validation test which includes material experts get a percentage of 85% with the criteria of "very good", teaching materials experts get a percentage of 90% with the criteria of "very good", and material experts get a percentage of 75% with the criteria of "good".

A method to determine the relative importance of geological parameters that control the hydraulic erodibility of rock

The most common methods used to evaluate the potential hydraulic erosion of rock are index-based methods, which correlate the force of flowing water and the capacity of a rock to resist erosion. This capacity is evaluated using erodibility indices, which combine a set of specific geological parameters. Nonetheless, there exists no clear consensus in regard to the relative importance assigned to the geological parameters. Our study proposes (i) a review of the existing index-based methods used to evaluate the hydraulic erodibility of rock, and (ii) a method to determine the relative importance of the geological parameters governing the erodibility of rock. The developed approach relies on a large data set of case studies providing details of unlined spillways subjected to erosion. We demonstrate that the analyzed geological parameters can be classified according to their relative importance—from highest to lowest—as follows: (1) joint shear strength, (2) nature of the potentially eroding surface, (3) rock block volume, (4) joint opening, (5) rock block's shape and orientation relative to flow direction, and (6) the rock mass deformation module. This ordering of the relative importance of the geological parameters agrees largely with previously established orderings that were based on field observations.

Preliminary Modeling of Rockfall Runout: Definition of the Input Parameters for the QGIS Plugin QPROTO

The identification of the most rockfall-prone areas is the first step of the risk assessment procedure. In the case of land and urban planning, hazard and risk analyses involve large portions of territory, and thus, preliminary methods are preferred to define specific zones where more detailed computations are needed. To reach this goal, the QGIS-based plugin QPROTO was developed, able to quantitatively compute rockfall time-independent hazard over a three-dimensional topography on the basis of the Cone Method. This is obtained by combining kinetic energy, passing frequency and detachment propensity of each rockfall source. QPROTO requires the definition of few angles (i.e., the energy angle ϕp and the lateral angle α) that should take into account all the phenomena occurring during the complex block movement along the slope. The outputs of the plugin are a series of raster maps reporting the invasion zones and the quantification of both the susceptibility and the hazard. In this paper, a method to relate these angles to some characteristics of the block (volume and shape) and the slope (inclination, forest density) is proposed, to provide QPROTO users with a tool for estimating the input parameters. The results are validated on a series of case studies belonging to the north-western Italian Alps.

Preliminary Modeling of Rockfall Runout: Definition of the Input Parameters for the Plugin QPROTO

The identification of the most rockfall-prone areas is the first step of the risk assessment procedure. In the case of land and urban planning, hazard and risk analyses involve large portions of territory and thus preliminary methods are preferred to define specific zones where more detailed computations are needed. To reach this goal, we developed the QGIS-based plugin QPROTO, able to quantitatively compute rockfall time-independent hazard over a three-dimensional topography on the basis of the Cone Method. This is obtained by combining kinetic energy, passing frequency and detachment propensity of each rockfall source. QPROTO requires the definition of few angles (i.e., the energy angle ϕ_p and the lateral angle α) that should take into account all the phenomena occurring during the complex block movement along the slope. The outputs of the plugin are a series of raster maps reporting the invasion zones and the quantification of both the susceptibility and the hazard. In this paper, we propose a method to relate these angles to some characteristics of the block (volume and shape) and the slope (inclination, forest density), to provide QPROTO users with a tool for estimating the input parameters. The results are validated on a series of case studies belonging to the North Western Italian Alps.

Application of Unmanned Aerial Vehicle Data and Discrete Fracture Network Models for Improved Rockfall Simulations

In this research, we present a new approach to define the distribution of block volumes during rockfall simulations. Unmanned aerial vehicles (UAVs) are utilized to generate high-accuracy 3D models of the inaccessible SW flank of the Mount Rava (Italy), to provide improved definition of data gathered from conventional geomechanical surveys and to also denote important changes in the fracture intensity. These changes are likely related to the variation of the bedding thickness and to the presence of fracture corridors in fault damage zones in some areas of the slope. The dataset obtained integrating UAV and conventional surveys is then utilized to create and validate two accurate 3D discrete fracture network models, representative of high and low fracture intensity areas, respectively. From these, the ranges of block volumes characterizing the in situ rock mass are extracted, providing important input for rockfall simulations. Initially, rockfall simulations were performed assuming a uniform block volume variation for each release cell. However, subsequent simulations used a more realistic nonuniform distribution of block volumes, based on the relative block volume frequency extracted from discrete fracture network (DFN) models. The results of the simulations were validated against recent rockfall events and show that it is possible to integrate into rockfall simulations a more realistic relative frequency distribution of block volumes using the results of DFN analyses.