Based on extensive experience in shield support design and the results of underground measurements observations, major factors influencing stability roof retreat longwall panels were determined. A practical method for assessing risk falls is presented. It a combination empirical methods expert techniques that enable investigators to determine probability potential consequences falls. This report includes an example applying one panel. The decision tool mining management when planning fall...

The case study describes longwall coal seam A in a hard mine, where face stability loss and periodic roof fall occurrences had been registered. authors have attempted to explain the situation based on in-situ measurements observations of working as well numerical simulation. calculations included several parameters, such powered support geometry form canopy ratio, which is factor that influences load distribution along canopy. Numerical simulations were realized rock mass model representing...

In Poland, the mining waste from underground coal mines is commonly deposited in surface dump sites, forming slopes or piles of materials dozens meters high. Because loose structure a mine slope, landslides may occur after heavy rainfall. This requires significant labor costs reforming sites and disturbs continuity depositing operations. Moreover, if located built-up areas, such as Janina dump, apparently can threaten even lives properties. Therefore, stability analysis necessary for...

This article focuses on the difficulties in ensuring longwall stability resulting from wrong geometric form of structure powered support sections.The authors proved, based in-situ measurements and numerical calculations, that proper cooperation with rock mass requires correct determination point for hydraulic legs along length canopy (ratio), as well inclination shield section roof support.The lack these two fundamental elements may lead to drops directly impact production results safety...

The main goal of the paper is numerical simulation for investigation damage causes in working a longwall located under unmined panel. presents results model-based research on stability roof zone subject to cave-in mining, taking into account influence mining conditions form an coal seam 115 m above exploited seam. It geometry rock mass study, discretization area solution, and gives overview assumptions used build model. authors discuss simulations phenomena formation falls longwall. Based...

Geomechanical assessments of lonGwall workinG stability-a case study the stability longwall mining is one most important and difficult aspects underground coal mining.the loss can threaten lives, disrupt continuity operations, it requires significant materials labour costs associated with replacing damages.in fact, affected by many factors combined.Each has its own unique complex geological conditions.therefore, any an individual analysis.in Poland, been applied in for years.the working...

Difficulties observed in operating powered roof support during work lower range... 45

In Poland, for underground hard coal seam extraction, the longwall method is used. Retreat longwalls with natural roof caving in gob are most common. Currently it estimated that about a half of output Poland originates from seams located areas rock burst hazard. The article shows information 18 bursts, and 14 other seismic events which occurred between 2003 2012 mines belonging to one companies Poland. addition, negative consequences those dynamic phenomena workings described. next part...

Abstract The problem of cooperation powered roof support with the floor in aspect shaping its design is presented. From analysis simplifying assumptions considered so far methods for determination support’s base pressure on floor, it results that they are not satisfied case bases catamaran type, commonly used currently manufactured supports. Model lying prepared by finite elements method described and computer simulation action given. Considering numerical analyses, factors influencing...

Abstract Results of experimental tests aiming at determination base pressure on the floor, carried out within “Geosoft” project, are presented. The included stand with use unique measuring instrumentation and special hydraulic cushion as well load roof support set to in operating longwall panel. measurement results confirmed necessity consider 3D model cooperation floor. Factors having impact distribution floor its maximal value were identified, taking into account test results.

Abstract Shield supports are usually perceived as devices consisting mainly of mechanical and hydraulic parts, while other apparatus, related to electronics, is often treated a necessary supplement the system which ensures its control. However, development features closely latest electronic equipment in mining complexes, connected with measuring registration possibilities, also allows for more frequent use various types monitoring. It enables observation operation complex real time or slight...

Currently available field rock mass deformability determination methods are rather difficult to perform, due their complexity and a time-consuming nature.This article shows results of suitability assessment Pen206 borehole jack (a hydraulic penetrometer) for measurements.This type the is widely used in Polish hard coal mining industry.It was originally intended only quick strength parameters determination.This describes an analysis scope basic modifications performed mainly on head.It...

Abstract The paper presents the research on pressure variation in elements securing shield support against overloading. chosen constructions of connecting pipe were analysed and its flow characteristic determined. operational parameters different connections also considered light their interaction with whole hydraulic control system. results allowed to determine optimal curve regard safety