综采工作面过厚煤层顶板支护技术研究

为更好地保障综采工作面安全顺利地通过厚煤层,以山西某矿1404综采工作面过厚煤层工程为例,基于过厚煤层时顶板现存的主要安全风险,分析了影响顶板安全管控的主要因素,通过进行风险分析,针对性地提出了一些有效的支护顶板措施,通过综合应用这些措施,有效支护了顶板,更好地保障了该综采工作面安全顺利地通过厚煤层,该研究可为类似工况下综采工作面安全顺利过厚煤层提供参考。

缓倾斜地层顶板离层水对综采工作面的危害及防治探讨

以重庆松藻矿区在打通的一综采工作面缓倾斜地层中掘进时发生的两次顶板水灾为例,对其顶板突水原因进行了探讨。通过分析该矿区的矿井地质及水文地质条件,认为矿井充水水源为上覆地层的离层水。该矿井的M7-3煤层开采后,导水裂隙切穿了上覆地层长兴组灰岩,贯通了玉龙山一段灰岩隔水层,进入玉龙岩二段岩溶裂隙含水层。由于含水层的上覆岩层在采掘过程中,因岩性差异发生不均衡沉降,形成了大量的离层空间。离层空间吸收、储存的大量地表降雨在采掘工作面推进到一定位置时,就会发生突水。据估算,S1821工作面上覆岩体离层、裂隙储水空间按三分之一计算为2.064×105m2,与该工作面抢险救灾期间排出的涌水量基本吻合。根据该矿离层水的赋存特点,提出了保证排水系统畅通,加强采煤设备管理,提高采面设计水平的防治水对策。

Determining areas in an inclined coal seam floor prone to water-inrush by micro-seismic monitoring

The failure depth of the coal seam floor is one important consideration that must be kept in mind when mining is carried out above a confined aquifer.Determining the floor failure depth is the essential precondition for predicting the water-resisting ability of the floor.We have used a high-precision microseismic monitoring technique to overcome the limited amount of data available from field measurements. The failure depth of a coal seam floor,especially an inclined coal seam floor,may be more accurately estimated by monitoring the continuous,dynamic failure of the floor.The monitoring results indicate the failure depth of the coal seam floor near the workface conveyance roadway（the lower crossheading） is deeper and that the failure range is wider here compared to the coal seam floor near the return airway（the upper crossheading）.The results of micro-seismic monitoring show that the dangerous area for water-inrush from the coal seam floor may be identified.This provides an important field measurement that helps ensure safe and highly efficient mining of the inclined coal seam above the confined aquifer at the Taoyuan Coal Mine.

Water protection in the western semiarid coal mining regions of China: A case study

The coal industry in China has been moving from the semiarid eastern to the drier western regions since the beginning of this century.Water protection is of the utmost concern for coal mining in these regions.Lu'an,as one of the state coal mining bases in China,has been seeing increasingly heavier pressure for the protection of water resources.This article considers Lu'an as an example and describes the ways these concerns may be alleviated.High mine-water utilization rates have effectively reduced wasting of water and,consequently,have reduced water demand.Using the top layers of the Ordavician as aquifuge barriers can prevent floor karst water inrush into the longwall face and can protect the regional Ordovician karst water resources at the same time.The strength of the overlying Quaternary clay can protect against roof collapse and has successfully preserved the Quaternary porous water resource.

Mining-induced variation in water levels in unconsolidated aquifers and mechanisms of water preservation in mines

Phreatic water resources are widely found in thick unconsolidated surface layers in western China, where water levels respond sensitively and quickly to large-scale underground mining in conjunction with shallow coal seams. Longwall face #32201 of the Bulianta Coal Mine, in the Shendong coalfield was selected as an industrial trail base, where field observations on ground-water levels were conducted when the working face was below a water-rich area. The space-time variation in the behavior of un-consolidated water levels in response to underground mining and its relation with of advance were observed through the field trials. The basic conditions for water preservation in mines are presented and the mechanisms of water preservation in mining analyzed, given the geological condition of two key strata and a severely weathered layer buried in the overburden. The field trails show that water preservation in mining shallow coal seams can be successful under suitable conditions, providing new technology for envi-ronmental protection in the desert coalfields of northwestern China.

Auxiliary transportation mode in a fully-mechanized face in a nearly horizontal thin coal seam

On fully-mechanized faces in nearly horizontal thin coal seams （NHTCS）, the selection of the auxiliary transportation mode is difficult. Generally, auxiliary transportation mainly includes trackless or rail transportation. Combined with a familiar NHTCS fully-mechanized face, a multi-attribute decision- making model was set up for the decision. The index weight was objectively determined with the fuzzy number and entropy method. The priority order of auxiliary transportation modes was obtained from the Preference Ranking Organization Method for Enrichment Evaluation （PROMETHEE）. The results show that： the net flow of the mode can be expressed by the function of the surrounding rock deformation of the roadway, the dimension of equipment and the thickness of the coal seam; Based on the cost type index, there is a positive correlation between the net flow with the height and width of the trackless auxiliary transportation equipment, respectively. The trackless auxiliary transportation equipment selection principle should be ＂height first then width＂. Combined with the field application of the trackless auxil- iary transportation in Liangshuijing coal mine, the proper method to achieve the safe and high-efficient exploitation of a NHTCS fully-mechanized face is trackless tvred vehicle auxiliary transportation.