This paper addresses the monitoring results in the maingate No. 080 5253 at the Paskov Mine, in the Czech Republic. In the main longwall gate in question, the convergence of the mine affected by longwall mining 080 210, movement from loosening of the rock layers using extensometers, and the load steel frame construction reinforcement by dynamometers is monitored. In addition to in-situ measurements, research laboratory measurements were carried out to evaluate the influence of geological conditions, based on the RQD parameter of boreholes drilled before the extraction. The results show that geology, the character of the overlying rocks, and rock stress ratios play important roles in the effectiveness of the combined rock bolt and steel frame supports. The effective action of the reinforcements also shows significant adverse effects on floor lift, and these factors are reflected in the extension and retraction of anchors in the overburden and significant deformation of the profile.

1 Introduction

Even with the existing knowledge and experience of underground excavation of coal seams in the difficult mining and geological conditions of the Ostrava- Karvina coal mining district (the OKR), the installation of high-capacity and high-density support systems is unable to prevent significant deformation of mining gates at large depths (c. 800–1000 m), during the mining operations (Souček et al. 2012). The originating deformations are connected with the redistribution of stresses in the rock mass due to the excavation of the coal seams and consequently, there is deformation and fracturing of the rock mass surrounding the operating longwall gates. This is the reason for the great increase in the use of various types of anchor (e.g. stranded anchors anchored along roots, rock bolts fully encapsulated in resin) Anchoring systems are used both in an independent sense (rock bolts or anchors anchored directly to the excavated surface) and in a combined sense, where:

This content is only available via PDF.
You can access this article if you purchase or spend a download.