Abstract
Improving roadway stability in deep underground mines is quite challenging, as the conventional support structures easily fail. Roadway collapse and large deformation occur just several months after tunnel excavation. In this study, a relatively new prereinforcement technique, the jet grouting (JG), is introduced to improve roadway stability. A field test was performed for evaluating the practicability and applicability of JG in soft coal mass. A series of laboratory tests were conducted to assess the properties of coalcrete (coal-grout after JG treatment). A two-dimensional numerical model was established for validating the input parameters. Based on the verified model, three JG support cases for roadway were modeled and compared with a conventional support case, namely, the currently used support in this mine “rock bolts + U-shaped steel set + shotcrete.” The results show that the proposed prereinforced JG support structures can considerably control the deformation and failure zone of the roadway and improve the bearing capacity of coal mass. The mechanism of maintaining roadway stability using JG techniques is further revealed. Some suggestions are further presented to improve the stability of the jet-grouted roadway.
Highlights
Improving roadway stability in deep underground mines is quite challenging, as the conventional support structures fail
Based on the verified model, three jet grouting (JG) support cases for roadway were modeled and compared with a conventional support case, namely, the currently used support in this mine “rock bolts + U-shaped steel set + shotcrete.” e results show that the proposed prereinforced JG support structures can considerably control the deformation and failure zone of the roadway and improve the bearing capacity of coal mass. e mechanism of maintaining roadway stability using JG techniques is further revealed
Due to the angle effect of the JG support system on the roadway, the high-stress concentration zone is in the corner, which is negative for the long-term stability of the whole support structure. e inverted arch can improve the stress state and provide a certain bearing capacity, which could effectively transfer the stress into deep rock and reduce floor heave
Summary
Experiment and Application of Coalcrete on Roadway Stability: A Comparative Analysis. With the conventional compound support system (U-shaped steel set + rock bolts + shotcrete), large roadway deformation still occurred just 1 month after tunneling work started. Considering these cases, the jet grouting technique was first tried in soft coal mass to improve its self-stabilization ability and form a reinforced support system for the roadway. The coalcrete columns can improve the shear strength of soft coal mass before excavation and resist the surrounding stress after tunneling by constructing a stable arch structure [25]. The model domain is 5D × 5D and the appropriate mesh discretization is 3-noded triangular elements. e geometry of the model is shown in Figure 3(a) and the enlarged rectangular region represents different support systems, i.e., conventional support system (rock bolts + U-shaped shed + shotcrete) (Figure 3(b)) and
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
