Abstract
This paper studies the stability and ground behavior of the main roadway excavated in a soft rock mass at PT Gerbang Daya Mandiri (GDM) underground coal mine in Indonesia. The stability and ground behavior of the main roadway under various geological and excavation conditions was analyzed and discussed through numerical simulations and field measurement data. Based on the results, it is found that the mechanical conditions of claystone and the geological conditions of the roof have an obvious impact on the stability of the main roadway. The large roof displacement of the roadway occurs when the roadway is excavated in the deteriorated claystone, whereas the small roof displacement occurs when the roadway excavation is made in the undeteriorated claystone and when the coal layer is present in the roof. Under undeteriorated conditions of claystone, the small failure zone and displacement of the roadway occur. The current support system using the steel arch SS400 is effective to control the roadway stability. As the claystone has deteriorated due to groundwater, the failure zone and displacement expand considerably, and the roadway stability decreases significantly. The use of the current support system (steel arch SS400) is difficult to control the stability of the main roadway. Under this situation, a stronger steel arch SS540 is recommended to apply. Furthermore, the presence of a coal layer during the excavation considerably improves the stability of the main roadway. Compared with the roadway excavated in claystone only, the displacement decreases significantly. In addition, by leaving a thicker coal layer in the roof, a better stability condition of the roadway can be achieved.
Highlights
In this research, the PT Gerbang Daya Mandiri (GDM) underground coal mine is selected as a representative mine site for the study
From this figure, when the roadway was excavated in undeteriorated claystone, the steel arch SS400 support with 1 m space could only stabilize the main roadway until 35 m depth, and it will be difficult to maintain the roadway at a deeper depth
The conditions of GDM underground coal mine are described in this research
Summary
The PT Gerbang Daya Mandiri (GDM) underground coal mine is selected as a representative mine site for the study. The small roof movement was observed when the main roadway was excavated in the undeteriorated claystone, and the coal layer was present in the roof. The total roof displacement obtained from Telltale 25, 29, and 28 was about 90 mm, 4.5 mm, and 1.5 mm, respectively From these trends, it can be considered that the presence and thickness of the coal layer in the roof have an obvious impact on the stability of the main roadway. Based on the field measurement data, it can be found that the stability and ground behavior of the main roadway varies greatly depending on the conditions of claystone and the presence of a coal layer in the roof. It is clear that a large displacement is expected when the roadway excavation is made in a deteriorated claystone and no coal layer is present in the roof. The results of the study will provide a fundamental understanding of the main roadway stability so that mining engineers of the GDM coal mine can use them as the guidelines for determining what geological and excavation conditions that they have to pay more attention to
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
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
