Fault-controlling safe slope design procedure in an open-pit mine case study: Tuncbilek-Kutahya (Turkey) coal field

Miocene age coaly Tuncbilek basin (Kutahya/Turkey), which is named as "Tuncbilek Series", is located at nearly the top level of the continental sequence. Lignite coal vein is bedded nearly at the base of the M-2 unit consisting of claystone-marl interlayers. In the basin, the lignite coal vein with low dip angle (10-30 degrees) has been operated through open-pit and underground mining operations since the 1920s. At Y-2-panel where the coal will be operated with the open-pit mining technique, firstly overburden material is removed by establishing benches, the coal bed is opened up, and then the coal is taken from the panel. Different panel geometries in the field are prepared for coal production. This research aims to predict further possible debris slides which may develop due to existing faults with high dip before excavation works in open-pit mine sites and to prevent land instabilities by changing the preplanned positions of the slope portions with the help of kinematic analyses. In order to safely design the overall slopes of the Y-2 panel of Tuncbilek coal field, the relationships between the slopes and existing faults which may cause debris slides and those between the slopes and bedding planes and joints were kinematically investigated using the stereographic projection techniques before the excavations. Debris slides were determined in the slopes of A, C, H and L, wedge-type failures were determined in the slopes of B and C, and toppling failure was determined in the combined slope of E and F. The results obtained from these analyses suggest that the preplanned slope positions against probable slope instabilities should be changed to N5E/45NW for slope B, N36W/40SW for slope C, N80E/45SE for slope D, N20E/45SE for slopes E and F, N40W/45NE for slope G, N50W/45NE for slope H and N40W/45NE for slope L during the excavation phase

Application of two new stereographic projection techniques to slope stability problems

Slope instabilities were observed in the benches of the Alipasa open pit albite mine in the Menderes Massif forming one of the tectonic zones of the Anatolides in Turkey. Tension crack patterns observed in the berms were formed depending on the discontinuity planes cutting each other in the orthogneiss rock unit Two new stereographic projection methods in the stability analyses were applied by considering two cases; the first one that used the overlay linear-element process based on the geometrical conditions relating to the ground movement directions on the survey monuments, dip direction-lines of the foliation planes and sloped bench faces, and the second one that based on the determination of relationships between tension cracks on the upper slope face and discontinuity sets into the slope forming release and lower surfaces of the sliding blocks. It is kinematicly investigated with the overlay linear-element process whether an agreement among these parameters is presence or not If there is, this case is indicated that the planar sliding was occurred on the foliation plane beforehand, or in a critical balance in terms of the planar-sliding of a slope. The proposed method will be useful to determine quickly and efficiently whether the relationships between the discontinuity sets into the rock masses and tension cracks on the berms or upper slope faces in an open pit or not In addition, whether the angular values from the kinematic analysis are in agreement with the ones directly measured from the field was also investigated. This study involved making stability assessment of the already failed and standing sloped bench faces in the open pit using the stereographic projection techniques and software. (C) 2014 Elsevier Ltd. All rights reserved

Abandoned stone quarries in and around the Izmir city centre and their geo-environmental impacts - Turkey

There are 70 abandoned quarries in and around Izmir city centre. Of these quarries, 56 are in andesites, 2 are in dasitic lavas, 4 are in flysch and 8 are in limestones. The quarries initially located near the Izmir city centre, are now within the city centre because of the expansion of the urbanization due to the rapid increase of population. Geo-environmental problems identified in the abandoned quarry sites are slope stability problems such as sliding and toppling. Geotechnical study of the abandoned stone quarries in and around the city centre of Izmir which has been carried out involves the recording and determining the properties of discontinuities for stability assessment of already-failed and standing slopes in the quarries, using stereographic projection techniques, and the statistical evaluation of different types of rock mass movements in these quarries. The number of mass movements that bad already occurred and are likely to occur in 70 quarries lying in and near Izmir have been determined as 84 totally. Stability analyses of rock slopes have shown that rock falls, toppling, plane and wedge failure-type rock mass movements are more common in the south of Izmir Bay, but toppling-type slope failures are more frequent in the north. (C) 2004 Elsevier B.V. All rights reserved