Abstract
The shield pressure cannot always be used to represent the upper load of longwall panels, since its value is steady or even decreases by the yielding action. However, the leg pressure increment of the shield (LPIS) at the initial stage is not influenced by yielding and could therefore be an important factor to judge the state of overlying loads. In this study, a mechanical model is established to analyze the relationship between the overlying loads of the main roof and LPIS after cutting. There is a linear positive correlation between leg pressure increment and overlying loads and a second-order relationship between leg pressure increment and length of main roof cantilever in the proposed model. Therefore, it can be used to determine the magnitude of roof weighting strength in different periods as well as the length of the main roof cantilever in a period. Finally, the mine pressure difference between the period of fully mechanized mining and the period of fully mechanized caving mining in the MinDong-1 coal mine serves to verify the rationality of the proposed model.
Highlights
Longwall mining plays a predominant role in coal mining in China, owing to its high-efficiency superiority in coal production [1, 2]
Erefore, the magnitude of the leg pressure increment ΔP can represent the strength of the strata pressure based on the results from the leg pressure increment of the shield (LPIS) model
We theoretically suggest selecting the same initial setting pressure to estimate the length of the cantilever in Chapter 2.2, it appeared that the initial setting pressure had various values influenced by field operations
Summary
Longwall mining plays a predominant role in coal mining in China, owing to its high-efficiency superiority in coal production [1, 2]. The shield’s load capacity increases along with the increase of the panel production and automation, as reported by the case in Shangwan mine located in Inner Mongolia It presently reaches 26,000 kN and has resulted in an increase in the diameter of the shield leg [9]. High capacity of the shield and the aforementioned theories cannot solve all the issues in the longwall panel Disasters such as shield crushing [10, 11] and rockburst [12] still occur during the retreating of some panels due to complex engineering-geological conditions. Shield pressure could be an effective factor to represent the upper loads of longwall panels, but its value is either steady or decreases with yielding as shown in Figure 1 (stage C). Results from the proposed LPIS model and some other monitoring approaches in longwall panels can support each other
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
