近距离煤层开采覆岩裂隙活化特征与隔水层稳定性

Activation Development Features of Overburden Fractures and Stability of Water-resisting Layer in Close Coal Seams Mining

  • 摘要:背景】陕北侏罗纪煤田近距离煤层重复采动覆岩裂隙活化发育加剧,易导致隔水层失稳,引起地下水流失。【方法】为揭示近距离煤层开采覆岩裂隙发育特征及隔水层稳定性,采用实测统计、物理相似模拟及理论分析相结合的方法,提出基于陕北侏罗纪煤田近距离煤层保水开采的主要煤岩组合类型划分,分析重复采动裂隙活化发育规律,建立重复采动隔水层稳定性判据。【结果和结论】研究表明,依据该煤田上部近距离两层可采煤层煤-水赋存条件及地质特征,可分为薄及中厚-厚型、厚-薄及中厚型、厚-厚型、薄及中厚-薄及中厚型4种类型。得出基于上述4类条件采动覆岩上行与下行裂隙发育的隔水层破坏特征,重复采动裂采比(上行裂隙发育高度/复合采高)一般为14~30,相比上部单一煤层开采显著减小,下行裂隙发育深度为复合采高的1.6~3.0倍。建立基于重复采动裂隙发育高度(深度)的隔水层稳定性判据,当隔水层厚度大于等于重复采动裂隙发育高度、深度、安全厚度之和时,隔水层稳定,反之失稳;给出陕北侏罗纪煤田重复采动隔水层稳定性评价,包括稳定-稳定、稳定-失稳、失稳-失稳3种情况。研究成果可为陕北侏罗纪煤田近距离煤层保水开采的隔水层稳定性判据与控制提供理论基础。

     

    Abstract: In the Jurassic coal field of Northern Shaanxi Province, close coal seams repeated mining can intensify activation development of overburden fractures, which easily leads to the instability of water-resisting layer and groundwater loss. In order to reveal the development characteristics of overburden fractures and the stability of water-resisting layer in close coal seams mining, the main coal-rock combination types based on water conservation mining of close coal seams in Jurassic coal field were proposed by using the method of measurement statistics, physical similarity simulation and theoretical analysis, and the fracture activation development law of repeated mining were analyzed. The water-resisting layer stability criterion of repeated mining was established. The research shows that according to the occurrence conditions and geological characteristics of the coal water in the two coal seams at the top of the coalfield, it can be divided into four types, thin and medium thick-thick type, thick - thin and medium thick type, thick - thick type, thin and medium - thick type. Based on the above four types of conditions, the failure characteristics of the water-resisting layer with upward and downward fracture development of mining overburden rock were obtained. The ratio of upward fracture development height to comprehensive mining thickness of repeated mining is generally 14-30, which is significantly reduced compared with the single coal seam mining, and the development depth of downward fracture is about 1.6 to 3.0 times of the comprehensive mining thickness. The stability criterion based on the height (depth) of the repeated mining fractures was established (When the thickness of water-resisting layer is greater than or equal to the sum of development height of fractures, development depth of fractures and safety layer thickness, the water-resisting layer is stable, and vice versa), and the water-resisting layer stability zoning of repeated mining in the Jurassic coal field in Northern Shaanxi was proposed, it includes three conditions: stable - stable, stable - unstable and unstable - unstable. The research results can provide a theoretical basis for the stability criterion and control of water-resisting layer in the Jurassic coal field in Northern Shaanxi.

     

/

返回文章
返回