Preprint Article Version 1 This version is not peer-reviewed

Overburden Failure and Ground Pressure Behaviour of Longwall Top Coal Caving in Hard Multi-layered Roof

Version 1 : Received: 10 April 2018 / Approved: 11 April 2018 / Online: 11 April 2018 (12:51:34 CEST)

How to cite: Zhu, Z.; Zhang, H.; Nemcik, J.; Cao, C.; Han, J. Overburden Failure and Ground Pressure Behaviour of Longwall Top Coal Caving in Hard Multi-layered Roof. Preprints 2018, 2018040149 (doi: 10.20944/preprints201804.0149.v1). Zhu, Z.; Zhang, H.; Nemcik, J.; Cao, C.; Han, J. Overburden Failure and Ground Pressure Behaviour of Longwall Top Coal Caving in Hard Multi-layered Roof. Preprints 2018, 2018040149 (doi: 10.20944/preprints201804.0149.v1).

Abstract

In the extra-thick coal seams and multi-layered hard roofs, the longwall hydraulic support yielding, coal face spalling, strong deformations of goaf-side entry, and severe ground pressure dynamic events typically occur at the longwall top coal caving longwall faces. Based on the Key strata theory an overburden caving model is proposed here to predict the multilayered hard strata behaviour. The proposed model together with the measured stress changes in coal seam and underground observations in Tongxin coal mine provides a new idea to analyse stress changes in coal and help to minimise rock bursts in the multi-layered hard rock ground. Using the proposed primary Key and the sub-Key strata units the model predicts the formation and instability of the overlying strata that leads to abrupt dynamic changes to the surrounding rock stress. The data obtained from the vertical stress monitoring in the 38 m wide coal pillar located adjacent to the longwall face indicates that the Key strata layers have a significant influence on ground behaviour. Sudden dynamically driven unloading of strata was caused by the first caving of the sub-Key strata while reloading of the vertical stress occurred when the goaf overhang of the sub-Key strata failed. Based on this findings several measures were recommended to minimise the undesirable dynamic occurrences including pre-split of the hard Key strata by blasting and using the energy consumption yielding reinforcement to support the damage prone gate road areas. Use of the numerical modelling simulations was suggested to improve the key theory accuracy.

Subject Areas

multi-layer hard roof; failure of overlying strata; ground pressure behaviour; longwall top coal caving

Readers' Comments and Ratings (0)

Leave a public comment
Send a private comment to the author(s)
Rate this article
Views 0
Downloads 0
Comments 0
Metrics 0
Leave a public comment

×
Alerts
Notify me about updates to this article or when a peer-reviewed version is published.