Evaluation of the deformations occured in the run-off mine road and open-pit slopes due to the subsidence: A case study for soma-kısrakdere coal-field [Sübsidans nedeniyle elek yolu ve açık ocak şevlerinde meydana gelen deformasyonların değerlendirilmesi: Soma-kısrakdere kömür sahası için örnek bir çalışma]

Km2 and km3-lignite seams occur in the kısrakdere coal zone of miocene aged soma formation. the thickness of the km2 coal seam varies between 1 and 25 meters above the contact with the underlying mudstones at the base of the neogene sequence in the soma-eynez coal field. this field is one of the major coal production areas in turkey. underground coal production has been conducted in the km2-coal seam located above the m2-marl unit with miocene in age. subsurface openings in işıklar longwall-panels is located at 291 m depth from the ground-surface level created due to the underground coal mining. limestone (m3) and marl (m2) layers deformed and formed a jointed structure due to the subsidence. thus,these voids fractured and collapsed into the openings,with resultant lowering of the ground surface on the run-off mine road. the boundary of the surface area affected from the subsidence is defined by the angle of influence. subsidence caused differential settlement,with the greatest amount on a fault zone which vertically cuts the longwall panels,not near the center of the opening. as a result,asymmetrical subsidence profile developed in the area. the extend and size of ground surface cracks are expected to increase until the subsidence is completed in the area. the development of ground-crack patterns on the run-away mine showed some differences along the subsidence profile. different crack patterns were observed in the extraction and the gap zones (subsided zone) of this profile. these patterns were used in the constitution of subsidence profile in this work. subsidence was investigated in the cross-sections constructed by either vertical or parallel to the run-off mine road. different break angles were determined on these sections. the causes obtained different break angles are due to the preparation of the cross-sections both parallel and vertical to the fault zone and the coal seam,and different topography. because the cross-section constructed in n-s direction has a topography with slope. the angle of influence (limit angle) about the coal production panels were investigated in two different cross-sections. in the cross-section with n-s direction,limit angles for both sides of the longwall panel were determined by using the finite element method. in the crosssection with e-w direction,limit angles were determined on the cross-section produced with the help of the different subsidence crack patterns developed on the ground surface and the measurements of deformation on the survey points along the run-off mine road. the results obtained from the two methods were correlated with each other. it was determined that angular differences acquired from the two methods have a range changing between 7° and 10°. © 2014,tmmob - jeoloji muhendisleri odasi. all rights reserved.