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Modelling of longwall roof rock behaviour – A rock mass classification approach
Published in A. Kidybiński, M. Kwaśniewski, Modelling of Mine Structures, 2021
For the four parameter classification scheme as discussed above, data from geotechnical logging of roof upto a height equal to 10 times the extracted seam thickness, should suffice.For ensuring quality, it would be useful to undertake underground diamond core drilling using double-tube core barrel. The values of uniaxial compressive strength of strata could be determined in the laboratory, or in the field using a point load strength tester. The average core size,which is used as a measure of the structure of the roof rocks, is determined from a semi-log plot of size distribution of core pieces obtained in drilling, similar to the standard grain size distribution of soils.
Geology of Urban Watersheds
Published in Daniel T. Rogers, Urban Watersheds, 2020
Stratigraphy is the study of rock layers or unconsolidated sediment and strata; particularly their ages, composition, and relationship with other layers (AGI 1962; Christopherson 2008). In geology, the term strata refers to the layers of rock or sediment with internally consistent characteristics that distinguishes it from contiguous layers (Krumbein and Sloss 1963). Each individual layer or stratum is generally one of a number of parallel and originally horizontal layers that were deposited by natural forces and lay one upon the other. Therefore, the study of stratigraphy of a particular area provides important clues concerning its geologic history. The origins of stratigraphy date back to Italy in the mid-1600s. A Danish anatomist named Nicolas Steno was studying shark teeth and noticed the similarity to fossils of shark teeth in Italy. He deduced that the fossils were remnants of past life. Based on his observations, he later deduced that deep rock layers in the Earth were older and that successive layers above gradually become younger. This was later expounded by Hutton and became known as the Principle of Superposition described below (Hongren 2004).
Deep mining rock mechanics in China—the 3rd mining technology revolution
Published in Vladimir Litvinenko, EUROCK2018: Geomechanics and Geodynamics of Rock Masses, 2018
The rock mechanics properties used in the simulation are shown at Table 1. The roof strata are in ascending order sandy mudstone, gritstone. While the floor strata are in decline order argillaceous siltstone and fine sandstone. In the numerical simulation, there were seven types of strata considered, from the top to the bottom as follows: loess, sandstone, gritstone, sandy mudstone, coal, argillaceous siltstone and fine sandstone.
GIS-based soil planar slide susceptibility mapping using logistic regression and neural networks: a typical red mudstone area in southwest China
Published in Geomatics, Natural Hazards and Risk, 2021
Shuai Zhang, Can Li, Jingyu Peng, Dalei Peng, Qiang Xu, Qun Zhang, Bate Bate
The topological attributes, such as elevation, slope angle, slope aspect, slope structure, and curvature, are derived from the digital elevation method (DEM) with a resolution of 30 m. These are generated from a triangulated irregular network (TIN) model. As shown in Fig. 8b, the potential soil planar slides in the study area are mainly located between elevations of 500 m and 1000 m. The soil planar slides in the red layer area of Nanjiang are mainly distributed within the elevation range of 230–1500 m, and especially between 500–1000 m. According to the statistics, the elevation of the soil planar slides follows a normal distribution. The landslide densities in elevations of 230–500 m, 500–1000 m and greater than 1000 m are 0.63 landslides/km2, 0.68 landslides/km2, and 0.20 landslide/km2, respectively (Fig. 9b). It can be found that not only does the slope structure at the elevation of 500–1000 m is mainly monoclinic, making it easy for a landslide to occur, but it is also due to intense human activities, including cropland irrigation and engineering excavations. These human activities are concentrated mainly within the same range of elevation, which further reduces the stability of the slope. As shown in Fig. 8c, the density points of landslides with a slope angle smaller than 10°, between 10°–30°, and larger than 30° are 0.542, 0.664, and 0.346 landslides/km2, respectively. Soil planar slides are normally distributed in the monoclinic region within the range of 10°–30°. Rainwater can gather and penetrate the surface of the gentle slopes easily. Moreover, the dip-direction of the bedding slope is consistent with the inclination direction, which leads to the occurrence of bedding failures along with the soil-bedrock interface. Local human activities and land use within the affected area can accelerate the occurrence of landslides. Furthermore, the soil planar slides are evenly distributed at different slope aspects in the red mudstone area of Nanjiang, where landslides in the directions of 90°–180° and 270°–360° are the most accounted for (Fig. 9d). The majority of the soil planar slides are distributed in dip slopes with a density of 0.5926 landslides/km2, followed by oblique slopes with a density of 0.5811 landslides/km2, and anti-dip slopes of 0.5515 landslides/km2 (Fig. 9e). The dip slopes are prone to landslides due to the underlying dipping strata. Large sheets of rock tend to slide down the dip slopes, whereas for anti-dip slopes, the effect is the opposite.