Research on the Deformation and Control Technology of Surrounding Rock in Entry Retaining along the Gob Side

Abstract

This paper studies and introduces the successful case of gob-side entry retaining technology and the typical mining pressure law in Luan mining area, which is the main mining coal seam in Qinshui coalfield. Qinshui coalfield has an estimated coal reserve of 300 billion tons, accounting for 9.58% of the total national coal reserve in China, especially anthracite, chemical coal, and coking coal. The methods of field investigation, theoretical analysis, physical experiment, and industrial test are adopted. Through the field investigation, theoretical analysis, physical experiments, and industrial test, the following conclusions have been drawn in this study: (1) A thorough engineering geological investigation was conducted on the entry retaining along the gob side on noncoal pillar mining working face, which covers multiple periods of mining process including the roadway excavation period, primary mining period, primary mining stability period, and secondary mining influence period. A series of analysis and tests were conducted such as core sampling, rock mechanics property testing, borehole detection, and flexible formwork support evaluation, which laid a foundation for identifying the mining pressure law of gob-side entry retaining by using noncoal pillar mining. (2) The mining pressure law was studied through the collection of the field measurements taken from the entry retaining along the gob side on noncoal pillar mining working face. The keys to achieve the roadway surrounding rock stability through noncoal pillar mining are obtained. According to the study, the stability control of retained roadway surrounding rock mainly depends on the stability of top coal, coal side, and shoulder angle coal. (3) In this study, a roadway reinforcement scheme is proposed to improve the surrounding rock control technology for gob-side entry retaining by noncoal pillar mining, whose effectiveness has been verified by a series of industrial test. Therefore, the wide adoption of the noncoal pillar mining method in Number #3 coal mine can significantly relieve the predicament of coal pressing under a large number of buildings in Luan mining area, which provides insightful guidance to the coal-free pillar mining in the whole Luan mining area.

Coalbed Methane Enhancement in Low-Permeability Reservoirs by Hydraulic Fracturing with Coated Ceramsite

“…Methane is the major component in CBM, accounting for over 95% of the total gas content on average (as shown in Figure and Table ). The CBM content of the Gaohe Block is above 8 m 3 /t in most areas and below 8 m 3 /t in only a small area in the east …”

“…The CBM content of the Gaohe Block is above 8 m 3 /t in most areas and below 8 m 3 /t in only a small area in the east. 31 The parameters of the coal reservoir in the block are presented in Table 2. The measured saturation of no.…”

Influence of Coal Mining on Historical Buildings: Case Study in Shanxi

“…The Lu’an mining area is located in the southeast of the Qinshui coalfield in Shanxi Province [ 31 ], west of the middle section of the Taihang Mountains, west of the Shangdang Basin, and belongs to the Changzhi Basin, as shown in Figure 6 . The mining area is 74.6km long from north to south, and 63.1 km wide from east to west, covering an area of 3044.65 km 2 [ 32 ]; the coal-bearing strata in the area are mainly the Taiyuan Group and Shanxi Group, mainly a set of coal-bearing clastic rock sedimentary construction formed on the basis of the weathering crust of Ordovician limestone [ 33 ], with a total stratigraphic thickness of 74.5~306.9 m, generally containing 8~16 layers of coal, with a total thickness of 13.88m and a coal-bearing coefficient of 8.1%.…”

Study on Safety Coefficient of Sedimentary Bauxite Strip Pillar under Valley Terrain

“…As far as the goaf of a sedimentary bauxite mine in a specific area is concerned, the composition and properties of the surrounding rock and the ore rock are often the same. This section mainly studies the influence of two types of parameters, the structural parameters of the goaf and the valley terrain parameters, on the stability of the pillar under the valley terrain [ 33 , 34 , 35 ]. Considering that the spatial relationship between the direction of the goaf and the valley will change the values of the two types of parameters, this section will also analyze and discuss the influence of the spatial relationship between the two on the stability of the pillar.…”