Innovative backfilling longwall panel layout for better subsidence control effect—separating adjacent subcritical panels with pillars

Abstract

In recent years, field trials of non-pillar longwall mining using complete backfill have been implemented successively in the Chinese coal mining industry. The objective of this paper is to get a scientific understanding of surface subsidence control effect using such techniques. It begins with a brief overview on complete backfill methods primarily used in China, followed by an analysis of collected subsidence factors under mining with complete backfill. It is concluded that non-pillar longwall panel layout cannot protect surface structures against damages at a relatively large mining height, even though complete backfill is conducted. In such cases, separated longwall panel layout should be applied, i.e., panel width should be subcritical and stable coal pillars should be left between the adjacent panels. The proposed method takes the principles of subcritical extraction and partial extraction; in conjunction with gob backfilling, surface subsidence can be effectively mitigated, thus protecting surface buildings against mining-induced damage. A general design principle and method of separated panel layout have also been proposed.

Strata Movement of Overburden-Separation Grouting Working Face and Its Influence on Gas Emission during Mining

“…Third, the overburden separation area is filled with high-pressure grouting through surface drilling to form a grouting-filling-compaction bearing area of a certain width in the middle of the goaf. The resultant composite bearing structure of "key overburden stratum structure-compaction bearing stratum in the filling area-section isolated coal pillars" can effectively control surface subsidence [14].…”

“…OSG works as follows: the slurry of fly ash is injected through ground drilling into the separation zone among rock strata under a high pressure to establish a compaction zone under the separation zone. Such a compaction zone serves to support the overburden key strata and prevent them from breaking, thus controlling surface subsidence [14][15][16]. Compared with strip mining and backfill mining, OSG boasts a high recovery rate of coal resources; moreover, it is free from the perplex of mutual interference because the grouting process and the coal production process are spatially isolated from each other, which ensures the coal mining efficiency.…”

A novel short‐wall caving zone backfilling technique for controlling mining subsidence

“…Therefore, a better technique is urgently needed to effectively control mining-induced surface subsidence and ensure sustainable development of coal resources. 23 These methods consist of gob filling, 24,25 bed separation zone grout injection, 12,13,22,24 piercolumn backfilling, 4,23 and caving zone filling. 8 Backfilling mining technology is a well-known technique for controlling surface deformation widely used in China and other Asian countries, 9 Poland, 10,11 and Australia [12][13][14][15] ; it solves the problem of gangue accumulation, 16,17 improves the resource recovery rate, 18,19 controls surface subsidence, 2,20 and protects buildings from collapse damage.…”

“…zone, 12,13,22 and caving zone. 23 These methods consist of gob filling, 24,25 bed separation zone grout injection, 12,13,22,24 piercolumn backfilling, 4,23 and caving zone filling. 23 Recently, gob filling mining technology has been widely utilized in China with a high filling rate and small surface subsidence coefficient.…”