1、英文原文Improved roadway roof support design for Anglo American Metallurgical Coals underground operationsI. Canbulat*In order to ensure the stability of roadways, Anglo American Metallurgical Coal (AAMC) has developed a roof support design methodology that integrates analytical, numerical and empirical
2、 modelling through an integrated design methodology. This methodology currently is based on a deterministic approach. However, an improved methodology, based on a stochastic modeling technique, has also been developed and is being evaluated for various roof support design practices. The main advanta
3、ge of this methodology is that the final design is based on the probability distributions of input parameters, thus the outcome is based on a distribution of factors of safety. This methodology has been evaluated at AAMC operations for the designs of roof support in critical areas and offers and imp
4、roved method for determining the roof support requirements. A demonstration of the application of this methodology for the design of install road roof support at Moranbah North Mine is presented in this paper.Keywords: Coal mine roof support, Uncertainty, Probabilistic designIntroductionLongwall min
5、ing is a highly productive underground mining method in which a block of coal (i.e. panel),approximately 200450 m wide and typically 24 km long is extracted in a single continuous operation. As the coal is cut, the longwall face is supported with hydraullically operated supports called shields, whic
6、h provide a safe working environment by supporting the roof and allowing the longwall equipment to advance. The predominant method of longwall mining in Australia is retreat longwall mining in which two sets of entries are driven either side of the proposed longwall block. The entries are usually 56
7、 m wide and are connected at the inbye end to establish the longwall block. The longwall face equipment (i.e. shearer and shield supports) is installed in this connecting roadway and as mining continues into the panel, back to the original development, the entries are allowed to collapse behind the
8、face line to form part of the mined out area.The entries are known as the maingate (MG) and tailgate (TG). Generally, the MG contains the conveyor belt and the pantechnicon for providing power and logistics to the longwall face and the TG serves as a return airway and as a second egress. A typical r
9、etreating longwall layout is presented in Fig. 1.Longwall retreat mining has traditionally produced coal using two methods, bidirectional and unidirectional mining cycles. The use of bidirectional cutting has always been seen as more productive on longer faces.However, as shearer power and haulage s
10、peeds have increased, thicker seams have been targeted, and environmental considerations increase, unidirectional cutting has become more competitive and can be more productive than bidirectional cutting (Mitchell, 2009).There have been significant improvements in longwall support design, performanc
11、e and reliability, since the first fully mechanised faces were imported from England in the late 1960s and early 1970s. Since that time,support capacity has increased from just a few hundred tonnes per four leg support, to well over 1000 t on a modern two leg support at Moranbah North Mine (MNM). Th
12、is has resulted in dramatic improvements in face and roof control in the tip to face region.Improvements in design and reliability of support hydraulics has also contributed to improved ground control on longwall faces, although poor maintenance of such systems can still result in inadequate support
13、, even on current high technology faces (Hebblewhite, 2009).Anglo American Metallurgical Coal (AAMC) operates four longwall mines located in Central Queensland.There is an increasing emphasis on the reliability at these operations as the longwalls are getting deeper and facing more geologically chal
14、lenging conditions; such as increasing depth, more adverse geological conditions resulting in higher vertical and horizontal stresses and weaker ground conditions. Under these adverse conditions,geotechnical designs (e.g. panel orientation, roof support and pillar design) become critical to mitigate
15、 the potential risks. In addition, Anglo Americans Vision is to achieve zero harm through the effective management of safety at all businesses and operations. In order to accomplish this vision, AAMC has developed a proactive ground control management system for the safe and efficient operation of u
16、nderground reserves.Proactive ground control management involves an understanding of the impacts of the geotechnical environment on likely ground behaviour and consists of approximately 15 major elements. One of the most important elements of this proactive ground control management is to utilise a roof support design methodology that considers different failure mechanisms and also takes into account all important elements. The design methodology becomes e
