榆林地区北部侏罗纪古河道砂体与采煤涌(突)水关系分析

Relationship between Jurassic ancient channel sand body and coal mining water inrush in the north of Yulin area

  • 摘要: 在水文地质条件看似简单的榆神-神府矿区,采煤涌(突)水事故时有发生,一些煤矿的涌水量位居鄂尔多斯盆地之首,以往普遍认为的充水含水层难以解释这些现象。基于20年来对直罗组底部铀储层(古河道砂岩)的研究,结合直罗组古河道砂体与延安组可采煤层的空间配置关系,以及砂岩型铀矿形成与开发的基本条件,特别是直罗组古河道隐伏露头与地表泉群(带)、采煤涌(突)水的相关性分析,认为直罗组古河道可能是榆神-神府矿区矿井涌(突)水的主要水源。主要认识有:(1)直罗组古河道砂体具有区域性的分布规模,在其上游形成的具有世界级规模的东胜铀矿田证实直罗组古河道是一套区域含水层,因为含水层是砂岩型铀矿形成发育和未来开发的必要条件。(2)在直罗组古河道隐伏露头的上方,集中发育了具有超常流量的泉群和泉带,它们距直罗组古河道越近其流量越大,说明直罗组古河道为重要的含水层,它为榆神-神府矿区泉带提供了主要的水源。(3)直罗组古河道含水层构成了延安组含煤岩系的直接顶板,采煤证实直罗组古河道含水层与煤矿涌(突)水具有明显的关系。位于古河道潜伏露头附近的煤矿易于发生涌(突)水事故,而位于古河道下方的煤矿涌水量罕见,且采煤涌(突)水量与古河道砂体厚度呈正相关。(4)从关键水文地质参数的空间配置、耦合关系及其采煤时域的角度,构建了榆神-神府矿区采煤涌(突)水的成因机理模型,该模型阐明了泉带的形成发育和演化机理,揭示了采煤涌(突)水的形成机制,为未来水害防治、保水采煤、煤-铀兼采等提供了基础地质“预警”信息。

     

    Abstract: In the Yushen-Shenfu mining area with seemingly simple hydrogeological conditions,some coal mining water inrush accidents occur from time to time. The water inrush of some coal mines ranks first in the Ordos Basin. It is difficult to explain these phenomena by the water filled aquifer generally considered in the past. Based on the research on the uranium reservoir(paleochannel sandstone)at the bottom of the Zhiluo formation in the past 20 years,combined with the spatial configuration relationship between the paleochannel sand body of the Zhiluo formation and the minable coal seam of the Yan’an formation,as well as the basic conditions for the formation and development of sandstonetype uranium deposits,especially the correlation analysis among the concealed outcrop of paleochannel of the Zhiluo Formation and surface spring groups(belts)and coal mining water inrush,it is considered that the paleochannel of the Zhiluo formation may be the main water source of mine water inrush in the YushenShenfu mining area. The main conclusions are as follows:① the paleochannel sand body of the Zhiluo formation has a regional distribution scale. The worldclass Dongsheng uranium ore field formed in its upstream proves that the paleochannel of the Zhiluo formation is a set of regional aquifer,because the aquifer is a necessary condition for the formation,development and future exploitation of sandstonetype uranium deposit.② Above the concealed outcrop of the paleochannel of the Zhiluo formation,spring groups and spring belts with extraordinary water yield are intensively developed. The closer they are to the paleochannel of the Zhiluo formation,the greater their water yield,indicating that the paleochannel of the Zhiluo formation is an important aquifer,which provides the main water source for the spring belt of the Yushen Shenfu mining area.③ The paleochannel aquifer of the Zhiluo formation constitutes the direct roof of coal measures of the Yan’an formation. Coal mining proves that the paleochannel aquifer of the Zhiluo formation has an obvious hydraulic connection with coal mine water inrush. The coal mine located near the latent outcrop of the paleochannel is prone to water inrush accidents,while the water inrush of the coal mine away from the ancient river channel is rare,and the water inrush of coal mining is positively correlated with the sandstone thickness of the paleochannel.④ From the perspective of spatial configuration and coupling relationship of key hydrogeological parameters and coal mining time domain,the genetic mechanism model of the water inrush of coal mining in the Yushen Shenfu mining area is constructed. The model expounds the formation,development and evolution mechanism of spring belt,reveals the formation mechanism of the water inrush of coal mining,and provides basic geological“early warning” information for future water disaster prevention,water conservation coal mining,coal uranium concurrent mining,etc.

     

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