平顶山东部矿区地应力场特征及其对煤与瓦斯突出的影响

Particular features of the underground stress state in the eastern mining area of Pingdingshan and their influence on the coal and gas outbursts

为了研究平顶山东部矿区地应力场特征,以及地应力对煤与瓦斯突出的影响,利用地应力实测资料,运用理论分析和数理统计计算相结合的方法,系统研究了东部矿区地应力的分布规律;并且进行了地应力区块划分,揭示了东部矿区地应力在突出中的作用。结果表明:1)东部矿区地应力场以水平构造应力为主,最大主应力方向为NEE-SWW向,最大水平主应力百米梯度为5.4 MPa左右,该区域内集聚了较高的水平构造应力,应力场类型为大地动力场;2)依据最大水平主应力随埋深增加而增大的应力梯度线,将东部矿区划分为应力升高区和应力梯度区;3)应力升高区由于地应力集中,提供了突出的动力,构造煤的发育则减少了突出阻力,造成了该区域频繁发生突出事故,突出的主导因素为地应力。

This paper is aimed at investigating the particular features of the underground stress state in the eastern mining area of Pingdingshan and their influence on the coal and gas outbursts.As is well known,according to the comprehensive hypothesis of the likely-to-be coal and gas outbursts,the underground stress is of the predominant significance that accounts for the coal and gas outburst accidents. It is just for this reason that we have done a measured statistics of the ground stress by joining the theoretical analysis with the scientific statistics. The paper has done a systematic study of the characteristics of ground stress state in the eastern mining area. What is more,we have analyzed the ground stress status-in-situ by dividing the ground stress into the corresponding blocks and chosen No. 10 area of the eastern Pingdingshan mining area as our study sample in hoping to make out the geologic-tectonic evolutional particularities. Looking into the variations of the tectonic coal thickness and the coal solidity factors in different stress blocks,we have worked out the average potential rate of the outburst coal volume and gas volume in the three coalbeds. The results of our investigation reveal the likely effects of the ground stress on the coal and gas outbursts in the area. The conclusion of our research can be stated systematically in the following way.（ 1） All the ground stress tends to increase with the increase of the depth. The ground stress status-in-situ of the aforementioned mining area is mainly affected by the horizontally framed stress,with its maximum dominant stress direction being the NEE-SWW,whereas the maximum horizontal stress gradient is about 5. 4 MPa per 100 meters,which accounts for the area＇s high-level tectonic stress as a type of dynamic stress state.（ 2） In accordance with the stress gradient line and the feature that the maximum horizontal stress tends to increase with the increase of the depth,we have divided the eastern mining area into the higher stress region and the stress gradient region.（ 3） Since the higher-stress region enjoys greater stress concentration,it is in a realistic position to provide much greater outstanding power,which implies a very favorable prospect for developing the tectonic coal by reducing the outstanding resistance. All the aforementioned reasons may account for the frequent outburst accidents in the region and serves as the dominant factor for the outburst accidents.