Abstract
In this study, the roof-cutting-type gob-side entry retaining is introduced, and its application in medium-thickness coal seams is studied. Based on the analysis of the construction procedure and principle, the mechanical model of the retained roadway structure and cantilever beam formed by roof cutting was established, and the support resistance and roof deformation were obtained. In addition, through technological design analysis and numerical simulation, the parameters of roof cutting were determined. The roof-cutting height and angle were designed to be 9 m and 15°, respectively. Flac3 D was used to analyze the stress evolution law under different mining conditions. The stress on the integrated coal side and roof subsidence was lower when the roof-cutting height was 8∼10 m and the cutting angle was 15°. Through field monitoring, the roof pressure, gob-side lateral gangue retaining pressure, anchor cable stress, and deformation of the surrounding rock eventually reached a stable state. This indicates that the roof cutting can effectively cut down the overlying strata over the gob and form a stable entry structure to meet the requirements of the next working face.
Highlights
The traditional gob-side entry retaining (GSER) solves the resource waste problem [10, 11], it has limitations: it has complex construction technology, it has high costs [9], most of the backfills are rigid materials and do not largely deform [12], and overwhelming under concentrated stress occurs, eventually resulting in instability of the roadway [13, 14]
There are many studies on the stability of retained roadway and gob-side support body. e study of stability mainly focuses on the deformation characteristics of the retained roadway [15] and the stress distribution characteristics under the influence of mining
E first step: the constant resistance and large deformation (CRLD) anchor cables are adopted to strengthen the original support in the prereserved roadway area. e second step: the bidirectional energy-cavity blasting (BECB) technology is carried out along the roof beside the gob, shown in Figures 2(a) and 2(b). e third step: the gangue retaining support is carried out along the cutting-line with the advance of the working face, so as to prevent the collapsed rock from entering the reserved roadway area
Summary
According to the analysis of the construction procedure and principle, the roof-cutting-type GSER has two key technologies: the CRLD anchor cable reinforced support and the roof cutting by directional blasting. After strengthening the roadway support with the CRLD anchor cable, the step is the roof cutting, which is called bilateral cumulative tensile blasting technology [22]. Compared with the traditional filling type GSER, the surrounding rock structure fundamentally changes due to the retaining roadway process; it is necessary to study the deformation mechanism and combine it with the field application to develop the corresponding supporting measures. Based on the above analysis of support resistance and surrounding rock deformation, the required support resistance and deformation tendency of the retained roadway can be preliminarily obtained and provide a certain reference for the support and gangue retaining support in the roadway
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
