الفهرس 
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Abstract
The main purpose of mine workings is the exploitation of ores and minerals that are used in different aspects of life The increasing demand for minerals and ores and the difficult mining conditions at greater depths make the longwall mining method a good choice in mining The accurate forecast of rock roof loading (RRL) provides longwall face stability during ore exploitation and allows the hydraulic supports to move more safely The main goal of this thesis is to study of some factors affecting the stability of supporting systems in longwall faces and selecting the suitable capacity of hydraulic supports Many researchers have proposed a lot of methods, approaches, and theories to
interpret the roof-support interaction A better understanding of strata behavior in a given geo-mining region is essential to enhance stability and reduce roof collapses The stability and balance of work inside the mines have been affected by many aspects, such as rock roof loading over the supporting systems The most important Approaches which are taken into consideration to determine the rock loading are the
cavability concept, Terzaghi, Wilson, Evans, Ryncarz, Kumar, and Bilinski
Approaches This study has shown that the significant natural factor affecting the stability of underground workings is roof conditions and their behavior over the supporting systems The most important technical factors that affect roof control are the rate of face advance and hydraulic support selection The major scope of this study is to find
answers to the mining problems that cause roof failure and hydraulic support
collapse. In this work, we try to solve these problems by:
1- Studying the technical and natural factors which affect the stability of the roof and the hydraulic supports.
2- Applying different methods and approaches to determine the rock roof loading over the supporting systems.
3- Laboratory testing of immediate roof rock samples to obtain their swelling
characteristics.
4- Best selection of hydraulic support capacity that is appropriate for working
conditions.
This study is applied at the Abu-Tartur phosphate underground phosphate mines The hydraulic supports have been damaged because of the lack in the capacity of them To understand the behavior of the immediate roof rocks some laboratory tests were performed on samples of immediate roof rocks (clayey shale)
to determine the free swelling index and the swelling pressure The results have shown that the free swelling index equals 100 %, and the swelling pressure in water and humid air equals 1342 KPa and 194 KPa, respectively Moreover it is found that there are three sources of loads acting on the supporting systems at Abu-Tartur phosphate underground mines These sources of loads are immediate roof cavability, main roof tilting, and swelling pressure The sum of these loads equals 1557 KPa The hydraulic supports that were used at
Abu-Tartur phosphate underground mines are the Joy Mining machines with a
capacity of 900 tons, which are not compatible with the roof loading conditions Then the hydraulic supports which will be used in the future must be of a larger capacity equal to 1286 tons instead of 900 tons, with a percentage increase in the hydraulic support capacity of about 43 %.